minimp3;

internal/minimp3/README

@@ -0,0 +1,3 @@
+This is vendored from https://github.com/tosone/minimp3.
+
+tosone/minimp3 is MIT licensed, minimp3 itself is PD.

internal/minimp3/decode.go

@@ -0,0 +1,215 @@
+package minimp3
+
+/*
+#define MINIMP3_IMPLEMENTATION
+
+#include "minimp3.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+int decode(mp3dec_t *dec, mp3dec_frame_info_t *info, unsigned char *data, int *length, unsigned char *decoded, int *decoded_length) {
+    int samples;
+    short pcm[MINIMP3_MAX_SAMPLES_PER_FRAME];
+    samples = mp3dec_decode_frame(dec, data, *length, pcm, info);
+    *decoded_length = samples * info->channels * 2;
+    *length -= info->frame_bytes;
+    unsigned char buffer[samples * info->channels * 2];
+    memcpy(buffer, (unsigned char*)&(pcm), sizeof(short) * samples * info->channels);
+    memcpy(decoded, buffer, sizeof(short) * samples * info->channels);
+    return info->frame_bytes;
+}
+*/
+import "C"
+import (
+	"context"
+	"io"
+	"sync"
+	"time"
+	"unsafe"
+)
+
+const maxSamplesPerFrame = 1152 * 2
+
+// Decoder decode the mp3 stream by minimp3
+type Decoder struct {
+	readerLocker  *sync.Mutex
+	data          []byte
+	decoderLocker *sync.Mutex
+	decodedData   []byte
+	decode        C.mp3dec_t
+	info          C.mp3dec_frame_info_t
+	context       context.Context
+	contextCancel context.CancelFunc
+	SampleRate    int
+	Channels      int
+	Kbps          int
+	Layer         int
+
+	originalEof bool // if the original reader is EOF, set this to true
+}
+
+// BufferSize Decoded data buffer size.
+var BufferSize = 1024 * 10
+
+// WaitForDataDuration wait for the data time duration.
+var WaitForDataDuration = time.Millisecond * 10
+
+// NewDecoder decode mp3 stream and get a Decoder for read the raw data to play.
+func NewDecoder(reader io.Reader) (dec *Decoder, err error) {
+	dec = new(Decoder)
+	dec.readerLocker = new(sync.Mutex)
+	dec.decoderLocker = new(sync.Mutex)
+	dec.context, dec.contextCancel = context.WithCancel(context.Background())
+	dec.decode = C.mp3dec_t{}
+	C.mp3dec_init(&dec.decode)
+	dec.info = C.mp3dec_frame_info_t{}
+	go func() {
+		for {
+			select {
+			case <-dec.context.Done():
+				return
+			default:
+			}
+			if len(dec.data) > BufferSize {
+				<-time.After(WaitForDataDuration)
+				continue
+			}
+			var data = make([]byte, 512)
+			var n int
+			n, err = reader.Read(data)
+
+			dec.readerLocker.Lock()
+			dec.data = append(dec.data, data[:n]...)
+			dec.readerLocker.Unlock()
+			if err == io.EOF {
+				dec.originalEof = true
+				break
+			}
+			if err != nil {
+				dec.originalEof = true
+				break
+			}
+		}
+	}()
+	go func() {
+		for {
+			select {
+			case <-dec.context.Done():
+				return
+			default:
+			}
+			if len(dec.decodedData) > BufferSize {
+				<-time.After(WaitForDataDuration)
+				continue
+			}
+			var decoded = [maxSamplesPerFrame * 2]byte{}
+			var decodedLength = C.int(0)
+			var length = C.int(len(dec.data))
+			if len(dec.data) == 0 {
+				<-time.After(WaitForDataDuration)
+				continue
+			}
+			frameSize := C.decode(&dec.decode, &dec.info,
+				(*C.uchar)(unsafe.Pointer(&dec.data[0])),
+				&length, (*C.uchar)(unsafe.Pointer(&decoded[0])),
+				&decodedLength)
+			if int(frameSize) == 0 {
+				<-time.After(WaitForDataDuration)
+				continue
+			}
+			dec.SampleRate = int(dec.info.hz)
+			dec.Channels = int(dec.info.channels)
+			dec.Kbps = int(dec.info.bitrate_kbps)
+			dec.Layer = int(dec.info.layer)
+			dec.readerLocker.Lock()
+			dec.decoderLocker.Lock()
+			dec.decodedData = append(dec.decodedData, decoded[:decodedLength]...)
+			if int(frameSize) <= len(dec.data) {
+				dec.data = dec.data[int(frameSize):]
+			}
+			dec.decoderLocker.Unlock()
+			dec.readerLocker.Unlock()
+		}
+	}()
+	return
+}
+
+// Started check the record mp3 stream started ot not.
+func (dec *Decoder) Started() (channel chan bool) {
+	channel = make(chan bool)
+	go func() {
+		for {
+			select {
+			case <-dec.context.Done():
+				channel <- false
+			default:
+			}
+			if len(dec.decodedData) != 0 {
+				channel <- true
+			} else {
+				<-time.After(time.Millisecond * 100)
+			}
+		}
+	}()
+	return
+}
+
+// Read read the raw stream
+func (dec *Decoder) Read(data []byte) (n int, err error) {
+	for {
+		select {
+		case <-dec.context.Done(): // if the decoder is stopped, then here should return EOF
+			err = io.EOF
+			return
+		default:
+		}
+		if len(dec.data) == 0 && len(dec.decodedData) == 0 && dec.originalEof {
+			err = io.EOF
+			return
+		} else if len(dec.decodedData) > 0 {
+			break
+		}
+		<-time.After(WaitForDataDuration)
+	}
+	dec.decoderLocker.Lock()
+	defer dec.decoderLocker.Unlock()
+	n = copy(data, dec.decodedData[:])
+	dec.decodedData = dec.decodedData[n:]
+	return
+}
+
+// Close stop the decode mp3 stream cycle.
+func (dec *Decoder) Close() {
+	if dec.contextCancel != nil {
+		dec.contextCancel()
+	}
+}
+
+// DecodeFull put all of the mp3 data to decode.
+func DecodeFull(mp3 []byte) (dec *Decoder, decodedData []byte, err error) {
+	dec = new(Decoder)
+	dec.decode = C.mp3dec_t{}
+	C.mp3dec_init(&dec.decode)
+	info := C.mp3dec_frame_info_t{}
+	var length = C.int(len(mp3))
+	for {
+		var decoded = [maxSamplesPerFrame * 2]byte{}
+		var decodedLength = C.int(0)
+		frameSize := C.decode(&dec.decode,
+			&info, (*C.uchar)(unsafe.Pointer(&mp3[0])),
+			&length, (*C.uchar)(unsafe.Pointer(&decoded[0])),
+			&decodedLength)
+		if int(frameSize) == 0 {
+			break
+		}
+		decodedData = append(decodedData, decoded[:decodedLength]...)
+		if int(frameSize) < len(mp3) {
+			mp3 = mp3[int(frameSize):]
+		}
+		dec.SampleRate = int(info.hz)
+		dec.Channels = int(info.channels)
+		dec.Kbps = int(info.bitrate_kbps)
+		dec.Layer = int(info.layer)
+	}
+	return
+}