20 May
2008
20 May
'08
6:33 p.m.
Florin Andrei wrote:
Well, you could use transcode to resize the image to the standard NTSC
size, maybe adjust the frame rate too, and then from within transcode
drive mpeg2enc as the last stage of the processing - the conversion to
MPEG2. It's a slower encoder than ffmpeg, but it's standards compliant
and the image quality is better. This is what I did for some years now
to create all my DVD-based home videos.
And the script to do that is here:
http://florin.myip.org/soft/conv-dvd/
The script assumes an NTSC DV (digital camcorder) source, so there's no
adjusting of the frame size or rate. But you can easily add options to
transcode for that kind of processing - just edit the script, there's a
place in it for custom transcode parameters.
NTSC DVD is 720x480, aspect ratio either 4:3 or 16:9 (non-square
pixels), at 29.97 frames per second interlaced (so it's 59.94 fields per
second).
If it's progressive (non-interlaced) then the frame rate is 23.97 fps
with 2:3 pulldown.
This whole frame rate and interlacing issue is not trivial. Make sure
you process the video stream the right way before encoding, otherwise
you end up with a russian roulette candidate.
I did pretty much all my movies entirely in the standard 30i format
(29.97 interlaced) - the entire processing chain, start to end, was 30i.
I don't have much experience with 24p (23.97 progressive). But it's a
popular, well known and well understood format, so it should work -
provided that the tools are standards-compliant.
If the source is not DV, you may have to adjust the input parameters (-x
and so on). Or perhaps transcode will just handle the autodetection for
you. Just try and see what happens.
--
Florin Andrei
http://florin.myip.org/