[FFmpeg-devel] time-cropping an FLV

[Cyrus A]

FLV seek and crop doesn't seem to work. I'm creating the source flv file 
from an MPEG-4/mp3 1500kbps file like so:

[cyrus at wkyt ~]$ file 
/roosevelt/finished/20070504_2300-065-27_Newsfirst_at_11.avi
/roosevelt/finished/20070504_2300-065-27_Newsfirst_at_11.avi: RIFF 
(little-endian) data, AVI, 480 x 384, ~30 fps, video: DivX 5, audio: 
MPEG-1 Layer 3 (stereo, 44100 Hz)

[cyrus at wkyt ~]$ cat 
'/roosevelt/finished/20070504_2300-065-27_Newsfirst_at_11.avi' | 
/roosevelt/ffmpeg_8896/ffmpeg -v 0 -i - -b 200k -s 320x256 -y 
'/roosevelt/flash_versions/20070504_2300-065-27_Newsfirst_at_11.flv'
FFmpeg version SVN-r8896, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration: --enable-libmp3lame
  libavutil version: 49.4.0
  libavcodec version: 51.40.4
  libavformat version: 51.12.1
  built on May  5 2007 13:14:55, gcc: 4.1.1 20060525 (Red Hat 4.1.1-1)

Seems stream 0 codec frame rate differs from container frame rate: 
30000.00 (30000/1) -> 29.97 (30000/1001)
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
invalid new backstep 590
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 591
invalid new backstep 515
frame=62339 fps=146 q=31.0 Lsize=   69697kB time=2080.0 bitrate= 
274.5kbits/s   
video:51228kB audio:16251kB global headers:0kB muxing overhead 3.287720%

[cyrus at wkyt ~]$ file 
/roosevelt/flash_versions/20070504_2300-065-27_Newsfirst_at_11.flv
/roosevelt/flash_versions/20070504_2300-065-27_Newsfirst_at_11.flv: 
Macromedia Flash Video

Then attempting to crop the file with the following command:

[cyrus at wkyt ~]$ /roosevelt/ffmpeg_8896/ffmpeg -ss 486 -t 24 -y -vcodec 
copy -acodec copy -i 
/roosevelt/flash_versions/20070504_2300-065-27_Newsfirst_at_11.flv 
/usr/local/jakarta-tomcat/webapps/ROOT/file70.flv
FFmpeg version SVN-r8896, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration: --enable-libmp3lame
  libavutil version: 49.4.0
  libavcodec version: 51.40.4
  libavformat version: 51.12.1
  built on May  5 2007 13:14:55, gcc: 4.1.1 20060525 (Red Hat 4.1.1-1)

Seems stream 0 codec frame rate differs from container frame rate: 
1000.00 (1000/1) -> 29.92 (359/12)
Input #0, flv, from 
'/roosevelt/flash_versions/20070504_2300-065-27_Newsfirst_at_11.flv':
  Duration: 00:34:40.1, start: 0.000000, bitrate: 64 kb/s
  Stream #0.0: Video: flv, yuv420p, 320x256, 29.92 fps(r)
  Stream #0.1: Audio: mp3, 44100 Hz, stereo, 64 kb/s
Output #0, flv, to '/usr/local/jakarta-tomcat/webapps/ROOT/file70.flv':
  Stream #0.0: Video: flv, yuv420p, 320x256, q=2-31, 1000.00 fps(c)
  Stream #0.1: Audio: mp3, 44100 Hz, stereo, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop encoding
frame=24000 fps=  0 q=0.0 Lsize=   26911kB time=315.2 bitrate= 
699.5kbits/s   
video:19800kB audio:6256kB global headers:0kB muxing overhead 3.278421%

Obviously "time=315.2" is not 24 seconds, as I specified. What's going 
on here?


info: Fedora core 6, 2.6.20, ffmpeg rev 8896, x86_64