...
2. Receiving the HLS stream from the server
HLS playback authentication using REST hook
A client authentication for HLS playback can be setup if necessary. To do this, the following parameter should be set in flashphoner.properties file
Code Block | ||||
---|---|---|---|---|
| ||||
hls_auth_enabled=true |
At client side, the parameter must be added to HLS URL to pass to WCS server a token obtained for example from backend server. The name of the parameter is defined with the following setting
Code Block | ||
---|---|---|
| ||
client_acl_property_name=aclAuth |
In this case, stream URL should be formed as follows
Code Block | ||||
---|---|---|---|---|
| ||||
var src = $("#urlServer").val() + "/" + streamName + "/" + streamName + ".m3u8";
var token = $("#token").val();
if (token.length > 0) {
src += "?aclAuth=" +token;
} |
REST hook /playHLS must be implemented on backend server. WCS server will send query to backend with token received from client
Code Block | ||||
---|---|---|---|---|
| ||||
URL:http://localhost:8081/apps/EchoApp/playHLS
OBJECT:
{
"nodeId" : "NTk1tLorQ00llGbPJuFexrKceubGCR0k@192.168.1.5",
"appKey" : "defaultApp",
"sessionId" : "/192.168.1.100:59473/192.168.1.5:8445",
"mediaSessionId" : "60709c5b-6950-40c3-8a3d-37ea0827ae32-727473703a2f2f73747238312e63726561636173742e636f6d2f6772616e646c696c6c6574762f6c6f77-HLS",
"name" : "test",
"mediaProvider" : "HLS",
"custom" : {
"token" : "12345789"
}
} |
Backend server should return 200 OK if token is checked successfully, and 403 Forbidden if token is wrong. In its turn, client will receive either HLS stream or 401 Unauthorized.
The parameter
Code Block | ||||
---|---|---|---|---|
| ||||
hls_auth_token_cache=10 |
defines token caching interval in seconds (10 seconds by default). /playHLS queries with certain token will not be sent to backend until the token is in cache i.e. either there is stream subscriber with tis token or caching interval is not expired. If caching interval parameter is set to 0
Code Block | ||||
---|---|---|---|---|
| ||||
hls_auth_token_cache=0 |
/playHLS queries are sent to backend on every HTTP GET request from client.
HLS authentication setting can be changed without server restart. In this case hls_auth_enabled
affects existing subscribers and hls_auth_token_cache
affects new subscribers only.
Adding cross-domain access control HTTP headers for HLS playback
By default, the followin access control headers are added to 200 OK response to HTTP GET request:
Code Block | ||||
---|---|---|---|---|
| ||||
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET
Access-Control-Max-Age: 3000 |
If necessary, for example, if HLS content and HLS player page are in different domains, custom access control headers can be added using the following parameter in flashphoner.properties file:
Code Block | ||||
---|---|---|---|---|
| ||||
hls_access_control_headers=Access-Control-Allow-Origin: *;Access-Control-Allow-Methods: GET, HEAD;Access-Control-Max-Age: 3000;Access-Control-Expose-Headers: Accept-Ranges, Content-Range, Content-Encoding, Content-Length |
In this case, the headers listed in the parameter will be added to 200 OK response:
Using nginx as reverse proxy for HLS playback
In some cases nginx web server can be used as reverse proxy for HLS playback from WCS server. Usually, it may require if HTTP headers adding does not help to workaround cross domain request restrictions in some browsers.
For example, if browser requires HLS player page and HLS stream to be in the same domain your.domain and on the same port 443 (HTTPS), nginx should be set up as follows:
Code Block | ||
---|---|---|
| ||
# HTTP requests are redirected from port 80 to 443
server {
listen 80;
server_name docs.flashphoner.com;
return 301 https://$server_name$request_uri;
}
# Server listens HTTPS port 443
server {
listen 443 ssl;
ssl_certificate /etc/letsencrypt/live/your.domain/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/your.domain/privkey.pem;
server_name your.domain;
server_tokens off;
client_max_body_size 500m;
proxy_read_timeout 10m;
root /usr/share/nginx/html;
location / {
}
error_page 404 /404.html;
location = /40x.html {
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
}
# Example web applications will be available by URL https://your.domain/client2
location /client2/ {
alias /usr/local/FlashphonerWebCallServer/client2/;
}
# HLS playlists and segments are proxying to your.domain on port 443. for example https://your.domain/test.m3u8
location ~* ^.+.(m3u8|ts)$ {
proxy_pass https://localhost:8445;
proxy_http_version 1.1;
proxy_set_header Host $server_name:$server_port;
proxy_set_header X-Forwarded-Host $http_host;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
} |
It also may be useful to cache HLS stream. In this case nginx should be additionally set up as follow:
1. In http
section of /etc/nginx.conf settings file proxy cache parameters are set
Code Block | ||
---|---|---|
| ||
proxy_cache_path /var/cache/nginx/proxy levels=1:2 keys_zone=proxy_cache:1024m max_size=2048m inactive=10d;
proxy_cache_min_uses 1;
proxy_ignore_headers X-Accel-Expires;
proxy_ignore_headers Expires;
proxy_ignore_headers Cache-Control; |
2. In server
section of site settings file caching of HLS segments is set, playlist should not be cached:
...
theme | RDark |
---|
...
Streams which can be played as HLS
Every stream published to WCS server with certain name, can be played as HLS
Code Block | ||
---|---|---|
| ||
http://wcs:8082/streamName/streamName.m3u8 |
A stream name can be set when publishing stream from browser or from RTMP кодировщика, or when capturing RTSP, RTMP or VOD stream using REST API
Since build 5.2.771, stream URI can be set for RTSP
Code Block | ||
---|---|---|
| ||
http://wcs:8082/rtsp%3A%2F%2Frtspserver%2Flive.sdp/rtsp%3A%2F%2Frtspserver%2Flive.sdp.m3u8 |
RTMP source
Code Block | ||
---|---|---|
| ||
http://wcs:8082/rtmp%3A%2F%2Frtmpserver%3A1935%2Flive%2Fstream/rtmp%3A%2F%2Frtmpserver%3A1935%2Flive%2Fstream.m3u8 |
or for VOD live translation from file
Code Block | ||
---|---|---|
| ||
http://wcs:8082/vod-live%3A%2F%2Ffile.mp4/vod-live%3A%2F%2Ffile.mp4.m3u8 |
In this case a stream will be captured by source URI, and after publishing to server the stream will be played as HLS. Note that URI should be encoded, all the characters except latin letters and digits must be replaced with character code.
Since build 5.2.1679 a stream may be played by source URI as HLS ABR
Code Block | ||
---|---|---|
| ||
http://wcs:8082/vod-live%3A%2F%2Ffile.mp4-HLS-ABR-STREAM/vod-live%3A%2F%2Ffile.mp4-HLS-ABR-STREAM.m3u8 |
When HLS subscriber connects to CDN Edge, if a stream with certain name or URI is already published to some Origin server, the stream from CDN will be played as HLS for this subscriber. If there is no stream with such name or URI in CDN, Edge will try to capture stream locally to play as HLS.
HLS segments automatic cut for stream published
Any of streams published via WebRTC, RTMP, MPEG-TS or captured from RTSP or RTMP source using REST API may be cut automatically to HLS segments. This feature may be enabled with the following parameter
Code Block | ||
---|---|---|
| ||
hls_auto_start=true |
Since build 5.2.1895 it is possible to start HLS ABR stream automatically if HLS ABR on a single node is used. This feature may be enabled with the following parameter
Code Block | ||
---|---|---|
| ||
hls_abr_auto_start=true |
HLS playback authentication using REST hook
A client authentication for HLS playback can be setup if necessary. To do this, the following parameter should be set in flashphoner.properties file
Code Block | ||||
---|---|---|---|---|
| ||||
hls_auth_enabled=true |
At client side, the parameter must be added to HLS URL to pass to WCS server a token obtained for example from backend server. The name of the parameter is defined with the following setting
Code Block | ||
---|---|---|
| ||
client_acl_property_name=aclAuth |
In this case, stream URL should be formed as follows
Code Block | ||||
---|---|---|---|---|
| ||||
var src = $("#urlServer").val() + "/" + streamName + "/" + streamName + ".m3u8";
var token = $("#token").val();
if (token.length > 0) {
src += "?aclAuth=" +token;
} |
REST hook /playHLS must be implemented on backend server in defaultApp application. WCS server will send query to backend with token received from client
Code Block | ||||
---|---|---|---|---|
| ||||
URL:http://localhost:8081/apps/EchoApp/playHLS
OBJECT:
{
"nodeId" : "NTk1tLorQ00llGbPJuFexrKceubGCR0k@192.168.1.5",
"appKey" : "defaultApp",
"sessionId" : "/192.168.1.100:59473/192.168.1.5:8445",
"mediaSessionId" : "60709c5b-6950-40c3-8a3d-37ea0827ae32-727473703a2f2f73747238312e63726561636173742e636f6d2f6772616e646c696c6c6574762f6c6f77-HLS",
"name" : "test",
"mediaProvider" : "HLS",
"custom" : {
"token" : "12345789"
}
} |
Backend server should return 200 OK if token is checked successfully, and 403 Forbidden if token is wrong. In its turn, client will receive either HLS stream or 401 Unauthorized.
