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Thread: Live-Record: Audio missing at the end of some recorded files

  1. #1

    Default Live-Record: Audio missing at the end of some recorded files

    Dear Wowza team,

    we use a FMLE3.2 to encode and stream a H.264 livestream to a Wowza Media Server V3.6.2.
    The Wowza Server Application is configured as live-record and automatically records the stream data into mp4 files.

    In this scenario we have the issue, that audio data is sometimes missing during the last seconds of a recorded mp4 file.

    More precisely, we have a continuos video stream as an input signal to the Flash Media Encoder.
    The internet connection on client-side is not the best with 500kb/s (T-Com), but it seems to be stable.
    After a random time Wowza starts to record a new file although we did not stop and restart the streaming on FMLE side.
    In this discontinued file the audio seems to be missing during the last 7 seconds although the video is still be shown.

    You can find an example here: http://www.dresden.de/de/02/030/stad...zung-live3.php

    My colleague has the idea that it might be an out-of-sync issue where the gap between audio and video data gets too high so that it still shows the buffered video-data whereas the audio data is missing and then starts a new publishing of the resnyced stream. Could this be the case or is that unlikely? What can we do to prevent this behavior?

    I thought of something like http://www.streaminglearningcenter.c...-playback.html, but this doesn't seem to be the case.

    Configuration is as follows





    Thanks in advance

    André

  2. #2
    Join Date
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    André,

    If there are two recordings, that indicates the connection was broken. You should see that in logs on both sides. FMLE will start trying to reconnect right away. That indicates a network issue, and your confidence in the encoder's connection doesn't seem very high. Wowza will not break recordings in this configuration unless the stream is stopped and started, either on purpose or because of network problems.

    Richard

  3. #3

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    Thanks Richard for your reply.

    Do you have any clue why we still have some seconds video at the end of such an interrupted file but no audio?
    How does the Wowza media server behave in such a case? I would expect that if the internet connection is interrupted the recorded file would be finished immediately as well, or does Wowza (for example) start to empty all buffers and uses all remaining data that could be delivered to the client (so to the record result).

    André
    Last edited by saxonytv; 04-02-2014 at 12:23 AM.

  4. #4
    Join Date
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    André,

    One reason in this case, using Flash as the live encoder, might be the audio is not loud enough for the default Microphone silence level. Take a look at this article.

    Otherwise, network issues, as seems indicated here, can be the cause. Audio and video are streamed separately, so there are many scenarios where audio and video are out of sync, or in your case missing for some period as the result of network problems upstream from Wowza, which just reflects and records the stream it gets.

    Richard

  5. #5

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    Thanks.

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