[Ffmpeg-devel] Comparison of gray codecs

[Michael Niedermayer]

Hi

On Wed, Sep 20, 2006 at 07:17:00PM +0300, Kostya wrote:
> On Tue, Sep 19, 2006 at 07:01:35PM +0200, Philippe De Muyter wrote:
> > Hi all,
> > 
> > I have tried to compress a 2.1G grayscale (y8) rawvideo 640x480 30fps video
> > (about 4 minutes) with all codecs found in the ffmpeg distro (SVN-r6290),
> > with the following command line :
> > 
> > 	./ffmpeg -y -i /tmp/rawvideo.avi -vcodec $codec /tmp/gray-$codec.avi
> > 
> > Below are the results.
> > 
> > All comparisons are made using an avi format output file :
> > 
> > 		Announced		Replay
> > 		Output			Quality
> [... skipped most of results ...]
> > huffyuv		yuv422p		2.0G	Good	0m46.260s
> > jpegls		gray		-	-	decode crash
> > ljpeg		gray		-	-	colorspace not supported
> > mjpeg		yuvj420p	63M	Bad	0m33.014s
> > 
> > Summary :
> > 
> > None of the tested codec succeeds in compressing gray video preserving
> > gray pixels.
> > 
> [summary skipped]
> 
> Here is a small patch which fixes grayscale JPEG-LS decoding so now you have the
> codec which supports grayscale encoding and is lossless or near-lossless.
> For lossy compression try passing '-pred x' option where 1 <= x <= 3. It won't
> result in blockiness too.
> 
> I hope Michael will approve this patch and it will be applied.

looks ok

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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