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

[Cyrus A]

V?ctor Paesa wrote:
>> 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
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at mplayerhq.hu
> http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel
>   
This experiement was on FC5 x86_64 Athlong X2 with the latest 2.6.17 RPM 
kernel. What kernel were you using?