The parameter
Code Block | ||||
---|---|---|---|---|
| ||||
hls_auth_token_cache=10 |
defines token caching interval in seconds (10 seconds by default). /playHLS queries with certain token will not be sent to backend until the token is in cache i.e. either there is stream subscriber with this token or caching interval is not expired. If caching interval parameter is set to 0
Code Block | ||||
---|---|---|---|---|
| ||||
hls_auth_token_cache=0 |
/playHLS queries are sent to backend on every HTTP GET request from client.
HLS authentication setting can be changed without server restart. In this case hls_auth_enabled
affects existing subscribers and hls_auth_token_cache
affects new subscribers only.
Custom backend application usage for HLS playback authentication
Since build 5.2.1008 it is possible to set backend application key in HLS URL, for example
Code Block | ||
---|---|---|
| ||
https://wcs:8445/streamName/streamName.m3u8?appKey=customAppKey&aclAuth=1254789 |
In this case REST hook /playHLS will be sent to backend application with defined key (customAppKey in the example above).
Unauthorized access to HLS segments prevention
To decrease server load, authentication token and stream availability in CDN are checked on HLS playlist request. The following parameter is added since build 5.2.436 to protect separate HLS segments
Code Block | ||
---|---|---|
| ||
hls_segment_name_suffix_randomizer_enabled=true |
In this case, randomly generated suffix is added to every segment file name, for example
Code Block | ||
---|---|---|
| ||
test16d2da4658f4374953a120f3c95bc715ea.ts |
So, brute force iteration over segments is escaped.
Note that suffix is not added to preloader segments.
Adding cross-domain access control HTTP headers for HLS playback
By default, the followin access control headers are added to 200 OK response to HTTP GET request:
Code Block | ||||
---|---|---|---|---|
| ||||
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET
Access-Control-Max-Age: 3000 |
If necessary, for example, if HLS content and HLS player page are in different domains, custom access control headers can be added using the following parameter in flashphoner.properties file:
Code Block | ||||
---|---|---|---|---|
| ||||
hls_access_control_headers=Access-Control-Allow-Origin: *;Access-Control-Allow-Methods: GET, HEAD;Access-Control-Max-Age: 3000;Access-Control-Expose-Headers: Accept-Ranges, Content-Range, Content-Encoding, Content-Length |
In this case, the headers listed in the parameter will be added to 200 OK response:
Mask support in ACAO header
Sometimes, for example, when load balancer AWS LB is used, it is necessary to set request origin address including port in ACAO header sent in response to GET request, for example
Code Block | ||
---|---|---|
| ||
Access-Control-Allow-Origin: http://test.flashphoner.com:8081 |
However, origin address is not always known while configuring the server. Therefore, since build 5.2.755 mask support in ACAO header can be enabled
Code Block | ||
---|---|---|
| ||
hls_acao_header_domain_mask=true |
This feature is enabled by default. In this case, if '*' character is set in the following parameter
Code Block | ||
---|---|---|
| ||
hls_access_control_headers=Access-Control-Allow-Origin: * |
server returns ACAO header with full request origin address in response to GET request
Code Block | ||
---|---|---|
| ||
Access-Control-Allow-Origin: http://lb.yourdomain.com:8081 |
This can be disabled if necessary
Code Block | ||
---|---|---|
| ||
hls_acao_header_domain_mask=false |
Using nginx as reverse proxy for HLS playback
In some cases nginx web server can be used as reverse proxy for HLS playback from WCS server. Usually, it may require if HTTP headers adding does not help to workaround cross domain request restrictions in some browsers.
For example, if browser requires HLS player page and HLS stream to be in the same domain your.domain and on the same port 443 (HTTPS), nginx should be set up as follows:
Code Block | ||
---|---|---|
| ||
# HTTP requests are redirected from port 80 to 443 server { listen 80; server_name docs.flashphoner.com; return 301 https://$server_name$request_uri; } # Server listens HTTPS port 443 server { listen 443 ssl; ssl_certificate /etc/letsencrypt/live/your.domain/fullchain.pem; ssl_certificate_key /etc/letsencrypt/live/your.domain/privkey.pem; server_name your.domain; server_tokens off; client_max_body_size 500m; proxy_read_timeout 10m; root /usr/share/nginx/html; location / { } error_page 404 /404.html; location = /40x.html { } error_page 500 502 503 504 /50x.html; location = /50x.html { } # Example web applications will be available by URL https://your.domain/client2 location /client2/ { alias expires -1; /usr/local/FlashphonerWebCallServer/client2/; } } |
Returning of static HTML pages on HLS port
Another way to workaround cross domain requests restrictions in browser is to return a static content, player page for example, on the same port that returns HLS content. To enable this feature, the following parameter should be set in flashphoner.properties file
Code Block | ||
---|---|---|
| ||
hls_static_enabled=true |
The p;ayer page should be in directory defined by the following parameter
Code Block | ||
---|---|---|
| ||
hls_static_dir=client2/examples/demo/streaming/hls_static |
In this case (by default) the path to the player page files is set relative to WCS installation directory. A full path may also be set, for example
Code Block | ||
---|---|---|
| ||
hls_static_dir=/var/www/html/hls_static |
If static content returning is enabled, browser will display the HLS player page by URL https://host:8445/hls-player.html. If this feature is disabled, server will return 404 Not found error by such URL.
Preloader for HLS stream playback
When first HLS subscribes connects to a stream on WCS server, especilally to CDN stream, it may take a time to split a stream to HLS segmets and to form a playlist. As a result, Safari browser on iOS devices may not be able to play HLS stream on the first attempt. To successfully play HLS stream in this case, the HLS preloader was added since build 5.2.371. The default preloader looks like this:
Default preloader segments are placed to /usr/local/FlashphonerWebCallserver/hls/.preloader
folder when server is started
Code Block | ||
---|---|---|
| ||
ls /usr/local/FlashphonerWebCallserver/hls/.preloader
-rw-r--r-- 1 root root 51888 Oct 13 04:47 index0.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index10.ts
-rw-r--r-- 1 root root 54332 Oct 13 04:47 index11.ts
-rw-r--r-- 1 root root 53392 Oct 13 04:47 index12.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index13.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index14.ts
-rw-r--r-- 1 root root 53956 Oct 13 04:47 index15.ts
-rw-r--r-- 1 root root 54144 Oct 13 04:47 index16.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index17.ts
-rw-r--r-- 1 root root 52640 Oct 13 04:47 index18.ts
-rw-r--r-- 1 root root 53580 Oct 13 04:47 index19.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index1.ts
-rw-r--r-- 1 root root 53580 Oct 13 04:47 index2.ts
-rw-r--r-- 1 root root 54520 Oct 13 04:47 index3.ts
-rw-r--r-- 1 root root 52452 Oct 13 04:47 index4.ts
-rw-r--r-- 1 root root 52640 Oct 13 04:47 index5.ts
-rw-r--r-- 1 root root 53204 Oct 13 04:47 index6.ts
-rw-r--r-- 1 root root 54708 Oct 13 04:47 index7.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index8.ts
-rw-r--r-- 1 root root 52828 Oct 13 04:47 index9.ts |
The minimal preloader segment duration is 2 seconds by default, and can be set in milliseconds with the following parameter
Code Block | ||
---|---|---|
| ||
hls_preloader_time_min=2000 |
Custom preloader configuration
To replace the default preloader to thecustom one, do the following:
1. Choose video clip (logo for example)
2. Encode video to H264, add audio track to the clip, set GOP and remove B-frames using ffmpeg
Code Block | ||||
---|---|---|---|---|
| ||||
ffmpeg -i clip.mp4 -f lavfi -i anullsrc=channel_layout=mono:sample_rate=44100 -c:v h264 -g 30 -bf 0 -shortest preloader.mp4 |
3. Download and install HLS tools from Apple site
4. Prepare custom preloader HLS segments with desired duration, for example 2 seconds
Code Block | ||||
---|---|---|---|---|
| ||||
mediafilesegmenter -t 2 -B index -start-segments-with-iframe preloader.mp4
tar -cvzf preloader.tar.gz index*.ts |
5. Make a folder for custom preloader
Code Block | ||||
---|---|---|---|---|
| ||||
mkdir /opt/custom_preloader |
6. Unpack preloader segments from archive prepared on step 4
Code Block | ||||
---|---|---|---|---|
| ||||
cd /opt/custom_preloader
tar -xvzf ~/preloader.tar.gz |
7. Set custom preloader folder and duration in server settings
Code Block | ||
---|---|---|
| ||
hls_preloader_time_min=2000
hls_preloader_dir=/opt/custom_preloader |
Known limits
A preloader aspect ratio should be the same as video published one. Otherwise, browser tries to scale video to preloader ratio, that can lead to picture distortion (stretching or compressing) for the first HLS subscriber.
HLS subscription management using REST API
REST query should be HTTP/HTTPS POST request as follows:
- HTTP: http://test.flashphoner.com:8081/rest-api/hls/startup
- HTTPS: https://test.flashphoner.com:8444/rest-api/hls/startup
Where:
- test.flashphoner.com - WCS server address
- 8081 - WCS server standard REST / HTTP port
- 8444 - standard HTTPS port
- rest-api - mandatory URL part
- /hls/startup - REST method used
REST queries and response sates
...
