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  1. Hello.
    I have two different avi files of the same film (two different vhsrips of an otherwise unavailable film). One of the files features better quality video, but it has mp3 audio. Conversely, the lesser quality video file has ac3 audio. What I'd like to do (and have been trying to do) is mux the better quality video with the ac3 track. However the 2 video files have a 2 second difference. Is it possible to sync them both (adding some sort of delay until the video track begins) and then mux them together?

    Thanks.
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  2. Member Wolfen's Avatar
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    Yah, Just demux the sound off the avis with virtualdub, Save somewhere you remember and mux the sound back to them, which ever one you want. There is a preview and time setting to sync the audio.
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  3. I'll give that a go. Is there anywhere that will show me the exact timing (including milliseconds) so that I can mux it perfectly?

    Thanks!
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  4. Member Wolfen's Avatar
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    To tell you the truth I've never had to sync audio but I know it can be done with virtualdub it can pretty well do almost anything to video. I know in the preview it has the frame by frame view. But anyway just ask around here, there is always help here for anything to do with video.
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  5. I'll keep at it. Might be worth comparing the times and adding silence in Audacity to make up the difference.
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  6. Had a go at it, I got it to sync (with virtualdub) at the start but it seemed to drop out of sync at various points in the film. I'll have to find another method.
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  7. Member Safesurfer's Avatar
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    Maybe try Syncview.
    "Just another sheep boy, duck call, swan
    song, idiot son of donkey kong - Julian Cope"
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  8. Will give it a go, thank you.
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  9. Member AlanHK's Avatar
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    Originally Posted by architectofpain
    I have two different avi files of the same film (two different vhsrips of an otherwise unavailable film). One of the files features better quality video, but it has mp3 audio.
    The AC3 is not necessarily better quality, especially if both are from VHS.
    Look at the audio rate.
    If you do a blind trial, can you really tell the difference?
    And if you edit the audio, it will be decoded and reencoded, so the original format won't matter.
    (Except if you use Delaycut, which can cut AC3 or add a delay losslessly.)

    A fuzzy source encoded at a high rate is still fuzzy.

    If there is static or hum, you might import into Audacity.
    The latest version has a much improved noise filter. Also it can use ffmpeg to import and export most formats, including AC3.
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  10. The audio bitrate of the AC3 file is 256 kbps while the mp3 file is 128 kbps.

    I'll try Delaycut, as it seems to be able to do what I am trying to do.

    EDIT:

    Here are both sets of file information (it seems I may have ripped the ac3 file to 320 kbps, depending on what happens I can just rip it again.) maybe the information will reveal why it didn't sync the first time?

    ====== INPUT FILE INFO ========================
    File is ac3
    Bitrate (kbit/s) 320
    Act rate (kbit/s) 320.000
    File size (bytes) 218063238
    Channels mode 2/0: L+R
    Sampling Frec 44100
    Low Frec Effects LFE: Not present
    Duration 01:30:51.580
    Frame length (ms) 34.800000
    Frames/second 28.735632
    Num of frames 156654
    Bytes per Frame 1392.0000
    Size % Framesize 870
    CRC present: YES
    =============================================
    ====== TARGET FILE INFO ======================
    Start Frame 0
    End Frame 156653
    Num of Frames 156654
    Duration 01:30:51.559
    NotFixedDelay 0.0000
    =============================================

    ====== INPUT FILE INFO ========================
    File is mpeg 1 layer 3
    Bitrate (kbit/s) 128
    Act rate (kbit/s) 128.000
    File size (bytes) 87253159
    Channels mode Joint Stereo
    Sampling Frec 44100
    Low Frec Effects LFE: Not present
    Duration 01:30:53.322
    Frame length (ms) 26.122449
    Frames/second 38.281250
    Num of frames 208760
    Bytes per Frame 417.9592
    Size % Framesize 200239
    CRC present: NO
    =============================================
    ====== TARGET FILE INFO ======================
    Start Frame 0
    End Frame 208759
    Num of Frames 208760
    Duration 01:30:53.322
    NotFixedDelay 0.0000
    =============================================

    Keeping in mind that the video associated with the mp3 file is to be the video source while the ac3 file is to be the audio source.

    Thanks.
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  11. Member AlanHK's Avatar
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    Originally Posted by architectofpain
    Sampling Frec 44100
    DVD has to be sampled at 48000. You're going to have to reencode anyway to do that.
    How are you making your "output" AC3?
    It probably has a sampling setting.

    Originally Posted by architectofpain
    I may have ripped the ac3 file to 320 kbps,
    No point having a higher output rate than your input. Wastes space you could use for improving video rate.
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  12. Originally Posted by AlanHK
    Originally Posted by architectofpain
    Sampling Frec 44100
    DVD has to be sampled at 48000. You're going to have to reencode anyway to do that.
    How are you making your "output" AC3?
    It probably has a sampling setting.
    I used AoA Audio Extractor. It has an ac3 setting.

    Originally Posted by AlanHK
    Originally Posted by architectofpain
    I may have ripped the ac3 file to 320 kbps,
    No point having a higher output rate than your input. Wastes space you could use for improving video rate.
    Yeah, I know this now. AoA Audio Extractor also allows you to choose the sample rate so I'll rerip the ac3 file to 256 and change the sample rate to 48000.

    Thanks.
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  13. I've been able to solve this, it was just a timing issue. Virtualdub did the trick just fine!
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