Converting 23.976 to 25fps [WAS: Re: [MPlayer-users] 3:2 pulldown]

[Martin Emrich]

On Sun, 11 Jan 2004 18:44:11 +0100
"Robert R. Wal" <rrw at hell.pl> wrote:

> On 04.01.10 Martin Emrich pressed the following keys:
> 
> > Hi!
> > 
> > Am Fr, den 09.01.2004 schrieb Martin Emrich um 17:20:
> > > [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> > > Hi!
> > > 
> > Took the original AVI, recoded it to very-high-bitrate MPEG4 with PCM
> > audio (Hacking the audio sample rate on the origial with MP3 audio didnt
> > work), plays fine, with no visible quality loss.
> > 
> > Then I hacked the header to an audio sample rate of 45983Hz
> > (44100*(25/23.976)). (I hacked the videe frame time to 0.0400sec =
> > 0x9c40, too, but mplayer didn't care, uses still 23.976fps; wonder where
> > it gets this number from...). 
> 
> The problem is your expression. Think for a moment: you want to play the
> sample faster and be perceived as 44100, so obviously the frequency has
> to be lower. So the expression is 44100 * (23.976/25). 

Actually, we did the same thing. You went from 42294 to 44100, I did from 44100 
to 45983. The error on my side was that I didn't hack the stream frametime. 
Looks like mplayer did interpret the -fps option very strangely; after
hacking the avi to the right framerate of 25fps (found it in the AVI last night),
the video syncs fine. But I won't open the champagne unless the SVCD plays in 
the DVD player... ;-)

Ciao

Martin