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• Insert still frames into H.264 video stream

  7 juillet 2021, par Bassinator

  I'm building an application that receives video packets which are encoded as H.264 from Microsoft Teams - I get one packet for each frame of video. Specifications of the packet contents are given here. For every packet I receive, I write the byte contents of the data[] buffer to a file. This resulting file is a playable H.264 encoded video.

  


  I'm trying to handle the scenario of syncing the audio and video streams from a Teams meeting, and inserting a still frame PNG as a "filler" when nobody has their camera on.

  


  I used the following FFMPEG command to generate n number of seconds of H.264 video from the filler frame :

  


  ffmpeg -loop 1 -i video_filler_frame.png -framerate 30 -c:v libx264 -t 2 -vf scale=1920:1080 C:\Code\temp\out.mp4


  


  This generates an MP4 file (H.264 encoded) - as a test in my code, I tried to read the contents of that generated file as a byte array and append them to the video file.

  


  However, this doesn't appear to work. I'm guessing this is because there is some kind of header or other metadata that prevents us from doing the simple solution of just appending the bytes of the next frame.

  


  My question is, how can I achieve what I am trying to do ? I'd like to splice in n number of frames as I am writing the individual packet contents to the file. In other words, for example, consider the following sequence :

  


  

  • Write packets of video to the file

  


  • My code determines that filler frames are needed at some point in this process

    

    • Insert needed number of filler frames to the file

    


    


  


  • Continue writing packets of video as they come in

  


  


• aarch64 : vp9itxfm : Skip empty slices in the first pass of idct_idct 16x16 and 32x32

  18 novembre 2016, par Martin Storsjö

  aarch64 : vp9itxfm : Skip empty slices in the first pass of idct_idct 16x16 and 32x32
  This work is sponsored by, and copyright, Google.
  Previously all subpartitions except the eob=1 (DC) case ran with
  
  the same runtime :
  vp9_inv_dct_dct_16x16_sub16_add_neon :   1373.2
  
  vp9_inv_dct_dct_32x32_sub32_add_neon :   8089.0
  By skipping individual 8x16 or 8x32 pixel slices in the first pass,
  
  we reduce the runtime of these functions like this :
  vp9_inv_dct_dct_16x16_sub1_add_neon :     235.3
  
  vp9_inv_dct_dct_16x16_sub2_add_neon :    1036.7
  
  vp9_inv_dct_dct_16x16_sub4_add_neon :    1036.7
  
  vp9_inv_dct_dct_16x16_sub8_add_neon :    1036.7
  
  vp9_inv_dct_dct_16x16_sub12_add_neon :   1372.1
  
  vp9_inv_dct_dct_16x16_sub16_add_neon :   1372.1
  
  vp9_inv_dct_dct_32x32_sub1_add_neon :     555.1
  
  vp9_inv_dct_dct_32x32_sub2_add_neon :    5190.2
  
  vp9_inv_dct_dct_32x32_sub4_add_neon :    5180.0
  
  vp9_inv_dct_dct_32x32_sub8_add_neon :    5183.1
  
  vp9_inv_dct_dct_32x32_sub12_add_neon :   6161.5
  
  vp9_inv_dct_dct_32x32_sub16_add_neon :   6155.5
  
  vp9_inv_dct_dct_32x32_sub20_add_neon :   7136.3
  
  vp9_inv_dct_dct_32x32_sub24_add_neon :   7128.4
  
  vp9_inv_dct_dct_32x32_sub28_add_neon :   8098.9
  
  vp9_inv_dct_dct_32x32_sub32_add_neon :   8098.8
  I.e. in general a very minor overhead for the full subpartition case due
  
  to the additional cmps, but a significant speedup for the cases when we
  
  only need to process a small part of the actual input data.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavcodec/aarch64/vp9itxfm_neon.S

• FFmpeg. avcodec_find_encoder(AV_CODEC_ID_H264) return false

  14 juillet 2016, par Иван Чванов

  The problem : I can not connect the h264 codec for encoding and decoding of frames.

  ---

  Description :

  I downloaded from here ffmpeg library https://ffmpeg.zeranoe.com/builds/, version dev.

  Connect it to your project QT :

  extern "C"
  
  {
  
      #include 
  
      #include 
  
      #include 
  
      #include 
  
      #include 
  
  }
  
      
  
  #pragma comment (lib, "avcodec.lib")
  
  #pragma comment (lib, "avformat.lib")
  
  #pragma comment (lib, "swscale.lib")
  
  #pragma comment (lib, "avutil.lib")

  Next prescribe av_register_all(); to include all codecs.

  Next, call the function : avcodec_find_encoder(AV_CODEC_ID_H264), returns false.

  In the ReadMe file, the library said that it was collected with —enable-libx264 and —enable-gpl compile the keys including h264 codec that is supposed to be.

  If the call : avcodec_find_encoder(AV_CODEC_ID_MPEG1VIDEO), it returns an object AVCodec, as it should.

  I use the MinGW compiler. OC Windows 7.

  How can I resolve or work around the problem ? Compile the library itself has not yet obtained. I understand you to connect sources and "poking" them, that too is meaningless.

  ---

  ** Once again, I will describe my problem : **

  I need to encode the codec h264 (can VP9) individual frames in one program, and then decode them in another program. You can use other libraries. The language C ++. It is necessary to use interframe compression codec, rather than simply pressed apart frames.

  Sorry for my english.

  Ideas. Advice. Suggestions.