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• How to compare audio channel differences with FFmpeg ?

  30 septembre 2021, par Deivedux

  I'm making a little script for myself to quickly go through a large volume of video and audio files to compress audio for extra space, but for extra efficiency, I also don't want to waste space by keeping both channels if they're identical.

  


  My issue is that I don't know how to, let's say, check if their decoded versions are at least a 99.99% match, in which case I'd only encode the left channel into mono.

  


  How would I go about doing this ?

  


• Restreaming and transcoding a hls stream with FFMPEG.WASM fails due to tcp connection

  13 juillet 2021, par Hoang Nguyen

  I'm trying to implement a feature which is live transcoding a hls stream (h265) to another hls stream (h264) so the video can be played using html5 video player as we know that h265 is not supported on browsers. Quick summery of my tech stack :

  


  -Electron desktop app as the client.
-FFMPEG.WASM library : https://ffmpegwasm.github.io/

  


  (*) The on-the-fly transcoding is supposed to happen right on the client side.

  


  My dev enviroment :

  


  "devDependencies": { "electron": "^13.1.5", "electron-packager": "^13.0.1", "electron-winstaller": "^2.7.0" }

  


  There are 2 ways to use this library, one is as normal html script, and the other is nodejs style which I have tried both and get different errors (though they are all about connection) :

  


  (*) Regular JS way

  


  <code class="echappe-js">&lt;script async defer src=&quot;https://unpkg.com/@ffmpeg/ffmpeg@0.10.1/dist/ffmpeg.min.js&quot;&gt;&lt;/script&gt;&#xA;Play
  &#xA;&lt;script&gt;&amp;#xA; async function loadPlayerHEVC() {&amp;#xA;var resource = &amp;#x27;http://10.70.39.32:80/streams/60dd68fdc88f570012526657/stream/60dd68fdc8....526657.m3u8&amp;#x27;&amp;#xA;                    const { createFFmpeg } = FFmpeg;&amp;#xA;                    const ffmpeg = createFFmpeg({ log: true });&amp;#xA;                    const { fetchFile } = FFmpeg;&amp;#xA;                    await ffmpeg.load();&amp;#xA;                    await ffmpeg.run(&amp;#x27;-re&amp;#x27;,&amp;#x27;-i&amp;#x27;, resource, &amp;#x27;-vcodec&amp;#x27;, &amp;#x27;libx264&amp;#x27;, &amp;#x27;-acodec&amp;#x27;, &amp;#x27;copy&amp;#x27;, &amp;#x27;-f&amp;#x27; ,&amp;#x27;hls&amp;#x27;, &amp;#x27;-hls_list_size&amp;#x27;, &amp;#x27;3&amp;#x27;, &amp;#x27;-hls_wrap&amp;#x27;, &amp;#x27;5&amp;#x27;, &amp;#x27;playlist.m3u8&amp;#x27; );&amp;#xA;                    // ffmpeg.exit(0);&amp;#xA;                }&amp;#xA;            &lt;/script&gt;&#xA;
  

  


  

  


  (*) Nodejs way

  


  async function tester(url)
{
    const { createFFmpeg, fetchFile } = require('@ffmpeg/ffmpeg');
    const ffmpeg = createFFmpeg({ log: true });
    await ffmpeg.load();
    await ffmpeg.run('tcp','-re', '-i', url, '-vcodec', 'libx264', '-acodec', 'aac', '-f', 'flv', '-hls_list_size', '3', '-hls_wrap', '5', 'playlist.m3u8');
    // ffmpeg.exit(0);
}


  


  

  


  URL for testing

  


  You guys can use this public stream to reproduce the scenario : http://113.163.94.245/hls-live/livepkgr/_definst_/liveevent/thbt.m3u8

  


  Any help would be much appreciated.

  


• ffmpeg convert vp9 video to mp4

  6 mai 2017, par Sulli

  I am using this command

  ffmpeg -i $youtubeUrl -strict -2 -c copy output.mp4

  (with $youtubeUrl generated by youtube-dl) to download this youtube video : https://www.youtube.com/watch?v=wnCJhq-JOck

  I can’t play the downloaded video though on Ubuntu or Windows (for a problem of vp09 codec) and I have to convert the video to webm and then back to mp4 to be able to play it :

  ffmpeg -i output.mp4 -vcodec libvpx-vp9 -strict experimental output_2.webm
  
  ffmpeg -i output_2.webm -strict 2 output_3.mp4

  This happens only with some youtube videos, not all of them.

  Is there a way to download all youtube videos in a readable format with only one command line, without having to convert to webm ?