Capturing VOD from a file¶

WCS offers possibility to capture a media stream from an MP4 file located on the local disk of the server (Video on Demand, VOD). The received stream can be played, republished, managed just like any stream on the WCS server. First of all, this option is intended to play previously recorded broadcasts in a browsers or a mobile application on the client side.

Overview¶

To capture VOD from a file, specify a link to the vod file as a stream name when calling the session.createStream() function, as follows:

vod://sample.mp4

where sample.mp4 is the name of the file that should be located in /usr/local/FlashphonerWebCallServer/media folder. Since build 5.2.687, a custom folder can specified with the following parameter in flashphoner.properties file

media_dir=/usr/local/FlashphonerWebCallServer/media

If a file with such name does not exist, the server returns the STREAM_STATUS.FAILED event, where the info field has the reason: File not found.

A stream created this way can be displayed to one user (personal VOD). Second viewer cannot subscribe to personal VOD stream, such stream cannot be transcoded, added to mixer or played by HLS.

If a full-featured online-broadcast is required, provide the link to a file as follows:

vod-live://sample.mp4

Multiple user can connect to such a stream simultaneously. VOD live stream can be transcoded, added to mixer or played by HLS.

Supported formats and codecs¶

Container: MP4
Video: H.264
Audio: AAC

Operation flowchart¶

The browser connects to the server via WebSocket and sends the publishStream command.
The browser captures the microphone and the camera and sends the WebRTC stream as H.264 + AAC to the server, enabling recording with the parameter record: true.
The WCS server records the stream to a file.
The browser stops publishing.
The second browser establishes a connection via WebSocket, creates a stream, specifies the file name, and sends the playStream command.
The second browser receives the WebRTC stream and plays this stream on the page.

Quick manual on testing¶

For the test we use the Player web application to play the file.
Upload the file to the /usr/local/FlashphonerWebCallServer/media/ directory.
Open the Player web application and enter the name of the file in the Stream field:
Click Start. The file starts playing:
Click Stop to stop the playback.
Delete the file from /usr/local/FlashphonerWebCallServer/media/
Click Start. You should see the FAILED status and the File not found message:

Call flow¶

Below is the call flow when using:

the Stream Recording example to publish the stream and record the file
recording.html
recording.js
the Player example to play the VOD stream
player.html
player.js

Establishing a connection to the server to publish and record the stream
Flashphoner.createSession() code

Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
  ...
});

Receiving from the server an event confirming successful connection
SESSION_STATUS.ESTABLISHED code

Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
  setStatus(session.status());
  //session connected, start playback
  publishStream(session);
}).on(SESSION_STATUS.DISCONNECTED, function(){
  ...
}).on(SESSION_STATUS.FAILED, function(){
  ...
});

Publishing the stream with recording enabled
Stream.publish() code

session.createStream({
  name: streamName,
  display: localVideo,
  record: true,
  receiveVideo: false,
  receiveAudio: false
  ...
}).publish();

Receiving from the server an event confirming successful publishing of the stream
STREAM_STATUS.PUBLISHING code

session.createStream({
  name: streamName,
  display: localVideo,
  record: true,
  receiveVideo: false,
  receiveAudio: false
}).on(STREAM_STATUS.PUBLISHING, function(stream) {
  setStatus(stream.status());
  onStarted(stream);
}).on(STREAM_STATUS.UNPUBLISHED, function(stream) {
  ...
}).on(STREAM_STATUS.FAILED, function(stream) {
  ...
}).publish();

Sending audio and video stream via WebRTC

Stopping publishing the stream
Stream.stop() code

function onStarted(stream) {
    $("#publishBtn").text("Stop").off('click').click(function(){
        $(this).prop('disabled', true);
        stream.stop();
    }).prop('disabled', false);
}

Receiving from the server an event confirming unpublishing of the stream
STREAM_STATUS.UNPUBLISHED code

session.createStream({
  name: streamName,
  display: localVideo,
  record: true,
  receiveVideo: false,
  receiveAudio: false
}).on(STREAM_STATUS.PUBLISHING, function(stream) {
  ...
}).on(STREAM_STATUS.UNPUBLISHED, function(stream) {
  setStatus(stream.status());
  showDownloadLink(stream.getRecordInfo());
  onStopped();
}).on(STREAM_STATUS.FAILED, function(stream) {
  ...
}).publish();

