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• Generate AcoustID/Chromaprint acoustic fingerprint in iOS

  28 mars 2023, par ttarik

  Chromaprint is an open-source software library for calculating an AcoustID audio fingerprint of an audio file.

  



  I'm trying to generate this audio fingerprint from a local file on iOS.

  



  The library can be built on Windows, Linux and OS X, where it creates a dynamic library as well as a standalone program (fpcalc) that accepts an audio file, decodes the audio and passes it to the chromaprint library to calculate the fingerprint. It doesn't really work on iOS for the following reasons :

  



  

  1. The standalone fpcalc program can't be run on iOS because you can't run an executable from an app

  


  2. The source code to the fpcalc program uses chromaprint and ffmpeg. From what I've read, ffmpeg is difficult to compile on iOS. The chromaprint docs state that the Accelerate framework can be used in OS X/iOS, but there is no example code to do this and I have no idea where to start.

  


  



  I've been having a bit of trouble actually building the library for iOS (CMake hates me), but I feel like the above problems are more relevant because even with the library compiled, it wouldn't just work out of the box.

  



  I'm trying to avoid this being a "write my code for me" question, but I am very much stuck on essentially every aspect of generating a chromaprint fingerprint for iOS.

  



  My goal, I think, is to recreate the functionality of the fpcalc program on iOS - to decode an audio file (stored on the device, of any audio type) and pass it to the chromaprint library to generate the fingerprint.

  



  I found this question about acoustic fingerprinting on iOS but it wasn't relevant to chromaprint/AcoustID and the answers were less than helpful. Echoprint Codegen is interesting, but I need a chromaprint fingerprint.

  


• Detecting runTime process is finished

  31 janvier 2018, par Ives

  I’m using FFmpeg to export the video.
  I run the exe file from my java code.

  val process = Runtime.getRuntime().exec("$ffmpeg .....)
  
  while (process.isAlive) {
  
     //waiting
  
  }
  
  
  
  if(process.exitValue() != 0) {
  
  //failed
  
  }
  
  else {
  
  //successful
  
  }

  If any errors occur in FFmpeg, process will return an exitValue not 0 to tell me there is something wrong.
  But when the file or dir includes forbidden characters, it will be a " No such file or directory" error in ffmpeg, however it doesn’t return anything to the java program, so the program sticks at process.isAlive part.
  Is there a better way to detect the process is finished or not ?

• Broadcast Screen using ffmpeg to encode H.264

  29 avril 2018, par Erick Weil

  Background History :

  So. doing a program, I need a way to broadcast my desktop screen, trought local network( maybe wi-fi ), to aproximately 40 clients, primarily in windows, but if it also works in linux, will be great.

  Started doing my own video compression protocol, in Java, taking the hilbert curve as a inspiration ( it transmit 10 fps, 1024x720, horrible 8-bit colors, using 5 MB of bandwith) but the color quality was very low, and fps wasn’t that good, cpu usage blowing up to 50%, memory 800M. 

  So i realized i’ll never be able to do a proper encoding algorithm and tried to use ffmpeg to encode the screenshots in a video and transmit this.

  I tried :

  • Xuggler : not supported anymore, examples worked, but it does lack tutorials and things that explain how it works
  • VLCJ : VLC wraper for java, requires the client of the transmission to have VLC installed.
  • JavaCV : java wrapper of openCV, to wrap ffmpeg. my program size blows up if i include this
  • FFMPEG : in c++ i created a project, communication with java trought JNI, the remuxing example worked,
    but i don’t now how to use it to do what I want

  The actual question :

  How can i make a c++ program able to encode image frames into a H264 stream and send it trought UDP ?

  i mean, is there any tutorial on ffmpeg, any place to start learning how to use it.