stream-chat-react/dist/plugins/encoders/mp3.js

React components to create chat conversations or livestream style chat

import { renderAudio, toAudioBuffer, } from '../../components/MediaRecorder/transcode/audioProcessing';
const ENCODING_BIT_RATE = 128; // kbps;
const COUNT_SAMPLES_PER_ENCODED_BLOCK = 1152;
const float32ArrayToInt16Array = (float32Arr) => {
    const int16Arr = new Int16Array(float32Arr.length);
    for (let i = 0; i < float32Arr.length; i++) {
        const float32Value = float32Arr[i];
        // Clamp the float value between -1 and 1
        const clampedValue = Math.max(-1, Math.min(1, float32Value));
        // Convert the float value to a signed 16-bit integer
        int16Arr[i] = Math.round(clampedValue * 32767);
    }
    return int16Arr;
};
const splitDataByChannel = (audioBuffer) => Array.from({ length: audioBuffer.numberOfChannels }, (_, i) => audioBuffer.getChannelData(i)).map(float32ArrayToInt16Array);
export async function encodeToMp3(file, sampleRate) {
    const lameJs = await import('@breezystack/lamejs');
    const audioBuffer = await renderAudio(await toAudioBuffer(file), sampleRate);
    const channelCount = audioBuffer.numberOfChannels;
    const dataByChannel = splitDataByChannel(audioBuffer);
    const mp3Encoder = new lameJs.Mp3Encoder(channelCount, sampleRate, ENCODING_BIT_RATE);
    const dataBuffer = [];
    let remaining = dataByChannel[0].length;
    for (let i = 0; remaining >= COUNT_SAMPLES_PER_ENCODED_BLOCK; i += COUNT_SAMPLES_PER_ENCODED_BLOCK) {
        const [leftChannelBlock, rightChannelBlock] = dataByChannel.map((channel) => channel.subarray(i, i + COUNT_SAMPLES_PER_ENCODED_BLOCK));
        dataBuffer.push(new Int8Array(mp3Encoder.encodeBuffer(leftChannelBlock, rightChannelBlock)));
        remaining -= COUNT_SAMPLES_PER_ENCODED_BLOCK;
    }
    const lastBlock = mp3Encoder.flush();
    if (lastBlock.length)
        dataBuffer.push(new Int8Array(lastBlock));
    return new Blob(dataBuffer, { type: 'audio/mp3;sbu_type=voice' });
}