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

Fri Nov 3 22:08:22 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).
>
[snip]
>
> I'll rebase to your SVN-6849, configure with --enable-mp3lame, and
> I'll tell you how it goes.
>

Bad news, I'm not able to reproduce your problem, SVN-r6849 also
generates 62 frames:

$ ./ffmpeg -i /cygdrive/n/rec_with_6849_and_chopped_with_6849.avi -r 1 -f
image2 frame%03d.jpg
FFmpeg version SVN-r6849, Copyright (c) 2000-2006 Fabrice Bellard, et al.
  configuration:  --enable-mp3lame --disable-shared
  libavutil version: 49.0.2
  libavcodec version: 51.23.0
  libavformat version: 50.6.0
  built on Nov  3 2006 21:46:54, 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=5.5 Lsize=       0kB time=62.0 bitrate=   0.0kbits/s
video:1705kB audio:0kB global headers:0kB muxing overhead -100.000000%

I'm afraid your problem is platform related. If you can, try to build on
a different one (try "make distclean" before, just in case).

Regards,
V?ctor