Recording: Audio processing changes to reduce audio desync #11683
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This gives the following advantages over the previous code: * The ffmpeg input filters are loaded from a filter "script" file instead of passed on the command line. This fixes some cases of recordings failing to process because the ffmpeg command line generated for the audio processing exceeded the max command line length limit. (Although that only really happens due to BBB bugs...) * Use absolute positions when trimming audio segments for cuts. Previously segments were trimmed to the length of the segment, and the results were concatenated. There's some possibility of accumulated errors in the segment lengths causing audio desync over time. The new code incrementally concatenates the segments, and cuts each segment end based on the absolute time since the start of the meeting, to avoid error accumulation.
This incorporates only the audio desync related changes from bigbluebutton#11626 * Add the aresample filter with async option to fill in timestamp gaps * Use the libopus decoder for opus audio instead of ffmpeg's builtin decoder
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Have you implemented this solution also on 2.2.x releases? I have desync problems between audio and video on recordings with BBB 2.2.31 |
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This won't be back ported. Ubuntu 16.04 (which is the basis for 2.2.x) is nearing end of life and the project is moving to 18.04 which is the basis for BigBlueButton 2.3. |
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But you have release BBB 2.2.36 only 26 days ago! If I upgrade my BBB cluster from 2.2.31 to 2.2.36 I will solve my desync problem on recordings? It's not possible a new versione 2.2.37 also with this desync fix? A lot of university use BBB 2.2.x and have this problem with lessons recordings and students and professors aren't happy |
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@flowerpower I suggest building a 2.3 server, take the raw archives from a "bad" out of sync recording. And process it with bbb record --rebuild to see if there is improvement. 2.3 RAP processing, is faster and can do many recordings in parallel.. if you are a large university getting all your recording processed in a separate pipeline could get you recordings quicker and allow bbb server to focus on meetings |
This PR incorporates two changes related to audio sync issues:
aresamplefilter with the async option to fill in timestamp gaps in the source audio, and prefer using the libopus decoder on opus input files. These changes were completely independent of the screenshare audio feature, and should be applied to all audio streams.