commit 605c44de79eb45b53e7fd802e1075eb209de4032
Author: Glenn Forbes <gizmoloon@gmail.com>
Date:   Tue Mar 17 19:40:39 2020 +0000

    Initial mess.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..cde1834
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+ffmpeg.exe
+ifstools.exe
+.vscode/launch.json
+package-lock.json
diff --git a/msadpcm.js b/msadpcm.js
new file mode 100644
index 0000000..d590636
--- /dev/null
+++ b/msadpcm.js
@@ -0,0 +1,198 @@
+const ADAPTATION_TABLE = [
+  230, 230, 230, 230, 307, 409, 512, 614,
+  768, 614, 512, 409, 307, 230, 230, 230,
+];
+
+function clamp(val, min, max) {
+  if(val < min) return min;
+  else if(val > max) return max;
+  else return val;
+}
+
+function expandNibble(nibble, state, channel) {
+  const signed = 8 <= nibble ? nibble - 16 : nibble;
+
+  let predictor = ((
+    state.sample1[channel] * state.coeff1[channel] +
+    state.sample2[channel] * state.coeff2[channel]
+  ) >> 8) + (signed * state.delta[channel]);
+
+  predictor = clamp(predictor, -0x8000, 0x7fff);
+
+  state.sample2[channel] = state.sample1[channel];
+  state.sample1[channel] = predictor;
+
+  state.delta[channel] = Math.floor(ADAPTATION_TABLE[nibble] * state.delta[channel] / 256);
+  if(state.delta[channel] < 16) state.delta[channel] = 16;
+
+  return predictor;
+}
+
+/**
+ * Decode a block of MS-ADPCM data
+ * @param  {Buffer}    buf           one block of MS-ADPCM data
+ * @param  {number}    channels      number of channels (usually 1 or 2, never tested on upper values)
+ * @param  {number[]}  coefficient1  array of 7 UInt8 coefficient values
+ *                                   usually, [ 256, 512, 0, 192, 240, 460, 392 ]
+ * @param  {number[]}  coefficient2  array of 7 UInt8 coefficient values
+ *                                   usually, [ 0, -256, 0, 64, 0, -208, -232 ]
+ * @return {Buffer[]}                array of decoded PCM buffer for each channels
+ */
+function decode(buf, channels, coefficient1, coefficient2) {
+  const state = {
+    coefficient: [ coefficient1, coefficient2 ],
+    coeff1: [],
+    coeff2: [],
+    delta: [],
+    sample1: [],
+    sample2: [],
+  };
+
+  let offset = 0;
+
+  // Read MS-ADPCM header
+  for(let i = 0 ; i < channels ; i++) {
+    const predictor = clamp(buf.readUInt8(offset), 0, 6);
+    offset += 1;
+
+    state.coeff1[i] = state.coefficient[0][predictor];
+    state.coeff2[i] = state.coefficient[1][predictor];
+  }
+
+  for(let i = 0 ; i < channels ; i++) { state.delta.push(buf.readInt16LE(offset)); offset += 2; }
+  for(let i = 0 ; i < channels ; i++) { state.sample1.push(buf.readInt16LE(offset)); offset += 2; }
+  for(let i = 0 ; i < channels ; i++) { state.sample2.push(buf.readInt16LE(offset)); offset += 2; }
+
+  // Decode
+  const output = [];
+
+  for(let i = 0 ; i < channels ; i++)
+    output[i] = [ state.sample2[i], state.sample1[i] ];
+
+  let channel = 0;
+  while(offset < buf.length) {
+    const byte = buf.readUInt8(offset);
+    offset += 1;
+
+    output[channel].push(expandNibble(byte >> 4, state, channel));
+    channel = (channel + 1) % channels;
+
+    output[channel].push(expandNibble(byte & 0xf, state, channel));
+    channel = (channel + 1) % channels;
+  }
+
+  //Converting all sound to stereo since it'll be easier later on.
