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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

  


  


• Need help accessing the key when trying to decrypt .ts files via ffmpeg

  4 juillet 2024, par Diz

  I have downloaded all the individual .ts files and the corresponding m3u8 file from a VOD and I now want to merge them together into a single watchable file.
The problem is, that the .ts files are encrypted and don't understand how to access the key.

  


  Here's the beginning of the m3u8 file :

  


  #EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:4
#EXT-X-PLAYLIST-TYPE:EVENT
#EXT-X-MEDIA-SEQUENCE:6484
#EXT-X-KEY:METHOD=AES-128,URI="irvine://aes",KEYFORMATVERSIONS="1",IV=0x1E9ABA2B3C916D47D592D9B1E7674F4B
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:24:59.682Z
#EXTINF:4.004,
index_1_6484.ts
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:25:03.686Z
#EXTINF:4.004,
index_1_6485.ts
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:25:07.690Z
#EXTINF:4.004,
index_1_6486.ts
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:25:11.694Z
#EXTINF:4.004,
index_1_6487.ts
...



  


  As far as I understood I only have the initialization vector and I need to access the URI to get the actual key.

  


  I have tried to decrypt the playlist with the following command :

  


  ffmpeg -i index_1.m3u8 -c copy output.ts


  


  But I would always get the following errors :

  


  Unable to open key file irvine://aes
Error when loading first segment 'index_1_6484.ts'
Error opening input: Invalid data found when processing input
Error opening input file index_1.m3u8.
Error opening input files: Invalid data found when processing input


  


  I have also tried just decrypting a single .ts file to start with, with similar results.

  


  ffmpeg -decryption_key 1E9ABA2B3C916D47D592D9B1E7674F4B -i index_1_6484.ts -codec copy index_1_6484_out.ts


  


• 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