REST query
...
Body example
...
Response example
...
Response state
...
Desctiption
...
/hls/startup
...
Code Block | ||||
---|---|---|---|---|
| ||||
{
"name":"test"
} |
200 - OK
404 - Stream not found
500 - Internal error
Start HLS agent for the stream
...
/hls/find_all
...
Code Block | ||||
---|---|---|---|---|
| ||||
[
"test"
] |
...
200 – OK
404 – Not found
...
Find all streams having HLS agents
...
/hls/terminate
...
Code Block | ||||
---|---|---|---|---|
| ||||
{
"name":"test"
} |
...
200 – OK
404 – Not found
...
Stop or restart HLS agent for the stream
Parameters
...
Description
...
Example
...
name
...
Stream published name
...
test
Issues
1. If HLS agent for the stream is started by REST query /hls/startup, and there are no active HLS subscribers, agent will stop after the following timeout in seconds
Code Block | ||
---|---|---|
| ||
hls_manager_provider_timeout=300 |
By default, the timeout is 5 minutes. Also it concerns HLS agents which are started automatically for streams published using the following parameter
Code Block | ||
---|---|---|
| ||
hls_auto_start=true |
2. If HLS agent for the stream is stopped by REST query /hls/terminate, and there are active HLS subscribers, this agent will be restarted. In this case, active HLS subscribers must reconnect to the stream.
Debug logs for HLS session
For an error report, debug logging can be enabled for HLS sessions using CLI
Code Block | ||||
---|---|---|---|---|
| ||||
update node-setting --value true hls_enable_session_debug |
Note that config flashphoner.properties will be overwritten after the command.
Known issues
1. Non-recoverable freeze of HLS stream played in iOS Safari through a CDN
Symptoms: one minute after publishing start image stops, sound continues to play
Solution:
b) enable transcoding on server using the following option in flashphoner.properties file
Code Block | ||||
---|---|---|---|---|
| ||||
disable_streaming_proxy=true |
b) if transcoding is undesirable, set the following option in flashphoner.properties file
Code Block | ||||
---|---|---|---|---|
| ||||
hls_discontinuity_enabled=true |
In this case, clicks are possible in audio, but video will not stop.
2. HLS segments writing stops when playing stream published in Firefox browser.
Symptoms: a few minutes after playback start HLS segments stop writing, in that case the stream directory in hls directory is not deleted, and messages in server log continue to appear
Code Block | ||||
---|---|---|---|---|
| ||||
INFO HLSStreamManager - HLSStreamProviderKeepaliveThread-80 Remove hls channel |
Publisher must publish stream again to recover.
Solution: use another browser to publish the stream which supposed to be played via HLS.
3. No video for the first subscriber when playing HLS in Safari on iOS 12.4
Symptoms: no video for the first subscriber when playing a stream as HLS in Safari on iOS 12.4, however video is played normally if there are other HLS-subscribers to the stream
Solution: set the minimum HLS playlist segments count not less than 2
Code Block | ||
---|---|---|
| ||
hls_min_list_size=2 |
4. No video for any subscriber when playing RTMP stream as HLS in Safari on iOS 12.4 if the following parameter is set to
Code Block | ||
---|---|---|
| ||
hls_auto_start=true |
Symptoms: no video for any subscriber when playing RTMP stream as HLS in Safari on iOS 12.4
Soluition: use mono sound when a file with stereo sound track is published, for example, set the followint command line options for ffmpeg
Code Block | ||
---|---|---|
| ||
-acodec aac -ac 1# HLS playlists and segments are proxying to your.domain on port 443. for example https://your.domain/test.m3u8 location ~* ^.+.(m3u8|ts)$ { proxy_pass https://localhost:8445; proxy_http_version 1.1; proxy_set_header Host $server_name:$server_port; proxy_set_header X-Forwarded-Host $http_host; proxy_set_header X-Forwarded-Proto $scheme; proxy_set_header X-Forwarded-For $remote_addr; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection "upgrade"; } } |
It also may be useful to cache HLS stream. In this case nginx should be additionally set up as follow:
1. In http
section of /etc/nginx.conf settings file proxy cache parameters are set
Code Block | ||
---|---|---|
| ||
proxy_cache_path /var/cache/nginx/proxy levels=1:2 keys_zone=proxy_cache:1024m max_size=2048m inactive=10d;
proxy_cache_min_uses 1;
proxy_ignore_headers X-Accel-Expires;
proxy_ignore_headers Expires;
proxy_ignore_headers Cache-Control; |
2. In server
section of site settings file caching of HLS segments is set, playlist should not be cached:
Code Block | ||
---|---|---|
| ||
location ~* ^.+.(ts)$ {
proxy_pass https://localhost:8445;
proxy_http_version 1.1;
proxy_set_header Host $server_name:$server_port;
proxy_set_header X-Forwarded-Host $http_host;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_cache proxy_cache;
proxy_cache_key $host$uri$is_args$args;
proxy_cache_valid 200 2m;
}
location ~* ^.+.(m3u8)$ {
proxy_pass https://localhost:8445;
proxy_http_version 1.1;
proxy_set_header Host $server_name:$server_port;
proxy_set_header X-Forwarded-Host $http_host;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_cache off;
expires -1;
} |
Passing a custom parameters when requesting a playlist
A custom parameters should be passed when requesting a playlist if reverse proxy authentication is set up:
Code Block | ||
---|---|---|
| ||
https://wcs:8445/test/test.m3u8?key1=value1&key2=value2 |
The feature is supported since build 5.2.1959. The parameters passed will be returned in every playlist for every segment, this allows to authorize a viewer correctly on proxy server.
There will be an additional parameter sessionId
in playlists, for example
Code Block | ||
---|---|---|
| ||
av_test_o/av_test_o.m3u8?sessionId=11&key1=value1&key2=value2 |
This is the internal WCS parameter to identify the subscriber for statistical purposes.
Returning of static HTML pages on HLS port
Another way to workaround cross domain requests restrictions in browser is to return a static content, player page for example, on the same port that returns HLS content. To enable this feature, the following parameter should be set in flashphoner.properties file
Code Block | ||
---|---|---|
| ||
hls_static_enabled=true |
The player page should be in directory defined by the following parameter
Code Block | ||
---|---|---|
| ||
hls_static_dir=client2/examples/demo/streaming/hls_static |
In this case (by default) the path to the player page files is set relative to WCS installation directory. A full path may also be set, for example
Code Block | ||
---|---|---|
| ||
hls_static_dir=/var/www/html/hls_static |
If static content returning is enabled, browser will display the HLS player page by URL https://host:8445/hls-player.html. If this feature is disabled, server will return 404 Not found error by such URL.
Preloader for HLS stream playback
When first HLS subscribes connects to a stream on WCS server, especilally to CDN stream, it may take a time to split a stream to HLS segmets and to form a playlist. As a result, Safari browser on iOS devices may not be able to play HLS stream on the first attempt. To successfully play HLS stream in this case, the HLS preloader was added since build 5.2.371. The default preloader looks like this:
Since build 5.2.408 preloaders are divided by stream aspect ratio: 16:9, 4:3, 2:1
Default preloader segments are placed to /usr/local/FlashphonerWebCallserver/hls/.preloader
folder when server is started
Code Block | ||
---|---|---|
| ||
tree /usr/local/FlashphonerWebCallServer/hls/.preloader
/usr/local/FlashphonerWebCallServer/hls/.preloader
├── 16x9
│ ├── index0.ts
│ ├── index10.ts
│ ├── index11.ts
│ ├── index12.ts
│ ├── index13.ts
│ ├── index14.ts
│ ├── index15.ts
│ ├── index16.ts
│ ├── index17.ts
│ ├── index18.ts
│ ├── index19.ts
│ ├── index1.ts
│ ├── index2.ts
│ ├── index3.ts
│ ├── index4.ts
│ ├── index5.ts
│ ├── index6.ts
│ ├── index7.ts
│ ├── index8.ts
│ └── index9.ts
├── 2x1
│ ├── index0.ts
│ ├── index10.ts
│ ├── index11.ts
│ ├── index12.ts
│ ├── index13.ts
│ ├── index14.ts
│ ├── index15.ts
│ ├── index16.ts
│ ├── index17.ts
│ ├── index18.ts
│ ├── index19.ts
│ ├── index1.ts
│ ├── index2.ts
│ ├── index3.ts
│ ├── index4.ts
│ ├── index5.ts
│ ├── index6.ts
│ ├── index7.ts
│ ├── index8.ts
│ └── index9.ts
└── 4x3
├── index0.ts
├── index10.ts
├── index11.ts
├── index12.ts
├── index13.ts
├── index14.ts
├── index15.ts
├── index16.ts
├── index17.ts
├── index18.ts
├── index19.ts
├── index1.ts
├── index2.ts
├── index3.ts
├── index4.ts
├── index5.ts
├── index6.ts
├── index7.ts
├── index8.ts
└── index9.ts |
The minimal preloader segment duration is 2 seconds by default, and can be set in milliseconds with the following parameter
Code Block | ||
---|---|---|
| ||
hls_preloader_time_min=2000 |
Disabling HLS preloader
HLS preloader can be disabled if necessary, this feature is available since build 5.2.396. To disable HLS preloader, the following parameter is used
Code Block | ||
---|---|---|
| ||
hls_preloader_enabled=false |
Custom preloader configuration
To replace the default preloader to thecustom one, do the following:
1. Choose video clip (logo for example) in three aspect ratios: 16:9, 4:3, 2:1
2. Encode video to H264, add audio track to the clip, set GOP and remove B-frames using ffmpeg
Code Block | ||||
---|---|---|---|---|
| ||||
ffmpeg -i clip16x9.mp4 -f lavfi -i anullsrc=channel_layout=mono:sample_rate=44100 -c:v h264 -g 30 -bf 0 -shortest 16x9/preloader16x9.mp4
ffmpeg -i clip4x3.mp4 -f lavfi -i anullsrc=channel_layout=mono:sample_rate=44100 -c:v h264 -g 30 -bf 0 -shortest 4x3/preloader4x3.mp4
ffmpeg -i clip2x1.mp4 -f lavfi -i anullsrc=channel_layout=mono:sample_rate=44100 -c:v h264 -g 30 -bf 0 -shortest 2x1/preloader2x1.mp4 |
3. Download and install HLS tools from Apple site
4. Prepare custom preloader HLS segments with desired duration, for example 2 seconds
Code Block | ||||
---|---|---|---|---|
| ||||
cd 16x9
mediafilesegmenter -t 2 -B index -start-segments-with-iframe preloader16x9.mp4
tar -cvzf preloader.tar.gz index*.ts |
This step should be repeated for all aspect ratios.
