Develop Reference

Using MP4box.js and onSegment callback is not called

Base problem: display a H264 live stream in a browser.
Solution: let's just convert it to fragmented mp4 and load chunk-by-chunk via websocket (or XHR) into MSE.
Sounds too easy. But I want to do the fragmentation on client side with pure JS.
So I'm trying to use MP4Box.js. On its readme page it states: it has a demo: "A player that performs on-the-fly fragmentation".
That's the thing I need!
However the onSegment callbacks which should feed MSE are not called at all:
var ws; //for websocket
var mp4box; //for fragmentation
function startVideo() {
mp4box = MP4Box.createFile();
mp4box.onError = function(e) {
console.log("mp4box failed to parse data.");
};
mp4box.onMoovStart = function () {
console.log("Starting to receive File Information");
};
mp4box.onReady = function(info) {
console.log(info.mime);
mp4box.onSegment = function (id, user, buffer, sampleNum) {
console.log("Received segment on track "+id+" for object "+user+" with a length of "+buffer.byteLength+",sampleNum="+sampleNum);
}
var options = { nbSamples: 1000 };
mp4box.setSegmentOptions(info.tracks[0].id, null, options); // I don't need user object this time
var initSegs = mp4box.initializeSegmentation();
mp4box.start();
};
ws = new WebSocket("ws://a_websocket_server_which_serves_h264_file");
ws.binaryType = "arraybuffer";
ws.onmessage = function (event) {
event.data.fileStart = 0; //tried also with event.data.byteOffset, but resulted error.
var nextBufferStart = mp4box.appendBuffer(event.data);
mp4box.flush(); //tried commenting out - unclear documentation!
};
}
window.onload = function() {
startVideo();
}
Now putting this into an HTML file would result this in the JavaScript console:
Starting to receive File Information
video/mp4; codecs="avc1.4d4028"; profiles="isom,iso2,avc1,iso6,mp41"
But nothing happens afterwards. Why is the onSegment not called here? (the h264 file which the websocket-server serves is playable in VLC - however it is not fragmented)

The problem was using the nextBufferStart in a wrong way.
This should be the correct one:
var nextBufferStart = 0;
...
ws.onmessage = function (event) {
event.data.fileStart = nextBufferStart;
nextBufferStart = mp4box.appendBuffer(event.data);
mp4box.flush();
};

web audio analyze entire buffer

I have the audio buffer of a prerecorded audio file in my application.
I'm trying to get the frequency domain data of the ENTIRE audio track, this is what I've tried:
getAudioDataFromBuffer: function(buf){
var src = g.audioContext.createBufferSource();
src.buffer = buf;
var anal = src.context.createAnalyser();
src.connect(anal);
var dataArray = new Uint8Array(buf.length);
anal.fftSize = 2048;
anal.getByteFrequencyData(dataArray);
return dataArray;
},
But this only gives me an array full of zeros.
I need this to compare two audio tracks, one is prerecorded and the other is recorded in the application. I'm thinking I could measure the correlation between their frequency domains.

I arrived to the solution seeing this answer and this discussion.
Basically you need to use an OfflineAudioContext. Here the code staring from an already loaded audio buffer:
var offline = new OfflineAudioContext(2, buffer.length ,44100);
var bufferSource = offline.createBufferSource();
bufferSource.buffer = buffer;
var analyser = offline.createAnalyser();
var scp = offline.createScriptProcessor(256, 0, 1);
bufferSource.connect(analyser);
scp.connect(offline.destination); // this is necessary for the script processor to start
var freqData = new Uint8Array(analyser.frequencyBinCount);
scp.onaudioprocess = function(){
analyser.getByteFrequencyData(freqData);
console.log(freqData);
};
bufferSource.start(0);
offline.oncomplete = function(e){
console.log('analysed');
};
offline.startRendering();

Here's a working example using the latest version of the Web Audio API:
Note: You need to start with an audioBuffer.. you can get one using the new File System Access API:
const [fileHandle] = await window.showOpenFilePicker();
const file = await fileHandle.getFile();
const arrayBuffer = await file.arrayBuffer();
const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
const audioBuffer = await audioCtx.decodeAudioData(arrayBuffer);
Once you have the audioBuffer, you can access it's contents using offlineAudioContext:
const offlineAudioContext = new OfflineAudioContext(
audioBuffer.numberOfChannels,
audioBuffer.length,
audioBuffer.sampleRate
);
const bufferSourceNode = offlineAudioContext.createBufferSource();
bufferSourceNode.start(0);
offlineAudioContext
.startRendering()
.then(renderedBuffer => {
const data = renderedBuffer.getChannelData(0);
for (let i = 0, length = data.length; i < length; i += 1) {
// careful here, as you can hang the browser by logging this data
// because 1 second of audio contains 22k ~ 96k samples!
if (!(i % 1000) && i < 250000) console.log(data[i]);
}
}

