Can I decimate duplicate frames to get 23.976

[MagicSparky]

Hi all,

I have a WMV File (progressive) with 29.976fps framerate. I want to convert it to an intermediate AVI file (huffyuv) cut it, and later convert to MPEG2.

After I frameserved it with Avisynth (DirectShowSource() without fps and convertfps) into Virtualdub and stepped through it, I saw many duplicate frames in the following pattern:

1+2 duplicates - 3,4,5,6 ok - 7+8 duplicates - 9,10,11,12 ok

... and so on.
All frames are progressive.
Can I decimate them to get a 23.976fps file? If yes, how to do it?

[Midzuki]

Hi there.

1+2 duplicates - 3,4,5,6 ok - 7+8 duplicates - 9,10,11,12 ok

does look like a 25fps --> 30fps conversion.

I have a WMV File (progressive) with 29.976fps framerate.
I want to convert it to an intermediate AVI file (huffyuv) cut it,
and later convert to MPEG2.

Avisynth will allow you to do a direct conversion from wmv to mpg.

Be most careful about the wma audio track.
Normally Avisynth's "(DSS, fps=nn.mmm, convertfps=true)" is sufficient to avoid
aud-vid sync problems, but there are some cases in which even "convertfps=true"
will not work ( https://forum.videohelp.com/topic346029.html ).

[MagicSparky]

Thanks Midzuki,

yes, I know I can convert directly with Avisynth - but I want to cut it a little bit with Vegas.
I tried this already:

DirectShowSource("test.wmv", fps=23.976, convertfps=true)

The audio is perfectly in sync with video. Can I do the same with Decimate(cycle=?) in Avsynth? Just want to now...

[Midzuki]

I tried this already:

DirectShowSource("test.wmv", fps=23.976, convertfps=true)

The audio is perfectly in sync with video.

Fortunately you're not dealing with HD p0rn.

Anyway... if your goal is to get a 23.976fps video, I think Decimate()
is not the best way to do it (in this particular case, I mean).
IIWY, I would use "SelectEvery" to obtain 25.000/24.975 fps,
then would call "AssumeFPS(24000, 1001, sync_audio=true)" plus
"ResampleAudio(48000)". HTH.

[manono]

If the framerate's 24.975fps, you can't make it 23.976fps without either making it play jerky or slowing the video, necessitating doing the same with the audio (Midzuki's plan). If you really have one duplicate frame in 6 (instead of 5), then the correct decimation when using Decomb's Decimate filter is:

Decimate(6)

[MagicSparky]

Thank you Midzuki and manono,

By the way, I made a typo (Virtualdub's first frame = 0):

1+2 duplicates - 3,4,5,6 ok - 7+8 duplicates - 9,10,11,12 ok

should be:

0+1 duplicates - 2,3,4,5 ok - 6+7 duplicates - 8,9,10,11 ok - 12,13 duplicates

I'll try it your suggestions. Thanks again!