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• How do I decrypt the HLS stream to a .ts file when I have the key and IV ?

  28 décembre 2017, par A___ea_

  I have access to all the .ts files.
  My .m3u8 starts like this :

  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXT-X-ALLOW-CACHE:YES
  
  #EXT-X-TARGETDURATION:13
  
  #EXT-X-KEY:METHOD=AES-128,URI="https://localserver/get_key?title_id=144", IV=0x4d1acfe1962002a4abedb8b68c65fa93
  
  #EXTINF:12.066667,
  
  1500_144_00000.ts
  
  #EXTINF:9.000000,
  
  1500_144_00001.ts
  
  EXTINF:9.000000,
  
  1500_144_00002.ts
  
  ...

  ... and the .m3u8 continues to show all the .ts files. It gives me the IV, and my Access key is f0d3321327cbaa1aa9ddba07801607442bebaad65b17ca75a15affd5

  No I’ve been searching my brain and the web for an answer on how to decrypt the .ts files (or the concatenated file) and I have seen suggestions using both openssl and ffmpeg but I can not seem to reach all the way with either tool.

  From what I’ve figured I can use the IV and Access_key to decrypt the stream using openssl. I have used the IV=4d1acfe1962002a4abedb8b68c65fa93 (removed 0x).

  I have so far tried to with the concatenated file :

  openssl aes-128-cbc -d -in concatenatedfile.ts -out decrypted_concatenatedfile.ts -nosalt -iv 4d1acfe1962002a4abedb8b68c65fa93 -K f0d3321327cbaa1aa9ddba07801607442bebaad65b17ca75a15affd5 

  But this just gives me

  bad decrypt
  
  139793444538016:error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt:evp_enc.c:539:

  I’ve seen suggestions that use a .key file and convert that to a readable format. But since I don’t have a .key file, but a ready string, I figure this is where I fail.

  I’ve tried using ffmpeg in accordance to this beautiful post by @aergistal.

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

  But here too I seem to fail with my long string key.

  Any suggestions on how to proceed using openssl or ffmpeg are very welcome.

  Kindly

• Low latency routing of rtp input to rtsp output with ffmpeg on a server

  29 mai 2020, par guillefix

  I want to be able to do some simple low-latency screen share. I know peer-to-peer would be the lowest latency, but it seems using an intermediate server is a lot easier to setup. I have found this awesome little library, which sets up an RTSP server, which I'm running on my digital ocean server. I then :

  



  

  1. Set up OBS to stream using RTP to the server on port 8558 with libx264 encoding.

  


  2. Run ffmpeg -re -stream_loop -1 -i rtp://127.0.0.1:8558 -c:v libx264 -c:a aac -f rtsp rtsp://localhost:8554/mystream on the server.

  


  3. Open rtsp://<server ip="ip">:8554/mystream</server> on VLC.

  


  



  However, the latency seems to be quite high. With my crappy internet it must have been like half a minute. A friend with better internet saw it fluctuating between 4-15 seconds. Furthermore, there seems to be a lot of artifacts on the video (problems with encoding ? I'm not sure why these happen ?)

  



  I attach below my OBS settings, and an example of artifacts.

  



  My question is : is there some settings on OBS and on ffmpeg that would allow this to have as low end-to-end latency as possible, while not having too many bad artifacts ? I'm not very well versed on video encoding and streaming, so this is all quite new to me. I'm willing to learn !

  



  

  



  

  


• lavc/sbrdsp : R-V V autocorrelate

  8 novembre 2023, par Rémi Denis-Courmont

  lavc/sbrdsp : R-V V autocorrelate
  With 5 accumulator vectors and 6 inputs, this can only use LMUL=2.
  
  Also the number of vector loop iterations is small, just 5 on 128-bit
  
  vector hardware.
  The vector loop is somewhat unusual in that it processes data in
  
  descending memory order, in order to save on vector slides :
  
  in descending order, we can extract elements to carry over to the next
  
  iteration from the bottom of the vectors directly. With ascending order
  
  (see in the Opus postfilter function), there are no ways to get the top
  
  elements directly. On the downside, this requires the use of separate
  
  shift and sub (the would-be SH3SUB instruction does not exist), with
  
  a small pipeline stall on the vector load address.
  The edge cases in scalar are done in scalar as this saves on loads
  
  and remains significantly faster than C.
  autocorrelate_c : 669.2
  
  autocorrelate_rvv_f32 : 421.0
  

  • [DH] libavcodec/riscv/sbrdsp_init.c
  • [DH] libavcodec/riscv/sbrdsp_rvv.S