I think you need more something like
AudioBuffer.getChannelData()
Returns a Float32Array containing the PCM data associated with the channel, defined by the channel parameter (with 0 representing the first channel).
Lookup at Mozilla or W3C documentation.
Cheers
Kilian

Uploading large files via XHR fails with Chrome, works with Firefox

I am uploading video files to my server. The files are at least 20MB, some over 100MB.
For improved user experience, I upload via JavaScript and XMLHttpRequest, this way I can display upload speed and remaining time.
And to avoid and trouble on the server (such as requests timing out and taking too long to process) I submit the file in little packages on the server, and have a php script re-assemble the file.
My script works great, with one weird catch - and until just now I thought it was because of my ISP.
Using Google chrome I can upload files up to 20MB with no problems. But anything larger gets errors: For example my 100MB file will not send anything to the server - the second package never arrives. On my 50MB file it happens after around 47%, with the 7th package. And another file doesn't even send the first package.
I restarted my computer, and it keeps happening at the same position/package number for each file - though the position has nothing in common compared to the other failed files.
It doesn't matter if you try to start after one of the failed packages, say If I start at #8 if 7 failed - it will continue to fail. If I ignore errors (rather than to try again) it will just send the rest of the file in empty chunks.
I had already tried from a different internet connection, though I had to use firefox there. And it worked fine. So I install firefox on my machiene, and BAM works like a charm, correctly sending the 100MB file.
What could be going wrong on Chrome?
$(document).on('click','#video_upload',function(evt){
uploadProcess('vod_video_file');
});
function toBlob(text)
{
var data = new ArrayBuffer(text.length);
var ui8a = new Uint8Array(data, 0);
for (var i = 0; i < text.length; i++) ui8a[i] = (text.charCodeAt(i) & 0xff);
if(typeof window.Blob == "function")
{
var blob = new Blob([data]);
}else{
var bb = new (window.MozBlobBuilder || window.WebKitBlobBuilder || window.BlobBuilder)();
bb.append(data);
var blob = bb.getBlob();
}
return blob;
}
function splitFile(dataArray, size) {
blobs = new Array();
for (var i = 0; i < dataArray.size; i += size)
{
var copy = dataArray.slice();
var partial = copy.slice(i, i+size);
blobs.push(partial);
}
return blobs;
}
function uploadProcess(fileInputId)
{
var file = document.getElementById(fileInputId).files[0];
var reader = new FileReader();
reader.readAsBinaryString(file);
reader.onloadend = function(evt)
{
var fr = evt.target.result;
fileUpload( fr );
}
}
function fileUpload(inputDataArray)
{
var since;
var intervalid;
var totalBytes = inputDataArray.length;
var packets = new Array();
var packetNum = 0;
var packetCount = 0;
var packetSize = 0;
function startUpload()
{
intervalid = setInterval(function(){updateUploadStats();},1000);
calculatePaketSize()
createPackets();
submitPacket();
}
function calculatePaketSize()
{
var ideal_size = 3*1024*1024;
var packet_count = Math.ceil( totalBytes/ideal_size);
packetSize = Math.ceil(totalBytes/packet_count);
}
function createPackets()
{
packets = splitFile(toBlob(inputDataArray), packetSize)
packetCount = packets.length;
}
function updateUploadStats(e)
{
//displaying upload progress in GUI
}
function submitPacket()
{
xhr = new XMLHttpRequest();
xhr.open("POST", 'index.php?controller=AdminVodVideo&action=VideoUpload&ajax=1&r='+packetNum+'&token='+token, true);
xhr.setRequestHeader("Content-type","application/octet-stream");
XMLHttpRequest.prototype.mySendAsBinary = function(text){
this.send(text);
}
var eventSource = xhr.upload || xhr;
eventSource.addEventListener("progress", function(e) {
updateUploadStats(e);
});
xhr.onreadystatechange = function()
{
if(xhr.readyState == 4)
{
if(xhr.status == 200)
{
//server will return the string 'upload failed' if the file to be received was empty.
if( xhr.responseText == 'upload failed')
{
console.log('FAILED , trying again in 3 s');
setTimeout(submitPacket,3000);
}
else
{
updateUploadStats();
packetNum++;
if(packetNum == packetCount)
{
processOnServer();
}
else
{
submitPacket();
}
}
}else{
// process error
console.log('we got a 500 error');
}
}
};
since = Date.now();
xhr.mySendAsBinary( packets[packetNum] );
}
function processOnServer()
{
//telling the server to piece the file back together.
}
startUpload();
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

