[FFmpeg-user] Convert to 24p

[Thomas Worth]

On Fri, Oct 28, 2011 at 9:52 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Thomas Worth <dev <at> rarevision.com> writes:
>
>> > What you need is MEncoder's pullup filter.
>> > Unfortunately, it does not yet work in FFmpeg, help on this issue is very
>> > welcome!
>>
>> You wouldn't use this to convert 25 fps to 23.976 fps for DVD. All
>> (good) standards conversions with progressive material are done 1:1,
>> only the audio is re-timed. Frame counts between PAL and NTSC DVDs
>> should always be the same. This is why the running times of European
>> versions of American movies are always slightly shorter.
>
> The problem you describe - playing 24000/1001 material at 25fps and similar -
> exists of course.
>
> The more common (and significantly older and more often reported) problem with
> framerates is playback of telecined material on a computer. This shows terrible
> artefacts and needs the pullup filter to be solved.

Yes, but DVDs are typically encoded progressive. Very rarely now would
anyone ever encounter telecined material unless they were recording it
from a 29.97 broadcast source like satellite or cable. Of course, if
someone captures from an analog source after the DVD player has
inserted 3:2, then it's a problem. And sometimes (rarely) a DVD will
be encoded 29.97 with 3:2. I have run into this problem transferring
some old NTSC VHS movies, which are of course encoded with 3:2 but
almost never with DVDs.


> (I suspect "Frame counts between PAL and NTSC DVDs should always be the same" is
> wrong or misleading, but I live in PAL country so the problem does not really
> affect me.)

It's not wrong. We've done it. Since good DVDs hold
non-interlaced/non-telecined material, the best way is to map frames
1:1 between NTSC and PAL for DVD is to time-stretch the audio and
leave the picture alone. Since you don't actually change the picture,
only the playback rate, the frame count stays the same.

You're in a PAL country, but you're watching many American movies
originally shot at 24.00 fps. The way they play on a PAL system
without jittery frames is by speeding up the picture 4% and adjusting
audio to match.

Another reason to fix the -r option. ;-)