All,
I noticed a small but critical issue with transcode (or possibly ffmpeg)
when I switched from a P4 32bit with Fedora to a Core2 64bit running
Ubuntu Gutsy.
I am using commands like this to generate stills:
transcode -i 0091411.avi -o frame. -x ffmpeg,null -y jpg,null -c 59719-59720
This dumps frame number 59719 as a jpeg file. 0091411.avi is one of
thousands of similar files I am working with, it has the following
properties and was made with mencoder:
tcprobe -i 0091411.avi
[tcprobe] RIFF data, AVI video
[avilib] V: 23.976 fps, codec=DIVX, frames=148450, width=704, height=464
[avilib] A: 48000 Hz, format=0x2000, bits=16, channels=2, bitrate=192
kbps,
[avilib] 12384 chunks, 148600320 bytes, CBR
[tcprobe] summary for 0091411.avi, (*) = not default, 0 = not detected
import frame size: -g 704x464 [720x576] (*)
frame rate: -f 23.976 [25.000] frc=1 (*)
audio track: -a 0 [0] -e 48000,16,2 [48000,16,2] -n 0x2000 [0x2000]
bitrate=192 kbps
length: 148450 frames, frame_time=41 msec, duration=1:43:11.602
When I run the transcode frame dump command I get these errors:
[mpeg4 @ 0x2aaaacff3e50]slice end not reached but screenspace end (-9 left
46310F, score= -9035)
In particular transcode yeilds a couple of these errors while parsing the
stream then dumps the required frame but with decoding errors visible in
the image. Several (3 or more) of the frames I specifically require from
this file are corrupt. Samples available upon req.
This "slice end..." error is thrown by decode_slice() in h263dec.c in
ffmpeg, I think.
When I used mplayer -vo jpeg to dump the video into frames the errors were
not evident and in particular my required frame was fine. Mplayer also
plays the video fine with no visible errors. Also mplayer did not throw
the "slice end..." errors. Unfortunatly I cannot feasibly use mplayer to
achieve my main ongoing purpose, only transcode does what I want.
Does anybody have some simple advice for avoiding this problem?
Failing that, should I start fiddling with source?
Versions I am using:
transcode -v
transcode v1.0.4 (C) 2001-2003 Thomas Oestreich, 2003-2004 T. Bitterberg,
2004-2007 Transcode Team
ffmpeg --version
FFmpeg version SVN-r11121, Copyright (c) 2000-2007 Fabrice Bellard, et al.
configuration:
libavutil version: 49.5.0
libavcodec version: 51.48.0
libavformat version: 52.1.0
built on Dec 1 2007 12:27:45, gcc: 4.1.3 20070929 (prerelease) (Ubuntu
4.1.2-16ubuntu2)
Apologies for the long message but I wanted to fully document my
issue. Yet more details, including jpegs or the avi available upon
request.
Thanks in advance,
Simon.