Establishing a connection to the server to play the stream
Flashphoner.createSession() code

Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
  ...
});

Receiving from the server an event confirming successful connection
SESSION_STATUS.ESTABLISHED code

Flashphoner.createSession({urlServer: url}).on(SESSION_STATUS.ESTABLISHED, function(session){
  setStatus(session.status());
  //session connected, start playback
  playStream(session);
}).on(SESSION_STATUS.DISCONNECTED, function(){
  ...
}).on(SESSION_STATUS.FAILED, function(){
  ...
});

Playing the stream
Stream.play() code

if (Flashphoner.getMediaProviders()[0] === "MSE" && mseCutByIFrameOnly) {
    options.mediaConnectionConstraints = {
        cutByIFrameOnly: mseCutByIFrameOnly
    }
}
if (resolution_for_wsplayer) {
    options.playWidth = resolution_for_wsplayer.playWidth;
    options.playHeight = resolution_for_wsplayer.playHeight;
} else if (resolution) {
    options.playWidth = resolution.split("x")[0];
    options.playHeight = resolution.split("x")[1];
}
stream = session.createStream(options).on(STREAM_STATUS.PENDING, function(stream) {
    ...
});
stream.play();

Receiving from the server an event confirming successful playing of the stream
STREAM_STATUS.PLAYING code

stream = session.createStream(options).on(STREAM_STATUS.PENDING, function(stream) {
    ...
}).on(STREAM_STATUS.PLAYING, function(stream) {
    $("#preloader").show();
    setStatus(stream.status());
    onStarted(stream);
}).on(STREAM_STATUS.STOPPED, function() {
    ...
}).on(STREAM_STATUS.FAILED, function(stream) {
    ...
}).on(STREAM_STATUS.NOT_ENOUGH_BANDWIDTH, function(stream){
    ...
});
stream.play();

Receiving of the audio-video stream via Websocket and playing it via WebRTC

Stopping publishing the stream
Stream.stop() code

function onStarted(stream) {
    $("#playBtn").text("Stop").off('click').click(function(){
        $(this).prop('disabled', true);
        stream.stop();
    }).prop('disabled', false);
    ...
}

Receiving from the server an event confirming successful stopping of the playback of the stream
STREAM_STATUS.STOPPED code

stream = session.createStream(options).on(STREAM_STATUS.PENDING, function(stream) {
    ...
}).on(STREAM_STATUS.PLAYING, function(stream) {
    ...
}).on(STREAM_STATUS.STOPPED, function() {
    setStatus(STREAM_STATUS.STOPPED);
    onStopped();
}).on(STREAM_STATUS.FAILED, function(stream) {
    ...
}).on(STREAM_STATUS.NOT_ENOUGH_BANDWIDTH, function(stream){
    ...
});
stream.play();

VOD loop¶

VOD live translation supports VOD loop: after end of file, capturing starts from file begin. This feature is enabled with the following parameter in flashphoner.properties file

vod_live_loop=true

VOD capturing from AWS S3 or from other S3 compatible storage¶

VOD stream can be captured from file placed to AWS S3 storage. Comparing with VOD capture from local disk, file from external storage is downloaded and captured sequentally.

