mp3 decoding but slow

assets/disk0/tvdos/bin/playmp3.js

@@ -0,0 +1,227 @@
+const Mp3 = require('mp3dec')
+const pcm = require("pcm")
+const interactive = exec_args[2] && exec_args[2].toLowerCase() == "/i"
+
+function printdbg(s) { if (0) serial.println(s) }
+
+class SequentialFileBuffer {
+
+    constructor(path, offset, length) {
+        if (Array.isArray(path)) throw Error("arg #1 is path(string), not array")
+
+        this.path = path
+        this.file = files.open(path)
+
+        this.offset = offset || 0
+        this.originalOffset = offset
+        this.length = length || this.file.size
+
+        this.seq = require("seqread")
+        this.seq.prepare(path)
+    }
+
+    /*readFull(n) {
+        throw Error()
+        let ptr = this.seq.readBytes(n)
+        return ptr
+    }*/
+
+    readStr(n) {
+        let ptr = this.seq.readBytes(n)
+        let s = ''
+        for (let i = 0; i < n; i++) {
+            if (i >= this.length) break
+            s += String.fromCharCode(sys.peek(ptr + i))
+        }
+        sys.free(ptr)
+        return s
+    }
+
+    readByteNumbers(n) {
+        let ptr = this.seq.readBytes(n)
+        try {
+            let s = []
+            for (let i = 0; i < n; i++) {
+                if (i >= this.length) break
+                s.push(sys.peek(ptr + i))
+            }
+            sys.free(ptr)
+            return s
+        }
+        catch (e) {
+            println(`n: ${n}; ptr: ${ptr}`)
+            println(e)
+        }
+    }
+
+    unread(diff) {
+        let newSkipLen = this.seq.getReadCount() - diff
+        this.seq.prepare(this.path)
+        this.seq.skip(newSkipLen)
+    }
+
+    rewind() {
+        this.seq.prepare(this.path)
+    }
+
+    seek(p) {
+        this.seq.prepare(this.path)
+        this.seq.skip(p)
+    }
+
+    get byteLength() {
+        return this.length
+    }
+
+    /*get remaining() {
+        return this.length - this.getReadCount()
+    }*/
+}
+
+
+
+con.curs_set(0)
+let [cy, cx] = con.getyx()
+let [__, CONSOLE_WIDTH] = con.getmaxyx()
+let paintWidth = CONSOLE_WIDTH - 16
+if (interactive) {
+    println("Decoding...")
+}
+
+
+printdbg("pre-decode...")
+let filebuf = new SequentialFileBuffer(_G.shell.resolvePathInput(exec_args[1]).full)
+const FILE_SIZE = filebuf.length
+let decoder = Mp3.newDecoder(filebuf)
+if (decoder === null) throw Error("decoder is null")
+
+const HEADER_SIZE = decoder.headerSize + 3
+const FRAME_SIZE = decoder.frameSize // only works reliably for CBR
+
+//serial.println(`header size: ${HEADER_SIZE}`)
+//serial.println(`frame size: ${FRAME_SIZE}`)
+
+audio.resetParams(0)
+audio.purgeQueue(0)
+audio.setPcmMode(0)
+audio.setPcmQueueCapacityIndex(0, 5) // queue size is now 24
+const QUEUE_MAX = audio.getPcmQueueCapacity(0)
+audio.setMasterVolume(0, 255)
+audio.play(0)
+
+let decodedLength = 0
+let readPtr = sys.malloc(8000)
+let decodePtr = sys.malloc(12000)
+
+function bytesToSec(i) {
+    // using fixed value: FRAME_SIZE(216) bytes for 36 ms on sampling rate 32000 Hz
+    return i / (FRAME_SIZE * 1000 / bufRealTimeLen)
+}
+function secToReadable(n) {
+    let mins = ''+((n/60)|0)
+    let secs = ''+(n % 60)
+    return `${mins.padStart(2,'0')}:${secs.padStart(2,'0')}`
+}
+function decodeAndResample(inPtr, outPtr, inputLen) {
+    // TODO resample
+    for (let k = 0; k < inputLen / 2; k+=2) {
+        let sample = [
+            pcm.u16Tos16(sys.peek(inPtr + k*2 + 0) | (sys.peek(inPtr + k*2 + 1) << 8)),
+            pcm.u16Tos16(sys.peek(inPtr + k*2 + 2) | (sys.peek(inPtr + k*2 + 3) << 8))
+        ]
+        sys.poke(outPtr + k, pcm.s16Tou8(sample[0]))
+        sys.poke(outPtr + k + 1, pcm.s16Tou8(sample[1]))
+        // soothing visualiser(????)
+//        printvis(`${sampleToVisual(sample[0])} | ${sampleToVisual(sample[1])}`)
+    }
+    return inputLen / 2
+}
+
+
+function printPlayBar() {
+}
+
+let stopPlay = false
+con.curs_set(0)
+if (interactive) {
+    con.move(cy, cy)
+    println("Push and hold Backspace to exit")
+}
+[cy, cx] = con.getyx()
+function printPlayBar(currently) {
+    if (interactive) {
+//        let currently = decodedLength
+        let total = FILE_SIZE - HEADER_SIZE
+
+        let currentlySec = Math.round(bytesToSec(currently))
+        let totalSec = Math.round(bytesToSec(total))
+
+        con.move(cy, 1)
+        print(' '.repeat(15))
+        con.move(cy, 1)
+
+        print(`${secToReadable(currentlySec)} / ${secToReadable(totalSec)}`)
+
+        con.move(cy, 15)
+        print(' ')
+        let progressbar = '\x84205u'.repeat(paintWidth + 1)
+        print(progressbar)
+
+        con.mvaddch(cy, 16 + Math.round(paintWidth * (currently / total)), 0xDB)
+    }
+}
+let t1 = sys.nanoTime()
+let bufRealTimeLen = 36
+try {
+    decoder.decode((ptr, len, pos)=>{
+
+        if (interactive) {
+            sys.poke(-40, 1)
+            if (sys.peek(-41) == 67) {
+                stopPlay = true
+                throw "STOP"
+            }
+        }
+
+        printPlayBar(pos)
+
+        let t2 = sys.nanoTime()
+
+        decodedLength += len
+
+//        serial.println(`Audio queue size: ${audio.getPosition(0)}/${QUEUE_MAX}`)
+
+        if (audio.getPosition(0) >= QUEUE_MAX) {
+            while (audio.getPosition(0) >= (QUEUE_MAX >>> 1)) {
+                printdbg(`Queue full, waiting until the queue has some space (${audio.getPosition(0)}/${QUEUE_MAX})`)
+//                serial.println(`Queue full, waiting until the queue has some space (${audio.getPosition(0)}/${QUEUE_MAX})`)
+                sys.sleep(bufRealTimeLen)
+            }
+        }
+
+
+
+        let declen = decodeAndResample(ptr, decodePtr, len)
+
+        audio.putPcmDataByPtr(decodePtr, declen, 0)
+        audio.setSampleUploadLength(0, declen)
+        audio.startSampleUpload(0)
+
+
+        let decodingTime = (t2 - t1) / 1000000.0
+        bufRealTimeLen = (declen) / 64000.0 * 1000
+        t1 = t2
+
+        printdbg(`Decoded ${decodedLength} bytes; target: ${bufRealTimeLen} ms, lag: ${decodingTime - bufRealTimeLen} ms`)
+
+
+    }) // now you got decoded PCM data
+}
+catch (e) {
+    if (e != "STOP") throw e
+}
+finally {
+    //audio.stop(0)
+    sys.free(readPtr)
+    sys.free(decodePtr)
+}