OpenSubtitles forum

Posted: **Thu Sep 20, 2012 6:38 pm**

Hi,

I didn't find any Hashing Algo for Javascript in the wiki,
but here is an implementation:

function OpenSubtitlesHash(uploadInput, callback){
function getHash(arrayBuffer) {
var tmp;
var fsize = arrayBuffer.byteLength;
var arr = new Uint16Array(arrayBuffer, 0, 8192 * 4);
var hash = {
3 : 0,
2 : 0,
1 : (fsize >> 16) & 0xFFFF,
0 : fsize & 0xFFFF
};
var offset = fsize >= 65536 ? (fsize - 65536) : 0;
for (var i = 0; i < 8192; i++)
{
hash = AddUINT64(hash, arr.subarray(i*4, i * 4 + 4));
}
arr = new Uint8Array(arrayBuffer, offset, 8192 * 8);
for (i = 0; i < 8192; i++)
{
tmp = arr.subarray(i * 8, i * 8 + 8);
hash = AddUINT64(hash, {
0: (tmp[1] << 8) + tmp[0],
1: (tmp[3] << 8) + tmp[2],
2: (tmp[5] << 8) + tmp[4],
3: (tmp[7] << 8) + tmp[6]
});
}
return UINT64FormatHex(hash);
}
function AddUINT64(a, b) {
var o = {
0 : 0,
1 : 0,
2 : 0,
3 : 0
};
var carry = 0;
for (var i = 0; i < 4; i++)
{
if ((a[i] + b[i] + carry) > 0xffff )
{
o[i] += (a[i] + b[i] + carry) & 0xffff;
carry = 1;
}
else
{
o[i] += (a[i] + b[i] + carry);
carry = 0;
}
}
return o;
}
function UINT64FormatHex(n) {
return parseInt(n[3], 10).toString(16) + parseInt(n[2], 10).toString(16) + parseInt(n[1], 10).toString(16) + parseInt(n[0], 10).toString(16);
}
uploadInput.onchange = function (e) {
e.preventDefault();
var file = uploadInput.files[0],
reader = new FileReader();
reader.onload = function (event) {
var hash;
try {
hash = getHash(event.target.result);
} catch(e) {
hash = 'error';
}
callback( hash );
};
reader.readAsArrayBuffer(file);
return false;
};
}

But it doesn't work with big files, because the file is read completely into memory first.
Is there any other implementation for Javascript which uses the HTML 5 FileReader API but with the .slice() method instead?

Posted: **Sun Sep 23, 2012 12:12 pm**

I changed the code, so now it works with the slice method, but sometimes the hash is wrong. From my tests 7 out of 10 are hashed correctly. Does someone know where the problem is?

hash.htm

Code: Select all

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>OpenSubtitlesHash HTML5/JS</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="opensubtitleshash.js"></script>
<script type="text/javascript">
window.onload = function() {
if(typeof window.FileReader !== 'undefined') {
document.getElementById('status').innerHTML = 'File API & FileReader available';
var uploadInput = document.getElementById('file');
var callback = function (hash, size) { document.getElementById('hash').innerHTML = 'hash= ' + "'" + hash + "'" + ';' + ' size= ' + "'" + size + "'"; } ;
OpenSubtitlesHash( uploadInput, callback );
}
}
</script>
</head>
<body>
<p id="status">File API & FileReader API not supported</p>
<p><input type="file" id="file"></p>
<p id="hash"></p>
</body>
</html>

opensubtitleshash.js

Code: Select all

function OpenSubtitlesHash(uploadInput, callback){
function getHash(file, slice_1, slice_2) {
var tmp;
var fsize = file.size;
var arr = new Uint16Array(slice_1);
var hash = {
3 : 0,
2 : 0,
1 : (fsize >> 16) & 0xFFFF,
0 : fsize & 0xFFFF
};
for (var i = 0; i < 8192; i++)
{
hash = AddUINT64(hash, arr.subarray(i*4, i * 4 + 4));
}
arr = new Uint16Array(slice_2);
for (var i = 0; i < 8192; i++)
{
hash = AddUINT64(hash, arr.subarray(i*4, i * 4 + 4));
}
return UINT64FormatHex(hash);
}
function AddUINT64(a, b) {
var o = {
0 : 0,
1 : 0,
2 : 0,
3 : 0
};
var carry = 0;
for (var i = 0; i < 4; i++)
{
if ((a[i] + b[i] + carry) > 0xffff )
{
o[i] += (a[i] + b[i] + carry) & 0xffff;
carry = 1;
}
else
{
o[i] += (a[i] + b[i] + carry);
carry = 0;
}
}
return o;
}
function UINT64FormatHex(n) {
return parseInt(n[3], 10).toString(16) + parseInt(n[2], 10).toString(16) + parseInt(n[1], 10).toString(16) + parseInt(n[0], 10).toString(16);
}
uploadInput.onchange = function (e) {
e.preventDefault();
var file = uploadInput.files[0];
var slice1 = new FileReader();
var slice2 = new FileReader();
var slice_1;
var slice_2;
var hash;
slice1.onload = function (event) {
slice_1 = event.target.result;
};
slice2.onload = function (event) {
slice_2 = event.target.result;
try {
// Getting the hash
result = getHash(file, slice_1, slice_2);
// Zero Padding - making sure the returned hash has always a length of 16
var pad = "0000000000000000";
hash = (pad+result).slice(-pad.length);
} catch(e) {
console.log(e);
hash = 'error';
}
callback( hash, file.size );
};
if(file.slice){
slice1.readAsArrayBuffer(file.slice(0,65536));
slice2.readAsArrayBuffer(file.slice(file.size-65536, file.size));
} else if(file.mozSlice){
slice1.readAsArrayBuffer(file.mozSlice(0,65536));
slice2.readAsArrayBuffer(file.mozSlice(file.size-65536, file.size));
} else if(file.webkitSlice){
slice1.readAsArrayBuffer(file.webkitSlice(0,65536));
slice2.readAsArrayBuffer(file.webkitSlice(file.size-65536, file.size));
}
return false;
};
}

Posted: **Thu Sep 27, 2012 5:23 pm**

you can check this file http://static.opensubtitles.org/addons/ ... widgets.js

Let me know, if it helps you

Posted: **Fri Sep 28, 2012 6:31 pm**

Yeah, thanks.That one works better

Posted: **Tue Oct 16, 2012 7:04 pm**

good idea is also check this https://github.com/ka2er/node-opensubtitles-api

Posted: **Wed Oct 31, 2012 11:20 am**

kirill would you mind to post here the whole working solution with working js hash function?

Posted: **Sun Apr 14, 2013 10:30 am**

it would also interests me, because I find out current implementation is somehow buggy

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