+  if (channels == 1) {
+    output.push(output[0]);
+  }
+
+  return output;
+}
+
+function readWav(buf) {
+
+  let offset = 0;
+
+  // 'RIFF'
+  const magic = buf.readUInt32BE(offset); offset += 4;
+  if(magic !== 0x52494646) {
+    console.log(magic);
+    throw "0x0000:0x0004 != 52:49:46:46";
+  }
+
+  const dataSize = buf.readUInt32LE(offset); offset += 4;
+
+  // 'WAVE'
+  const format = buf.readUInt32BE(offset); offset += 4;
+  if(format !== 0x57415645) throw "0x0008:0x000B != 57:41:56:45";
+
+  let wavFormat, wavData;
+
+  while(offset < buf.length) {
+    const name = buf.readUInt32BE(offset); offset += 4;
+    const blockSize = buf.readUInt32LE(offset); offset += 4;
+
+    // 'fmt '
+    if(name === 0x666D7420) {
+      wavFormat = {
+        format:        buf.readUInt16LE(offset +  0),
+        channels:      buf.readUInt16LE(offset +  2),
+        sampleRate:    buf.readUInt32LE(offset +  4),
+        byteRate:      buf.readUInt32LE(offset +  8),
+        blockAlign:    buf.readUInt16LE(offset + 12),
+        bitsPerSample: buf.readUInt16LE(offset + 14),
+      };
+
+      offset += 16;
+
+      if(wavFormat.format === 0x01) {
+        // console.log(`${filename} is PCM file`);
+        continue;
+      }
+      else if(wavFormat.format === 0x02) {
+        // console.log(`${filename} is MS-ADPCM file`);
+
+        const extraSize = buf.readUInt16LE(offset); offset += 2;
+        wavFormat.extraSize = extraSize;
+        wavFormat.extra = {
+          samplesPerBlock:  buf.readUInt16LE(offset + 0),
+          coefficientCount: buf.readUInt16LE(offset + 2),
+          coefficient: [ [], [] ],
+        };
+
+        offset += 4;
+
+        for(let i = 0 ; i < wavFormat.extra.coefficientCount ; i++) {
+          wavFormat.extra.coefficient[0].push(buf.readInt16LE(offset + 0));
+          wavFormat.extra.coefficient[1].push(buf.readInt16LE(offset + 2));
+          offset += 4;
+        }
+      }
+      else throw `WAVE format ${wavFormat.format} is unknown`;
+    }
+    // 'data'
+    else if(name === 0x64617461) {
+      wavData = buf.slice(offset, offset + blockSize);
+      offset += blockSize;
+    }
+    else {
+      offset += blockSize;
+    }
+  }
+
+  if(wavFormat && wavData) return { format: wavFormat, data: wavData };
+  else throw "'fmt ' or/and 'data' block not found";
+}
+
+exports.decodeKeysoundOut = (buff, vol) => {
+  const adpcmData = readWav(buff);
+  const blockSize = adpcmData.format.blockAlign;
+
+  let totalBuff = Buffer.alloc(1);
+  const totalBlocks = adpcmData.data.length / blockSize;
+  let totalOffset = 0;
+
+  for(let i = 0 ; i < adpcmData.data.length ; i += blockSize) {
+    const adpcmBlock = adpcmData.data.slice(i, i + blockSize);
+    const decoded = decode(
+      adpcmBlock,
+      adpcmData.format.channels,
+      adpcmData.format.extra.coefficient[0],
+      adpcmData.format.extra.coefficient[1]
+    );
+
+    const pcmBlockSize = decoded[0].length * 2;
+    if (totalBuff.length == 1) {
+      totalBuff = Buffer.alloc(pcmBlockSize * totalBlocks * 2);
+    }
+
+    for(let s = 0 ; s < pcmBlockSize/2; s++) {
+      for(let c = 0 ; c < decoded.length ; c++) {
+        totalBuff.writeInt16LE(decoded[c][s], totalOffset);
+        totalOffset += 2;
+      }
+    }
+  }
+
+  return {data: totalBuff, channels: adpcmData.format.channels, samplingRate: adpcmData.format.sampleRate, volume: vol};
+}
\ No newline at end of file
diff --git a/popnchart.js b/popnchart.js
new file mode 100644
index 0000000..37fff70
--- /dev/null
+++ b/popnchart.js
@@ -0,0 +1,100 @@
+const fs = require("fs");
+
+class PopnChart {
+
+    constructor(filename, offsetKeysounds=false) {
+        this.filename = filename;
+        this.data = fs.readFileSync(filename);
+
+        let newFormat = false;
+        if (this.data.readInt8(16) == 69) {
+            newFormat = true;
+        } else if (this.data.readInt8(12) == 69) {
+            newFormat = false;
+        } else {
+            throw "Chart format not supported.";
+        }
+
+        this.events = [];
+
+        let offset = 0;
+        while (offset < this.data.length) {
+            const eventOffset = this.data.readInt32LE(offset);
+            offset += 5;
+            const eventFlag = this.data.readInt8(offset);
+            offset += 1;
+
+            let eventParam = 0;
+            let eventValue = 0;
+            
+            let joined = this.data.slice(offset, offset+2);
+            offset += 2;
+            if (eventFlag === 2 || eventFlag === 7) {