5. Make a folder for custom preloader
Code Block | ||||
---|---|---|---|---|
| ||||
mkdir /opt/custom_preloader
mkdir /opt/custom_preloader/16x9
mkdir /opt/custom_preloader/4x3
mkdir /opt/custom_preloader/2x1 |
6. Unpack preloader segments from archive prepared on step 4
Code Block | ||||
---|---|---|---|---|
| ||||
cd /opt/custom_preloader/16x9
tar -xvzf ~/preloader16x9.tar.gz |
This step should also be repeated for all aspect ratios.
7. Set custom preloader folder and duration in server settings
Code Block | ||
---|---|---|
| ||
hls_preloader_time_min=2000
hls_preloader_dir=/opt/custom_preloader |
HLS subscription management using REST API
REST query should be HTTP/HTTPS POST request as follows:
- HTTP: http://test.flashphoner.com:8081/rest-api/hls/startup
- HTTPS: https://test.flashphoner.com:8444/rest-api/hls/startup
Where:
- test.flashphoner.com - WCS server address
- 8081 - WCS server standard REST / HTTP port
- 8444 - standard HTTPS port
- rest-api - mandatory URL part
- /hls/startup - REST method used
REST queries and response sates
REST query | Body example | Response example | Response state | Desctiption | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
/hls/startup |
| 200 - OK 404 - Stream not found 500 - Internal error | Start HLS agent for the stream | |||||||||||||||
/hls/find_all |
|
| 200 – OK 404 – Not found | Find all streams having HLS agents | ||||||||||||||
/hls/terminate |
| 200 – OK 404 – Not found | Stop or restart HLS agent for the stream | |||||||||||||||
/hls/profiles |
|
| 200 – OK 400 – Bad request 404 – Not found | Get HLS profile statistics | ||||||||||||||
/hls/subscribers |
|
| 200 – OK 400 – Bad request 404 – Not found | Get HLS subscribers statistics | ||||||||||||||
/hls/connections |
|
| 200 – OK 400 – Bad request 404 – Not found 500 - Internal server error | Get a list of HLS clients connected to the server | ||||||||||||||
/hls/enableRecording |
| 200 – OK 400 – Bad request 404 – Not found 409 - Conflict 500 - Internal server error | Enable HLS stream debug segments recording | |||||||||||||||
/hls/disableRecording |
| 200 – OK 400 – Bad request 404 – Not found | Disable HLS stream debug segments recording |
Parameters
Parameter name | Description | Example |
---|---|---|
name | Stream published name | test |
hlsId | Stream published name | test |
profileName | Quality profile name to get a statistics | v_test |
offset | Offset from HLS streams statistics list start | 0 |
size | Maximum HLS streams statistics list size | 10 |
ids | HLS streams list to enable/disable debug segment recording | [ "test", "test-HLS-ABR-STREAM" ] |
state | HLS stream state | ACTIVE |
logs | Messages about stream issues | [] |
Issues
1. If HLS agent for the stream is started by REST query /hls/startup, and there are no active HLS subscribers, agent will stop after the following timeout in seconds
Code Block | ||
---|---|---|
| ||
hls_manager_provider_timeout=300 |
By default, the timeout is 5 minutes. Also it concerns HLS agents which are started automatically for streams published using the following parameter
Code Block | ||
---|---|---|
| ||
hls_auto_start=true |
2. If HLS agent for the stream is stopped by REST query /hls/terminate, and there are active HLS subscribers, this agent will be restarted. In this case, active HLS subscribers must reconnect to the stream.
LL HLS stream issues displaying
Since build 5.2.1709 LL HLS stream issues are displaying in response on /hls/find_all
REST API query:
Code Block | ||||
---|---|---|---|---|
| ||||
{
"test": {
"handler": "com.flashphoner.server.client.handler.wcs4.WCS4Handler@74dbf27b",
"state": "ACTIVE",
"writer": "HLS-test",
"streamStatus": "PLAYING",
"writerStarted": "true",
"logs": [
"2023-07-18T10:22:52.457 WARNING: Playback speed changed to 0.779, segment 49, media type: video",
"2023-07-18T10:22:56.614 WARNING: Gap{from=112000, to=114000, duration=2000}, media type: video",
"2023-07-18T10:22:56.615 WARNING: Fps changed from 30 to 27, segment 50 , media type: video",
"2023-07-18T10:22:56.624 WARNING: Segment 51.1 have no data, pts 112400, duration 400, media type: video",
...
]
}
} |
By default, up to 50 last issues are displayed for every stream. This value may be changed with the following parameter
Code Block | ||
---|---|---|
| ||
hls_metrics_log_size=50 |
The following issues are detected:
Fps changed from x to y
- stream FPS leap over 10 %Segment x does not start with keyframe
- stream keyframe interval is more than one segment durationPlayback speed changed to x
- stream playback speed has changedSegment interval is too big
- an interval in milliseconds between a subsequent segments is too big- Video resolution changed from x to y - stream resolution has changed
Gap{from=x, to=y, duration=z}
- stream gap detected,EXT-X-GAP
tag is added to the playlist
Any of those issues means a source stream publishing quality degradation and may lead to freezes, out of audio and video sync and even HLS playback stopping in some browsers. In this case, a possible packets loss or bandwidth issues should be resolved, or pablishing technology shuld be changed from WebRTC to a more noise-resistant, RTMP or SRT for example.
