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Thread: PCMU depacketizer and packetizer

  1. #1
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    Default PCMU depacketizer and packetizer

    The stream coming into my media server is H264 + PCMU over RTSP.

    Wowza drops the audio track because it doesnt know how to depacketize PCMU from the RTSP stream (warning reported: "Failed to find an appropriate depacketizer for this track (PCMU)").

    However I know that for the same stream (H264 + PCMU) coming into the media server over RTMP, the audio track is not dropped, and can reach a RTMP client without any problem.

    Similarly, if the stream comes in the media server over RTMP, but a client request the stream over RTSP, wowza drops the audio because it doesnt know how to packetize PCMU for RTSP (warning reported: "RTPPlayer.describe: No audio packetizer[8]: G711_MULAW").

    Why is that? Why can Wowza handle the same content fine over RTMP but not with RTSP?

  2. #2
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    Hi,
    PCMU is not currently supported for RTSP output.
    I will pass on to our product management team that you are interested
    in getting this added to the product. Currently there isn't a time frame
    for adding this.

    Daren

  3. #3
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    What about RTSP input?
    Support for both input and output are equally important.

  4. #4
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    Hi
    It is already supported for RTSP input, which is why it works with RTMP playback, and why the transcoder is able to decode and convert to AAC.

    Daren

  5. #5
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    As far as i can tell, no, it is not supported for RTSP input.

    As reported in my original post, when the stream coming into my media server is H264 + PCMU over RTSP, wowza drops the audio track because it doesnt know how to depacketize PCMU from the RTSP stream (warning reported: "Failed to find an appropriate depacketizer for this track (PCMU)").

    If Wowza has the capability to depacketize PCMU over RTSP, please explain why I get the warning mentioned, and explain how to enable this capability.

  6. #6
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    Hi,
    Try adding the 'rtspFilterUnknownTracks' property given in this guide.

    Daren
    Last edited by daren_j; 03-17-2015 at 12:24 AM.

  7. #7
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    Interesting, filtering unknown tracks does work. It appears that my source has 3 tracks; video, audio, and application. It is odd that having an extra track creates problem to the depacketizer of the audio track.

    Ive noticed that Wowza 4.1.2 is using the RTPDePacketizerG711ALaw module, eventhough the track is MuLaw. Im guessing the module is general enough to handle both variants? Anyhow, it does work. I get a H264 + PCMU stream over RTSP in the media server, and a RTMP client can play both H264 and PCMU tracks.

    However with Wowza 2.2.4, even after filtering unknown tracks, the audio track does not go through.
    Ive noticed that Wowza 2.2.4 has a RTPDePacketizerG711ALaw module, but is not selected to handle the audio track. Could it be that this version of the depacketizer does not handle PCMU? Is there a way to handle depacketization of PCMU with Wowza 2.2.4?

  8. #8
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    Hi,
    Glad that it's resolved for you with that property in 4.1.2.
    If that property doesn't work in 2.2.4, unfortunately there really isn't anything else, and was likely fixed in a later release.

    Daren

  9. #9
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    To be more accurate, in Wowza 2.2.4, the property "rtspFilterUnknownTracks" does work; it does filter problematic tracks from a source. However, when unknown tracks are not an issue, Wowza 2.2.4 is not able to handle incoming PCMU tracks. Hence why I asked if there is a way to handle depacketization of PCMU with Wowza 2.2.4?

  10. #10
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    Hi,
    There isn't a way, sorry.

    Daren

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