List of allowed rates and frameSizes? (Segmentation faults otherwise)

[OnkelTem]

I wonder what is the allowed combinations of rate and frameSize options for prism.opus.Encoder?

From my experiments just a limited list is actually allowed, step left or right - and it's crashing with segmentation fault error.

Here is a code for example which crashes:

import prism from 'prism-media';
import fs from 'fs';
import { PassThrough } from 'stream';

const samplingRate = 32000; // (1)
const frameSize = 60; // (2)

const stream = fs.createReadStream('01.wav');
const transcoderStream = new prism.FFmpeg({
  args: ['-i', '-', '-f', 's16le', '-filter:a', `aresample=${samplingRate}`, '-channel_layout', 'mono'],
});

const encoderOptions = {
  rate: samplingRate,
  channels: 1,
  frameSize: Math.round((frameSize / 1000) * samplingRate),
};
console.log(encoderOptions, 'Encoder options');

const encodeStream = new prism.opus.Encoder(encoderOptions);

stream.pipe(transcoderStream).pipe(encodeStream).pipe(new PassThrough());

If you change lines (1) and (2) to:

const samplingRate = 48000; // (1)
const frameSize = 20; // (2)

or

const samplingRate = 16000; // (1)
const frameSize = 60; // (2)

it won't crash.

I would like to have a helper function for generating appropriate inputs for prism.opus.Encoder.