+                joined.swap16();
+                const hx = joined.toString("hex");
+
+                eventParam = parseInt(hx.slice(1, 4), 16);
+                eventValue = parseInt(hx.slice(0, 1), 16);
+            } else {
+                eventParam = joined.readUInt8(0);
+                eventValue = joined.readUInt8(1);
+            }
+
+            if (newFormat) {
+                const longNoteData = this.data.readInt32LE(offset);
+                offset += 4;
+            }
+            
+            this.events.push([eventOffset, eventFlag, eventParam, eventValue]);
+        }
+
+        this.bpm = 0;
+        this.bpmTransitions = [];
+
+        this.playEvents = [];
+        this.uniqueKeysounds = [];
+
+        this.notecount = 0;
+
+        const sampleColumns = [0, 0, 0, 0, 0, 0, 0, 0, 0];
+
+        for (const event of this.events) {
+            let [offset, eventType, param, value] = event;
+
+            if (eventType == 7 || eventType == 2) {
+                if (this.uniqueKeysounds.indexOf(param) == -1) {
+                    this.uniqueKeysounds.push(param);
+                }
+            }
+            
+            switch (eventType) {
+                case 1:
+                    if (sampleColumns[param] != 0) {
+                        this.playEvents.push([offset, sampleColumns[param]]);
+                    }
+                    this.notecount += 1;
+                    break;
+                case 2:
+                    if (offsetKeysounds) {
+                        param -= 1;
+                    }
+                    sampleColumns[value] = param;
+                    break;
+                case 3:
+                    this.playEvents.push([offset, 0]);
+                    break;
+                case 4:
+                    this.bpm = param;
+                    this.bpmTransitions.push(param);
+                    break;
+                case 7:
+                    if (offsetKeysounds) {
+                        param -= 1;
+                    }
+                    this.playEvents.push([offset, param]);
+            }
+        }
+    }
+}
+
+module.exports = PopnChart;
\ No newline at end of file
diff --git a/popntowav.js b/popntowav.js
new file mode 100644
index 0000000..a42f251
--- /dev/null
+++ b/popntowav.js
@@ -0,0 +1,121 @@
+const MSADPCM = require("./msadpcm");
+const Popnchart = require("./popnchart");
+const Twodx = require("./twodx");
+
+const child_process = require("child_process");
+const fs = require("fs");
+const path = require("path");
+const SampleRate = require("node-libsamplerate");
+const wav = require("wav");
+
+if (process.argv.length < 3) {
+    console.log("Usage: node popntowav ifs_file");
+    process.exit();
+}
+
+let arg1 = process.argv[2];
+let outputFilename = process.argv[3];
+
+child_process.execSync(`ifstools ${arg1}`);
+const ifsname = path.basename(arg1).slice(0, -4);
+let twodxPath = `${ifsname}_ifs/${ifsname}.2dx`;
+let chartPath = `${ifsname}_ifs/${ifsname}_op.bin`;
+
+if (!fs.existsSync(chartPath)) {
+    chartPath = `${ifsname}_ifs/${ifsname}_hp.bin`;
+}
+
+let cleanUp = true;
+
+let soundContainer = new Twodx(twodxPath);
+let chart = new Popnchart(chartPath, !soundContainer.late_bg);
+//The sound container is full of MSADPCM keysounds, so each one needs decoded.
+let decodedKeysounds = soundContainer.keysounds.map((keysound) => MSADPCM.decodeKeysoundOut(keysound.data, keysound.unk2));
+
+if (cleanUp) fs.rmdirSync(path.basename(arg1).slice(0, -4)+"_ifs", {recursive: true});
+
+let highestSample = 0;
+//Outputting stereo 44.1Khz regardless.
+const channels = 2;
+const samplingRate = 44100;
+//Because Int32.    
+const bytes = 4;
+let lowestVolume = 100;
+
+for (var i = 0; i<decodedKeysounds.length; i++) {
+    let keysound = decodedKeysounds[i];
+    if (keysound.samplingRate != samplingRate) {
+        let options = {
+            type: 0,
+            channels: 2,
+            fromDepth: 16,
+            toDepth: 16,
+            fromRate: keysound.samplingRate,
+            toRate: samplingRate
+        }
+        const resample = new SampleRate(options);
+        
+        resample.write(keysound.data);
+        keysound.data = Buffer.from(resample.read());
+    }
+    lowestVolume = keysound.volume < lowestVolume ? keysound.volume : lowestVolume;
+    decodedKeysounds[i] = keysound;
+}
+
+//Gotta find the proper endOfSong
+//Trying to do this by getting the largest offset,
+//and then adding its associated keysound length
+//to get the true ending.
