[Ffmpeg-devel] Comparison of gray codecs

[Kostya]

On Wed, Sep 20, 2006 at 08:08:23PM +0200, Michael Niedermayer wrote:
> 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

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