To capture VOD from AWS S3 file, specify a link to the VOD file as a stream name when calling the session.createStream() function, as follows:

vod://s3/bucket/sample.mp4

where

bucket is S3 bucket name
sample.mp4 is file name

Since build 5.2.939 it is possible to set the full file URL in S3 storage, this allows to capture VOD from other S3 compatible storages (Digital Ocean, Selectel etc)

Digital Ocean Spaces URL example

vod://s3/https://ams3.digitaloceanspaces.com/myspace/folder/file.mp4

Selectel URL example

vod://s3/https://s3.selcdn.ru/mystorage/file.mp4

Operation flowchart¶

Browser requests VOD capture from AWS file
WCS server sends request to AWS
File is downloaded to WCS server
WebRTC stream from file is sending to browser for playback

Set up¶

S3 credentials configuration¶

AWS¶

To download files from AWS S3 bucket, S3 credentials must be set in flashphoner.properties file

aws_s3_credentials=zone;login;hash

Where

zone - AWS region where bucket is placed
login - Access Key ID
hash - Secret Accesss Key

S3 credentials setting example:

aws_s3_credentials=eu-central-1;AA22BB33CC44DE;DhlAkpZ4adclHhbLwhTNL4hvWTo80Njo

Digital Ocean Spaces¶

To download files from DO Spaces set the credentials as

aws_s3_credentials=ams3;access_key;secret

Where

ams3 - digitaloceanspaces.com subdomain
access_key - storage access key
secret - storage access secret code

Selectel¶

To download files from Selectel S3 set the credentials as

aws_s3_credentials=ru-1a;login;password

Where

ru-1a - storage region
login - user name
password - password

Capturing VOD stream from file while it is downloading¶

To capture stream from file while it is downloading, the following parameter should be set

vod_mp4_container_new=true

If channel bandwidth between WCS and S3 storage is low, or this channel is not stable enough, file bufferization may be enabled. The buffer size is set in milliseconds with the following parameter

vod_mp4_container_new_buffer_ms=10000

In this case, buffer size is 10 seconds.

File format requirements¶

Header section (moov) should always be before data section (mdat). File structure should be like this:

Atom ftyp @ 0 of size: 32, ends @ 32
Atom moov @ 32 of size: 357961, ends @ 357993
...
Atom free @ 357993 of size: 8, ends @ 358001
Atom mdat @ 358001 of size: 212741950, ends @ 213099951

File structure can be checked with AtomicParsley utility

AtomicParsley file.mp4 -T 1

If the file structure does not match the requiremets, this file will not be played. Wrong file structure can be fixed if necessary with ffmpeg without reencoding

ffmpeg -i bad.mp4 -acodec copy -vcodec copy -movflags +faststart good.mp4

File name requirements¶

Official AWS S3 documentation does not recommend to use spaces along another special characters, but does not prohibits them. If the file name contains spaces, they should be replaced by %20, for example

vod://s3/bucket/sample%20with%20spaces.mp4

VOD capture management with REST API¶

REST query should be HTTP/HTTPS POST request as:

HTTP: http://test.flashphoner.com:8081/rest-api/vod/startup
HTTPS: https://test.flashphoner.com:8444/rest-api/vod/startup

Where:

test.flashphoner.com - WCS server address
8081 - standard REST / HTTP port
8444 - standard HTTPS port
rest-api - mandatory part of URL
/vod/startup - REST method used

REST queries and responses¶

REST method	Request body	Response body	Response status	Description
`/vod/startup`	`{ "uri":"vod-live://sample.mp4", "localStreamName": "test" }`		200 OK 404 Not found 409 Conflict 500 Internal error	Capture VOD stream from file
`/vod/find`	`{ "localStreamName": "test" }`	`[ { "localMediaSessionId": "29ec3236-1093-42bb-88d6-d4ac37af3ac0", "localStreamName": "test", "uri": "vod-live://sample.mp4", "status": "PROCESSED_LOCAL", "hasAudio": true, "hasVideo": true, "record": false, "loop": false } ]`	200 OK 404 Not found	Find VOD streams by criteria
`/vod/find_all`		`[ { "localMediaSessionId": "29ec3236-1093-42bb-88d6-d4ac37af3ac0", "localStreamName": "test", "uri": "vod-live://sample.mp4", "status": "PROCESSED_LOCAL", "hasAudio": true, "hasVideo": true, "record": false, "loop": false } ]`	200 OK 404 Not found	Find all VOD streams
`/vod/terminate`	`{ "uri":"vod://sample.mp4", "localStreamName": "test" }`		200 OK 404 Not found	Stop VOD stream

