[Ffmpeg-devel] mjpeg issue

Michael Niedermayer michaelni
Thu Oct 12 10:56:30 CEST 2006


On Wed, Oct 11, 2006 at 06:49:23PM +0200, Georges Le Goualher wrote:
> Hi,
> I'm resending this mail now that I've subscribed to ffmpeg-devel list 
> and that I've uploaded the sample files in the ffmpeg upload area (I 
> hope the transfert went well....).
> I've noticed an issue when trying to play (with ffplay) or transcode 
> (using ffmpeg) a MJPEG video file encoded using the Pegasus Lossless JPEG:
> Pegasus compressor accepts  in particular 24 bits as well as 8 bits 
> video data inputs. FFmpeg copes very well with all inputs however it 
> fails with the 8 bits video data.
> I've created two samples to illustrate this problem. I've put these 2 
> samples on the ffmpeg download area:
> The following file is a 24 bits video input data (NTSC) encoded with 
> Pegasus Lossless JPEG (file size: approx. 40 MB)
> upload.mplayerhq.hu/MPlayer/incoming/sampleMJPEG/sampleMJPEG-PegasusLosslessCompressor_24bits.avi
> This file works great with ffplay or ffmpeg.
> The following file is a 8 bits video input data (NTSC) encoded with 
> Pegasus Lossless JPEG (file size: approx. 24 MB).
> upload.mplayerhq.hu/MPlayer/incoming/sampleMJPEG-PegasusLosslessCompressor_8bits.avi
> On that file the following commands crash :
> ffplay sampleMJPEG-PegasusLosslessCompressor _8bits.avi
> or
> ffmpeg -i sampleMJPEG-PegasusLosslessCompressor _8bits.avi
> As the crash of ffplay or ffmpeg is not always exactly the same (it 
> seems that there's an access to a bad memory area somewhere), here are 
> some additional elements I have noticed when dealing with the 8 bits file:
> with ffmpeg:
> #
> ffmpeg.exe -i samplepegasusJL.avi -target pal-dvd -vcodec mpeg2video -y 
> out.mpg
> ...
> [mjpeg @ 006DEDF0]unknown colorspace
> (previous line display hundred of times)

well 8bit (paletted i assume) pegasus lossless jpeg isnt supported, a patch
would certainly be welcome, this also shouldnt be too hard to implement


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is

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