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• Convert wav to mp3 using Meteor FS Collections on Startup

  28 juillet 2015, par TheBetterJORT

  I’m trying to transcode all wav files into a mp3 using Meteor and Meteor FS Collections. My code works when I upload a wav file to the uploader — That is it will convert the wav to a mp3 and allow me to play the file. But, I’m looking for a Meteor Solution that will transcode and add the file to the DB if the file is a wav and exist in a certain directory. According to the Meteor FSCollection it should be possible if the files have already been stored. Here is their example code : *GM is for ImageMagik, I’ve replaced gm with ffmpeg and installed ffmpeg from atmosphereJS.

  Images.find().forEach(function (fileObj) {
  
    var readStream = fileObj.createReadStream('images');
  
    var writeStream = fileObj.createWriteStream('images');
  
    gm(readStream).swirl(180).stream().pipe(writeStream);
  
  });

  I’m using Meteor-CollectionFS [https://github.com/CollectionFS/Meteor-CollectionFS]-

  if (Meteor.isServer) {
  
    Meteor.startup(function () {
  
          Wavs.find().forEach(function (fileObj) {
  
        var readStream = fileObj.createReadStream('.wavs/mp3');
  
        var writeStream = fileObj.createWriteStream('.wavs/mp3');
  
        this.ffmpeg(readStream).audioCodec('libmp3lame').format('mp3').pipe(writeStream);
  
        Wavs.insert(fileObj, function(err) {
  
        console.log(err);
  
      });
  
        });
  
        });
  
  }

  And here is my FS.Collection and FS.Store information. Currently everything resides in one JS file.

  Wavs = new FS.Collection("wavs", {
  
    stores: [new FS.Store.FileSystem("wav"),
  
      new FS.Store.FileSystem("mp3",
  
  
  
      {
  
        path: '~/wavs/mp3',
  
        beforeWrite: function(fileObj) {
  
          return {
  
            extension: 'mp3',
  
            fileType: 'audio/mp3'
  
          };
  
        },
  
        transformWrite: function(fileObj, readStream, writeStream) {
  
          ffmpeg(readStream).audioCodec('libmp3lame').format('mp3').pipe(writeStream);
  
        }
  
      })]
  
  });

  When I try and insert the file into the db on the server side I get this error : MongoError : E11000 duplicate key error index :

  Otherwise, If I drop a wav file into the directory and restart the server, nothing happens. I’m new to meteor, please help. Thank you.

• Thread count option in FFmpeg for FASTEST conversion to h264 ?

  5 septembre 2013, par Saptarshi Biswas

  I need to maximize speed while converting videos using FFmpeg to h264

  • Any input format of source videos
  • User's machine can have any number of cores
  • Power and memory consumption are non-issues

  Of course, there are a whole bunch of options that can be tweaked but this question is particularly about choosing the best -thread <count></count> option. I am trying to find an ideal thread count as a function of

  • no. of cores
  • input video format
  • h264-friendly values maybe ?
  • anything else missed above ?

  I am aware the default -thread 0 follows one-thread-per-core approach which is supposed to be optimal. But I am not sure if this is time or space-optimized. Also, on certain testcases, I've seen more threads (say 4 threads on my dual core test machine) finishes quicker than the default.

  Any other direction, say configure options w.r.t. threads, worth pursuing ?

• Thread count option in FFmpeg for FASTEST conversion to h264 ?

  9 février, par S B

  I need to maximize speed while converting videos using FFmpeg to h264

  



  

  • Any input format of source videos

  


  • User's machine can have any number of cores

  


  • Power and memory consumption are non-issues

  


  



  Of course, there are a whole bunch of options that can be tweaked but this question is particularly about choosing the best -thread <count></count> option. I am trying to find an ideal thread count as a function of

  



  

  • no. of cores

  


  • input video format

  


  • h264-friendly values maybe ?

  


  • anything else missed above ?

  


  



  I am aware the default -thread 0 follows one-thread-per-core approach which is supposed to be optimal. But I am not sure if this is time or space-optimized. Also, on certain testcases, I've seen more threads (say 4 threads on my dual core test machine) finishes quicker than the default.

  



  Any other direction, say configure options w.r.t. threads, worth pursuing ?