[MEncoder-users] Color Space Problem with a Sequence of RGB JPEG Images

[Reimar Döffinger]

On Wed, Oct 07, 2009 at 11:25:49PM +0200, Irv Elshoff wrote:
> Both Mencoder and FFmpeg include and use "libopenjpeg" 
> (http://www.openjpeg.org).

No they don't.

> ImageMagick and my own JPEG image generating 
> program use "libjpeg6b" from the Independent JPEG Group 
> (http://www.ijg.org/).  ImageMagick has no problem with RGB JPEG 
> images.  Neither does MATLAB, by the way (presumably another proprietary 
> image reader).
> 
> It looks like the problem is in the JPEG input routines (= library).
> 
> I'd appreciate any opinion on the matter.
> 
> Are caveats about "RGB JPEG" something that needs to better documented?

FFmpeg supports RGB JPEG, but only in lossless mode.
Adding support should be simple enough if you find out how to know
whether the image is encoded as YUV 4:4:4 or RGB, it seems to me it
would result in the same JPEG headers (but I haven't read the spec).