Buffer length problem for long recordings.

[seannyD]

...
MP3 Worker uk_1499943820618_uk_lowp_taka_1 mp3Worker.js:41:3
uncaught exception: buffer over flow (unknown)

Related to Audior/Recordmp3js#23 and akrennmair/libmp3lame-js#8

[seannyD]

This part of the code:

function enlargeMemory() {
  abort('Cannot enlarge memory arrays. Either (1) compile with -s TOTAL_MEMORY=X with X higher than the current value ' + TOTAL_MEMORY + ', (2) compile with ALLOW_MEMORY_GROWTH which adjusts the size at runtime but prevents some optimizations, or (3) set Module.TOTAL_MEMORY before the program runs.');
}
var TOTAL_STACK = Module['TOTAL_STACK'] || 5242880;
var TOTAL_MEMORY = Module['TOTAL_MEMORY'] || 16777216;
var FAST_MEMORY = Module['FAST_MEMORY'] || 2097152;
// Initialize the runtime's memory
// check for full engine support (use string 'subarray' to avoid closure compiler confusion)
assert(typeof Int32Array !== 'undefined' && typeof Float64Array !== 'undefined' && !!(new Int32Array(1)['subarray']) && !!(new Int32Array(1)['set']),
       'Cannot fallback to non-typed array case: Code is too specialized');
var buffer = new ArrayBuffer(TOTAL_MEMORY);

Suggests there's a maximum memory limit that can be set by:

Module = {};
Module.TOTAL_MEMORY = 128;// low number to test 
mp3codec = Lame.init();

But there are problems with the non-min version of the code. Even with the default settings, we get an error

RangeError: invalid or out-of-range index

I'm condiering switching to https://github.com/zhuker/lamejs

[seannyD]

https://github.com/zhuker/lamejs didn't like my e.data.buf in the splice command.
I just updated the bitrate call to mp3Worker_2.js, so maybe that will work with one of the other attempts?

This project uses lamejs: https://github.com/zzarcon/microm/blob/728ade6789fe110c8419adfc9b1b209f0a261992/lib/converter.js

But we may as well convert totally to using microm.

[seannyD]

In recordmp3.js, I need to pass the arrayBuffer to the encoderWorker.
Then in mp3Worker_2.js, I need to extract the sound buffer correctly:

var wav = lamejs.WavHeader.readHeader(new DataView(e.data.buf));
var samples = new Int16Array(e.data.buf, wav.dataOffset, wav.dataLen / 2);

Then use the example encoding code from:
https://github.com/zhuker/lamejs/blob/master/example.html

[seannyD]

This seems to suggest there's a memory limit on workers themselves:
https://stackoverflow.com/questions/36175480/web-worker-out-of-memory-when-processing-large-array

[seannyD]

The program now cuts the recordings into manageable chunks before converting to wav (and then converts the wav chunks to mp3). The ID3 tags are also working again now.

A branch tried to do the whole conversion to mp3 directly from samples, but ran into problems.