Audio Sync Issues on 23.976/29.970

[Arlong]

Hello,

I hope this is the correct section for my question and this thing has not been discussed before!

Here's the problem: I ripped the movie "Final Fantasy VII: Advent Children" from the R1 DVD version - frame rate is 29.970. AVS script is simple:

mpeg2source("D:\FINAL_FANTASY_VII\VIDEO_TS\ff7.d2v", idct=5)
tfm(d2v="ff7.d2v",order=-1,mode=6,PP=6,slow=2,micmatching=2,sco=0,cthresh=8,chroma=true,MI=64)
tdecimate(mode=1,hybrid=1)

...followed by Crop and Resize, that's all. I think the IVTC process went fine, 'cause video is playing smooth and frame rate is 23.976. Movie length in 29.970FPS is 01:30:33, but in 23.970FPS is 01:26:50. I thought the change in duration was pretty obvious, since the variation of number of frames in a second... but now I'm not so sure, because audio remains 01:30:33 no matter what.
Video and audio can't have two differents length, and indeed muxing audio on 23.976 video introduce a costant desync.
I heard that an IVTC process doesn't need an audio stretching, because

using IVTC to get 23,976fps won't change the length of the video and/or the audio.

Sound comforting, but what did I do wrong? Maybe the decimation process is not suitable for my source? DGIndex says "98% FILM".

I'd like to apologize if my question may sound stupid, but I'm a total noob with those issues. Please help me! :thanks:

[Guest]

I'm not that familiar with tritical's stuff, but if it's 98% film, why do you have hybrid=1 on TDecimate()? Try removing that.

[Arlong]

Thanks for your attention neuron2 ^_^

So here's a very strange thing I really can't explain by myself: my previous encode (with the "hybrid=1" thing) was done in x264. Following your advice, I removed "hybrid=1" and I trimmed the first 10.000 frames to ensure the desync was gone (an XviD encoding, just to gain some speed). It was ok.

My AVS turned into this:

mpeg2source("D:\FINAL_FANTASY_VII\VIDEO_TS\ff7.d2v", idct=5)
tfm(d2v="ff7.d2v",mode=6,PP=6,slow=2,micmatching=2,sco=0,cthresh=8,chroma=true,MI=48,display=false)
tdecimate(mode=1)

ColorMatrix(d2v="ff7.d2v")

crop(4,2,712,476,true)

LanczosResize(640,352)

RemoveGrain(mode=2)

Then I launched the final encode with meGUI, x264, automated 2pass, HQ-Insane preset - just like the first, wrong encode. I ended up with the same result: length was 01:26:50. Damn.
At this point I tried a single pass (Q=2) with XviD in VDM, with the very same AVS posted before, the same used for the x264 encoding. The resulting AVI is 01:30:33 just as it has to be.

Is my PC cursed or something? :confused:
Why XviD does "well" and x264 does "bad" even if AVS script is the same and codec's settings don't manage FPS?

PS: meGUI has a default checkmarked option in its settings window ("DGIndex") that says "Auto Force Film at 95 Percent". Could it be involved? :scared: