88 lines
2.7 KiB
JavaScript
88 lines
2.7 KiB
JavaScript
const fs = require("fs");
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//This is adapted from https://github.com/mon/SDVX-Song-Extractor/blob/master/bm2dx.py.
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//I'm personally not very good at data exploration.
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class Sample {
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constructor(data, offset, key_no) {
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const header = data.toString("ascii", offset, offset+4);
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offset += 4;
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const header_lead = data.readUInt32LE(offset);
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offset += 4;
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if (header !== "2DX9" || header_lead != 24) {
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throw "Invalid 2DX header.";
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}
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const size = data.readUInt32LE(offset);
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offset += 6;
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//Previously the keysound number was stored here.
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//In popn files this doesn't appear to be the case.
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//So we assume keysounds are sequential in these files.
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this.key_no = key_no;
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//These two bytes are set to 0000 on keysounds which are
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//used as background tracks. This keysound needs to be
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//identified as it should be at the start of the container.
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this.is_bg = data.toString("hex", offset, offset+2) == "0000";
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offset += 2;
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//These values were for attenuation and loop point in SDVX 2dxs.
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//I have no clue how to make use of these.
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this.unk1 = data.readUInt16LE(offset);
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offset += 2;
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this.unk2 = data.readUInt16LE(offset);
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offset += 6;
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this.data = data.slice(offset, offset+size);
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}
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}
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class Twodx {
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constructor(path) {
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this.path = path;
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this.data = fs.readFileSync(path);
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this.offset = 0;
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this.name = this.data.toString("ascii", 0, 16);
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this.offset += 16;
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this.header_len = this.data.readUInt32LE(this.offset);
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this.offset += 4;
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this.file_count = this.data.readUInt32LE(this.offset);
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this.offset += 52;
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const offsets = this.generateOffsets();
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this.keysounds = this.generateSamples(offsets);
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}
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generateOffsets() {
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return [...Array(this.file_count).keys()].map((_) => {
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const ind = this.data.readUInt32LE(this.offset);
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this.offset += 4;
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return ind;
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});
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}
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generateSamples(offsets) {
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const keysounds = [];
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for (let i = 0; i<offsets.length; i++) {
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const keysound = new Sample(this.data, offsets[i]);
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if (keysound.is_bg) {
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//BG tracks are placed at the start of the list
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//as this makes it easier to deal with keysound
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//indices in chart files.
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this.late_bg = i != 0;
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keysounds.unshift(keysound);
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} else {
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keysounds.push(keysound);
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}
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}
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return keysounds;
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}
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}
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module.exports = Twodx; |