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• ffmpeg doesn't recognize the local key file for decrypting a m3u8

  3 juillet 2021, par Rockt

  Ok so here is the situation.

  


  I have a m3u8 file which is encrypted using AES-128. Using a simple python script I download the m3u8 and the key file and then serves it over the local network with the aid of SimpleHTTPServer. Then I run a separate shell script to get the m3u8 and key file from the local server and it get the job done without any problems.

  


  Now instead of getting the files from the local server, I want to decrypt them locally from the command line. So I replaced the key path of the m3u8 from,

  


  #EXT-X-KEY:METHOD=AES-128,URI="https://example.com/key"


  


  to

  


  #EXT-X-KEY:METHOD=AES-128,URI="file://local/path/to/video.key"


  


  And when executed the following from the command line,

  


  ffmpeg -safe 0 -protocol_whitelist file,http,https,tcp,tls,crypto -allowed_extensions ALL -i playlist.m3u8 "output.mp4"


  


  It gives me these two errors and exits.

  


  Unable to open key file file://local/path/to/video.key
playlist.m3u8: Invalid data found when processing input


  


  Now my question is why ffmpeg doesn't give any errors when I serve the key file over a local server, and why things get changed when I do it this way ? Any help maybe ?

  


• Making a simple video directly using C

  13 août 2020, par thedeathstar1997

  I am working on an Ising Lattice simulation (2D binary image) using C and I want to generate a video of the simulation. Currently I am saving every step as a ppm image and using ffmpeg to convert the folder of images into an mp4 video. Is there any way to directly generate a video in the C code ? I know that C has a library for ffmpeg but the documentation got me very confused.

  


• aacenc_tns : redo coefficient quantization and decision making

  12 septembre 2015, par Rostislav Pehlivanov

  aacenc_tns : redo coefficient quantization and decision making
  This finally (and again) gets rid of basically everything the
  
  specifications say about how TNS should be done. The main
  
  problem used to be that a single filter was used for all
  
  coefficients which despite being explicitly recommended by
  
  the specifications usually sounds wrong, therefore it’s
  
  a corner case in the current TNS implementation.
  This commit also changes the coefficient bit size, as apparently
  
  it’s better to use lower precision in case the windows are eight
  
  short. This is apparently what fdk_aac uses, looking at the bit
  
  stream and makes sense. Also the order when 8 SHORT windows happen
  
  is important as 7 was too much and according to PSNR was worse
  
  while 5 is just about correct.
  Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  

  • [DH] libavcodec/aacenc_tns.c
  • [DH] libavcodec/aacenc_tns.h