rochars / wavefile

const byteData = require("byte-data");

/**

 * Get the chunks of a RIFF file.

 * @param {Uint8Array|!Array<number>} buffer the RIFF file bytes.

 * @param {boolean} bigEndian true if its RIFX.

 * @return {object}

 */

function getChunks(buffer, bigEndian) {

    // RIFF container

    let chunkId = byteData.fromBytes(

            buffer.slice(0, 4), 8, {"char": true}

        );

    let chunkSize = byteData.fromBytes(

            buffer.slice(4, 8), 32, {'be': bigEndian}

        )[0];

    let format = byteData.fromBytes(

            buffer.slice(8, 12), 8, {"char": true}

        );

    let chunks = [];

    let len = buffer.length;

    let i = 12;

    while(i < len) {

        let subChunkSize = byteData.fromBytes(

            buffer.slice(i + 4, i + 8), 32, {'be': bigEndian})[0];

        chunks.push({

                "subChunkId": byteData.fromBytes(buffer.slice(i, i + 4), 8, {"char": true}),

                "subChunkSize": subChunkSize,

                "subChunkData": buffer.slice(i + 8, i + 8 + subChunkSize)

            });

        i = i + 8 + subChunkSize;

    }

    return {

        "chunkId": chunkId,

        "chunkSize": chunkSize,

        "format": format,

        "subChunks": chunks

    }

}

module.exports.getChunks = getChunks;