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• FFMPEG or FFPLAY, catch FFT signal in real time as floats

  25 avril 2021, par NVRM

  Looking to extract in real time a FFT snapshot of waveforms data with ffplay, in the view of creating animations.

  


  This is exactly what I am looking to catch, but this demo is using JavaScript in a browser. (Source own post)

  


  


  


  const audio = document.getElementById('music');
audio.load();
audio.play();

const ctx = new AudioContext();
const audioSrc = ctx.createMediaElementSource(audio);
const analyser = ctx.createAnalyser();

audioSrc.connect(analyser);
analyser.connect(ctx.destination);

analyser.fftSize = 256;
const bufferLength = analyser.frequencyBinCount;
const frequencyData = new Uint8Array(bufferLength);

setInterval(() => {
   analyser.getByteFrequencyData(frequencyData);
   console.log(frequencyData);
}, 1000);

  


  <audio src="http://strm112.1.fm/reggae_mobile_mp3" crossorigin="use-URL-credentials" controls="true"></audio>

  


  


  



  ---

  


  I tried many variations around the method posted on https://trac.ffmpeg.org/wiki/Waveform .

  


  

  


  The problem is the output format for FFT is PCM (Pulse Code Modulation), and not real time.

  


  ---

  


  In a generic way, is there a simple way to do this, while the sound is playing, to retrieve this data ?

  


  ffplay -fft file.mp3 > fft.json


  


  ---

  


  Using C, same stuff : Apply FFT on pcm data and convert to a spectrogram

  


  FFMPEG waveform filter documentation

  


• How do I know ffmpeg-php is installed ?

  18 juillet 2014, par Rob Avery IV

  I just followed the instructions from this link on how to install ffmpeg-php on my dedicated server : http://www.ndchost.com/wiki/server-administration/install-ffmpeg

  At the bottom, it says to run the command php -i|grep ffmpeg and if it outputs the following lines then it is installed :

  ffmpegffmpeg support (ffmpeg-php) => enabled
  
  ffmpeg-php version => 0.6.0
  
  ffmpeg.allow_persistent => 0 => 0

  When I run it, it gives me this :

  ffmpeg
  
  ffmpeg-php version => 0.6.0-svn
  
  ffmpeg-php built on => Jul 18 2014 08:46:12
  
  ffmpeg-php gd support  => enabled
  
  ffmpeg libavcodec version => Lavc52.108.0
  
  ffmpeg libavformat version => Lavf52.93.0
  
  ffmpeg swscaler version => SwS0.12.0
  
  ffmpeg.allow_persistent => 0 => 0
  
  ffmpeg.show_warnings => 0 => 0
  
  PWD => /usr/local/src/ffmpeg-php-0.6.0
  
  _SERVER["PWD"] => /usr/local/src/ffmpeg-php-0.6.0
  
  _ENV["PWD"] => /usr/local/src/ffmpeg-php-0.6.0

  I got 2/3 lines, but the one is not character-for-character the same.

  Is ffmpegffmpeg support (ffmpeg-php) => enabled the same as ffmpegffmpeg support (ffmpeg-php) => enabled in this context ?

  EDIT :
  Running this command ffmpeg -version gives me this result :

  FFmpeg version SVN-r26402, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on Jul 18 2014 08:41:45 with gcc 4.4.7 20120313 (Red Hat 4.4.7-3)
  
    configuration: --enable-libmp3lame --disable-mmx --enable-shared
  
    libavutil     50.36. 0 / 50.36. 0
  
    libavcore      0.16. 1 /  0.16. 1
  
    libavcodec    52.108. 0 / 52.108. 0
  
    libavformat   52.93. 0 / 52.93. 0
  
    libavdevice   52. 2. 3 / 52. 2. 3
  
    libavfilter    1.74. 0 /  1.74. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
  FFmpeg SVN-r26402
  
  libavutil     50.36. 0 / 50.36. 0
  
  libavcore      0.16. 1 /  0.16. 1
  
  libavcodec    52.108. 0 / 52.108. 0
  
  libavformat   52.93. 0 / 52.93. 0
  
  libavdevice   52. 2. 3 / 52. 2. 3
  
  libavfilter    1.74. 0 /  1.74. 0
  
  libswscale     0.12. 0 /  0.12. 0

• Compile ffmpeg for armv7s

  14 août 2014, par user3929400

  I am trying to compile ffmpeg on OSX 10.9. I want to use the ffmpeg framework in an iOS testapplication using xCode.

  I want to link the libfaac to ffmpeg and compile it for armv7s. When I follow the compilation guide (https://trac.ffmpeg.org/wiki/CompilationGuide/MacOSX) on the ffmpeg site, it does not work.

  I used the following configuration :

  ./configure  --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --arch=armv7s

  Another configuration I tried is

  ./configure  --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --arch=armv7s --enable-cross-compile --target-os=darwin

  The difference between both configuration is the cross compile and target os.

  Both configuration produces the following error message :

  GNU assembler not found, install gas-preprocessor

  Although, I have copied gas-preprocessor.pl into the directories /usr/local/bin and /usr/bin and modified the file read-write props by using chmod +x gas-preprocessor.pl

  Can somebody help me to configure ffmpeg by giving for example an example configuration which does work ?