audio-player: wasm decoding merged with pcm player

cmd/audio-player/main.go

@@ -1,27 +1,73 @@
 package main
 
 import (
-	"fmt"
+	"bytes"
+	"reflect"
 	"syscall/js"
+	"unsafe"
 
 	"bitbucket.org/ausocean/av/codec/adpcm"
 )
 
 func main() {
-	c := make(chan struct{}, 0)
+	dec := NewDecoder()
-
+	dec.Start()
-	println("WASM Go Initialized")
-	// register functions
-	registerCallbacks()
-
-	<-c
 }
 
-func registerCallbacks() {
+// Decoder is a client side adpcm decoder
-	js.Global().Set("decode", js.FuncOf(decode))
+type Decoder struct {
+	inBuf                  []uint8
+	onImgLoadCb, initMemCb js.Func
+	console                js.Value
+	done                   chan struct{}
 }
 
-func decode(this js.Value, args []js.Value) interface{} {
+// NewDecoder returns a new instance of decoder
-	fmt.Println("calculating")
+func NewDecoder() *Decoder {
-	return adpcm.EncBytes(args[0].Int())
+	return &Decoder{
+		console: js.Global().Get("console"),
+		done:    make(chan struct{}),
+	}
+}
+
+func (s *Decoder) setupOnImgLoadCb() {
+	s.onImgLoadCb = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		// reader := bytes.NewReader(s.inBuf)
+
+		//DECODING HAPPENS HERE
+
+		decoded := bytes.NewBuffer(make([]byte, 0, len(s.inBuf)*4))
+		dec := adpcm.NewDecoder(decoded)
+		dec.Write(s.inBuf)
+
+		s.inBuf = decoded.Bytes()
+
+		return nil
+	})
+}
+
+func (s *Decoder) setupInitMemCb() {
+	// The length of the data array buffer is passed.
+	// Then the buf slice is initialized to that length.
+	// A pointer to that slice is passed back to the browser.
+	s.initMemCb = js.FuncOf(func(this js.Value, i []js.Value) interface{} {
+		length := i[0].Int()
+		s.console.Call("log", "length:", length)
+		s.inBuf = make([]uint8, length)
+		hdr := (*reflect.SliceHeader)(unsafe.Pointer(&s.inBuf))
+		ptr := uintptr(unsafe.Pointer(hdr.Data))
+		s.console.Call("log", "ptr:", ptr)
+		js.Global().Call("gotMem", ptr)
+		return nil
+	})
+}
+
+// Start sets up all the callbacks and waits for the close signal
+// to be sent from the browser.
+func (s *Decoder) Start() {
+	s.setupInitMemCb()
+	js.Global().Set("initMem", s.initMemCb)
+	s.setupOnImgLoadCb()
+	js.Global().Set("loadData", s.onImgLoadCb)
+	<-s.done
 }

cmd/audio-player/main.js

@@ -1,45 +1,10 @@
-window.onload = function () {
+const go = new Go()
-    initWasm()
+// memoryBytes is an Uint8Array pointing to the webassembly linear memory.
-    document.getElementById('input').addEventListener('change', playFile)
+let memoryBytes;
-}
+let bytes;
-
+let mod, inst
-function playFile() {
+console.log("Initializing wasm...")
-    console.log(decode(48000))
+WebAssembly.instantiateStreaming(
-    const input = event.target.files[0]
-
-    const reader = new FileReader()
-    reader.onload = event => playData(event.target.result)
-    reader.onerror = error => reject(error)
-    reader.readAsArrayBuffer(input)
-}
-
-function playData(array) {
-    var data = new Uint8Array(array)
-    console.log("playing file")
-    var player = new PCMPlayer({
-        encoding: '16bitInt',
-        channels: 1,
-        sampleRate: 48000,
-        flushingTime: 2000
-    });
-    player.feed(data)
-}
-
-function initWasm() {
-    if (!WebAssembly.instantiateStreaming) {
-        // polyfill
-        WebAssembly.instantiateStreaming = async (resp, importObject) => {
-            const source = await (await resp).arrayBuffer()
-            return await WebAssembly.instantiate(source, importObject)
-        }
-    }
-
-    const go = new Go()
-    let mod, inst
-    // memoryBytes is an Uint8Array pointing to the webassembly linear memory.
-    let memoryBytes;
-    console.log("Initializing wasm...")
-    WebAssembly.instantiateStreaming(
     fetch('lib.wasm'), go.importObject).then(
     result => {
         mod = result.module
@@ -48,12 +13,69 @@ function initWasm() {
         console.log("Initialization complete.")
         run()
     }
-    )
+)
 
-    async function run() {
+async function run() {
     await go.run(inst)
     inst = await WebAssembly.instantiate(mod, go.importObject) // reset instance
-    }
+}
-
+
-
+// gotMem sets the webassembly linear memory with the data buffer result
+// at the slice header pointer passed from Go.
+function gotMem(pointer) {
+    memoryBytes.set(bytes, pointer);
+    // Now the data can be loaded from the slice.
+    loadData();
+}
+
+// // displayImage takes the pointer to the target image in the wasm linear memory
+// // and its length. Gets the resulting byte slice and creates an image blob.
+// function displayImage(pointer, length) {
+//     let resultBytes = memoryBytes.slice(pointer, pointer + length);
+//     let blob = new Blob([resultBytes], {
+//         'type': imageType
+//     });
+//     document.getElementById('targetImg').src = URL.createObjectURL(blob);
+// }
+
+// document.getElementById('input').addEventListener('change', function () {
+//     let reader = new FileReader();
+
+//     reader.onload = (ev) => {
+//         bytes = new Uint8Array(ev.target.result);
+//         initMem(bytes.length);
+//         let blob = new Blob([bytes], {
+//             'type': imageType
+//         });
+//         document.getElementById("sourceImg").src = URL.createObjectURL(blob);
+//     };
+//     imageType = this.files[0].type;
+//     reader.readAsArrayBuffer(this.files[0]);
+// });
+window.onload = function () {
+
+    document.getElementById('input').addEventListener('change', function () {
+        const input = event.target.files[0]
+        const reader = new FileReader()
+
+        reader.onload = event => {
+            bytes = new Uint8Array(event.target.result)
+
+            initMem(bytes.length)
+
+            // bytes should be decoded at this point, if not try memoryBytes.set(bytes, pointer)
+
+            console.log("playing file")
+            var player = new PCMPlayer({
+                encoding: '16bitInt',
+                channels: 1,
+                sampleRate: 48000,
+                flushingTime: 2000
+            });
+            player.feed(bytes)
+        }
+        reader.onerror = error => reject(error)
+        reader.readAsArrayBuffer(input)
+
+    })
 }