In chrome App, video file is not saved with its original data/size - google-chrome

Question

In appCtrl.js, for saving video file -
$('#save_file').click(function(e) {
var config = {type: 'saveFile', suggestedName: chosenEntry.name};
chrome.fileSystem.chooseEntry(config, function(writableEntry) {
//blob content is the DataUrl
var blob = new Blob([$scope.blobContent], {type: 'video/mp4'});
$scope.writeFileEntry(writableEntry, blob, function(e) {
console.log('Write complete :)');
});
});
});
$scope.writeFileEntry = function(writableEntry, opt_blob, callback) {
if (!writableEntry) {
console.log('Nothing selected.');
return;
}
writableEntry.createWriter(function(writer) {
writer.onerror = $scope.errorHandler;
writer.onwriteend = callback;
// If we have data, write it to the file. Otherwise, just use the file we
// loaded.
if (opt_blob) {
writer.truncate(opt_blob.size);
$scope.waitForIO(writer, function() {
writer.seek(0);
writer.write(opt_blob);
});
}
else {
chosenEntry.file(function(file) {
writer.truncate(file.fileSize);
waitForIO(writer, function() {
writer.seek(0);
writer.write(file);
});
});
}
}, $scope.errorHandler);
}
$scope.waitForIO = function(writer, callback) {
// set a watchdog to avoid eventual locking:
var start = Date.now();
// wait for a few seconds
var reentrant = function() {
if (writer.readyState===writer.WRITING && Date.now()-start<4000) {
setTimeout(reentrant, 100);
return;
}
if (writer.readyState===writer.WRITING) {
console.error("Write operation taking too long, aborting!"+
" (current writer readyState is "+writer.readyState+")");
writer.abort();
}
else {
callback();
}
};
setTimeout(reentrant, 100);
};
In above code the video file is saved but when i tried to play that saved file in Window Media Player or VLC player , it prompt me as Window media player cannot play the file.The player might not support the file type or might not support the codec that was used to compress the file.
Can u please guide me where m getting wrong, as its my first chrome app.
Thanks in advance.

Answer 1

Change the method to store blob like this.
function dataURItoBlob(dataURI, callback) {
// convert base64 to raw binary data held in a string
// doesn't handle URLEncoded DataURIs
var byteString = atob(dataURI.split(',')[1]);
// separate out the mime component
var mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0]
// write the bytes of the string to an ArrayBuffer
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
return new Blob([ab], {type: 'video/mp4'});
};
To handle click.
$('#save_file').click(function(e) {
var config = {type: 'saveFile', suggestedName: chosenEntry.name};
chrome.fileSystem.chooseEntry(config, function(writableEntry) {
var blob = dataURItoBlob($scope.blobContent);
$scope.writeFileEntry(writableEntry, blob, function(e) {
console.log('Write complete :)');
});
});
});