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• how to begin streaming while ffmpeg is still transcoding the file in PHP

  15 janvier 2013, par Joyal

  I want to transcode an AVI video to mp4 with ffmpeg, but while is still transcoding, I would like to watch the video transcoded on a flash video player in realtime , Im using jwplayer , I made some test with mp4 and works great , but Im not able to make it work while is transcoding

  I made a php script to run the command in background

  ffmpeg.exe -threads 1 -y -i "a.avi" -s 1280x720 -f mp4 -vcodec libx264 -b 2000000 -ab 128000 -ar 44100 "a.mp4"

  on the jwplayer i have as source "a.mp4"

• Is async.js needed to process multiple ffmpeg conversions at the same time ?

  15 février 2019, par jurelik

  I’m trying to convert youtube videos to mp3 via my Node.js server, using ’ytdl-core’ and ’fluent-ffmpeg’. Since the server is intended to process multiple requests at the same time, it got me thinking whether or not async.js is needed to convert videos in a time efficient manner.

  The interesting thing however, is that upon testing the handling of multiple requests with and without using async.js, the result seems to be the same both ways - the time it takes to convert 3 videos is the same.

  Here is the code I’m using without async.js :

  server.get('/download/:id', (req, res) => {
  
  
  
    const id = req.params.id;
  
    let stream = ytdl(`https://www.youtube.com/watch?v=${id}`);
  
  
  
    ffmpeg(stream)
  
      .audioCodec('libmp3lame')
  
      .audioBitrate(128)
  
      .toFormat('mp3')
  
      .save(`public/downloads/${id}.mp3`)
  
      .on('error', err => {
  
        console.log(err);
  
      })
  
      .on('end', () => {
  
        console.log('file downloaded');
  
        send(req, `public/downloads/${id}.mp3`).pipe(res);
  
      });
  
  });

  And this is the code using async.js :

  let queue = async.queue((task, callback) => {
  
    let stream = ytdl(`https://www.youtube.com/watch?v=${task.id}`);
  
  
  
    ffmpeg(stream)
  
    .audioCodec('libmp3lame')
  
    .audioBitrate(128)
  
    .toFormat('mp3')
  
    .save(`public/downloads/${task.id}.mp3`)
  
    .on('error', err => {
  
      console.log(err);
  
      callback(err)
  
    })
  
    .on('end', () => {
  
      send(task.req, `public/downloads/${task.id}.mp3`).pipe(task.res);
  
      callback('file sucessfully downloaded');
  
    });
  
  }, 5);
  
  
  
  queue.drain = function() {
  
    console.log('all items downloaded');
  
  }
  
  
  
  server.get('/download/:id', (req, res) => {
  
    queue.push({req: req, id: req.params.id, res: res}, err => {
  
      console.log(err);
  
    });
  
  });

  Does anyone have any ideas why both methods seem to finish conversion at roughly the same time ? I would imagine using async.js should finish converting the videos faster due to processing in parallel, but that isn’t the case.

  Any thoughts would be much appreciated !

• Static ffmpeg library windows

  29 novembre 2022, par peter

  Im trying to use the ffmpeg libraries (libavutil, libswscale, ...) in a bigger project by statically linking them, im not interested in the binaries. Now the issue comes down to getting them statically built. I tried searching for pre-compiled builds but without success.

  


  Following the docs, i compiled them on wsl2 for win64 with

  


  ./configure --arch=x86_64 --target-os=mingw32 --cross-prefix=i686-w64-mingw32- --disable-shared --enable-static
make


  


  After that i copied the libavformat/libavformat.a as libavformat.lib (which should be fine since they are cross-compiled ar archives ?) into my project and linked them with CMake.

  


  When compiling smth like

  


  AVFormatContext* pFormatContext = avformat_alloc_context();


  


  i get a linker error saying

  


  lld-link : error : undefined symbol: avformat_alloc_context


  


  When looking at the libs with dumpbin -linkermember libavformat.lib, i can see

  


  >dumpbin -linkermember libavformat.lib
...
  135CD92 _avformat_alloc_context
...


  


  notice the underscore.

  


  Can i not link the cross-compiled *.a files directly into a windows executable ?

  


  Honestly at this point any ideas are welcome.

  


  Thanks