50% of the mp3 file is getting silence

[audior]

50% of the mp3 file is getting silence

[pradu14]

I suspect is has something to do with the way libmp3lame.js encodes the WAV files and somehow along the way the buffer gets doubled, but I haven’t found any solution for this as of now.

[adamthehutt]

I'm experiencing this issue as well. Anyone have ideas?

[hussion]

I'm also experiencing this issue as well. i hope it will be solved

[roparz]

My solution:

First, in the file recordmp3.js, function encode64, divide len by 2.

function encode64(buffer) {
    var binary = '',
        bytes = new Uint8Array( buffer ),
        len = bytes.byteLength / 2;     // <======= here
    for (var i = 0; i < len; i++) {
        binary += String.fromCharCode( bytes[ i ] );
    }
    return window.btoa( binary );
}

With that code, the MP3 preview is fixed.

Second, add the following function in recordmp3.js

// inspired from the interleave function in recorderWorker.js
function getHalfBuffer(buffer) {
    var length = buffer.length / 2,
        result = new Float32Array(length),
        index = 0,
        bufIndex = 0,
    while (index < length) {
        result[index++] = buffer[bufIndex];
        bufIndex++;
    }
    return result;
}

And use it line 107:

var mp3Blob = new Blob([new Uint8Array(getHalfBuffer(e.data.buf))], {type: 'audio/mp3'});

With that code, the MP3 upload is fixed.

[espiritudelvino]

This solution worked for me, thank you!

Only needed a minor change: missing semicolon, no big deal

function getHalfBuffer(buffer) {
    var length = buffer.length / 2,
        result = new Float32Array(length),
        index = 0,
        bufIndex = 0;
    while (index < length) {
        result[index++] = buffer[bufIndex];
        bufIndex++;
    }
    return result;
}

[roparz]

Hi everyone,

I made a fork here: https://github.com/roparz/Recordmp3js

I made some changes in the code:

• the old version was creating the mp3 file in three steps: capturing audio input, encoding input to wav and then transform the wav file to mp3. This new version bypass the wav encoding and transform directly the audio input to mp3. I didn't make performance tests but I can guess that the encoding is a little bit faster now.
• I also fixed the problem with the audio capture, the microphone input is not anymore sent to the speakers.

Hope this will help some of you.