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• C run linux shell command(fmpeg) 10x slower than typing directly in terminal

  14 novembre 2014, par dadylonglegs

  CLOSED

  I’m writing an application that execute a linux shell command (ffmpeg) from my C code. Such as :

  char command[2000];
  
  sprintf(command, "ffmpeg -i %s/%s -r 1 -vf scale=-1:120 -vframes 1 -ss  00:00:00 %s.gif", publicFolder, mediaFile, mediaFile);
  
  system(command);

  To extract video thumbnail from a specific video. But the strange that it is too much slower when executing shell command form C compare to typing directly to the terminal. I have no idea about this.
  Can anybody help me pls ?. Thanks in advance.

• ffmpeg return black and white image

  16 décembre 2011, par njai

  Video capture device is kworld dvd maker 2 (em2861)
  It returns the image in "black and white" with green line at the bottom of screen ; but when I tested it with webcam, it worked properly.

  Here is 30s video. http://www.youtube.com/watch?v=7q2wFGVwGGI

  How can I convert it to color ?

  [root@localhost ~]# ffmpeg -f video4linux2 -i /dev/video0 -vcodec mpeg4 -y output.mp4
  
  ffmpeg version git-2011-11-05-5fd1a69, Copyright (c) 2000-2011 the FFmpeg developers
  
  built on Nov  5 2011 21:10:52 with gcc 4.4.4 20100726 (Red Hat 4.4.4-13)
  
  configuration: --enable-libx264 --enable-gpl --enable-libvpx
  
  libavutil    51. 23. 0 / 51. 23. 0
  
  libavcodec   53. 27. 0 / 53. 27. 0
  
  libavformat  53. 18. 0 / 53. 18. 0
  
  libavdevice  53.  4. 0 / 53.  4. 0
  
  libavfilter   2. 47. 0 /  2. 47. 0
  
  libswscale    2.  1. 0 /  2.  1. 0
  
  libpostproc  51.  2. 0 / 51.  2. 0
  
  [video4linux2,v4l2 @ 0x2a64780] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
  Duration: N/A, start: 1320637788.113946, bitrate: 165888 kb/s
  
  Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 720x576, 165888 kb/s, 25 tbr, 1000k tbn, 25 tbc
  
  Incompatible pixel format 'yuyv422' for codec 'mpeg4', auto-selecting format 'yuv420p'
  
  [buffer @ 0x2a63920] w:720 h:576 pixfmt:yuyv422 tb:1/1000000 sar:0/1 sws_param:
  
  [buffersink @ 0x2a63cc0] auto-inserting filter 'auto-inserted scale 0' between the filter    'src' and the filter 'out'
  
  [scale @ 0x2a64560] w:720 h:576 fmt:yuyv422 -> w:720 h:576 fmt:yuv420p flags:0x4
  
  Output #0, mp4, to 'output.mp4':
  
  Metadata:
  
  encoder         : Lavf53.18.0
  
  Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 720x576, q=2-31, 200 kb/s, 25    tbn, 25 tbc
  
  Stream mapping:
  
  Stream #0.0 -> #0.0 (rawvideo -> mpeg4)
  
  Press [q] to stop, [?] for help
  
  frame=  969 fps= 25 q=31.0 Lsize=    1547kB time=00:00:38.76 bitrate= 327.0kbits/s    
  
  video:1538kB audio:0kB global headers:0kB muxing overhead 0.561411%

• Video recoding with ffmpeg

  8 novembre 2011, par Aleks G

  I asked in another question (http://stackoverflow.com/questions/8012494/sorry-this-video-cannot-be-played-streaming-mp4-to-android/8012874#8012874) about video playback in android using VideoView. Apparently, the problem there is due to the way my video is encoded, as another video (512Kb mp4 off the web) plays correctly using my code. As videos are uploaded by my end users to the web site, I don't have any control of the videos themselves, however I do have control over re-coding these. I re-code them using ffmpeg to bring them to a standard MP4 (H.264+AAC) format and scale them to the same size (320x240).

  Here's the ffmpeg info of a video that would not play :

  sh-3.2$ ffmpeg -i video.bad.mp4
  
  FFmpeg version SVN-r25679-snapshot, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on Nov  5 2010 09:34:37 with gcc 4.3.2
  
    configuration: --prefix=/usr --enable-shared --enable-libmp3lame --enable-gpl --enable-libvorbis --enable-pthreads --enable-libfaac --enable-libxvid --enable-postproc --enable-libgsm --enable-x11grab --enable-libx264 --enable-libtheora --extra-cflags=-Wall --enable-swscale --enable-libdc1394 --enable-nonfree --disable-mmx --disable-stripping --enable-avfilter --disable-altivec --disable-armv5te --disable-armv6 --disable-vis --enable-nonfree --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-version3
  
    libavutil     50.32. 6 / 50.32. 6
  
    libavcore      0.12. 0 /  0.12. 0
  
    libavcodec    52.94. 3 / 52.94. 3
  
    libavformat   52.84. 0 / 52.84. 0
  
    libavdevice   52. 2. 2 / 52. 2. 2
  
    libavfilter    1.56. 0 /  1.56. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.bad.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf52.84.0
  
    Duration: 00:00:45.93, start: 0.000000, bitrate: 591 kb/s
  
      Stream #0.0(und): Video: h264, yuv420p, 320x240 [PAR 1:1 DAR 4:3], 535 kb/s, 15 fps, 15 tbr, 15 tbn, 30 tbc
  
      Stream #0.1(und): Audio: aac, 48000 Hz, stereo, s16, 51 kb/s

  And here's the ffmpeg info of a video that plays correctly :

  sh-3.2$ ffmpeg -i video.mp4
  
  FFmpeg version SVN-r25679-snapshot, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on Nov  5 2010 09:34:37 with gcc 4.3.2
  
    configuration: --prefix=/usr --enable-shared --enable-libmp3lame --enable-gpl --enable-libvorbis --enable-pthreads --enable-libfaac --enable-libxvid --enable-postproc --enable-libgsm --enable-x11grab --enable-libx264 --enable-libtheora --extra-cflags=-Wall --enable-swscale --enable-libdc1394 --enable-nonfree --disable-mmx --disable-stripping --enable-avfilter --disable-altivec --disable-armv5te --disable-armv6 --disable-vis --enable-nonfree --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-version3
  
    libavutil     50.32. 6 / 50.32. 6
  
    libavcore      0.12. 0 /  0.12. 0
  
    libavcodec    52.94. 3 / 52.94. 3
  
    libavformat   52.84. 0 / 52.84. 0
  
    libavdevice   52. 2. 2 / 52. 2. 2
  
    libavfilter    1.56. 0 /  1.56. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: mp41
  
      title           : crazytown - http://www.archive.org/details/Cartoon-Crazytown
  
      encoder         : Lavf51.10.0
  
    Duration: 00:07:50.40, start: 0.000000, bitrate: 578 kb/s
  
      Stream #0.0(und): Video: h264, yuv420p, 320x240, 510 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
  
      Stream #0.1(und): Audio: aac, 48000 Hz, stereo, s16, 63 kb/s

  I have two questions here, actually. First, which of the details in my "bad" video does android not like ? And, second, what parameters should I use with ffmpeg to recode my videos ? As present I use this :

  ffmpeg -i $input_video_file -y -s 320x240 -vcodec libx264 -vpre medium -acodec libfaac -b 510K -ar 48000 -aspect 4:3 $tmpfile.mp4
  
  qt-faststart $tmpfile.mp4 $output_video_file.mp4

  But this produces a video that's not playable on android. Any help is greatly appreciated.