ZiNgA BuRgA Wrote:Basically, after conversion and muxing, the audio and video, at first, are fine, but slowly desynch as you go into the video.

The typical cause for the above is bad framerate, however, this is not the case here (and since AVI doesn't support VFR last time I checked...), interestingly enough.

AVI doesn't naturally support VFR, but people have been able to implement VFR into AVI anyway. (I think by sticking null chunks for missing frames.)

It screams VFR or incorrect FR to me. But I have never dealt with VFR material before, so I really have no experience regarding that, and know next to nothing about the characteristics and behavior of VFR material when encoding.

Maybe upload a video sample?

ZiNgA BuRgA Wrote:I put the video through an AVS script, which is basically a DirectShowSource, and pass it onto x264.  Playing the AVS file works fine, which suggests the problem lies in x264.

ZiNgA BuRgA Wrote:I'm converting the video with VirtualDubMod, then converting with x264 - this works fine, though two conversions isn't the most convenient, and I'm somewhat stumped as to why I'm getting these dodgey results.

Both these suggest the problem lies with x264. (yeah, repeating what you said...)

ZiNgA BuRgA Wrote:Some things I've tried:
- I tried AVISource instead, but the synch was worse?
- Added AssumeFPS(23.976) / ChangeFPS(23.976) / ConvertFPS(23.976) to the AVS file, all to no avail

As Squee suggested, you can try ffmpegsource. But even if it works, that just dodging the problem.

If it's really VFR, assumeFPS won't fix anything. ChangeFPS and ConvertFPS should maybe? fix the problem, as they try to add, blend or decimate frames to make the video into a constant bitrate. But that's only if the video is recognized properly as VFR in the first place.

Again, no VFR experience here. I've only used change/convertFPS for CFR material before, so don't take what's said above as definite in any case.