+let buffSize = 0;
+for (const event of chart.playEvents) {
+    const [offset, keysoundNo] = event;
+    let off = parseInt((offset*samplingRate)/1000)*channels*bytes;
+    const keysound = decodedKeysounds[keysoundNo];
+    if (keysound) {
+        if ((off + (keysound.data.length)*2) > buffSize) {
+            buffSize = off + (keysound.data.length*2);
+        }
+    }
+}
+
+//Creating a buffer to store Int32s.
+//This is overcompensating to deal with overflow from digital summing.
+//Final Timestamp in milliseconds * sampling rate * 2 channels * 4 bytes.
+const finalBuffer = Buffer.alloc(buffSize);
+
+chart.playEvents.forEach((event) => {
+    const [offset, keysoundNo] = event;
+    //Grabbing the relevant offset for the buffer.
+    const convertedOffset = parseInt((offset*samplingRate)/1000)*channels*bytes;
+    const keysound = decodedKeysounds[keysoundNo];
+
+    if (keysound) {
+        const keysoundData = keysound.data;
+        for (var i = 0; i<keysoundData.length; i += 2) {
+            const keysoundBytes = keysoundData.readInt16LE(i);
+            const finalBytes = finalBuffer.readInt32LE(convertedOffset+(i*2));
+            let mixedBytes = keysoundBytes+finalBytes;
+    
+            highestSample = Math.max(Math.abs(mixedBytes), highestSample);
+            finalBuffer.writeInt32LE(mixedBytes, convertedOffset+(i*2));
+        }
+    }
+});
+
+//We've got summed 16bit values, but they need normalising so we can hear them,
+//from a 32bit buffer.
+//2147483647 is just so I don't have to import a MAX_INT32 module.
+//We're normaslising against the highest volume seen.
+//After normalising, these values will be scaled correctly from 16bit to 32bit.
+const normaliseFactor = parseInt(2147483647/highestSample);
+for (var i = 0; i<finalBuffer.length; i += 4) {
+    const buffBytes = finalBuffer.readInt32LE(i) * normaliseFactor;
+    finalBuffer.writeInt32LE(buffBytes, i);
+}
+
+//The 2dx container names usually contain null bytes too.
+let filename = soundContainer.name;
+filename = filename.slice(0, filename.indexOf("\u0000"));
+
+let writer = new wav.FileWriter("output\\"+outputFilename+".wav", {bitDepth: 32});
+writer.write(finalBuffer);
\ No newline at end of file
diff --git a/twodx.js b/twodx.js
new file mode 100644
index 0000000..c137c9a
--- /dev/null
+++ b/twodx.js
@@ -0,0 +1,64 @@
+const fs = require("fs");
+
+class Keysound {
+    constructor(data, offset, key_no) {
+        const header = data.toString("ascii", offset, offset+4);
+        offset += 4;
+        const header_lead = data.readUInt32LE(offset);
+        offset += 4;
+        if (header !== "2DX9" || header_lead != 24) {
+            throw "Invalid 2DX header.";
+        }
+
+        const size = data.readUInt32LE(offset);
+        offset += 6;
+
+        this.key_no = key_no;
+        this.is_bg = data.toString("hex", offset, offset+2) == "0000";
+        offset += 2;
+        //These values were for attenuation and loop point in SDVX 2dxs.
+        //I have no clue how to make use of these.
+        this.unk1 = data.readUInt16LE(offset);
+        offset += 2;
+        this.unk2 = data.readUInt16LE(offset);
+        offset += 6;
+        this.data = data.slice(offset, offset+size);
+    }
+}
+
+class Twodx {
+    constructor(path) {
+        this.path = path;
+        const data = fs.readFileSync(path);
+
+        let offset = 0;
+
+        this.name = data.toString("ascii", 0, 16);
+        offset += 16;
+        this.header_len = data.readUInt32LE(offset);
+        offset += 4;
+        this.file_count = data.readUInt32LE(offset);
+        offset += 52;
+
+        this.keysounds = [];
+
+        let trackOffsets = [...Array(this.file_count).keys()].map((_) => {
+            const ind = data.readUInt32LE(offset);
+            offset += 4;
+            return ind;
+        });
+
+        for (let i = 0; i<trackOffsets.length; i++) {
+            const keysound = new Keysound(data, trackOffsets[i]);
+            if (keysound.is_bg) {
+                this.late_bg = i != 0;
+                this.keysounds.unshift(keysound);
+            } else {
+                this.keysounds.push(keysound);
+            }
+        }
+    }
+    
+}
+
+module.exports = Twodx;
\ No newline at end of file