Web Call Server 5.1 - EN
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WCS can capture an RTMP video stream published by another server, by request. The captured stream can be broadcast to any of supported platforms using any of supported technologies. Managing of RTMP stream capturing is performed using REST API.

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A REST-query must be an HTTP/HTTPS POST request as follows:

  • - HTTP: http://test.flashphoner.com:

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  • 8081/rest-api/pull/rtmp/pull
  • - HTTPS: https://test.flashphoner.com:

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  • 8444/rest-api/pull/rtmp/pull

Where:

  • - test.flashphoner.com - is the address of the WCS server
  • -

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  • 8081 - is the standard REST / HTTP port of the WCS server
  • - 

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  • 8444 - is the standard HTTPS port
  • - rest-api - is the required part of the URL
  • - /pull/rtmp/pull - is the REST method used

REST-methods and response statuses

REST-method

Example of REST-query

Example of REST response

Response status

Description

/pull/pull

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{  
   "uri":"rtmp://myserver.com/live/myStream",
   "record": "true"
}

409 - Conflict

500 - Internal error


Pull the WebRTC stream at the specified URL


/pull/find_all


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{
"localMediaSessionId": "5a072377-73c1-4caf-abd3",
"remoteMediaSessionId": null,
"localStreamName": "rtmp://myserver.com/live/myStream",
"remoteStreamName": null,
"uri": "rtmp://myserver.com/live/myStream",
"status": "PROCESSED_REMOTE"
}

200 – streams are found

500 - Internal error

Find all pulled WebRTC streams

/pull/terminate

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{  
   "uri":"rtmp://myserver.com/live/myStream"
}

200 - stream terminated

500 - Internal error

Terminate the pulled WebRTC stream

 Parameters

Parameter name

Description

Example

uri

URL of the WebRTC stream

wss://demo.flashphoner.com:8443

localMediaSessionId

Session identifier

5a072377-73c1-4caf-abd3

remoteMediaSessionId

Session identifier on the remote server

12345678-abcd-dead-beaf

localStreamName

Local name assigned to the captured stream. By this name the stream can be requested from the WCS server

testStream

remoteStreamName

Captured stream name on the remote server

testStream

status

Current stream status

NEW

Configuration

In the /usr/local/FlashphonerWebCallServer/conf directory you can find the SDP description file for the RTMP agent rtmp_agent.sdp:

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Below is the call flow when capturing an RTMP stream from another server

Known issues


Excerpt

1

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. A stream containing B-frames does not play or plays with artifacts (latencies, lags)

Symptoms:

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  • a stream sent by the

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  • RTMP encoder does not play or plays with latencies or lags
  • warnings in

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

Solution:

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change the encoder settings so, that B-frames were not used (lower encoding profile, specify in the command line etc).

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

In this case, warnings will be displayed in the client log:

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

Solution: use Fraunhofer AAC codec with the following parameter in flashphoner.properties file

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use_fdk_aac=true

3. When publishing and then playing and recording H264 + AAC stream video may be out of sync with sound, or no sound at all.

Symptoms: when playing H264 + AAC stream published on server, and when recordingsuch stream, sound is out of sync with video or absent

Solution:

a) set the following parameter in flashphoner.properties file

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disable_drop_aac_frame=true

This parameter also turns off AAC frames dropping.

b) use Fraunhofer AAC codec

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use_fdk_aac=true

4. Sound may be distorted or absent when resampled to 11025 Hz

Symptoms: when H264 + AAC stream published on WCS server is played with AAC sample rate 11025 Hz, sound is distorted or absent

Solution: do not use 11025 Hz sample rate, or escape AAC sound resampling to this rate, for example, do not set this sample rate in SDP settings.


5. Some RTMP functions does not supported and will be ignored:

  • FCSubscribe
  • FCPublish
  • FCUnpublish
  • onStatus
  • onUpstreamBase
  • releaseStream

6. When recording the captured stream to the disk, only audio is recorded

Symptoms: when the "record": "true" parameter is set in the /pull/rtmp/pull REST query, the received file lacks video track, only audio is present.
Solution: in the SDP setting set the SDP settings set the

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a=sendonly

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