[Ffmpeg-devel] Cropping and resizing

Harald Milz hm
Tue Mar 14 18:11:13 CET 2006


sorry for posting a question concerning use here in the devel list but I
could get no ander in ffmpeg-users or anywhere else. 

I'm trying to use ffmpeg to rescale 4:3 letterboxed videos to 16:9
anamorphous. The straightforward command should be: 

ffmpeg -i vdrsync.mpv  -croptop 84 -cropbottom 84 -cropleft 0 \
        -cropright 0 -aspect 16:9  -b 15000  -s 720,576 \
        -f rawvideo -vcodec mpeg2video  -ilme \
        -ildct  -y vdrsync1.mpv

Cropping does work fine but the "-s ..." adds new black bars at the top and
bottom, instead of rescaling the 406 vertical pixels to 576. Strange. 

It does work, however, if I run two separate processes, like,

ffmpeg -i tc1.mpv -croptop 84 -cropbottom 84 -b 15000 \
        -f rawvideo -vcodec mpeg2video  - |
ffmpeg -i - -aspect 16:9  -b 15000  -s 720x576 -b 15000 \
        -f rawvideo -vcodec mpeg2video  -ilme -ildct -y tc3.m1v

Is there any way to correctly use _one_ command? This is with

ffmpeg version 0.4.9-pre1, build 4718, Copyright (c) 2000-2004 Fabrice
  built on Feb 27 2005 17:54:09, gcc: 3.3.4 (pre 3.3.5 20040809)

With the advent of dual-core CPUs, using two processes is probably the
better choice but for now I'd rather avoid the additional context switches.
With two processes, it takes ages to convert a two hour recording... 


Collaboration, n.:
	A literary partnership based on the false assumption that the
other fellow can spell.

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