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  1. Source: Field-Blended PAL DVD

    Process: MeGUI + AVISynth using QTGMC + Srestore. After processing, I combine video and original (PCM) audio using MeGUI's Adaptive Muxer.

    Result: 23.976 fps progressive video + original PCM audio.

    Issue: A/V out of sync. For each video (primarily 4 to 6-minute music videos, so far) result, I'm ending up with a video stream that is slightly longer duration than the audio stream, by .2 to .3 seconds, and the audio-visual sync is visibly delayed.

    Does this duration discrepancy possibly have something to do with the final result being 23.976 fps when in fact it should be 24 fps? While the percentage of discrepancy between A/V on my outcome files isn't exactly the same, it's aweful close to the duration discrepancy between 23.976 and 24.

    thanks in advance~
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  2. One stream being longer than the other does not say anything about a/v sync. How much does the sync differ? How are you measuring said difference? What does your script look like? How are you demuxing the streams? What parameters are you setting for muxing?
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  3. Originally Posted by sneaker View Post
    One stream being longer than the other does not say anything about a/v sync. How much does the sync differ? How are you measuring said difference? What does your script look like? How are you demuxing the streams? What parameters are you setting for muxing?
    @sneaker, thanks for the quick reply. On one 6-minute music video, .230 seconds duration discrepancy, as measured by Subler on my Mac after converting on PC. As for measuring a/v sync discrepancy, I can't say, but I'd guess by a similar amount. I'm only able to subjectively view the video and I can see that the audio and video are offset. I don't know of a way to measure.

    Script: (something similar to below... not in front of my PC to check order, right now. I'll verify in a bit and edit if I'm offf)

    SetMTmode (5)
    DGIndex (with all of it's default scripting after indexing...)
    <input>
    QTGMC ()
    Srestore ()

    I'm not actively demuxing, other than in MeGUI's pane the Queue for the video and the Queue for the audio are separate tabs... once I run the video Queue I end up with the various streams, and then I go straight to the Adaptive Muxer in MeGUI and combine the video with the original audio that was automatically demuxed. I'm not using any settings, per se, that I know of - just whatever Adaptive Muxer does, on it's own/by default.

    apologies if I'm misunderstanding some of your questions. ...still pretty newb to all of this.
    Last edited by U2Joshua; 17th Dec 2016 at 11:54.
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  4. QTGMC().SRestore() does not change the running time of the video. The audio and video in an A/V file don't have to start at the same time, nor do they have to be the same length.

    Do the audio and video start out in sync then get progressively out of sync? Or is the audio out of sync by the same amount over the entire video. If the latter, all you need to do is add an audio delay/advance when you mux.
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  5. Originally Posted by jagabo View Post
    QTGMC().SRestore() does not change the running time of the video. The audio and video in an A/V file don't have to start at the same time, nor do they have to be the same length.

    Do the audio and video start out in sync then get progressively out of sync? Or is the audio out of sync by the same amount over the entire video. If the latter, all you need to do is add an audio delay/advance when you mux.
    Thanks, @jagobo... hard to know, for sure. I'm thinking it's off to the same degree from beginning to end - not progressively worse throughout. That said, I know Subler allows to make manual offset changes (I've done this before), but it can be a very frustrating exercise trying to manually adjust. I don't feel like I can ever get it right... any tips/tricks?
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  6. DgIndex names the audio it extracts with the audio delay as part of the name (a negative delay indicates and advance). For example:

    Code:
    Brunette T80 2_0ch 256Kbps DELAY -37ms.ac3
    That's sometimes wrong because the audio skew can change in a VOB set. When it's wrong all you can do is determine the delay manually, as you're doing with Subler. Many media players (MPCHC, for example) have similar audio skew setting you can use. Once you have the correct delay all you need to do is remux the video and audio with the that delay.
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  7. Got it. Thanks for your help.
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