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• how do we check similarity between hash values of two audio files in python ?

  14 avril 2022, par Reshma Walhekar

  About the data :
we have 2 video files which are same and audio of these files is also same but they differ in quality.
that is one is in 128kbps and 320kbps respectively.

  


  we have used ffmpeg to extract the audio from video, and generated the hash values for both the audio file using the code : ffmpeg -loglevel error -i 320kbps.wav -map 0 -f hash -
the output was : SHA256=4c77a4a73f9fa99ee219f0019e99a367c4ab72242623f10d1dc35d12f3be726c
similarly we did it for another audio file to which we have to compare ,
C :\FFMPEG>ffmpeg -loglevel error -i 128kbps.wav -map 0 -f hash -
SHA256=f8ca7622da40473d375765e1d4337bdf035441bbd01187b69e4d059514b2d69a

  


  Now we know that these audio files and hash values are different but we want to know how much different/similar they are actually , for eg : like some distance in a-b is say 3

  


  can someone help with this ?

  


• how to make ffmpeg output frames at correct rate down to millisecond

  9 février 2017, par Pavel K.

  using ffmpeg, i am fetching frames from udp stream (hd264 at 25 fps) using following command :

  ffmpeg -loglevel debug -i udp ://231.20.20.146:2005 -fflags nobuffer -r 1 -preset ultrafast -vf scale=432:243 -f image2pipe -vcodec ppm pipe:1

  at the other end of the pipe i am running a very simple binary which outputs the time at which it receives a frame.

  however, even though i specify fps 1, frames enter the pipe with some delay, with 100-200ms delay.

  what causes this delay ? is it the decoding of the frames and encoding of ppm image ? and how can i force ffmpeg to send images at least at the correct distance between each other, so that each frame would arrive exactly 1000ms after previous frame ?

  ps. the first 6 frames are buffered and enter the pipe almost at once. here is an example of recorded ms values :

  5350
  5368
  5385
  5493
  5599
  5676
  5785
  6221
  7243
  8235
  9218
  10219
  11227
  12268
  13268
  14242
  15288
  16219
  17297
  18222
  19284
  20272

• Compiling FFMPEG on CentOS DigitalOcean

  29 juillet 2015, par coder_uk

  I set up a DigitalOcean instance running CentOS 6.5 and successfully followed the guide to compile FFMPEG (https://trac.ffmpeg.org/wiki/CompilationGuide/Centos). Hurrah !

  But of course I realised that by default, DigitalOcean creates a root user and so ffmpeg now lives in /root/bin/ffmpeg. Which isn’t ideal because when I want to exec the ffmpeg bin from nginx, I would have to run nginx as root for it to have permission.

  Questions ...

  1) Long-shot, but presumably if I change the owner of the ffmpeg binary to nginx, it still won’t work, because nginx won’t be able to access the /root folder it is in. Correct ?

  2) I could run nginx as root (’user root’). But this seems like a very bad idea. Correct ?

  3) Which leaves me with the option of creating a new user, and then compiling ffmpeg into its home folder. But : which user ? EC2 creates ’ec2-user’, so should I make my own equivalent for DO ? But then won’t I have to run nginx as that user, else I’ll run into the same problem ?

  Or should I compile ffmpeg into the ’nginx’ home folder, if indeed it has one ? Is that how it is supposed to be done ?

  Since compiling ffmpeg takes ages, I don’t want to keep doing it, and the static files all seem very out of date. Thanks