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.
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:
where sample.mp4 - is the name of the file that should be located in the /usr/local/FlashphonerWebCallServer/media/ directory.
If a file with such a name does not exist, the server returns the StreamStatusEvent FAILED message, where the "info" field has the reason: "File not found".
A stream created this way can be displayed to one user (personal VOD). If a full-featured online-broadcast is required, provide the link to a file as follows:
Multiple user can connect to such a stream simultaneously.
Supported formats and codecs
- Container: MP4
- Video: H.264
- Audio: AAC
- The browser connects to the server via Websocket and sends the publish 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 play command.
- The second browser receives the WebRTC stream and plays this stream on the page.
Quick manual on testing
1. For the test we use the Player web application to play the file.
2. Upload the file to the /usr/local/FlashphonerWebCallServer/media/ directory.
3. Open the Player web application and enter the name of the file in the Stream field:
4. Click Start. The file starts playing:
5. Click Stop to stop the playback.
6. Delete the file from /usr/local/FlashphonerWebCallServer/media/
7. Click Start. You should see the FAILED status and the "File not found" message:
Below is the call flow when using:
the Stream Recording example to publish the stream and record the file
the Player example to play the VOD stream
1. Establishing a connection to the server to publish and record the stream.
2. Receiving from the server an event confirming successful connection.
ConnectionStatusEvent ESTABLISHED code
3. Publishing the stream with recording enabled.
4. Receiving from the server an event confirming successful publishing of the stream.
StreamStatusEvent, status PUBLISHING code
5. Sending audio and video stream via WebRTC.
6. Stopping publishing the stream.
7. Receiving from the server an event confirming unpublishing of the stream.
StreamStatusEvent, status UNPUBLISHED code
8. Establishing a connection to the server to play the stream.
9. Receiving from the server an event confirming successful connection.
ConnectionStatusEvent ESTABLISHED code
10. Playing the stream.
11. Receiving from the server an event confirming successful playing of the stream.
StreamStatusEvent, status PLAYING code
12. Receiving of the audio-video stream via Websocket and playing it via WebRTC
13. Stopping publishing the stream.
14. Receiving from the server an event confirming successful stopping of the playback of the stream.
StreamStatusEvent, status STOPPED code
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 capturing from AWS S3
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:
- bucket is S3 bucket name
- sample.mp4 is file name
1. Browser requests VOD capture from AWS file
2. WCS server sends request to AWS
3. File is downloaded to WCS server
4. WebRTC stream from file is sending to browser for playback
To download files from AWS S3 bucket, S3 credentials must be set in flashphoner.properties file
To capture stream from file while it is downloading, the following parameter should be set
File format requirements
Header section (moov) should always be before data section (mdat). File structure should be like this:
File structure can be checked with AtomicParsley utility
Wrong file structure can be fixed if necessary with ffmpeg without reencoding
VOD capture management with REST API
REST query should be HTTP/HTTPS POST request as:
- 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 query example
REST response example
409 - Conflict
500 - Internal error
Capture VOD stream from file
200 – OK
404 – not found
Find VOD streams by criteria
200 – OK
404 – not found
Find all VOD streams
200 - Stream is stopped
404 - Stream not found
Stop VOD stream
File name to capture
|Stream has audio
|Stream has video
|Stream is recording
/rest-api/vod/startup query can be used for VOD live translations creation only. However, find, find_all and 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
In this case, VOD stream stays published during 60 seconds.
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:
Solution: switch to FDK AAC decoder
2. Files with B-frames can be played unsmoothly, with artifacts and freezes
Symptoms: periodic freezes and artifacts while playing VOD file, warnongs in the client log
Solution: reencode this file to exclude B-frames, for example
3. When VOD is captured from a long-duration file, server process can terminate with Out of memory in case of exceeding maximum number of regions of virtual memory (vm.max_map_count)
Symptoms: server process terminates; "Map failed" in server log and in error*.log
Solution: increase maximum number of regions of virtual memory