[Ffmpeg-devel] mjpeg issue

Georges Le Goualher georges.legoualher
Wed Oct 11 18:49:23 CEST 2006


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)


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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