HLS statistics displaying
Since build 5.2.1777 it is possible to get HLS statistics via REST API
HLS common data
In the response to the /hls/find_all
query HLS agents list is returned containing a common HLS data:
Code Block | ||||
---|---|---|---|---|
| ||||
[{
"id": "test",
"streamName": "test",
"status": "ACTIVE",
"waitingSize": 0,
"profiles": [
"a_test",
"v_test"
],
"subscribers": 1,
"playlist": "#EXTM3U\n#EXT-X-VERSION:9\n#EXT-X-INDEPENDENT-SEGMENTS\n#EXT-X-MEDIA:TYPE=AUDIO,URI=\"a_test/a_test.m3u8\",GROUP-ID=\"audio\",NAME=\"none\",DEFAULT=YES,AUTOSELECT=YES,CHANNELS=\"2\"\n#EXT-X-STREAM-INF:BANDWIDTH=1761281,CODECS=\"avc1.640028,mp4a.40.2\",RESOLUTION=1280x720,FRAME-RATE=29.0,AUDIO=\"audio\"\nv_test/v_test.m3u8\n",
"createdDate": 1697605114475,
"logs": []
}] |
Where
- id - HLS stream identifier
- streamName - a source stream name which is cut to a segments
- waitingSize - HTTP requests count waiting for response
- profiles - audio and video profiles list
- subscribers - HLS subscribers count
- playlist - HLS manifest content
- createdDate - HLS agent creation date as integer
- logs - HLS stream issues log
if there are a much HLS streams on the server, the list may be limited by the following parameters
Code Block | ||||
---|---|---|---|---|
| ||||
{
"offset":0,
"size":10
} |
Where
- offset - from which item the list should be dispalyed, 0 by default
- size - a maximum list items to display, 10 by default
Audio and video profiles data
In the response to the /hls/profiles
query an audio or video HLS profile statistics is returned:
Code Block | ||||
---|---|---|---|---|
| ||||
{
"name": "v_test",
"stream": {
"appKey": "defaultApp",
"sessionId": "test-HLS",
"mediaSessionId": "81b8b278-612e-4b72-9153-454be9df0a34-test-HLS",
"name": "test",
"published": false,
"hasVideo": false,
"hasAudio": true,
"status": "PLAYING",
"sdp": "v=0\r\no=- 1988962254 1988962254 IN IP4 0.0.0.0\r\nc=IN IP4 0.0.0.0\r\nt=0 0\r\na=sdplang:en\r\nm=video 0 RTP/AVP 112\r\na=rtpmap:112 H264/90000\r\na=fmtp:112 packetization-mode=1; profile-level-id=42001f\r\na=recvonly\r\n",
"videoCodec": "H264",
"record": false,
"width": 1280,
"height": 720,
"bitrate": 0,
"minBitrate": 0,
"maxBitrate": 0,
"quality": 0,
"parentMediaSessionId": "f3401d2e-7e9a-4e18-a353-d323c947ac94",
"history": false,
"gop": 0,
"fps": 0,
"audioBitrate": 0,
"codecImpl": "",
"transport": "UDP",
"cvoExtension": true,
"createDate": 1697605114875,
"mediaType": "play",
"audioState": {
"muted": false
},
"videoState": {
"muted": false
},
"mediaProvider": "HLS"
},
"keyFrameReceived": true,
"videoProfile": {
"type": "video",
"width": 1280,
"height": 720,
"fps": 29,
"bitrate": 1720,
"codec": "",
"quality": 0,
"audioGroupId": "audio"
},
"metrics": {
"minFPS": 29.962547,
"avgFPS": 30.000088,
"maxFPS": 30.04292,
"countGaps": 0,
"resolutionChanges": 0,
"queueSize": 10,
"startPts": 375400,
"currentPts": 375400
},
"subscribers": 1
} |
Where:
- name - profile name
- stream - profile stream data in
/stream/find
like form - keyFrameReceived - is there any key frame received
- audioProfile, videoProfile - audio or video profile settings
- type - profile type: video or audio
- width - profile picture width as defined
- height - profile picture width as defined
- fps - profile video frame rate as defined
- bitrate - profile bitrate as defined
- codec - profile codec as defined
- quality - profile quality as defined
- audioGroupId - audio profile id used in video profile
- rate - audio profile samplerate
- channels - audio profile channels number
- groupId - audio profile id to bind to video profile
- metrics - current profile metrics:
- minFPS - minimal FPS
- avgFPS - average FPS
- maxFPS - maximum FPS
- countGaps - gaps count inserted to the stream
- resolutionChanges - video resolution changes count
- queueSize - stream frame queue size
- startPts - start MPEG timestamp
- currentPts - current MPEG timestamp
- subscribers - HLS subscribers to the profile count
HLS subscribers count
In the response to the /hls/subscribers
query an HLS stream subscribers list is returned:
Code Block | ||||
---|---|---|---|---|
| ||||
[
{
"id": "192.168.0.83-59000-Mozilla/5.0 (X11; Linux x86_64) Chrome/118.0.0.0",
"ip": "192.168.0.83",
"port": 59000,
"userAgent": "Mozilla/5.0 (X11; Linux x86_64) Chrome/118.0.0.0",
"active": true,
"metrics": {
"profileTime": {
"test": 71,
"v_test": 541353
},
"requestsNumber": 5930,
"requestsStatuses": {
"200 OK": 5930
},
"profileSwitches": 1,
"maxResponseTime": 29,
"minResponseTime": 0,
"avgResponseTime": 0.4436762225969646
}
}
] |
Where:
- id - subscriber identifier
- ip - subscriber IP address
- port - subscriber source port
- userAgent -
User-Agent
header sent by subscriber - active - subscriber is active
- metrics - current subscriber metrics:
- profileTime - the time the subscriber requested the profile shown by profile
- requestsNumber - subscribers requests number
- requestStatuses - response status codes count sent to the subscriber shown by response status code
- profileSwitches - HLS ABR profile switches count for the subscriber
- maxResponseTime - maximum response time
- minResponseTime - minimum response time
- avgResponseTime - average response time
HLS subscribers and connections displaying issues
In the response to the /hls/find_all
, /hls/profiles
, /hls/subscribers
queries a current HLS subscribers count and information are returned as per browser tabs. But HLS network connections count displaying at WCS statistics page
Code Block | ||||
---|---|---|---|---|
| ||||
curl -s http://localhost:8081/?action=stat¶ms=connections_hls |
may differ from HLS subscribers count. In the most cases, HLS subscribers use HTTP 2 protocol to connect and download a segments, then all the browser tabs receiving HLS streams from the same WCS server will use the same network connection.
In this case connections count displayed by connections_hls
parameter is usually equal to HLS port connections count displayed by netstat
command:
Code Block | ||||
---|---|---|---|---|
| ||||
sudo netstat -np | grep ESTABLISHED | grep java | grep 8445 |
Where 8445 is HTTPS HLS port of WCS server
Displaying a list of HLS clients connected to the server
Since build 5.2.1968 it is possible to display a list of HLS clients connected to the server. The list is returned in response to the /hls/connections
query:
Code Block | ||||
---|---|---|---|---|
| ||||
[
{
"ip": "192.168.0.83",
"port": 51708,
"userAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36"
}
] |
Where:
- ip - client address
- port - client source port
- userAgent -
User-Agent
header sent by the client
For HTTPS clients all the tabs of the same browser window on the same PC will be displayed at one position because HTTP/2 uses the same TCP connection for all HTTPS connections.
A clients count in the list will be the same as the statistics page value
Code Block | ||||
---|---|---|---|---|
| ||||
curl -s 'http://wcs:8081/?action=stat¶ms=connections_hls' |
HLS stream segments recording to disk for debugging purposes
Since build 5.2.1913 it is possible to record a segments and a playlists for a certain HLS stream played by subscribers for debugging purposes. Segments will be recorded to the folder set by the following parameter
Code Block | ||
---|---|---|
| ||
hls_debug_dir=hls-debug |
Segments recording for a certain stream may be started with REST API query /hls/enableRecording
Code Block | ||||
---|---|---|---|---|
| ||||
POST /rest-api/hls/enableRecording HTTP/1.1
Host: localhost:8081
Content-Type: application/json
{
"ids": [
"test",
"test-HLS-ABR-STREAM"
]
} |
Use the REST API query /hls/disableRecording
to stop the recording
Code Block | ||||
---|---|---|---|---|
| ||||
POST /rest-api/hls/disableRecording HTTP/1.1
Host: localhost:8081
Content-Type: application/json
{
"ids": [
"test",
"test-HLS-ABR-STREAM"
]
} |
Use a various media parsing and playing tools like ffmpeg, ffprobe etc to work with a segments recorded. Also, the debud stream recording may be played from the server using the URL with -DEBUG
suffix
Code Block | ||
---|---|---|
| ||
https://wcs:8445/test-DEBUG/test-DEBUG.m3u8 |
If the stream with a certain name was recorded, and then a new stream was published with the same name, a new recording will overwrite the previous one.
HLS ABR support
For a streams with video track (video only or audio+video) WCS supports HLS ABR in CDN (a qualities are encoded on a dedicated Transcoder node) and on a single node.
Warning |
---|
HLS ABR does not work for audio only streams, WCS will return |
Legacy HLS ABR implementation in builds 5.2.484 - 5.2.582
Since build 5.2.484 HLS ABR playlists support was added. This feature can be enabled with the following parameter
Code Block | ||
---|---|---|
| ||
hls_master_playlist_enabled=true |
Master playlist file name can be set using the following parameter
Code Block | ||
---|---|---|
| ||
hls_manifest_file=index.m3u8 |
Browser should get master playlist by URL
Code Block | ||
---|---|---|
| ||
https://wcs_address:8445/streamName/index.m3u8 |
Where
- wcs_address - WCS server address
- streamName - stream name
- index.m3u8 - master playlist file name
When master playlist is requested for the stream, server checks if streams are published according to transcoding profiles listed in cdn_profiles.yml file, for example:
Code Block | ||
---|---|---|
| ||
profiles:
-720p:
video:
height: 720
bitrate: 1000
codec: h264
-480p:
video:
height: 480
bitrate: 1000
codec: h264
-240p:
video:
height: 240
bitrate: 400
codec: h264 |
All the streams published by profiles on server, will be added to master playlist, for example:
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=1280x720,CODECS="avc1.42e01f,mp4a.40.2"
../streamName-720p/streamName-720p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=852x480,CODECS="avc1.42e01f,mp4a.40.2"
../streamName-480p/streamName-480p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=400000,RESOLUTION=426x240,CODECS="avc1.42e01f,mp4a.40.2"
../streamName-240p/streamName-240p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=1280x720,CODECS="avc1.42e01f,mp4a.40.2"
../streamName/streamName.m3u8 |
Then browser switches between HLS streams listed in master playlist depending on channel bandwidth.
