I'm using a streaming server in Node.js to stream MP3 files. While the whole file streaming it is ok, I cannot use the Content-Range header to stream the file seeking to a start position and util a end position.
I calculate the start and end bytes from seconds using ffprobe like
ffprobe -i /audio/12380187.mp3 -show_frames -show_entries frame=pkt_pos -of default=noprint_wrappers=1:nokey=1 -hide_banner -loglevel panic -read_intervals 20%+#1
That will give me the exact bytes from 10 seconds in this case to the first next packet.
This becomes in Node.js as simple as
const args = [
'-hide_banner',
'-loglevel', loglevel,
'-show_frames',//Display information about each frame
'-show_entries', 'frame=pkt_pos',// Display only information about byte position
'-of', 'default=noprint_wrappers=1:nokey=1',//Don't want to print the key and the section header and footer
'-read_intervals', seconds+'%+#1', //Read only 1 packet after seeking to position 01:23
'-print_format', 'json',
'-v', 'quiet',
'-i', fpath
];
const opts = {
cwd: self._options.tempDir
};
const cb = (error, stdout) => {
if (error)
return reject(error);
try {
const outputObj = JSON.parse(stdout);
return resolve(outputObj);
} catch (ex) {
return reject(ex);
}
};
cp.execFile('ffprobe', args, opts, cb)
.on('error', reject);
});
Now that I have start and end bytes, my media server will get the ranges in this way from a custom value passed to it like bytes=120515-240260
var getRange = function (req, total) {
var range = [0, total, 0];
var rinfo = req.headers ? req.headers.range : null;
if (rinfo) {
var rloc = rinfo.indexOf('bytes=');
if (rloc >= 0) {
var ranges = rinfo.substr(rloc + 6).split('-');
try {
range[0] = parseInt(ranges[0]);
if (ranges[1] && ranges[1].length) {
range[1] = parseInt(ranges[1]);
range[1] = range[1] < 16 ? 16 : range[1];
}
} catch (e) {}
}
if (range[1] == total)
range[1]--;
range[2] = total;
}
return range;
};
At this point I will get this range [ 120515, 240260, 4724126 ], where I have like [startBytes,endBytes,totalDurationInBytes]
I therfore can create a file read stream passing that range:
var file = fs.createReadStream(path, {start: range[0], end: range[1]});
and then compose the response header using
var header = {
'Content-Length': range[1],
'Content-Type': type,
'Access-Control-Allow-Origin': req.headers.origin || "*",
'Access-Control-Allow-Methods': 'POST, GET, OPTIONS',
'Access-Control-Allow-Headers': 'POST, GET, OPTIONS'
};
if (range[2]) {
header['Expires'] = 0;
header['Pragma'] = 'no-cache';
header['Cache-Control']= 'no-cache, no-store, must-revalidate';
header['Accept-Ranges'] = 'bytes';
header['Content-Range'] = 'bytes ' + range[0] + '-' + range[1] + '/' + total;
header['Content-Length'] = range[2];
//HTTP/1.1 206 Partial Content
res.writeHead(206, header);
} else {
res.writeHead(200, header);
}
so to obtain
{
"Content-Length": 4724126,
"Content-Type": "audio/mpeg",
"Access-Control-Allow-Origin": "*",
"Access-Control-Allow-Methods": "POST, GET, OPTIONS",
"Access-Control-Allow-Headers": "POST, GET, OPTIONS",
"Accept-Ranges": "bytes",
"Content-Range": "bytes 120515-240260/4724126"
}
before doing the pipe of the read stream to the output
file.pipe(res);
The problem is that the browser I don't get any audio in the HTML5 <audio> tag, while it was streaming the contents when not using any Content-Range header.
Here you can see the dump of the ReadStream object from the node api that shows how the range was ok
start: 120515,
end: 240260,
autoClose: true,
pos: 120515
So what is happening on the browser side that prevents to load the file?
[UPDATE]
It turns out that it works Safari but not in Google's Chrome! I can then assume that the Content-Range it correctly devised, but Chrome has some flawness with it.