Parameters¶

Parameter	Description	Example
uri	File name to capture	`vod://sample.mp4`
localStreamName	Stream name	`test`
status	Stream status	`PROCESSED_LOCAL`
localMediaSessionId	Mediasession Id	`29ec3236-1093-42bb-88d6-d4ac37af3ac0`
hasAudio	Stream has audio	`true`
hasVideo	Stream has video	`true`
record	Stream is recording	`false`
loop	Stream is looping	`false`

VOD looping on demand¶

Since build 5.2.1528 it is possible to enable VOD looping while creating VOD live translation via REST API

{
    "uri":"vod-live://sample.mp4",
    "localStreamName": "test",
    "loop": true
}

By default, if loop parameter is not set, vod_live_loop is applied. If the parameter is set, its value is applied as follows

true - file will be looped
false - file will be played once, then VOD live translation will stop

The loop parameter has a precedence over vod_live_loop value.

Known limits¶

/vod/startup query can be used for VOD live translations creation only. However, /vod/find, /vod/find_all and /vod/terminate queries can be applied both to VOD and VOD live translations.

VOD stream publishing timeout after all subscribers gone off¶

By default, VOD stream stays published on server during 30 seconds after last subscriber gone off, if file duration exceeds this interval. This timeout can be changed with the following parameter

vod_stream_timeout=60000

In this case, VOD stream stays published during 60 seconds.

Known issues¶

1. AAC frames of type 0 are not supported by ffmpeg decoder and will be ignored while stream pulled playback¶

Symptoms

Warnings in the client log:

10:13:06,815 WARN AAC - AudioProcessor-c6c22de8-a129-43b2-bf67-1f433a814ba9 Dropping AAC frame that starts with 0, 119056e500

Solution

Switch to FDK AAC decoder

use_fdk_aac=true

2. Files with B-frames can be played unsmoothly, with artifacts and freezes¶

Symptoms

Periodic freezes and artifacts while playing VOD file, warnings in the client log

09:32:31,238 WARN 4BitstreamNormalizer - RTMP-pool-10-thread-5 It is B-frame!

Solution

Reencode this file to exclude B-frames, for example

ffmpeg -i bad.mp4 -preset ultrafast -acodec copy -vcodec h264 -g 24 -bf 0 good.mp4

3. VOD playback may require a lot of memory¶

When VOD is captured from a long-duration file, or a number of VOD streams are captured simultaneously, server process can terminate with Out of memory

Symptoms

Server process terminates with Map failed in server log and in error*.log

19:30:53,277 ERROR DefaultMp4SampleList - Thread-34 java.io.IOException: Map failed
    at sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:940)
    at com.googlecode.mp4parser.FileDataSourceImpl.map(FileDataSourceImpl.java:62)
    at com.googlecode.mp4parser.BasicContainer.getByteBuffer(BasicContainer.java:223)
    at com.googlecode.mp4parser.authoring.samples.DefaultMp4SampleList$SampleImpl.asByteBuffer(DefaultMp4SampleList.java:204)
    at com.flashphoner.media.F.A.A.A$1.A(Unknown Source)
    at com.flashphoner.media.M.B.C.D(Unknown Source)
    at com.flashphoner.server.C.A.B.A(Unknown Source)
    at com.flashphoner.server.C.A.B.C(Unknown Source)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.OutOfMemoryError: Map failed
    at sun.nio.ch.FileChannelImpl.map0(Native Method)
    at sun.nio.ch.FileChannelImpl.map(FileChannelImpl.java:937)
    ... 8 more

Event: 1743.157 Thread 0x00007fc480375000 Exception <a 'java/lang/OutOfMemoryError': Map failed> (0x00000000a1d750b0) thrown at [/HUDSON/workspace/8-2-build-linux-amd64/jdk8u161/10277/hotspot/src/share/vm/prims/jni.cpp, line 735]

Solution

Increase maximum number of regions of virtual memory
```
sysctl -w vm.max_map_count=262144
```
Starting from build 5.2.57, set the following parameter
```
vod_mp4_container_isoparser_heap_datasource=true
```