Changes between Version 7 and Version 8 of Ticket #2210, comment 6


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Timestamp:
Jan 31, 2013, 4:19:27 AM (3 years ago)
Author:
agni451
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  • Ticket #2210, comment 6

    v7 v8  
    11I have to use async because I do not re-encode the video and audio together (I need to pass the video through Avisynth with QTGMC for deinterlacing, and I need to pad the end of the audio to match the video length).  With TV streams, there are sometimes the odd gap in the audio stream.  It plays fine as a TS because the timecodes keep it in line.  When the video and audio streams are separated, re-encoded separately, and then muxed back together (in my case, in an mkv file) any gaps in audio disappear and this leads to the audio becoming increasingly out of sync with each error.  I need to insert silence for those gaps to keep the audio in sync, and async does that for me.  Unfortunately, it seems to be confused by the change in audio channel layout and adds far more than it should.  Like I said, this generally happens during the commercials, but it has occurred during the actual program. 
    22 
    3 As for the file I provided, it really only demonstrates the audio change confusion, but not really why I use async.  According to ffprobe, there ''is'' a gap in the audio of 32ms just as it changes from stereo back to 6ch.  If you were to demux the TS file and remux into mkv for example, that gap would disappear and the rest of the clip would be 32ms out of sync.  That might not be noticeable, but I've seen gaps of 768ms, which would be a huge problem.  Even half a dozen 32ms gaps spread over a clip would cause real sync problems by the end, so I need to fill those gaps with silence as they come.  Async works very well for that (usually). 
     3As for the file I provided, it really only demonstrates the audio change confusion, but not really why I use async.  According to ffprobe, there ''is'' a gap in the audio of 32ms just as it changes from stereo back to 6ch.  If you were to demux the TS file and remux into mkv for example, that gap would disappear and the rest of the clip would be 32ms out of sync.  That might not be noticeable, but I've seen gaps of 768ms, which would be a huge problem.  Even half a dozen 32ms gaps spread over a clip would cause real sync problems by the end, so I need to fill those gaps with silence as they come.  Async works very well for that (except in this case).