Now the specification is by rfc2616 and I'm following strictly that one for the byte-range-resp-spec so I pass
"Accept-Ranges": "bytes",
"Content-Range": "bytes 120515-240260/4724126"
and this should work on Chrome too according to the RFC specs. This it should work as-it-is as specified by Mozilla docs as well here
I'm using expressjs framework and I've made it like this:
// Readable Streams Storage Class
class FileReadStreams {
constructor() {
this._streams = {};
}
make(file, options = null) {
return options ?
fs.createReadStream(file, options)
: fs.createReadStream(file);
}
get(file) {
return this._streams[file] || this.set(file);
}
set(file) {
return this._streams[file] = this.make(file);
}
}
const readStreams = new FileReadStreams();
// Getting file stats and caching it to avoid disk i/o
function getFileStat(file, callback) {
let cacheKey = ['File', 'stat', file].join(':');
cache.get(cacheKey, function(err, stat) {
if(stat) {
return callback(null, stat);
}
fs.stat(file, function(err, stat) {
if(err) {
return callback(err);
}
cache.set(cacheKey, stat);
callback(null, stat);
});
});
}
// Streaming whole file
function streamFile(file, req, res) {
getFileStat(file, function(err, stat) {
if(err) {
console.error(err);
return res.status(404).end();
}
let bufferSize = 1024 * 1024;
res.writeHead(200, {
'Cache-Control': 'no-cache, no-store, must-revalidate',
'Pragma': 'no-cache',
'Expires': 0,
'Content-Type': 'audio/mpeg',
'Content-Length': stat.size
});
readStreams.make(file, {bufferSize}).pipe(res);
});
}
// Streaming chunk
function streamFileChunked(file, req, res) {
getFileStat(file, function(err, stat) {
if(err) {
console.error(err);
return res.status(404).end();
}
let chunkSize = 1024 * 1024;
if(stat.size > chunkSize * 2) {
chunkSize = Math.ceil(stat.size * 0.25);
}
let range = (req.headers.range) ? req.headers.range.replace(/bytes=/, "").split("-") : [];
range[0] = range[0] ? parseInt(range[0], 10) : 0;
range[1] = range[1] ? parseInt(range[1], 10) : range[0] + chunkSize;
if(range[1] > stat.size - 1) {
range[1] = stat.size - 1;
}
range = {start: range[0], end: range[1]};
let stream = readStreams.make(file, range);
res.writeHead(206, {
'Cache-Control': 'no-cache, no-store, must-revalidate',
'Pragma': 'no-cache',
'Expires': 0,
'Content-Type': 'audio/mpeg',
'Accept-Ranges': 'bytes',
'Content-Range': 'bytes ' + range.start + '-' + range.end + '/' + stat.size,
'Content-Length': range.end - range.start + 1,
});
stream.pipe(res);
});
}
router.get('/:file/stream', (req, res) => {
const file = path.join('path/to/mp3/', req.params.file+'.mp3');
if(/firefox/i.test(req.headers['user-agent'])) {
return streamFile(file, req, res);
}
streamFileChunked(file, req, res);
});
Full sources of site here
Try to fix to Your code:
this will enforce browser to act with resource as chunked.
var header = {
'Content-Length': range[1],
'Content-Type': type,
'Access-Control-Allow-Origin': req.headers.origin || "*",
'Access-Control-Allow-Methods': 'POST, GET, OPTIONS',
'Access-Control-Allow-Headers': 'POST, GET, OPTIONS',
'Cache-Control': 'no-cache, no-store, must-revalidate',
'Pragma': 'no-cache',
'Expires': 0
};
if(/firefox/i.test(req.headers['user-agent'])) {
res.writeHead(200, header);
}
else {
header['Accept-Ranges'] = 'bytes';
header['Content-Range'] = 'bytes ' + range[0] + '-' + range[1] + '/' + total;
header['Content-Length'] = range[2];
res.writeHead(206, header);
}