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• FFMPEG API (compiling with specific formats)

  14 janvier 2012, par JS.

  I am trying to compile FFMPEG to support a single video type (*.mp4).

  I have everything working when I compile for all, but I do not want the extra over-head when I will only use a single format.

  Here's my compile FLAGS now (non-working for MP4). I am sure there are other codecs/decoders I need to specifically enable, but am just having a hard time finding them.

  Compiler directives showing the build flags below :

  FLAGS="$FLAGS --disable-everything"
  
  FLAGS="$FLAGS --enable-encoder=mpeg4video" ## This is the question, what all needs enabling?

  I just do not know video standards well enough to know exactly which codecs / encoders / etc. to turn on.

  av_register_all();
  
  avdevice_register_all();
  
  
  
  byteCtx = av_alloc_put_byte(buffer, BUFFER_SIZE, 0, f, ReadFunc, NULL, SeekFunc);
  
  if (!byteCtx) {
  
      return;
  
  }
  
  // Open video file (here's the failure, doesn't happen when compiled for all)
  
  inputFormat = av_find_input_format("MP4");
  
  if (!inputFormat) {
  
      LOGE(ANDROID_LOG_ERROR, "NDK:", "Null inputformat!");
  
      return;
  
  }

• ffmpeg : How to use blackdetect filter and cut black frames at once

  25 juin 2012, par cache

  I use the following command to detect black screen interval :

  " ffmpeg -i black.mp4 -vf blackdetect=d=1:pic_th=0.70:pix_th=0.10 -an -f null "

  and it gives me output containing this line :
  "[blackdetect @ 0x219a580] black_start:0 black_end:1.44 black_duration:1.44"

  Now I want to cut off black screens in the video from 0-1.44s.

  So my question is : How to use blackdetect filter and cut black frames at once

  Thanks !

• 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.