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  1. I have a question. If I have a couple of links to m3u8's and when I go to download the video, the audio is out of sync or late. Is there a reason for this? The original stream is fine, video seems to have no glitches, just a problem with the sound being off. Just curious if anyone has run into this or know how to fix?
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  2. Originally Posted by sharknamedpeppy View Post
    I have a question. If I have a couple of links to m3u8's and when I go to download the video, the audio is out of sync or late. Is there a reason for this? The original stream is fine, video seems to have no glitches, just a problem with the sound being off. Just curious if anyone has run into this or know how to fix?
    My ISP's TV streaming website also has this problem.
    I just fix the audio afterwards with ffmpeg
    Code:
    ffmpeg.exe -i "movie.mp4" -itsoffset 1.00 -i "movie.mp4" -map 0:v -map 1:a -c copy "movie-audio-delayed.mp4"
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  3. Average video editor Sviests's Avatar
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    Originally Posted by sharknamedpeppy View Post
    I have a question. If I have a couple of links to m3u8's and when I go to download the video, the audio is out of sync or late. Is there a reason for this? The original stream is fine...
    This could be PTS (presentation timestamp) .PTS is used to achieve synchronization of the audio+video (since most likely they are separate streams). I've had some cases where sound is delayed for a bit,but the offset feature for FFMPEG as mentioned in post above can fix this.

    Most commonly the issues i had was with aac audio streams,where extracting them would give me different durations (eg. video gives 2min,audio gives 1min 58sec).
    Simply extracting them with a custom .m4a container (the codec still stays aac) separately and then merging with video solved that issue for me too.

    In rare cases there's something with segment sizes (both audio and video match the segment sizes,but number of segments are different),but that more translates of out of sync in the manifest playback,not extracted file.
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  4. I have a question. If I have a couple of links to m3u8's and when I go to download the video, the audio is out of sync or late. Is there a reason for this? The original stream is fine, video seems to have no glitches, just a problem with the sound being off. Just curious if anyone has run into this or know how to fix?
    For a video file you have downloaded, if the audio is out of synch at the same rate from start to finish.

    If you aren't confident with Ffmpeg from the command line you can fix audio synch issues in Avidemux (free app)

    Load video by using the Open function or drag n' drop Video in question into the window.

    1. Select Copy Video
    2. Select Copy audio
    3. Tick the Shift Box. Depending if audio is before or after lip movement - enter positive or negative value here (with a minus sign if negative). Value is in milliseconds so 1000ms = 1 second
    4. SAVE

    Experiment till you get it correct.

    Image
    [Attachment 58812 - Click to enlarge]
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  5. What if the audio in the very beginning of the mp4 is in sync, but then around 3-4 minutes after playing it becomes out of sync? Does that mean if I try and extract the audio and use FFmpeg, it may not work due to the fact is was correct in the beginning and later messed up? It's a little squirrely, I've never taken down an mp4 and have the source glitched like that.

    I could provide the two links to the m3u8's, so someone else might see what I'm talking about. But I'd rather it be through DM for that, as I don't think I could post them publicly.
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  6. Originally Posted by sharknamedpeppy View Post
    What if the audio in the very beginning of the mp4 is in sync, but then around 3-4 minutes after playing it becomes out of sync? Does that mean if I try and extract the audio and use FFmpeg, it may not work due to the fact is was correct in the beginning and later messed up? It's a little squirrely, I've never taken down an mp4 and have the source glitched like that.

    I could provide the two links to the m3u8's, so someone else might see what I'm talking about. But I'd rather it be through DM for that, as I don't think I could post them publicly.
    Then cut the video in parts, fix the out of sync one only, merge it with the part that's correct.
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  7. Without going into too much detail, was it a 'Live' source (?) or something that can be grabbed again - a VOD for instance ? If it can be grabbed again, and hope for better luck, then that would be much simpler than any convoluted editing solutions.
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  8. Originally Posted by codehound View Post
    Without going into too much detail, was it a 'Live' source (?) or something that can be grabbed again - a VOD for instance ? If it can be grabbed again, and hope for better luck, then that would be much simpler than any convoluted editing solutions.
    I tried both Live and VOD. They both issued the same result.
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