[FFmpeg-user] Mixed telecined non-telecined media to constant frame rate.

[Nicholas Robbins]

> On Tuesday, January 21, 2014 12:37 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> > Nicholas Robbins <nickrobbins <at> yahoo.com> writes:
> 
>>  Indeed if I don't put in any fps filter I see that I 
>>  have frames at the following pkt_pts's
>>  ...
>>  20020
>>  20053
>>  20087
>>  20120*
>>  20187
>>  20220
>>  20254
>>  20287*
>>  20354
> 
> I didn't look at the source but it doesn't seem absurd 
> to me (although probably buggy) that this is what 
> pullup produces (fieldmatch,decimate are worse imo 
> because they simply ignore the input timestamps).

So now, I have a suggestion for a new filter. It alters the PTS by something like (pardon the syntax)

NewPTS(i) = Sum(j=0, j<N, OllPTS[i-j])/N + (OldPTS(i)-OldPTS(i-N))*(N-1)/2N

It removes judder in pullup'ed cases if the original was 24->30 converted, with N=4. If the original was 25->30 then N=5 works. If N=20 it does both.

It leaves non-juddered sections alone regardless of N (it does introduce N frames of judder at any transition)  

Ideally it would also multiply the timebase by 2N. (so that the new PTS's are garunteed to be integers)

Should I move this conversation over to ffmpeg-devel? I can code myself for hobby and academic purposes, but have never contributed to something as big as ffmpeg. 

For example, with N=4, it takes the quoted 

>>  20020
>>  20053
>>  20087
>>  20120*
>>  20187
>>  20220
>>  20254
>>  20287*
>>  20354

and turns it into 

160059
160393
160727
161061
161395
161729
162063
162397
162731

of course the timebase would have to be adjusted by *8.
 



-Nick Robbins