NTSC to PAL conversion

[kassandro]

Is it possible to convert a 30 fps xvid NTSC avi to a 25 fps PAL avi without reencoding by dropping frames? In the average every 6th frame has to be dropped and of course B-frames have the highest dropping priority.

[Koepi]

short answer: no.

Read about NTSC, PAL, 23.976, 29.97, 25fps,... and get the idea what's going wrong if you just drop frames ;)

Koepi

[kassandro]

Originally posted by Koepi
short answer: no.

Read about NTSC, PAL, 23.976, 29.97, 25fps,... and get the idea what's going wrong if you just drop frames ;)

Koepi
Of course, motion gets distorted a little bit. But frame or field blending, which require reencoding, are worse in my opinion.
Is it possible or not to drop frames without reencoding? It should be much easier for mjpeg clips (there are quite a few digi-cams, which only generate 15/30 fps clips).

[scharfis_brain]

Of course, motion gets distorted a little bit.

Do you really know about this 'little bit' ?
A video will become unviewable, when dropping frames from 29.97p to 25p.
even with blending the motion is terribly influent.
please forget about such conversions. Its not worth to think about that.

you may try it in avisynth, to see what your method will like like:

avisource("29-97p.avi")
changefps(25)

plus, 29.97 to 25 isn't a fractional ratio, this means you have to be able to drop frames arbitary.
there will not be a fixed pattern. It swims away with time.

[kassandro]

Originally posted by scharfis_brain
Do you really know about this 'little bit' ?
A video will become unviewable, when dropping frames from 29.97p to 25p.

I have tested it with avisynth and it is not unviewable in my opinion.



plus, 29.97 to 25 isn't a fractional ratio, this means you have to be able to drop frames arbitary.
there will not be a fixed pattern. It swims away with time.
I think we can safely play a 29.97 fps video at 30 fps. Remember that we play 24 fps cinema film all the time at 25 fps.