Warning |
---|
When browser requests master playlist for the certain stream, transcoded stream must already be published on server and must be cut to HLS segments |
To provide HLS streams by profiles, the following should be done:
1. On a standalone server:
1.1. Periodically check if streams are transcoded to parameters set by profiles, and launch transcoding if necessary using REST API
Code Block | ||||
---|---|---|---|---|
| ||||
curl -s -X POST -d "{\"uri\":\"transcoder://tcode_test-240p\",\"remoteStreamName\":\"test\",\"localStreamName\":\"test-240p\",\"encoder\":{\"width\":320,\"height\":240}}" http://localhost:8081/rest-api/transcoder/startup
curl -s -X POST -d "{\"uri\":\"transcoder://tcode_test-480p\",\"remoteStreamName\":\"test\",\"localStreamName\":\"test-480p\",\"encoder\":{\"width\":640,\"height\":480}}" http://localhost:8081/rest-api/transcoder/startup
curl -s -X POST -d "{\"uri\":\"transcoder://tcode_test-720p\",\"remoteStreamName\":\"test\",\"localStreamName\":\"test-720p\",\"encoder\":{\"width\":1280,\"height\":720}}" http://localhost:8081/rest-api/transcoder/startup |
1.2. Periodically launch HLS cut for the streams, for example
Code Block | ||||
---|---|---|---|---|
| ||||
curl -s -X POST -d "{\"name\":\"test\"}" http://localhost:8081/rest-api/hls/startup
sleep 1
curl -s -X POST -d "{\"name\":\"test-240p\"}" http://localhost:8081/rest-api/hls/startup
sleep 1
curl -s -X POST -d "{\"name\":\"test-480p\"}" http://localhost:8081/rest-api/hls/startup
sleep 1
curl -s -X POST -d "{\"name\":\"test-720p\"}" http://localhost:8081/rest-api/hls/startup |
2. On an Edge server in CDN periodically request HLS streams by transcoding profiles, for example
Code Block | ||||
---|---|---|---|---|
| ||||
curl -s http://localhost:8082/test/test.m3u8
sleep 1
curl -s http://localhost:8082/test-240p/test-240p.m3u8
sleep 1
curl -s http://localhost:8082/test-480p/test-480p.m3u8
sleep 1
curl -s http://localhost:8082/test-720p/test-720p.m3u8
sleep 1 |
Actual HLS ABR implementation in build 5.2.585 and newer
Since build 5.2.585 HLS ABR implementation is significally changed. As usual, HLS ABR can be used in CDN only, but Edge server captures all the transcoded streams for ABR manifest stream variants within the same mediasession to syhchronize the stream variants. This requires to configure Tanscoder nodes and Edge nodes simultaneously, and adds some limits. Let's explore it below.
Transcoder node settings
To synchronize all the variants of the same stream, encoding should be aligned on Transcoder node
Code Block | ||
---|---|---|
| ||
transcoder_align_encoders=true |
Also, FPS filter should be enabled
Code Block | ||
---|---|---|
| ||
video_filter_enable_fps=true
video_filter_fps=25 |
All stream variants key frames (GOPs) should be synchronized. For example, we will send key frame every 2 seconds for 25 fps stream
Code Block | ||
---|---|---|
| ||
video_filter_fps_gop_synchronization=50 |
HLS Edge node settings
HLS preloader and streams resizing should be disabled on HLS Edge node
Code Block | ||
---|---|---|
| ||
hls_preloader_enabled=false
hls_player_width=0
hls_player_height=0 |
The transcoding profiles should be set as follows in cdn_profiles.yml file
Code Block | ||||
---|---|---|---|---|
| ||||
profiles:
-240p:
audio:
codec : mpeg4-generic
rate : 48000
video:
height : 240
bitrate : 300
gop : 50
codec : h264
-480p:
video:
height : 480
bitrate : 600
gop : 50
codec : h264
-720p:
video:
height : 720
bitrate : 1000
gop : 50
codec : h264 |
Note that audio parameters can be set for the first profile only because those parameters should be identical for all the profiles, and will be applyed according to the first profile.
Then HLS ABR should be enabled
Code Block | ||
---|---|---|
| ||
hls_abr_enabled=true |
Usage
Client should request ABR manifest giving a stream name with a special suffix
Code Block | ||
---|---|---|
| ||
https://server:8445/test_0-HLS-ABR-STREAM/test_0-HLS-ABR-STREAM.m3u8 |
The suffix can be set with the following parameter
Code Block | ||
---|---|---|
| ||
hls_abr_stream_name_suffix=-HLS-ABR-STREAM |
The playlist contains links to stream variants playlists, a client can switch between then
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=614400,RESOLUTION=852x480,CODECS="avc1.42e01f,mp4a.40.2"
-480p/-480p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1024000,RESOLUTION=1278x720,CODECS="avc1.42e01f,mp4a.40.2"
-720p/-720p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=307200,RESOLUTION=426x240,CODECS="avc1.42e01f,mp4a.40.2"
-240p/-240p.m3u8 |
If stream name contains no suffix, HLS will be played without ABR support.
Transcoding to higher resolutions prevention
If stream transcoding to higher resolutions is disabled on HLS ABR Edge server
Code Block | ||
---|---|---|
| ||
cdn_strict_transcoding_boundaries=true |
then stream variants conforming to higher resolution profiles will not be cut for the stream, and will not be vailable to a player.
Known limits
1. HLS Edge can be used for HLS streaming only, client sessions of another kinds will not work.
2. Stream recording, snapshots, mixing, stream capturing from another server and other captured stream management functions will not work.
HLS ABR on a single node
In most cases, it's more convenient to use CDN to play HLS ABR, because this is more scalable solution at server performance point. However, since build 5.2.1582 it is possible to transcode a stream to a certain HLS ABR qualities on a single server
Code Block | ||
---|---|---|
| ||
hls_abr_enabled=true
hls_abr_with_cdn=false |
In this case, HLS preloader and default transcoding must be disabled because a stream will be transcoded by defined profiles
Code Block | ||
---|---|---|
| ||
hls_preloader_enabled=false
hls_player_width=0
hls_player_height=0 |
FPS equalizing should also be enabled
Code Block | ||
---|---|---|
| ||
transcoder_align_encoders=true
video_filter_enable_fps=true
video_filter_fps=30
video_filter_fps_gop_synchronization=60 |
HLS ABR transcoding quality profiles should be set in /usr/local/FlashphonerWebCallServer/conf/hls_abr_profiles.yml
file
Code Block | ||||
---|---|---|---|---|
| ||||
profiles:
-180p:
audio:
codec : mpeg4-generic
rate : 48000
video:
height : 180
bitrate : 300
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30
-240p:
audio:
codec : mpeg4-generic
rate : 48000
video:
height : 240
bitrate : 500
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30
-480p:
audio:
codec : mpeg4-generic
rate : 48000
video:
height : 480
bitrate : 1000
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30
-720p:
audio:
codec : mpeg4-generic
rate : 48000
video:
height : 720
bitrate : 1500
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30 |
Low Latency HLS is also supported for HLS ABR
Code Block | ||
---|---|---|
| ||
hls_ll_enabled=true
hls_new_http_stack=true |
Warning |
---|
When using HLS ABR on a single server, any published stream will be transcoded to a number of qualities. This requires a lot of server CPU cores and RAM. |
Transcoding to higher resolutions prevention
Since build 5.2.1611, if a stream published has a less picture height than some profiles listed in hls_abr_profiles.yml
, then all the variants with higher resolutions will not be encoded and will not be included to manfest. For example, the manifest will look as follows when original stream has 960x540 resolution:
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=300000,RESOLUTION=320x180,CODECS="avc1.42e01f,mp4a.40.2"
180/180.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=500000,RESOLUTION=428x240,CODECS="avc1.42e01f,mp4a.40.2"
240/240.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=848x480,CODECS="avc1.42e01f,mp4a.40.2"
480/480.m3u8 |
because there will not be upscale to 1280x720.
If the stream resolution is lower than a minimal profile, this stream will be transcoded to the minimal available profile, and the only variant will be included to manifest
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=300000,RESOLUTION=320x180,CODECS="avc1.42e01f,mp4a.40.2"
180/180.m3u8 |
If there is a profile without both width and height parameters, the stream will be transcoded to its original resolution with GOP and FPS defined in the profile, and this variant will always be included to manifest:
Code Block | ||
---|---|---|
| ||
profiles:
original:
video:
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30 |
Qualities order in HLS ABR manifest
Before build 5.2.1606, HLS ABR manifest qualities are sorted in profile names alphabetical order, for example, such cdn_profiles.yml
or hls_abr_profiles.yml
Code Block | ||||
---|---|---|---|---|
| ||||
profiles:
360:
video:
height : 360
bitrate : 1000
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30
720:
video:
height : 720
bitrate : 2000
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30
1080:
video:
height : 1080
bitrate : 2500
codec : h264
codecImpl : OPENH264
gop : 60
fps : 30 |
give the following manifest
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=1920x1080,CODECS="avc1.42e01f,mp4a.40.2"
1080/1080.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=640x360,CODECS="avc1.42e01f,mp4a.40.2"
360/360.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2000000,RESOLUTION=1280x720,CODECS="avc1.42e01f,mp4a.40.2"
720/720.m3u8 |
Since build 5.2.1606, manifest qualities order equals to profiles order in cdn_profiles.yml
or hls_abr_profiles.yml
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=640x360,CODECS="avc1.42e01f,mp4a.40.2"
360/360.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2000000,RESOLUTION=1280x720,CODECS="avc1.42e01f,mp4a.40.2"
720/720.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=1920x1080,CODECS="avc1.42e01f,mp4a.40.2"
1080/1080.m3u8 |
If there are two profiles with the same name in the setup, server will use only the last profile with the same name.
