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• Publish audio to an RTMP server for real time live streaming in C or C++

  19 mai 2021, par Antenaina

  I want to publish audio stream to an RTMP server, for real time audio live streaming, from mobile device (with Android for example).
  
Suppose the mobile device has a way to yield to me those datas in real time (ex : using Oboe library). Packet by packet (a packet contains a certain number of audio frames).
  
When live streaming, there are some really custom computations to those datas that requires that I must send then little by little (packet by packet ?) to the RTMP server.
  
I'm trying to use FFMPEG for that purpose, and have similar problem with this thread's question : How to publish self made stream with ffmpeg and c++ to rtmp server ?. But the answer there is not detailed is not enough for me.
  
I tried reading FFMPEG code source, with the help of the documentation, but there are still some challenges I must face since I'm new to the streaming domain. What I need to know is :

  


  

  • How to properly configure FFMPEG for that purpose ? (AVFormatContext ?)

  


  • What is the proper way to write the stream (AVStream) ? (I read somewhere that the packet needs to be of a specific size, and other stuffs too)

  


  


  For simplicity :

  


  

  • I can handle the audio packet by packet and encoded.

  


  • Audio is encoded as mp3.

  


  • Audio has default sample rate of 44100 Hz, 320kb/s bitrate and some other details already known so that FFMPEG doesn't need to guess it.

  


  


  Further informations :
  
I'm using react-native. For android : native modules to communicate with Java, JNI to communicate Java with C++, Oboe to record and play audio. For iOS : not a problem for the moment.
  
I use node-media-server as RTMP server.
  
Thanks !

  


• Convert SDR-JPEG to HDR-AVIF [closed]

  27 avril 2024, par Jonas Janzen

  I would like to convert a jpg file into an avif file that is to be saved in HDR10-capable metadata (PQ curve, 2020 color space, 10 bit).

  


  The idea is to save normal SDR images in HDR-capable containers so that they can be displayed in all their glory on HDR-capable displays.

  


  I want to play with inverse tone mapping, to manipulate the output, so I implemented in Python via subprocess.

  


  So far I just want the input image to be saved in AVIF as HDR and look the same at the end as before, so that I can then make changes in the next step.

  


  I used the following command for this :

  


  ffmpeg_command = [
'ffmpeg',

  


  Input File
'-i', temp_file,

  


  Used Library
'-c', 'libaom-av1',

  


  '-still-picture', '1',

  


  Output Metadata
'-pix_fmt', 'yuv420p10le',
'-strict', 'experimental',
'-color_primaries', 'bt2020',
'-color_trc', 'smpte2084',
'-colorspace', 'bt2020nc',
'-color_range', 'pc',

  


  Output File
output_file
]

  


  So far my attempts have only been successful with the HLG characteristic. Here you can see that the images are really brighter in the peaks on my HDR monitor.

  


  With the PQ characteristic curve, the images are far too oversaturated.

  


  I guess this is because the HLG curve is compatible with the gamma curve, but PQ is not.

  


  Now my question is what I need to change.

  


  Which curve does FFMpeg expect as input.

  


  In Python I can change the images mathematically without any problems.

  


  The Example Images are again tone mapped down to jpg, to show what happened.

  


  enter image description here
enter image description here

  


• FFmpeg with node.js. Transcode a file to another format

  19 juin 2014, par user2757842

  Have a bit of a problem with this, I have an .avi file in which I would like to transcode into a .flv file using FFmpeg, here is what I have so far :

  var ffmpeg = require('fluent-ffmpeg');
  
  
  
  //make sure you set the correct path to your video file
  
  var proc = new ffmpeg({ source: 'C:/Users/Jay/Documents/movie/drop.avi', nolog: true })
  
  
  
  //Set the path to where FFmpeg is installed
  
  .setFfmpegPath("C:\Users\Jay\Documents\FFMPEG")
  
  
  
  //set the size
  
  .withSize('50%')
  
  
  
  // set fps
  
  .withFps(24)
  
  
  
  // set output format to force
  
  .toFormat('flv')
  
  
  
  // setup event handlers
  
  .on('end', function() {
  
      console.log('file has been converted successfully');
  
  })
  
  .on('error', function(err) {
  
      console.log('an error happened: ' + err.message);
  
  })
  
  // save to file <-- the new file I want -->
  
  .saveToFile('C:/Users/Jay/Documents/movie/drop.flv');

  It seems straightforward enough and I can do it through the FFmpeg command line, but I am trying to get it working within a node.js app, here is the error it is returning :

  C:\Users\Jay\workspace\FFMPEGtest\test.js:17
  
  .withSize('50%')
  
   ^
  
  TypeError: Cannot call method 'withSize' of undefined
  
      at Object.<anonymous> (C:\Users\Jay\workspace\FFMPEGtest\test.js:17:2)
  
      at Module._compile (module.js:456:26)
  
      at Object.Module._extensions..js (module.js:474:10)
  
      at Module.load (module.js:356:32)
  
      at Function.Module._load (module.js:312:12)
  
      at Function.Module.runMain (module.js:497:10)
  
      at startup (node.js:119:16)
  
      at node.js:906:3
  
  </anonymous>

  It throws the same error for each built in FFmpeg function (.toFormat, .withFPS etc)

  If anyone has a solution to this, I’d greatly appreciate it