progressive desync converting NTSC->PAL

[bkman]

Hi,

I'm trying to convert an NTSC movie to a PAL DVD, and am experiencing some difficulties. The video has already been to MPEG-2 via the avisynth script: directshowsource("blah.mp4", fps=23.976).assumefps(25)

And now I am trying to encode the audio to AC3 with behappy and timestretch(23.976->25), but I keep getting a progressive desync when the two are muxed back together.

Any ideas as to why the rate seems to differ between the audio and the video?

[Boulder]

Try with DirectShowSource("blah.mp4",fps=23.976).AssumeFPS(25,true). Open it in VDub and save the audio track as WAV. Encode this WAV file without any framerate conversions and see if the problem still exists.

[bkman]

A direct stream copy results in an unusual sample rate, that I can't encode or resample with SSRC, but using virtualdub's resampler in full processing mode I can save the wav and encode it. And it syncs correctly!

Why does it work this way, and not when I do a framerate conversion on the audio separately? Also, this method leaves the pitch uncorrected, I assume. Anything that can be done about that?

[Boulder]

You could try using Directshowsource().AssumeFPS(25,true).SSRC(48000,fast=false) but it'll still leave the pitch uncorrected.

What I do is demux the original audio track, decode to WAV and use SoundStretch (in the SoundTouch package) to do the framerate conversion, then encode to the final format. For some reason I never got the 23.976->25fps conversion working in BeSweet.

The command line syntax is simply soundstretch.exe "path\source.wav" "path\destination.wav" -tempo=4.2709376.

[bkman]

Ok, I figure if I use: assumefps(25,true).timestretch(pitch=95.904).ssrc(44100)*
and encode directly with BeHappy, that will give me a good result with about the right pitch with no intermediate files.

I can only guess the problem was that a framerate conversion just on the audio ends up at a slightly different rate than that resulting from assumefps. Thanks for the help!

* (48000 doesn't work due to acceptable ratio requirements, but resampleaudio can do it)
Edit: Crap, DVD doesn't support 41000 AC3. Will have to be resampleaudio.