[Ffmpeg-devel] mjpeg issue (JPEG-LS)

Georges Le Goualher georges.legoualher
Mon Oct 9 17:31:54 CEST 2006


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 within dropland: if you can't get them just let me know

The following file is a 24 bits video input data (NTSC) encoded with 
Pegasus Lossless JPEG (file size: approx. 40 MB)

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).

On that file the following commands crash :
ffplay sampleMJPEG-PegasusLosslessCompressor _8bits.avi
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 
[mjpeg @ 006DEDF0]unknown colorspace
(previous line display hundred of times)

ffmpeg.exe -i 1.avi
FFmpeg version SVN-r6366, Copyright (c) 2000-2006 Fabrice Bellard, et al.
 configuration:  --enable-gpl --enable-a52 --enable-memalign-hack
 libavutil version: 49.0.1
 libavcodec version: 51.16.0
 libavformat version: 50.5.0
 built on Oct  4 2006 17:10:38, gcc: 3.4.5 (mingw special)
[mjpeg @ 006DEDF0]unknown colorspace
Input #0, avi, from '1.avi':
 Duration: 00:00:04.9, start: 0.000000, bitrate: 41775 kb/s
 Stream #0.0: Video: mjpeg, yuvj420p, 636x480, 30.00 fps(r)
Must supply at least one output file

with ffplay:
[mjpeg @ 006453D8]unknown colorspace
[mjpeg @ 006453D8]Pegasus lossless jpeg header found
[mjpeg @ 006453D8]lossless RGB p:1 >>:0

Best Regards,


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