Is there a way of Creating lnk file using javascript

I would like to give the users in my website the ability to download a "lnk" file.
My idea is to generate this file with to contain an address that can be used only once.
Is there a way to generate this file in javascript?
The flow is something like -
the user presses a button
the javascript generates this file and downloads it to the user's machine
the user sends this file to another user to use this one-time-address from his machine
Is something like this is doable in javascript from the client side? or would i need to generate this file using java server side?

This is a faithful translation of mslink.sh.
I only tested my answer in Windows 8.1, but I would think that it works in older versions of Windows, too.
function create_lnk_blob(lnk_target) {
function hex_to_arr(s) {
var result = Array(s.length / 2);
for (var i = 0; i < result.length; ++i) {
result[i] = +('0x' + s.substr(2*i, 2));
}
return result;
}
function str_to_arr(s) {
var result = Array(s.length);
for (var i = 0; i < s.length; ++i) {
var c = s.charCodeAt(i);
if (c >= 128) {
throw Error("Only ASCII paths are suppored :-(");
}
result[i] = c;
}
return result;
}
function convert_CLSID_to_DATA(s) {
var idx = [[6,2], [4,2], [2,2], [0,2],
[11,2], [9,2], [16,2], [14,2],
[19,4], [24,12]];
var s = idx.map(function (ii) {
return s.substr(ii[0], ii[1]);
});
return hex_to_arr(s.join(''));
}
function gen_IDLIST(s) {
var item_size = (0x10000 + s.length + 2).toString(16).substr(1);
return hex_to_arr(item_size.replace(/(..)(..)/, '$2$1')).concat(s);
}
var HeaderSize = [0x4c, 0x00,0x00,0x00],
LinkCLSID = convert_CLSID_to_DATA("00021401-0000-0000-c000-000000000046"),
LinkFlags = [0x01,0x01,0x00,0x00], // HasLinkTargetIDList ForceNoLinkInfo
FileAttributes_Directory = [0x10,0x00,0x00,0x00],
FileAttributes_File = [0x20,0x00,0x00,0x00],
CreationTime = [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00],
AccessTime = [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00],
WriteTime = [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00],
FileSize = [0x00,0x00,0x00,0x00],
IconIndex = [0x00,0x00,0x00,0x00],
ShowCommand = [0x01,0x00,0x00,0x00], //SW_SHOWNORMAL
Hotkey = [0x00,0x00], // No Hotkey
Reserved = [0x00,0x00],
Reserved2 = [0x00,0x00,0x00,0x00],
Reserved3 = [0x00,0x00,0x00,0x00],
TerminalID = [0x00,0x00],
CLSID_Computer = convert_CLSID_to_DATA("20d04fe0-3aea-1069-a2d8-08002b30309d"),
CLSID_Network = convert_CLSID_to_DATA("208d2c60-3aea-1069-a2d7-08002b30309d"),
PREFIX_LOCAL_ROOT = [0x2f],
PREFIX_FOLDER = [0x31,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00],
PREFIX_FILE = [0x32,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00],
PREFIX_NETWORK_ROOT = [0xc3,0x01,0x81],
PREFIX_NETWORK_PRINTER = [0xc3,0x02,0xc1],
END_OF_STRING = [0x00];
if (/.*\\+$/.test(lnk_target)) {
lnk_target = lnk_target.replace(/\\+$/g, '');
var target_is_folder = true;
}
var prefix_root, item_data, target_root, target_leaf;
if (lnk_target.substr(0, 2) === '\\\\') {
prefix_root = PREFIX_NETWORK_ROOT;
item_data = [0x1f, 0x58].concat(CLSID_Network);
target_root = lnk_target.subtr(lnk_target.lastIndexOf('\\'));
if (/\\\\.*\\.*/.test(lnk_target)) {
target_leaf = lnk_target.substr(lnk_target.lastIndexOf('\\') + 1);
}
if (target_root === '\\') {
target_root = lnk_target;
}
} else {
prefix_root = PREFIX_LOCAL_ROOT;
item_data = [0x1f, 0x50].concat(CLSID_Computer);
target_root = lnk_target.replace(/\\.*$/, '\\');
if (/.*\\.*/.test(lnk_target)) {
target_leaf = lnk_target.replace(/^.*?\\/, '');
}
}
var prefix_of_target, file_attributes;
if (!target_is_folder) {
prefix_of_target = PREFIX_FILE;
file_attributes = FileAttributes_File;
} else {
prefix_of_target = PREFIX_FOLDER;
file_attributes = FileAttributes_Directory;
}
target_root = str_to_arr(target_root);
for (var i = 1; i <= 21; ++i) {
target_root.push(0);
}
var id_list_items = gen_IDLIST(item_data);
id_list_items = id_list_items.concat(
gen_IDLIST(prefix_root.concat(target_root, END_OF_STRING)));
if (target_leaf) {
target_leaf = str_to_arr(target_leaf);
id_list_items = id_list_items.concat(
gen_IDLIST(prefix_of_target.concat(target_leaf, END_OF_STRING)));
}
var id_list = gen_IDLIST(id_list_items);
var data = [].concat(HeaderSize,
LinkCLSID,
LinkFlags,
file_attributes,
CreationTime,
AccessTime,
WriteTime,
FileSize,
IconIndex,
ShowCommand,
Hotkey,
Reserved,
Reserved2,
Reserved3,
id_list,
TerminalID);
return new Blob([new Uint8Array(data)], { type: 'application/x-ms-shortcut' });
}
var blob = create_lnk_blob('C:\\Windows\\System32\\Calc.exe');
Use it like:
var blob_to_file = create_lnk_blob('C:\\Windows\\System32\\Calc.exe');
var blob_to_folder = create_lnk_blob('C:\\Users\\Myself\\Desktop\\'); // with a trailing slash
Demo: http://jsfiddle.net/5cjgLyan/2/

