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https://github.com/benvanik/node-transcoding

node.js video transcoding library
https://github.com/benvanik/node-transcoding

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node.js video transcoding library

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node-transcoding -- Media transcoding and streaming for node.js

====================================



node-transcoding is a library for enabling both offline and real-time media

transcoding. In addition to enabling the manipulation of the input media,

utilities are provided to ease serving of the output.



Currently supported features:



* Nothing!



Coming soon (maybe):



* Everything!



## Quickstart



    npm install transcoding

    node

    > var transcoding = require('transcoding');

    > transcoding.process('input.flv', 'output.m4v',

        transcoding.profiles.APPLE_TV_2, function(err, sourceInfo, targetInfo) {

          console.log('completed!');

        });



## Installation



With [npm](http://npmjs.org):



    npm install transcoding



From source:



    cd ~

    git clone https://[email protected]/benvanik/node-transcoding.git

    npm link node-transcoding/



### Dependencies



node-transcoding requires `ffmpeg` and its libraries `avformat` and `avcodec`.

Make sure it's installed and on your path. It must be compiled with libx264 to

support most output - note that some distributions don't include this and you

may have to compile it yourself. Annoying, I know.



#### Source



    ./configure \

        --enable-gpl --enable-nonfree --enable-pthreads \

        --enable-libfaac --enable-libfaad --enable-libmp3lame \

        --enable-libx264

    sudo make install



#### Mac OS X



The easiest way to get ffmpeg is via [MacPorts](http://macports.org).

Install it if needed and run the following from the command line:



    sudo port install ffmpeg +gpl +lame +x264 +xvid



You may also need to add the MacPorts paths to your `~./profile`:



    export C_INCLUDE_PATH=$C_INCLUDE_PATH:/opt/local/include/

    export CPLUS_INCLUDE_PATH=$CPLUS_INCLUDE_PATH:/opt/local/include/

    export LIBRARY_PATH=$LIBRARY_PATH:/opt/local/lib/



#### FreeBSD



    sudo pkg_add ffmpeg



#### Linux



    # HAHA YEAH RIGHT GOOD LUCK >_>

    sudo apt-get install ffmpeg



## API



### Sources/targets



All APIs take a source and target. Sources can be either strings representing

file paths or Node readable streams. Targets can be either strings representing

file paths or Node writable streams. Note that if possible you should use file

paths, as it enables much faster access to the underlying data (~2x speed

increase).



### Media Information



Whenever 'info' is used, it refers to a MediaInfo object that looks something

like this:



    {

      container: 'flv',

      duration: 126,         // seconds

      start: 0,              // seconds

      bitrate: 818000,       // bits/sec

      streams: [

        {

          type: 'video',

          codec: 'h264',

          profile: 'Main',

          profileId: 77,

          profileLevel: 30,

          resolution: { width: 640, height: 360 },

          bitrate: 686000,

          fps: 29.97

        }, {

          type: 'audio',

          language: 'eng',

          codec: 'aac',

          sampleRate: 44100, // Hz

          channels: 2,

          bitrate: 131000

        }

      ]

    }



Note that many of these fields are optional, such as bitrate, language, profile

information, and even fps/duration. Don't go using the values without checking

for undefined first.



### Querying Media Information



To quickly query media information (duration, codecs used, etc) use the

`queryInfo` API:



    var transcoding = require('transcoding');

    transcoding.queryInfo(source, function(err, info) {

      // Completed

    });



### Transcoding Profiles



Transcoding requires a ton of parameters to get the best results. It's a pain in

the ass. So what's exposed right now is a profile set that tries to set the

best options for you. Pick your profile and pass it into the transcoding APIs.



    var transcoding = require('transcoding');

    for (var profileName in transcoding.profiles) {

      var profile = transcoding.profiles[profileName];

      console.log(profileName + ':' + util.inspect(profile));

    }



### Simple Transcoding



If you are doing simple offline transcoding (no need for streaming, extra

options, progress updates, etc) then you can use the `process` API:



    var transcoding = require('transcoding');

    transcoding.process(source, target, transcoding.profiles.APPLE_TV_2, {}, function(err, sourceInfo, targetInfo) {

      // Completed

    });



Note that this effectively just wraps the advanced API, without the need to

track events.



### Advanced Transcoding



    var transcoding = require('transcoding');

    var task = transcoding.createTask(source, target, transcoding.profiles.APPLE_TV_2);



    task.on('begin', function(sourceInfo, targetInfo) {

      // Transcoding beginning, info available

      console.log('transcoding beginning...');

      console.log('source:');

      console.log(util.inspect(sourceInfo));

      console.log('target:');

      console.log(util.inspect(targetInfo));

    });

    task.on('progress', function(progress) {

      // New progress made, currrently at timestamp out of duration

      // progress = {

      //   timestamp: 0,        // current seconds timestamp in the media

      //   duration: 0,         // total seconds in the media

      //   timeElapsed: 0,      // seconds elapsed so far

      //   timeEstimated: 0,    // seconds estimated for total task

      //   timeRemaining: 0,    // seconds remaining until done

      //   timeMultiplier: 2    // multiples of real time the transcoding is

      //                        // occuring in (2 = 2x media time)

      // }

      console.log(util.inspect(progress));

      console.log('progress ' + (progress.timestamp / progress.duration) + '%');

    });

    task.on('error', function(err) {

      // Error occurred, transcoding ending

      console.log('error: ' + err);

    });

    task.on('end', function() {

      // Transcoding has completed

      console.log('finished');

    });



    // Start transcoding

    task.start();



    // At any time, abort transcoding

    task.stop();



### HTTP Live Streaming



* [IETF Spec](http://tools.ietf.org/html/draft-pantos-http-live-streaming-07)

* [Apple Docs](http://developer.apple.com/library/ios/#documentation/networkinginternet/conceptual/streamingmediaguide/Introduction/Introduction.html)



If you are targeting devices that support HTTP Live Streaming (like iOS), you

can have the transcoder build the output in realtime as it processes. This

enables playback while the transcoding is occuring, as well as some other fancy

things such as client-side stream switching (changing audio channels/etc).



    var task = transcoding.createTask(source, null, profile, {

      liveStreaming: {

        path: '/some/path/',

        name: 'base_name',

        segmentDuration: 10,

        allowCaching: true

      }

    });



This will result in a playlist file and the MPEGTS segments being placed under

`/some/path/` with the name `base_name.m3u8`. The playlist file will be

automatically updated as new segments are generated, and files can be assumed to

be static once they are available.