[Ffmpeg-devel] cutting a file and getting still images

Fri Nov 3 21:25:28 CET 2006

Hi,
> Cyrus A wrote:
>> I'm trying to crop a 30-minute or hour-long segment of video down to 1
>> minute and then immediately generate 60 still frames (one for each
>> second) from the resulting chopped video.
>>
>> Here are the commands I used:
>>
>> long input file generated with:
>> ffmpeg -v 0 -i /dev/video0 -async 1 -y -vcodec mpeg4 -acodec mp3 -t
>> 1780 -b 1750k -ab 192 -s 480x384 -r ntsc -vtag DX50
>> 'long_input_file.avi'
>>
>> "cut" command:
>> ffmpeg -ss 180 -t 60 -y -vcodec copy -acodec copy -i
>> long_input_file.avi short_output_file.avi
>>
>> still frames generation:
>> ffmpeg -i short_output_file.avi -r 1 -f image2 frame%03d.jpg
>>
>>
>> Console output for second command:
>>
>> FFmpeg version SVN-r6849, Copyright (c) 2000-2006 Fabrice Bellard, et
>> al.
>>  configuration:  --enable-mp3lame
>>  libavutil version: 49.0.2
>>  libavcodec version: 51.23.0
>>  libavformat version: 50.6.0
>>  built on Oct 31 2006 12:55:14, gcc: 4.1.1 20060525 (Red Hat 4.1.1-1)
>>
>> Seems that stream 0 comes from film source: 30000.00 (30000/1) ->
>> 29.97 (30000/1001)
>> Input #0, avi, from 'short_output_file.avi':
>>  Duration: 00:01:00.3, start: 0.000000, bitrate: 1972 kb/s
>>  Stream #0.0: Video: mpeg4, yuv420p, 480x384, 29.97 fps(r)
>>  Stream #0.1: Audio: mp3, 48000 Hz, stereo, 192 kb/s
>> Output #0, image2, to 'frame%03d.jpg':
>>  Stream #0.0: Video: mjpeg, yuvj420p, 480x384, q=2-31, 200 kb/s,  1.00
>> fps(c)
>> Stream mapping:
>>  Stream #0.0 -> #0.0
>> Press [q] to stop encoding
>> frame=    1 q=5.9 Lsize=       0kB time=1.0 bitrate=   0.0kbits/s
>> video:22kB audio:0kB global headers:0kB muxing overhead -100.000000%
>>
>> Result:
>>
>> Only the first image (frame001.jpg) is created.
>>
>> Observations:
>>
>> The ffmpeg long file generation command works well. The file looks and
>> sounds good. Similarly,the "cutting" command above seems to work well.
>> I can get any size video from any part of the longer video with ease.
>> The videos play normally in mplayer as well as DivX and WMP on
>> windows.  However, it's the stills frame generation that seems broken.
>> Two caveats:
>>
>> First, if the stills generation command is run on a file that was
>> "cut" using "-ss 0 -t 60" (no seek), the stills are generated
>> correctly. Anything other than "-ss 0" causes problems.
>>
>> Second, videos recorded by an old version of ffmpeg (0.4.8 -- probably
>> early 2005 or late 2004) seem to be "cut" and "stills extracted"
>> correctly by the series of commands above.
>>
>> file command output for avi recorded with "old" ffmpeg and chopped
>> with rev6849:  RIFF (little-endian) data, AVI, 480 x 384, ~30 fps,
>> video: DivX 4, audio: MPEG-1 Layer 3 (mono, 44100 Hz)
>>
>> file command output for avi recorded and chopped with rev6849: RIFF
>> (little-endian) data, AVI, 480 x 384, ~30 fps, video: DivX 5, audio:
>> MPEG-1 Layer 3 (stereo, 48000 Hz)
>>
>> I don't think the recording rate nor the DivX 4 vs DivX5 differences
>> have anything to do with my problem, but I could be wrong.
>>
>> FILES:
>>
>> A file recorded with "old" ffmpeg and chopped on rev 6849 can be found
>> here:
>>
>> http://wkyt.dynalias.com/rec_with_old_chopped_with_6849.avi
>>
>> A file recorded with rev 6849 and chopped with rev 6849 can be found
>> here:
>>
>> http://wkyt.dynalias.com/rec_with_6849_and_chopped_with_6849.avi
>>
>> Please let me know what you think of this problem. It is the very
>> final step in a system I've been working on sporadically for about 9
>> months. I might just take the rest of the week off if I can get this
>> to work. Thanks again for your help.
>>
>> Cyrus
>>
>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at mplayerhq.hu
>> http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel
> Ok, apparently my last message was too long because nobody has responded
> yet. Just do this:
>
> Download this file:
>
> http://wkyt.dynalias.com/rec_with_6849_and_chopped_with_6849.avi
>
> and run the following command to get 1 still frame for each second of
> video:
>
> fmpeg -i rec_with_6849_and_chopped_with_6849.avi -r 1 -f image2
> frame%03d.jpg
>
> Then tell me if it works.
>

No, it's not long, it is a good description (and I appreciate it).

I've tried SVN-r6811, with my usual set of configure flags, and it
generated 62 frames:

$ ffmpeg -i /cygdrive/n/rec_with_6849_and_chopped_with_6849.avi -r 1 -f
image2 frame%03d.jpg
FFmpeg version SVN-r6811, Copyright (c) 2000-2006 Fabrice Bellard, et al.
  configuration:  --enable-mp3lame --enable-a52 --disable-static
--enable-shared --enable-pthreads --enable-swscaler --enable-avisynth
--enable-gpl --extra-cflags=-march=pentium4
  libavutil version: 49.0.2
  libavcodec version: 51.22.0
  libavformat version: 50.6.0
  built on Oct 28 2006 00:09:36, gcc: 3.4.4 (cygming special) (gdc 0.12,
using dmd 0.125)

Seems that stream 0 comes from film source: 30000.00 (30000/1) -> 29.97
(30000/1001)
Input #0, avi, from '/cygdrive/n/rec_with_6849_and_chopped_with_6849.avi':
  Duration: 00:01:00.0, start: 0.000000, bitrate: 1979 kb/s
  Stream #0.0: Video: mpeg4, yuv420p, 480x384, 29.97 fps(r)
  Stream #0.1: Audio: mp3, 48000 Hz, stereo, 192 kb/s
Output #0, image2, to 'frame%03d.jpg':
  Stream #0.0: Video: mjpeg, yuvj420p, 480x384, q=2-31, 200 kb/s,  1.00
fps(c)
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame=   62 q=4.6 Lsize=       0kB time=62.0 bitrate=   0.0kbits/s
video:1707kB audio:0kB global headers:0kB muxing overhead -100.000000%

I'll rebase to your SVN-6849, configure with --enable-mp3lame, and
I'll tell you how it goes.

Regards,
V?ctor