mdfpwm support

index.ts

@@ -1,9 +1,10 @@
 import { Hono } from 'hono'
 const app = new Hono()
 const joypixels = require("emoji-toolkit");
-import { mkdirSync, writeFileSync, existsSync, rmSync, readFileSync, readFile } from 'fs'
+import { mkdirSync, writeFileSync, existsSync, rmSync, readFileSync, readFile, writeFile } from 'fs'
 import { $ } from 'bun';
 import ytSearch from 'yt-search';
+import { writeMDFPWMv3 } from './mdfpwmWriter';
 let ytdlpPath = "yt-dlp"
 if(existsSync("./yt-dlp")) {
     ytdlpPath = "./yt-dlp"
@@ -22,8 +23,34 @@ app.post("/youtube", async (c) => {
 
     let title = body.title;
     let artist = body.artist;
+    let filename;
+    if(body.mdfpwm) {
+        filename = "cache/"+Bun.hash(title+"-"+artist)+".mdfpwm"
 
-    let filename = "cache/"+Bun.hash(title+"-"+artist)+".dfpwm"
+        if(!existsSync(filename)) {
+            const searchResult = await ytSearch(`${artist} ${title}`);
+            const video = searchResult.videos[0];
+            if (!video) throw new Error("No video found");
+            console.log(video)
+
+            await $`${ytdlpPath} --audio-format opus -x ${video.url} -o test`;
+                        console.timeEnd("yt-dlp")
+
+            // this makes left.dfpwm & right.dfpwm
+            await $`ffmpeg -i test.opus -filter_complex "[0:a]channelsplit=channel_layout=stereo[left][right]; [left]highpass=f=60,lowpass=f=15000,dynaudnorm[leftf]; [right]highpass=f=60,lowpass=f=15000,dynaudnorm[rightf]" -map "[leftf]"  -ar 48000 -f dfpwm left.dfpwm -map "[rightf]" -ar 48000 -f dfpwm right.dfpwm`
+            rmSync("test.opus")
+
+            writeFileSync(filename, writeMDFPWMv3(
+                readFileSync("left.dfpwm"),
+                readFileSync("right.dfpwm"),
+                { title: title, artist: artist, album: title }
+            ))
+
+            rmSync("right.dfpwm")
+            rmSync("left.dfpwm")
+        }
+    } else {
+        filename = "cache/"+Bun.hash(title+"-"+artist)+".dfpwm"
 
         if(!existsSync(filename)) {
             const searchResult = await ytSearch(`${artist} ${title}`);
@@ -34,10 +61,11 @@ app.post("/youtube", async (c) => {
             await $`ffmpeg -i test.opus -af "highpass=f=60, lowpass=f=15000, dynaudnorm" -ar 48000 -ac 1 -f dfpwm "${filename}"`;
             rmSync("test.opus")
         }
+    }
     
     return c.body(readFileSync(filename), {
         headers: {
-            'Content-Type': 'audio/vnd.dfpwm',
+            'Content-Type': `audio/vnd.${body.mdfpwm ? "m" : ""}dfpwm`,
             'Content-Disposition': `attachment; filename="${filename}"`,
         },
     });

mdfpwmWriter.ts

@@ -0,0 +1,49 @@
+export interface MDFPWMMetadata {
+  title?: string;
+  artist?: string;
+  album?: string;
+}
+
+function toS1(str: string): Buffer {
+  const utf8 = Buffer.from(str, "utf-8");
+  const len = utf8.length;
+  return Buffer.concat([Buffer.from([len]), utf8]);
+}
+
+export function writeMDFPWMv3(
+  left: Buffer,
+  right: Buffer,
+  meta: MDFPWMMetadata = {}
+): Buffer {
+  if (left.length !== right.length) {
+    throw new Error("Left and right DFPWM buffers must be the same length");
+  }
+
+  let length = left.byteLength*2;
+  const mdfpwm = []
+  mdfpwm.push(Buffer.from("MDFPWM\x03", "ascii"));
+  mdfpwm.push(Buffer.alloc(4));
+  mdfpwm.push(toS1(meta.artist || ""));
+  mdfpwm.push(toS1(meta.title || ""));
+  mdfpwm.push(toS1(meta.album || ""));
+  mdfpwm[1]!.writeUint32LE(length)
+
+  for(let i =0; i < length / 12000; i++) {
+    const lStart = i * 6000;
+    const rStart = i * 6000;
+
+    const lChunk = left.subarray(lStart, lStart + 6000);
+    mdfpwm.push(lChunk);
+    if (lChunk.length < 6000) {
+        mdfpwm.push(Buffer.alloc(6000 - lChunk.length, 0x55));
+    }
+
+    const rChunk = right.subarray(rStart, rStart + 6000);
+    mdfpwm.push(rChunk);
+    if (rChunk.length < 6000) {
+        mdfpwm.push(Buffer.alloc(6000 - rChunk.length, 0x55));
+    }
+  }
+
+  return Buffer.concat(mdfpwm)
+}