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• Call ffmpeg in c++ with system() function fails

  2 septembre 2014, par zhen lee

  I write a c++ program which needs to convert some(say:10) mp4 videos to flv videos.
  I use ffmpeg in my program for each video like this :

  system("ffmpeg -i video -filter:v yadif -ar 44100 -sameq -y -f flv temp.flv")

  however,it turns out :only first video will be converted successfully,the others will fail.
  it means :
  when i change the input order of which video to convert and re-execution the program,it behave the same:only the first video(will be different each time as i changed the input video order) will be converted successfully.

  The error message like :

  [h264 @ 0xaee0740] concealing 45 DC, 45 AC, 45 MV errors
  [h264 @ 0xaee0ce0] AVC : nal size 305665
  Last message repeated 1 times
  [h264 @ 0xaee0ce0] no frame !
  [h264 @ 0xaee1280] AVC : nal size 572993
  Last message repeated 1 times
  [h264 @ 0xaee1280] no frame !
  [aac @ 0xad9ccc0] channel element 0.13 is not allocated
  Error while decoding stream #0:1
  [aac @ 0xad9ccc0] channel element 0.13 is not allocated
  Error while decoding stream #0:1
  [aac @ 0xad9ccc0] channel element 0.13 is not allocated
  Error while decoding stream #0:1
  ......
  The most strange thing is :when i run ffmpeg command in bash shell,all video will be converted successfully .

  After google it,I have try these(certainly failed) :

  1. remove -sameq option,the result is same ;

  2. write ffmpeg commod in a shell script ConvertToFlv.sh like :

     /usr/local/bin/ffmpeg -i "$dir/$1" -filter:v yadif -ar 44100 -sameq -y -f flv "$dir/temp.fiv"

     then call this script in program like

     system("ConvertToFlv.sh"+video)

     or

     system("sh ConvertToFlv.sh"+video)

     The result is same.

  The ffmpeg configure is :

    ffmpeg version 0.9.1.git Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Dec 17 2012 16:17:30 with gcc 4.1.2 20080704 (Red Hat 4.1.2-48)
  
    configuration: --enable-gpl --enable-postproc --enable-nonfree --enable-postproc --enable-swscale --enable-avfilter --enable-pthreads --enable-libxvid --enable-libx264 --enable-libmp3lame --enable-libfaac --disable-ffserver --disable-ffplay
  
    libavutil      51. 41.100 / 51. 41.100
  
    libavcodec     54.  4.100 / 54.  4.100
  
    libavformat    54.  1.100 / 54.  1.100
  
    libavdevice    53.  4.100 / 53.  4.100
  
    libavfilter     2. 62.101 /  2. 62.101
  
    libswscale      2.  1.100 /  2.  1.100
  
    libswresample   0.  7.100 /  0.  7.100
  
    libpostproc    52.  0.100 / 52.  0.100

  and my machine envirment is :

  Linux master 2.6.18-194.el5 #1 SMP Fri Apr 2 14:58:14 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

  I’m irritable now,I hope someone can give me some advice,really appreciate it.

• How to compile ffmpeg for an iphone application

  27 décembre 2012, par Swati

  I am trying to compile ffmpeg for my iphone app so that i can convert amr file to mp3

  I downloaded latest version of ffmpeg and tried to configure it via terminal on my mac.

  but i couldn't succeed, it always shows numerous errors :

  cannot find make command
  
  
  
  /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc is unable to create an executable file.
  
  
  
  libavcodec.a    file not found
  
  libavfilter.a   file not found
  
  libavutil.a     file not found
  
  libswscale.a    file not found
  
  libavdevice.a   file not found
  
  libavformat.a   file not found
  
  libswresample.a file not found

  i tried following links :
  FFmpeg on iPhone

  FFmpeg on iPhone

  Using FFMPEG library with iPhone SDK for video encoding

  and many more...

  could not fins step by step instructions..
  Hope somebody can guide me with ffmpeg config

• Join two videos with unmatching audio streams in ffmpeg

  1er janvier 2013, par graup

  I already know how to concat multiple files using ffmpeg (e.g. like this).

  However, I have a specific problem. Due to an error while recording, the first video's video stream ends after about 14 minutes, while the audio stream is about 20 minutes long.
  The second video has complete video and audio streams.

  I hope this will make my situation clear :

  File 1:
  
  V1: vvvvvvvvvvvvvvv________
  
  A1: aaaaaaaaaaaaaaaaaaaaaaa
  
  
  
  File 2:
  
  V2: vvvvvvvvvvvv
  
  A2: aaaaaaaaaaaa
  
  
  
  Result after converting to MPEG-TS, concatting and encoding to mp4:
  
      vvvvvvvvvvvvvvvvvvvvvvvvvvv________
  
      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  
  
  
  Expected:
  
      vvvvvvvvvvvvvvv________vvvvvvvvvvvv
  
      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

  Anyone know how to do that ?