This would be simple if your website allows php.
If your script is part of an html file, just write the the javascript as if you were writing it to send a static lnk file. Then, at the lnk address part, break apart the javascript into two parts, breaking into html. Then at that point, put in
<?php /*PHP code set a variable *? /* PHP code to generate proper string*/ PRINT /*PHP variable*/
?>

I think make it pure client is impossible.
Even the web rtc protocol need at least one iceServer to signal other client.
And I think the easiest way to do that is use http://peerjs.com/
you could first create a clinet token of the room owner
//room owner side
peer.on('open', function(my_peer_id) {
console.log('My peer ID is: ' + my_peer_id);
});
And send the token to any other you want (by text file, web chat ...etc)
Then other connect it use the token above
//the other one
var conn = peer.connect(other_peer_id);
After the room owner detected someone entered the room.
Disconnect from signal server, so the token will become unusable
//room owner side
peer.disconnect()
About generate and read file by client side, I recommend you read article below.
http://www.html5rocks.com/en/tutorials/file/dndfiles/ read from file
How to use filesaver.js save as file
I believe the compatibility of fileReader api and blob doesn't matter.
Since there will never be a browser which support webrtc but not support fileReader api

Firefox Extension/Addon : Reading a text file from remote server(URL)

After wasting my two days to find out what's going wrong with this script, finally I decide to ask it.
What I am trying to do
I am trying to read a text file from remote server. Then storing all text file updates to an SQLITE database at the time of my Firefox Extension/Addon get loaded.
What I tried
var updatereader = {
start: function () {
//alert('reading update');
var fURL = null;
var ioService = null;
var fURI = null;
var httpChannel = null;
fURL = "http://www.example.com/addon/mlist.txt";
ioService = Components.classes["#mozilla.org/network/io-service;1"].getService(Components.interfaces.nsIIOService);
fURI = ioService.newURI(fURL, null, null);
httpChannel = ioService.newChannelFromURI(fURI).QueryInterface(Components.interfaces.nsIHttpChannel);
httpChannel.asyncOpen(updatereader.StreamReader, null);
},
onUpdateCompleted: function () {
},
StreamReader:
{
fOutputStream: null,
fPointer: null,
tempFile: "mlist.txt",
onStartRequest: function (aRequest, aContext) {
//alert('onStart');
updatereader.StreamReader.fOutputStream = Components.classes["#mozilla.org/network/file-output-stream;1"].createInstance(Components.interfaces.nsIFileOutputStream);
updatereader.StreamReader.fPointer = Components.classes["#mozilla.org/file/directory_service;1"].getService(Components.interfaces.nsIProperties).get("ProfD", Components.interfaces.nsIFile);
updatereader.StreamReader.fPointer.append(updatereader.StreamReader.tempFile);
updatereader.StreamReader.fOutputStream.init(updatereader.StreamReader.fPointer, 0x02 | 0x20 | 0x08, 0644, 0);
},
onDataAvailable: function (aRequest, aContext, aInputStream, aOffset, aCount) {
//control flow is not entering here - may be here is somehting missing
var sStream = null;
var tempBuffer = null;
sStream = Components.classes["#mozilla.org/scriptableinputstream;1"].createInstance(Components.interfaces.nsIScriptableInputStream);
sStream.init(aInputStream);
tempBuffer = sStream.read(aCount);
updatereader.StreamReader.fOutputStream.write(tempBuffer, aCount);
},
onStopRequest: function (aRequest, aContext, aStatusCode) {
//alert('onStop');
var currentDate = new Date();
