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• Django Celery FFMPEG: convert video files

  3 January 2012, by sultan

  I'm trying to convert video files using FFMPEG via Celery tasks. The generated command to be executed looks like

  ffmpeg -i /path/to/flv -ar 22050 -ab 96k -r 24 -b 600k -f flv path/to/flv/transcoded/flv_movie.flv

  and when I call the task TranscodeVideoTask.delay(src=filepath, dst=destination_path)
  I get flv_movie.flv file but its size is only about 200Kb and debug output

  Press [q] to stop, [?] for help
  
  [h264 @ 0x10205a200] Reference 3 >= 3
  
  [h264 @ 0x10205a200] error while decoding MB 7 5, bytestream (690)
  
  [h264 @ 0x10205a200] concealing 762 DC, 762 AC, 762 MV errors
  
  frame=   40 fps=  0 q=2.0 Lsize=     136kB time=00:00:01.66 bitrate= 668.2kbits/s dup=0 drop=9    
  
  video:114kB audio:20kB global headers:0kB muxing overhead 1.814991%

  TranscodeVideoTask source

  @task(name="transcode.media")
  
  def TranscodeVideoTask(src, dst):
  
      command = commands.get("flv") % {"src": src, "dst": dst}
  
      os.system(src, dst)
  
      filename = os.path.join(dst, "flv_movie.flv")
  
      YamdiInjector.yamdi(filename, dst)

  When the same command executed manually in the console it works just fine.

  UPDATE
  So far I've composed the following ffmpeg instructions in my bash file and it converts almost every avi file I tested already

  #!/bin/sh
  
  INPUT=$1
  
  OUTPUT=$2/flv_movie.flv
  
  
  
  echo "Input file: ${INPUT}"
  
  echo "Output file: ${OUTPUT}"
  
  echo `ffmpeg -y -i $INPUT -ar 44100 -ab 128k -ac 2 -sameq -f flv $OUTPUT`

  What may cause this strange problem?

  Sultan

• How to encode video with ffmpeg for playback on Android?

  3 January 2012, by Sean

  I've got a c++ library that is encoding video in realtime from webcams to mp4 files (H264). The settings i've got are as follows:

      codecContex->profile=FF_PROFILE_H264_BASELINE; //Baseline
  
      codecContex->gop_size=250;
  
      codecContex->max_b_frames=0;
  
      codecContex->max_qdiff=4;
  
      codecContex->me_method=libffmpeg::ME_HEX;
  
      codecContex->me_range=16;
  
      codecContex->qmin=10;
  
      codecContex->qmax=51;
  
      codecContex->qcompress=0.6;
  
      codecContex->keyint_min=10;
  
      codecContex->trellis=0;
  
      codecContex->level=13; //Level 1.3
  
      codecContex->weighted_p_pred = 2;
  
      codecContex->flags2|=CODEC_FLAG2_WPRED+CODEC_FLAG2_8X8DCT;

  This creates MP4 files that play on iOS devices and on Windows Phone 7 devices but not on Android devices. I've read that Android only supports movies encoded with the baseline profile. These settings should produce a baseline movie but when I look at the generated MP4 file with MediaInfo it says it's AVC(High@L1.3). This might be why it's not working but I can't seem to get it to generate something with AVC(Baseline@L1.3)...

  If I remove the last line:

  codecContex->flags2|=CODEC_FLAG2_WPRED+CODEC_FLAG2_8X8DCT;

  Then MediaInfo reports the file as being "AVC(Main@L1.3)" instead - but those flags are part of the Baseline profile!

• FFMPEG video joiner

  31 March 2012, by Udhay

  I am working on merging videos, but is not merging my videos. Here is the code

  exec(cat file1.flv file2.flv > trailer/output.flv);<br />
exec("ffmpeg -i trailer/output.flv -sameq trailer/output.flv);

  But if the size of file1 is 1MB and file2 is 2MB and output is coming as 3MB. But it is playing only the file1.