[FFmpeg-devel] couple of bugs when time-cropping

[Cyrus Adkisson]

Hi everybody.

I've run across a couple of bugs in the current snapshot of ffmpeg. I'm 
not sure how long they've been in there because I don't regularly test 
the snapshots, but I know one of them was fine as of version 9758. That 
bug is one that has to do with video cropping (timewise, not 
resolution-wise). Here is the command used to cut a smaller file from a 
larger one (these are standard Flash files):

ffmpeg -ss 504.0 -t 114.0 -y -vcodec copy -acodec copy -i source.flv 
target.flv

As of 9758, it worked well enough. Under version 18184, it gets the 
start-point right, but just gives the rest of the file without cutting 
at the designated duration -t value. I could just be out of the loop on 
a command-line change or something... if so, what has replaced -t? I 
know at least one old, old version of ffmpeg had -t as the "end point" 
rather than "duration". If that's the case, then I can see where ffmpeg 
is confused since 114 < 504. In this case, -t should then be 618. Did we 
go back to that method? Nope. Just checked it. Same problem.

The second bug happens in both versions. It has to do with a newly 
time-cropped video (see command above) being mega-pixelated at the start 
and then correcting itself back into high-def glory. See here for an 
example:

http://www.news12archives.com/watch?v=4173

Anyone got any ideas what's going on with either of these issues?

Cyrus

------------------------------------
using: 2.6.22.9-61.fc6, x86_64

[]# ./ffmpeg -version
FFmpeg version SVN-r9758, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration: --enable-libmp3lame
  libavutil version: 49.4.1
  libavcodec version: 51.40.4
  libavformat version: 51.12.1
  built on Jul 19 2007 11:12:19, gcc: 4.1.1 20070105 (Red Hat 4.1.1-51)
ffmpeg      SVN-r9758
libavutil   3212289
libavcodec  3352580
libavformat 3345409

[]# ./ffmpeg -version
FFmpeg version SVN-r18184, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-libmp3lame
  libavutil     50. 2. 0 / 50. 2. 0
  libavcodec    52.22. 3 / 52.22. 3
  libavformat   52.32. 0 / 52.32. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libswscale     0. 7. 1 /  0. 7. 1
  built on Mar 25 2009 09:53:17, gcc: 4.1.2 20070626 (Red Hat 4.1.2-13)
FFmpeg SVN-r18184
libavutil     50. 2. 0 / 50. 2. 0
libavcodec    52.22. 3 / 52.22. 3
libavformat   52.32. 0 / 52.32. 0
libavdevice   52. 1. 0 / 52. 1. 0
libswscale     0. 7. 1 /  0. 7. 1