Force transcoding of a maximum ABR quality only if there are B-frames in a source stream
To reduce a server load while video encoding, since WCS build 5.2.1840 it is possible to transcode a maximum ABR quality (which is usually the original stream resolution and bitrate) only if there are B-frames in a source stream. The feature may be enabled by the following parameter
Code Block | ||
---|---|---|
| ||
h264_b_frames_force_transcoding=true |
In this case the server will detect B-frames in a stream analizing a certain frames count (10 by default)
Code Block | ||
---|---|---|
| ||
frame_cnt_to_determine_their_type=10 |
If there are B-frames in the stream, the maximum ABR quality will be transcoded and will be available for playback in the HLS manifest
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=640x360,CODECS="avc1.42e01f,mp4a.40.2"
360/360.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2000000,RESOLUTION=1280x720,CODECS="avc1.42e01f,mp4a.40.2"
720/720.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=1920x1080,CODECS="avc1.42e01f,mp4a.40.2"
1080/1080.m3u8 |
If there are no B-frames in the stream, the maximum ABR quality will not be transcoded
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=1000000,RESOLUTION=640x360,CODECS="avc1.42e01f,mp4a.40.2"
360/360.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2000000,RESOLUTION=1280x720,CODECS="avc1.42e01f,mp4a.40.2"
720/720.m3u8 |
The original quality should be requested separately from a playing client.
Since build 5.2.1916, the feature is available for HLS ABR in CDN. To activate it, all the CDN servers should be updated to build 5.2.1916 or newer, and the following parameters should be set on Edge server
Code Block | ||
---|---|---|
| ||
cdn_strict_transcoding_boundaries=true
h264_b_frames_force_transcoding=true |
Maximum playlist size
Maximum playlist size in segments is defined by the following parameter
Code Block | ||
---|---|---|
| ||
hls_list_size=8 |
By default, HLS playlist size is 8 segments. Note that HLS cut is just started, a segments quantity in the first playlists will be less than value set.
HLS segments storage
Using disk
In builds before 5.2.1713HLS segments are written to server hard drive to the /usr/local/FlashphonerWebCallServer/hls
folder by default. Starting from build 5.2.687, the folder for saving segments can be changed using the following parameter
Code Block | ||
---|---|---|
| ||
hls_dir=/usr/local/FlashphonerWebCallServer/hls |
(Preloader folder is configured separately with parameter hls_preloader_dir.)
The number of stored segments corresponds to the specified playlist size. The less segments number, the less playback latency. However subscribers with poor channel could request HLS segments which are already gone from playlist and disk if playlist is short. To fix it, since build 5.2.581 the certain number of segments can be stored on disk after they gone from playlist. This feature can be enabled by the following parameter
Code Block | ||
---|---|---|
| ||
hls_hold_segments_before_delete=true |
By default, 5 last segments will be stored
Code Block | ||
---|---|---|
| ||
hls_hold_segments_size=5 |
For example, if playlist contains 3 segments
Code Block | ||
---|---|---|
| ||
#EXTM3U
#EXT-X-VERSION:8
#EXT-X-TARGETDURATION:11
#EXT-X-MEDIA-SEQUENCE:15
#EXT-X-DISCONTINUITY-SEQUENCE:1
#EXTINF:3.415,
test_017.ts
#EXTINF:10.417,
test_018.ts
#EXTINF:9.084,
test_019.ts |
3 current segments and 5 previous segments will be stored on disk
Code Block | ||
---|---|---|
| ||
test_012.ts
test_013.ts
test_014.ts
test_015.ts
test_016.ts
test_017.ts
test_018.ts
test_019.ts |
Using memory
Under high load, for example on HLS streaming dedicated server, segments reading from hard drive to send them to subscribers can increase the latency. In this case, HLS segments storing in memory should be enabled
Code Block | ||
---|---|---|
| ||
hls_store_segment_in_memory=true |
Segments will be read from memory to send them to subscribers. Note this will require more Java heap memory.
Since build 5.2.1713 HLS segments are stored in memory by default.
Debug logs for HLS session
For an error report, debug logging can be enabled for HLS sessions using CLI
Code Block | ||||
---|---|---|---|---|
| ||||
update node-setting --value true hls_enable_session_debug |
Note that config flashphoner.properties will be overwritten after the command.
Low Latency HLS support
Since WCS build 5.2.1181, Low Latency HLS (LL HLS) is supported. The feature may be enabled with the following parameters
Code Block | ||
---|---|---|
| ||
hls_ll_enabled=true
hls_new_http_stack=true |
In this case, players supporting LL HLS (HLS.JS for example) will play additional HLS segments reducing playback latency comparing with players which do not play those segments (VideoJS for example).
It is necessary to provide a stable FPS and keyframe interval for a published stream to play it as LL HLS correctly. Therefore, it is recommended to publish the source strem as RTMP with the following example parameters
Recommended settings for LL HLS playback
Since build 5.2.1345, the recommended settings to play Low latency HLS are follow:
Code Block | ||
---|---|---|
| ||
hls_ll_enabled=true
hls_auto_start=true
hls_preloader_enabled=false
hls_player_width=848
hls_player_height=480
video_filter_enable_fps=true
video_filter_fps=30
video_encoder_h264_gop=60 |
Since build 5.2.1965, the following parameter is enough to play LL HLS, a defaults may be used for other settings
Code Block | ||
---|---|---|
| ||
hls_ll_enabled=true |
Using HTTP/2 and HTTP/1
According to specification, LL HLS must be played using HTTP/2, i.e. via secure connection
Code Block | ||
---|---|---|
| ||
https://wsc:8445/test/test.m3u8 |
It is also possible to use HTTP/1 via unsecure connection with WCS
Code Block | ||
---|---|---|
| ||
http://wsc:8082/test/test.m3u8 |
Note that LL HLS via HTTP/1 works in main browsers except Safari, and this feature is not recommended to use in production.
LL HLS segments folder
By default, LL HLS segments are written to streams subdolder to the folder
Code Block | ||
---|---|---|
| ||
ll_hls_dir=/usr/local/FlashphonerWebCallServer/ll-hls |
If folder has changed
Code Block | ||
---|---|---|
| ||
ll_hls_dir=/opt/ll-hls |
it is necessary to set file access permissions using the command
Code Block | ||||
---|---|---|---|---|
| ||||
/usr/local/FlashphonerWebCallServer/bin/webcallserver set-permissions |
and restart WCS to apply the changes.
Maximum LL HLS playlist size
Maximum LL HLS playlist size in segments is defined by the following parameter
Code Block | ||
---|---|---|
| ||
ll_hls_list_size=12 |
By default, LL HLS playlist size is 12 full segments. Note that LL HLS cut is just started, a full segments quantity in the first playlists will be less than value set.
LL HLS preloader
Since build 5.2.1729, a special preloader can be used for LL HLS as like as usual HLS
Code Block | ||
---|---|---|
| ||
hls_preloader_enabled=true |
LL HLS preloader files are placed by default to the folder
Code Block | ||
---|---|---|
| ||
ll_hls_preloader_dir=/usr/local/FlashphonerWebCallServer/ll-hls/.preloader |
The folder can be changed, for example
Code Block | ||
---|---|---|
| ||
ll_hls_preloader_dir=/opt/preloader |
Default LL HLS preloader consists of the following files, one per each standard video streams aspect ratio
Code Block | ||
---|---|---|
| ||
16x9.mp4
2x1.mp4
4x3.mp4 |
If stream aspect ration is unknown, 16:9 preloader file will be used. If there are no preloader files at all, LL HLS stream cut will start without a preloader like
Code Block | ||
---|---|---|
| ||
hls_preloader_enabled=false |
Custom LL HLS preloader setup
A custom LL HLS preloader can be set up if necessary. The media files in three standard aspects 16:9, 4:3 и 2:1 should be prepared according to the following requirements:
- MP4 container, video codec H264, audio codec AAC
- the files should allow instant playback (MP4
moov
atom must precedemdat
one) - the files should not containt B frames
- the file duration should be near 1 minute
- the file should have a smooth FPS
- keyframe interval should be near 2 seconds
Suppose a source files are prepared in a proper aspects in OBS Studio or in a video editor. Use the following command example to convert a preloader files to conform the requirements above:
Code Block | ||||
---|---|---|---|---|
| ||||
ffmpeg -i 16x9-source.mp4 -bf 0 -acodec aac -vcodec h264 -preset ultrafast -g 60 -strict -2 -r 30 -ar 48000 -movflags faststart -ss 00:00:00 -t 00:01:00 16x9.mp4 |
Then the default preloader files should be replaced by custom preloader files, and WCS should be restarted.
To restore default preloader it is enough to remove custom preloader files and restart WCS.
A settings applied both for LL and non-LL HLS
Since build 5.2.1965 all the settings with hls_
prefix are applied both to LL and non-LL HLS.
The following parameters are applied to LL HLS only and not applied to non-LL HLS
Parameter | Description | Default value |
---|---|---|
ll_hls_max_number_of_parent_segments_containing_partials | A maximum partial segments number per one parent segment | 5 |
ll_hls_part_hold_back_count | PART-HOLD-BACK attribute value in playlist | 6 |
ll_hls_partial_time_max | A maximum partial segment size in milliseconds | 400 |
m4s container support
Since build 5.2.1626 m4s container is supported for HLS segments cut, and since build 5.2.1632 the container is enabled by default for HLS ABR too
Code Block | ||
---|---|---|
| ||
ll_hls_fragmented_mp4=true |
Since build 5.2.1724, m4s container is supported for HLS ABR in CDN.
