spessasynth_lib/soundfont/dls/read_samples.js

import { findRIFFListType, readRIFFChunk } from "../basic_soundfont/riff_chunk.js";
import { readBytesAsString } from "../../utils/byte_functions/string.js";
import {
    SpessaSynthGroupCollapsed,
    SpessaSynthGroupEnd,
    SpessaSynthInfo,
    SpessaSynthWarn
} from "../../utils/loggin.js";
import { consoleColors } from "../../utils/other.js";
import { readLittleEndian, signedInt16 } from "../../utils/byte_functions/little_endian.js";
import { DLSSample } from "./dls_sample.js";

const W_FORMAT_TAG = {
    PCM: 0x01,
    ALAW: 0x6
};

/**
 * @param dataChunk {RiffChunk}
 * @param bytesPerSample {number}
 * @returns {Float32Array}
 */
function readPCM(dataChunk, bytesPerSample)
{
    const maxSampleValue = Math.pow(2, bytesPerSample * 8 - 1); // Max value for the sample
    const maxUnsigned = Math.pow(2, bytesPerSample * 8);
    
    let normalizationFactor;
    let isUnsigned = false;
    
    if (bytesPerSample === 1)
    {
        normalizationFactor = 255; // For 8-bit normalize from 0-255
        isUnsigned = true;
    }
    else
    {
        normalizationFactor = maxSampleValue; // For 16-bit normalize from -32,768 to 32,767
    }
    const sampleLength = dataChunk.size / bytesPerSample;
    const sampleData = new Float32Array(sampleLength);
    for (let i = 0; i < sampleData.length; i++)
    {
        // read
        let sample = readLittleEndian(dataChunk.chunkData, bytesPerSample);
        // turn into signed
        if (isUnsigned)
        {
            // normalize unsigned 8-bit sample
            sampleData[i] = (sample / normalizationFactor) - 0.5;
        }
        else
        {
            // normalize signed 16-bit sample
            if (sample >= maxSampleValue)
            {
                sample -= maxUnsigned;
            }
            sampleData[i] = sample / normalizationFactor;
        }
    }
    return sampleData;
}

/**
 * @param dataChunk {RiffChunk}
 * @param bytesPerSample {number}
 * @returns {Float32Array}
 */
function readALAW(dataChunk, bytesPerSample)
{
    const sampleLength = dataChunk.size / bytesPerSample;
    const sampleData = new Float32Array(sampleLength);
    for (let i = 0; i < sampleData.length; i++)
    {
        // read
        const input = readLittleEndian(dataChunk.chunkData, bytesPerSample);
        
        // https://en.wikipedia.org/wiki/G.711#A-law
        // re-toggle toggled bits
        let sample = input ^ 0x55;
        
        // remove sign bit
        sample &= 0x7F;
        
        // extract exponent
        let exponent = sample >> 4;
        // extract mantissa
        let mantissa = sample & 0xF;
        if (exponent > 0)
        {
            mantissa += 16; // add leading '1', if exponent > 0
        }
        
        mantissa = (mantissa << 4) + 0x8;
        if (exponent > 1)
        {
            mantissa = mantissa << (exponent - 1);
        }
        
        const s16sample = input > 127 ? mantissa : -mantissa;
        
        // convert to float
        sampleData[i] = s16sample / 32678;
    }
    return sampleData;
}

/**
 * @this {DLSSoundFont}
 * @param waveListChunk {RiffChunk}
 */
export function readDLSSamples(waveListChunk)
{
    SpessaSynthGroupCollapsed(
        "%cLoading Wave samples...",
        consoleColors.recognized
    );
    let sampleID = 0;
    while (waveListChunk.chunkData.currentIndex < waveListChunk.chunkData.length)
    {
        const waveChunk = readRIFFChunk(waveListChunk.chunkData);
        this.verifyHeader(waveChunk, "LIST");
        this.verifyText(readBytesAsString(waveChunk.chunkData, 4), "wave");
        