if (aStatusCode == 0) {
fileInputStream = Components.classes["#mozilla.org/network/file-input-stream;1"].createInstance(Components.interfaces.nsIFileInputStream);
updatereader.StreamReader.fOutputStream.close();
fileInputStream.init(updatereader.StreamReader.fPointer, 0x01, 0, 0);
lineInputStream = fileInputStream.QueryInterface(Components.interfaces.nsILineInputStream);
//pass data to somewhere
var dbH = new dbstore();
dbH.updateData(lineInputStream);
lineInputStream.close();
updatereader.StreamReader.fPointer.remove(false);
updatereader.onUpdateCompleted();
} else {
}
}
}
}
Problem:
Getting nothing in lineInputStream which passes the read data to somewhere else for storing it.
Area of problem:
Program control flow is not entring to this section
onDataAvailable:
Not getting any error.

First of all, there doesn't really seem to be any need to read the file to the disk first (unless it is really, really big).
I'd just use XMLHttpRequest to get the file, which when run from a privileged context (e.g. add-on code, but not a website) can access any and every valid URI.
XMLHttpRequest will simplify almost everything, e.g. no more onDataAvailable, (usually) no more manual text converting, etc.
Also, no need to ever hit the disk during the transfer.
Code would look something like this:
var req = new XMLHttpRequest();
req.open("GET", "http://www.example.com/addon/mlist.txt"); // file:/// would work too, BTW
req.overrideMimeType("text/plain");
req.addEventListener("load", function() {
// Do something with req.responseText
}, false);
req.addEventListener("error", function() {
// Handle error
}, false);
req.send();
If you want to use XMLHttpRequest in a non-window, e.g. js code module or js components, then you need to first initialize a constructor. This is not required for windows, including XUL windows and by that XUL overlays.
// Add XMLHttpRequest constructor, if not already present
if (!('XMLHttpRequest' in this)) {
this.XMLHttpRequest = Components.Constructor("#mozilla.org/xmlextras/xmlhttprequest;1", "nsIXMLHttpRequest");
}
SDK users should use the request module, or net/xhr if a lower-level API is required.
PS: If you're still interested in using raw channels, here is a minimal example I coded up in a Scratchpad (to run, open a Scratchpad for a privileged location, e.g. about:newtab).
You shouldn't alert from your own implementation: alert() will spin the event loop and causes reentrant code, which is not supported in this context.
var {
classes: Cc,
interfaces: Ci,
results: Cr,
utils: Cu
} = Components;
Cu.import("resource://gre/modules/XPCOMUtils.jsm")
Cu.import("resource://gre/modules/Services.jsm");
var ConverterStream = Components.Constructor(
"#mozilla.org/intl/converter-input-stream;1",
"nsIConverterInputStream",
"init");
var RC = Ci.nsIConverterInputStream.DEFAULT_REPLACEMENT_CHARACTER;
function Listener() {
this.content = "";
}
Listener.prototype = {
QueryInterface: XPCOMUtils.generateQI([Ci.nsIStreamListener]),
onStartRequest: function(req, ctx) {
console.log("start");
},
onDataAvailable: function(req, ctx, stream, offset, count) {
console.log("data", count);
try {
var cs = new ConverterStream(stream, null /* utf-8 */, 4096, RC);
try {
var str = {};
while (cs.readString(4096, str)) {
this.content += str.value;
}
}
finally {
cs.close();
}
}
catch (ex) {
console.error("data", ex.message, ex);
}
},
onStopRequest: function(req, ctx, status) {
console.log("stop", status,
this.content.substr(0, 20), this.content.length);
}
};
var uri = Services.io.newURI("http://example.org", null, null);
Services.io.newChannelFromURI(uri).asyncOpen(new Listener(), null);