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• Recommendations for real-time pixel-level analysis of television (TV) video

  6 décembre 2011, par Randall Cook

  [Note : This is a rewrite of an earlier question that was considered inappropriate and closed.]

  I need to do some pixel-level analysis of television (TV) video. The exact nature of this analysis is not pertinent, but it basically involves looking at every pixel of every frame of TV video, starting from an MPEG-2 transport stream. The host platform will be server-class, multiprocessor 64-bit Linux machines.

  I need a library that can handle the decoding of the transport stream and present me with the image data in real-time. OpenCV and ffmpeg are two libraries that I am considering for this work. OpenCV is appealing because I have heard it has easy to use APIs and rich image analysis support, but I have no experience using it. I have used ffmpeg in the past for extracting video frame data from files for analysis, but it lacks image analysis support (though Intel's IPP can supplement).

  In addition to general recommendations for approaches to this problem (excluding the actual image analysis), I have some more specific questions that would help me get started :

  1. Are ffmpeg or OpenCV commonly used in industry as a foundation for real-time
     video analysis, or is there something else I should be looking at ?
  2. Can OpenCV decode video frames in real time, and still leave enough
     CPU left over to do nontrivial image analysis, also in real-time ?
  3. Is sufficient to use ffpmeg for MPEG-2 transport stream decoding, or
     is it preferable to just use an MPEG-2 decoding library directly (and if so, which one) ?
  4. Are there particular pixel formats for the output frames that ffmpeg
     or OpenCV is particularly efficient at producing (like RGB, YUV, or YUV422, etc) ?

• command for ffmpeg encode h264 baseline profile level 1

  25 décembre 2011, par Morteza M.

  Can anyone suggest a command to encode video to h264 baseline profile ( level 1) ?

  Here is a link for reference : http://blog.mediacoderhq.com/h264-profiles-and-levels/

  I used this command but ffmpeg says it is Main profile not baseline.

  ffmpeg -i <source> -vcodec libx264 -coder 0 -flags +loop+mv4 \
  
  -partitions +parti4x4+parti8x8+parti4x4+partp8x8+partb8x8 -me_method hex -subq 7 \
  
  -trellis 1 -refs 5 -bf 0 -flags2 +mixed_refs -coder 0 -me_range 16 -threads 2 \
  
  -s 240x160 -b:v 64k -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 \
  
  -qmin 10 -qmax 51 -qdiff 4 -strict experimental -acodec aac -ac 1 -ab 48000 \
  
  -f mpegts udp://127.0.0.1:10006?pkt_size=1316
  
  </source>

• FFmpeg : Read profile level information from mp4

  31 mars 2016, par Martin

  I have a mp4 file and need the profile level of it. FFmpeg says, it has baseline profile, which is what I need, but I need also the level.

  Here is what I get from FFmpeg :

  ffmpeg version 0.8, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on Jul 20 2011 13:32:19 with gcc 4.4.3
  
    configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-libfaac --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264
  
    libavutil    51.  9. 1 / 51.  9. 1
  
    libavcodec   53.  7. 0 / 53.  7. 0
  
    libavformat  53.  4. 0 / 53.  4. 0
  
    libavdevice  53.  1. 1 / 53.  1. 1
  
    libavfilter   2. 23. 0 /  2. 23. 0
  
    libswscale    2.  0. 0 /  2.  0. 0
  
    libpostproc  51.  2. 0 / 51.  2. 0
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test-show.mp4':
  
    Metadata:
  
      major_brand     : f4v 
  
      minor_version   : 0
  
      compatible_brands: isommp42m4v 
  
      creation_time   : 2012-03-21 16:00:00
  
    Duration: 00:56:07.40, start: 0.000000, bitrate: 2004 kb/s
  
      Stream #0.0(eng): Video: h264 (Baseline), yuv420p, 854x480 [PAR 1:1 DAR 427:240], 1904 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
  
      Metadata:
  
        creation_time   : 2012-03-21 16:00:00
  
      Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, s16, 96 kb/s
  
      Metadata:
  
        creation_time   : 2012-03-21 16:00:00
  
  At least one output file must be specified

  Is there any option other than -i I can use to get the level information ?