converting ByteArray into blob using javascript

Question

I'm using flash to capture audio, encode it to mp3, then send it to javascript as ByteArray. Now I want the javascript to save it as MP3 on my computer (not flash saves it to my computer). I am using Blob and then getDataURL, but the file isn't playing when saved. I used to do the same exact method to save WAV files and it worked perfectly fine. Here's the JS code:

var getDataFromSWF = function (bytes) {
            var myBlob = new Blob([bytes], { type: "audio/mpeg3" });

            var url = (window.URL || window.webkitURL).createObjectURL(myBlob);
            var link = window.document.createElement('a');
            link.href = url;

//            $("label").text(url);
            link.download = 'output.mp3';
            var click = document.createEvent("Event");
            click.initEvent("click", true, true);
            link.dispatchEvent(click);

//            console.log(bytes);
        }

I'm pretty much sure that the byteArray is fine because if I let the SWF save the file it works OK too. But I want to know what's wrong with the JS code. (note: i'm new to BLOB)

Pang · Accepted Answer · 2021-04-13 02:55:32Z

1

Try this to get the Blob

function base64toBlob(base64Data, contentType) {
    var sliceSize = 1024;
    var byteCharacters = atob(base64Data);
    var bytesLength = byteCharacters.length;
    var slicesCount = Math.ceil(bytesLength / sliceSize);
    var byteArrays = new Array(slicesCount);
    for (var sliceIndex = 0; sliceIndex < slicesCount; ++sliceIndex) {
        var begin = sliceIndex * sliceSize;
        var end = Math.min(begin + sliceSize, bytesLength);
        var bytes = new Array(end - begin);
        for (var offset = begin, i = 0 ; offset < end; ++i, ++offset) {
            bytes[i] = byteCharacters[offset].charCodeAt(0);
        }
        byteArrays[sliceIndex] = new Uint8Array(bytes);
    }
    return new Blob(byteArrays, { type: contentType });
}

edited Apr 13, 2021 at 2:55

Pang

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answered Mar 8, 2016 at 13:01

Geo

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1 Comment

Zunair Over a year ago

I was sending byte array and was receiving base64 as response content - nothing worked but this - thanks much!

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