You can switch back to the ts container if necessary
Code Block | ||
---|---|---|
| ||
ll_hls_fragmented_mp4=false |
Using a common network stack for HLS and Low Latency HLS
Since build 5.2.1749 the parameter allowing an unified network stack usage both for HLS and Low latency HLS is added. The parameter is enabled by default:
Code Block | ||
---|---|---|
| ||
use_new_hls=true |
In this case:
- m4s container is used by default to record an HLS segments
- parameters with
hls
prefix are applied both to HLS and LL HLS - parameters with
ll_hls
prefox are applied to LL HLS and to m4s container
Warning |
---|
Since build 5.2.1793, the parameter is removed. The unified network stack is always used to deliver both HLS and LL HLS segments. |
Manifest URL setup
Since build 5.2.1852, an URL templates to request a stream main playlist (manifest) may be customized. By default, the following templates are used:
Code Block | ||
---|---|---|
| ||
hls_path_template={streamName}/{streamName}.m3u8
hls_abr_path_template={streamName}{abrSuffix}/{streamName}{abrSuffix}.m3u8 |
Where:
- streamName - stream published name
- abrSuffix - HLS ABR stream suffix set by
hls_abr_stream_name_suffix
parameter
In this case, the following URLs should be used to get HLS manifest
Code Block | ||
---|---|---|
| ||
https://wcs:8445/stream/stream.m3u8 |
and to get HLS ABR manifest
Code Block | ||
---|---|---|
| ||
https://wcs:8445/stream-HLS-ABR-STREAM/stream-HLS-ABR-STREAM.m3u8 |
For example, if a fixed manifest name different for HLS ABR and non-ABR streams is preferred to use, then the following templates should be set
Code Block | ||
---|---|---|
| ||
hls_path_template={streamName}/playlist.m3u8
hls_abr_path_template={streamName}/playlist{abrSuffix}.m3u8 |
In this case, the following URLs should be used to get HLS manifest
Code Block | ||
---|---|---|
| ||
https://wcs:8445/stream/playlist.m3u8 |
and to get HLS ABR manifest
Code Block | ||
---|---|---|
| ||
https://wcs:8445/stream/playlist-HLS-ABR-STREAM.m3u8 |
HLS provider shutdown when source stream is stopped
Since build 5.2.1920 it is possible to control HLS provider shutdown when a source stream publishing on the server is stopped. By default, the HLS provider is stopped with a delay
Code Block | ||
---|---|---|
| ||
hls_delayed_shutdown=true |
The delay depends on playlist size
Code Block | ||
---|---|---|
| ||
hls_list_size=8 |
Thus, a subscribers playing the HLS stream may play a rest of playlist if the source stream is stopped.
The delayed shutdown may be disabled if needed
Code Block | ||
---|---|---|
| ||
hls_delayed_shutdown=false |
In this case HLS provider will be stopped right after the source stream is stopped.
HLS segments size control
By default HLS segments will be cut either by key frame receiving or by reaching the size set by the following parameter (2000 ms by default)
Code Block | ||
---|---|---|
| ||
hls_time_min=2000 |
Since build 5.2.1974 it is possible to enable HLS segments cutting by key frame receiving only
Code Block | ||
---|---|---|
| ||
hls_always_start_segment_with_key_frame=true |
In this case a segment size may exceed hls_time_min
value, bur a minimal segment size may be less. The following parameter is used to strictly limit the minimal segments size
Code Block | ||
---|---|---|
| ||
hls_keep_min_segment_duration=true |
In this case a segment size will not be less than hls_time_min
.
HLS streams automatic transcoding
In WCS builds before 5.2.2036 HLS streams are transcoded automatically by default to the resolution defined
Code Block | ||
---|---|---|
| ||
hls_player_width=640
hls_player_height=480 |
It is not necessary today because a stream may be transcoded by an HLS ABR profile. Therefore HLS transcoding is disabled by default since WCS build 5.2.2036
Code Block | ||
---|---|---|
| ||
hls_player_width=0
hls_player_height=0 |
The settings are deprecated and may be removed later.
Known issues
1. Non-recoverable freeze of HLS stream played in iOS Safari through a CDN
Symptoms: one minute after publishing start image stops, sound continues to play
Solution:
b) enable transcoding on server using the following option in flashphoner.properties file
Code Block | ||||
---|---|---|---|---|
| ||||
disable_streaming_proxy=true |
b) if transcoding is undesirable, set the following option in flashphoner.properties file
Code Block | ||||
---|---|---|---|---|
| ||||
hls_discontinuity_enabled=true |
In this case, clicks are possible in audio, but video will not stop.
2. HLS segments writing stops when playing stream published in Firefox browser.
Symptoms: a few minutes after playback start HLS segments stop writing, in that case the stream directory in hls directory is not deleted, and messages in server log continue to appear
Code Block | ||||
---|---|---|---|---|
| ||||
INFO HLSStreamManager - HLSStreamProviderKeepaliveThread-80 Remove hls channel |
Publisher must publish stream again to recover.
Solution: use another browser to publish the stream which supposed to be played via HLS.
3. No video for the first subscriber when playing HLS in Safari on iOS 12.4
Symptoms: no video for the first subscriber when playing a stream as HLS in Safari on iOS 12.4, however video is played normally if there are other HLS-subscribers to the stream
Solution: set the minimum HLS playlist segments count not less than 2
Code Block | ||
---|---|---|
| ||
hls_min_list_size=2 |
4. No video for any subscriber when playing RTMP stream as HLS in Safari on iOS 12.4 if the following parameter is set to
Code Block | ||
---|---|---|
| ||
hls_auto_start=true |
Symptoms: no video for any subscriber when playing RTMP stream as HLS in Safari on iOS 12.4
Soluition: use mono sound when a file with stereo sound track is published, for example, set the followint command line options for ffmpeg
Code Block | ||
---|---|---|
| ||
-acodec aac -ac 1 |
5. If stream transcoded by CDN is played as HLS, and if stream aspect ratio is changed during transcoding, HLS preloader is shown by original stream aspect ratio
Symptoms: when stream transcoded is requested by setting profile name, test-640x480p for example, 16x9 preloader is shown if original stream is 1280x720
Solution: turn on aspect ratio preserving on Transcoder CDN nodes
Code Block | ||
---|---|---|
| ||
video_transcoder_preserve_aspect_ratio=true |
6. If the source stream contains B-fames, the picture can twitch in some players
Symptoms: a strong picture twitching while playing a stream via HLS, this may lokk like low FPS
Solution: update WCS to build 5.2.863, where the problem is solved
7. Audio may be missed on the first connection to the stream when playing native LL HLS in Safari browser
Symptoms: stream is playing as LL HLS but there is no sound
Solution: update WCS to build 5.2.1345 or newer where the issue is solved
8. Chrome browser on Ubuntu 22.04 may raise CORS error while downloading HLS playlists via HTTPS
Symptoms: Chrome browser on Ubuntu 22.04 plays HLS via HTTPS normally, then CORS error occurs while downloading another playlist
Solution: do not send HTTP requests from Chrome to the same site HLS via HTTPS is playing from
9. LL HLS ABR stream may be played with a big delay in iOS Safari 16.
Symptoms: all the subscribers using iOS Safari 16, play LL HLS ABR stream with a big delay (more than 20 seconds) from published stream
Solution: update WCS to build 5.2.1677 to use m4s container by default for LL HLS and wait for a posssible fix in iOS Safari 17
10. HLS ABR may not be played if m4s container is used
Symptoms: HLS ABR segments are not cut with server log message
Code Block | ||
---|---|---|
| ||
02:18:01,957 ERROR HlsAbrStreamProvider - HLS-HTTPS-pool-5-thread-1 Failed to check stream null
java.lang.NullPointerException |
Solution: update WCS to build 5.2.1677 where the issue is resolved
11. VLC requires LL HLS manifest to include at least 4-6 segments for the first subscriber
Symptoms: audio and video are out of sync when VLC plays LL HLS in m4s container, or playback is freezing while switching a quality in LL HLS ABR
Solution: update WCS to build 5.2.1677 and increase a minimal manifest size
Code Block | ||
---|---|---|
| ||
hls_min_list_size=6 |
12. Audio only HLS stream in ts container is playing with a notable clicks in Safari browser
Symptoms: Audio only HLS stream clicks while playing in native HTML5 player in Safari browser
Solution: since build 5.2.1690, use m4s container for audio only streams
13. Encoder resources leak may appear under a high load when using HLS ABR
Symptoms: when HLS ABR is used and server CPU load is high (for instance, an encoding profiles number for all the streams published exceeds CPU capabilities), encoding resources may not be freed after publishing is stopped, and this may be visible on server statistics page, for example
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streams_hls=0
...
native_resources.video_encoders=5 |
Solution: update WCS to build 5.2.1947 and set the following parameter
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handler_async_disconnect=false |