        /**
         * @type {RiffChunk[]}
         */
        const waveChunks = [];
        while (waveChunk.chunkData.currentIndex < waveChunk.chunkData.length)
        {
            waveChunks.push(readRIFFChunk(waveChunk.chunkData));
        }
        
        const fmtChunk = waveChunks.find(c => c.header === "fmt ");
        if (!fmtChunk)
        {
            throw new Error("No fmt chunk in the wave file!");
        }
        // https://github.com/tpn/winsdk-10/blob/9b69fd26ac0c7d0b83d378dba01080e93349c2ed/Include/10.0.14393.0/shared/mmreg.h#L2108
        const waveFormat = readLittleEndian(fmtChunk.chunkData, 2);
        const channelsAmount = readLittleEndian(fmtChunk.chunkData, 2);
        if (channelsAmount !== 1)
        {
            throw new Error(`Only mono samples are supported. Fmt reports ${channelsAmount} channels`);
        }
        const sampleRate = readLittleEndian(fmtChunk.chunkData, 4);
        // skip avg bytes
        readLittleEndian(fmtChunk.chunkData, 4);
        // blockAlign
        readLittleEndian(fmtChunk.chunkData, 2);
        // it's bits per sample because one channel
        const wBitsPerSample = readLittleEndian(fmtChunk.chunkData, 2);
        const bytesPerSample = wBitsPerSample / 8;
        
        // read the data
        let failed = false;
        const dataChunk = waveChunks.find(c => c.header === "data");
        if (!dataChunk)
        {
            this.parsingError("No data chunk in the WAVE chunk!");
        }
        let sampleData;
        switch (waveFormat)
        {
            default:
                failed = true;
                sampleData = new Float32Array(dataChunk.size / bytesPerSample);
                break;
            
            case W_FORMAT_TAG.PCM:
                sampleData = readPCM(dataChunk, bytesPerSample);
                break;
            
            case W_FORMAT_TAG.ALAW:
                sampleData = readALAW(dataChunk, bytesPerSample);
                break;
            
        }
        
        // read sample name
        const waveInfo = findRIFFListType(waveChunks, "INFO");
        let sampleName = `Unnamed ${sampleID}`;
        if (waveInfo)
        {
            let infoChunk = readRIFFChunk(waveInfo.chunkData);
            while (infoChunk.header !== "INAM" && waveInfo.chunkData.currentIndex < waveInfo.chunkData.length)
            {
                infoChunk = readRIFFChunk(waveInfo.chunkData);
            }
            if (infoChunk.header === "INAM")
            {
                sampleName = readBytesAsString(infoChunk.chunkData, infoChunk.size).trim();
            }
        }
        
        // correct defaults
        let sampleKey = 60;
        let samplePitch = 0;
        let sampleLoopStart = 0;
        let sampleLoopEnd = sampleData.length - 1;
        let sampleDbAttenuation = 0;
        
        // read wsmp
        const wsmpChunk = waveChunks.find(c => c.header === "wsmp");
        if (wsmpChunk)
        {
            // skip cbsize
            readLittleEndian(wsmpChunk.chunkData, 4);
            sampleKey = readLittleEndian(wsmpChunk.chunkData, 2);
            // section 1.14.2: Each relative pitch unit represents 1/65536 cents.
            // but that doesn't seem true for this one: it's just cents.
            samplePitch = signedInt16(
                wsmpChunk.chunkData[wsmpChunk.chunkData.currentIndex++],
                wsmpChunk.chunkData[wsmpChunk.chunkData.currentIndex++]
            );
            
            // pitch correction: convert hundreds to the root key
            const samplePitchSemitones = Math.trunc(samplePitch / 100);
            sampleKey += samplePitchSemitones;
            samplePitch -= samplePitchSemitones * 100;
            
            
            // gain is applied it manually here (literally multiplying the samples)
            const gainCorrection = readLittleEndian(wsmpChunk.chunkData, 4);
            // convert to signed and turn into decibels
            sampleDbAttenuation = (gainCorrection | 0) / -655360;
            // no idea about ful options
            readLittleEndian(wsmpChunk.chunkData, 4);
            const loopsAmount = readLittleEndian(wsmpChunk.chunkData, 4);
            if (loopsAmount === 1)
            {
                // skip size and type
                readLittleEndian(wsmpChunk.chunkData, 8);
                sampleLoopStart = readLittleEndian(wsmpChunk.chunkData, 4);
                const loopSize = readLittleEndian(wsmpChunk.chunkData, 4);
                sampleLoopEnd = sampleLoopStart + loopSize;
            }
        }
        else
        {
            SpessaSynthWarn("No wsmp chunk in wave... using sane defaults.");
        }
        
        if (failed)
        {
            console.error(`Failed to load '${sampleName}': Unsupported format: (${waveFormat})`);
        }
        
        this.samples.push(new DLSSample(
            sampleName,
            sampleRate,
            sampleKey,
            samplePitch,
            sampleLoopStart,
            sampleLoopEnd,
            sampleData,
            sampleDbAttenuation
        ));
        
        
        sampleID++;
        SpessaSynthInfo(
            `%cLoaded sample %c${sampleName}`,
            consoleColors.info,
            consoleColors.recognized
        );
    }
    SpessaSynthGroupEnd();
}