A node.js snippet to stream media files to a Chromecast device

chromecast.js

// A node.js snippet to stream media files to a Chromecast device.

// An ac3 or dts audio stream in matroska containers is transcoded to mp3
// using ffmeg. Seeking using left and right keys won't be available.

var Client                = require('castv2-client').Client;
var DefaultMediaReceiver  = require('castv2-client').DefaultMediaReceiver;
var mdns                  = require('mdns');

var ffmpeg = require('fluent-ffmpeg');

var mime = require('mime');
var path = require('path');

var send = require('send');

var sprintf = require("sprintf-js").sprintf;

var keypress = require('keypress');

var browser = mdns.createBrowser(mdns.tcp('googlecast'));

var fs = require('fs');
var http = require('http');

var file = process.argv[2];

if (!file) {
    console.log('Please specify a media file as an argument.');
    return;
}

console.log('media to serve: ' + file);

var Player;

var start;
var current;

var paused;

var httpResponse;
var transcode; // ffmpeg transcoding command

browser.on('serviceUp', function(service) {
    console.log('found device "%s" at %s:%d', service.name, service.addresses[0], service.port);
    ondeviceup(service.addresses[0]);
    browser.stop();
});

browser.start();

keypress(process.stdin);

function ondeviceup(host) {

    var client = new Client();

    client.connect(host, function() {
        console.log('connected, launching app ...');

        client.launch(DefaultMediaReceiver, function(err, player) {
            var media = {
                contentId: 'http://192.168.1.2:8080/content',
                contentType: mime.lookup(file),
                streamType: 'BUFFERED'
            };

            console.log('media mime: ' + media.contentType);

            var transcodeAudio = false;

            // mkv might need transcoding audio (ac3 or dts) to mp3
            if (media.contentType == 'video/x-matroska') {
                ffmpeg.ffprobe(file, function(err, metadata) {
                    console.dir(metadata);
                    if ((metadata.format.nb_streams > 1)
                        && (metadata.streams[0].codec_name == 'ac3'
                            || metadata.streams[1].codec_name == 'ac3'
                            || metadata.streams[0].codec_name == 'dca'
                            || metadata.streams[1].codec_name == 'dca')) {
                        transcodeAudio = true;
                        console.log('transcoding required -> switching streaming mode to live');
                        media.streamType = 'LIVE';
                    }
                });
            }

            transcode = null;

            // start the http server
            var server = http.createServer(function(request, response) {
                if (transcodeAudio) {
                    httpResponse = response;
                    transcode = ffmpeg(file)
                                .videoCodec('copy')
                                .audioCodec('libmp3lame')
                                .audioBitrate('192k')
                                .format('matroska')
                                .on('error', function(err) {
                                    console.log('an error occurred: ' + err.message);
                                });
                    transcode.pipe(response);
                } else
                    send(request, file).pipe(response);
            }).listen(8080);

            server.on('request', function(request, response) {
                var start = 0, end = 0;
                var stat = fs.statSync(file);
                var range = request.headers['range'];
                if (range != null) {
                    start = parseInt(range.slice(range.indexOf('bytes=') + 6, range.indexOf('-')));
                    end = parseInt(range.slice(range.indexOf('-') + 1, range.length));
                }
                if (isNaN(end) || end == 0)
                    end = stat.size - 1;

                response.statusCode = 206;
                response.setHeader('Content-Range', 'bytes '
                                    + start
                                    + '-'
                                    + end
                                    + '/'
                                    + stat.size);
            });

            player.on('status', function(status) {
                console.log('status broadcast playerState=%s', status.playerState);
            });

            console.log('app "%s" launched, loading media %s ...', player.session.displayName, media.contentId);

            player.load(media, { autoplay: true }, function(err, status) {
                console.log('media loaded playerState=%s', status.playerState);

                Player = player;

                start = new Date();
                current = 0;
                paused = false;
            });
        });
    });

    client.on('error', function(err) {
        console.log('Error: %s', err.message);
        client.close();
    });
}

process.stdin.on('keypress', function (ch, key) {
    if (key && key.name == 'space' && Player) {
        paused = !paused;
        if (paused)
            Player.pause();
        else
            Player.play();
    }

    if (key && key.name == 'right' && Player) {
        var now = new Date();
        var diff = now - start;
        current = current + diff / 1000 + 10; // +10 sec
        start = now;
        console.log(sprintf("seeking to: %02d:%02d:%02d",
                            Math.floor(current / 3600),
                            Math.floor((current % 3600) / 60),
                            Math.floor(current % 60) ));

        if (transcode) {
            transcode.kill();
            console.log("restarting trasncoding at " + current + "seconds");
            transcode = ffmpeg(file)
                        .videoCodec('copy')
                        .audioCodec('libmp3lame')
                        .audioBitrate('192k')
                        .format('matroska')
                        .seekInput(current)
                        .on('error', function(err) {
                            console.log('an error occurred: ' + err.message);
                        });
            transcode.pipe(httpResponse);
        }

        Player.seek(current, function(err, status) {
        });
    }

    if (key && key.name == 'left' && Player) {
        var now = new Date();
        var diff = now - start;
        current = current + diff / 1000 - 10; // -10 sec
        start = now;
        console.log(sprintf("seeking to: %02d:%02d:%02d",
                            Math.floor(current / 3600),
                            Math.floor((current % 3600) / 60),
                            Math.floor(current % 60) ));

        if (transcode) {
            transcode.kill();
            console.log("restarting trasncoding at " + current + "seconds");
            transcode = ffmpeg(file)
                        .videoCodec('copy')
                        .audioCodec('libmp3lame')
                        .audioBitrate('192k')
                        .format('matroska')
                        .seekInput(current)
                        .on('error', function(err) {
                            console.log('an error occurred: ' + err.message);
                        });
            transcode.pipe(httpResponse);
        }

        Player.seek(current, function(err, status) {
        });
    }

    if (key && key.ctrl && key.name == 'c')
        process.exit();
});

process.stdin.setRawMode(true);
process.stdin.resume();