From 2216e81897450fd5339c14b36ba7c2567412bebe Mon Sep 17 00:00:00 2001
From: Hraban Luyat <hraban@0brg.net>
Date: Thu, 19 Feb 2015 00:51:09 +0000
Subject: [PATCH] Bare API wrapper: encode & decode floats

---
 api.go       | 122 +++++++++++++++++++++++++++++++++++----------------
 opus_test.go |  20 +++++++++
 2 files changed, 103 insertions(+), 39 deletions(-)

diff --git a/api.go b/api.go
index 709b070..24f76db 100644
--- a/api.go
+++ b/api.go
@@ -9,44 +9,10 @@ import (
 #cgo CFLAGS: -std=c99 -Wall -Werror -pedantic
 // Statically link libopus
 #cgo LDFLAGS: libopusbuild/lib/libopus.a -lm
-#include <stdio.h>
-#include <stdlib.h>
 #include <opus/opus.h>
-
-int
-engavg(const float *ar, int numfloats, char *buf, int bufsize)
-{
-    double sum = 0;
-
-    for (int i = 0; i < numfloats; i++) {
-        sum += ar[i];
-    }
-
-    int n = snprintf(buf, bufsize, "%g", sum / numfloats);
-    if (n < 0 || n >= bufsize) {
-        return -1;
-    }
-
-    return n;
-}
-
 */
 import "C"
 
-func engavg(ar []float32) string {
-	buf := make([]byte, 30)
-	n := int(C.engavg(
-		(*C.float)(&ar[0]),
-		C.int(len(ar)),
-		(*C.char)(unsafe.Pointer(&buf[0])),
-		C.int(cap(buf))))
-	if n < 0 {
-		return fmt.Sprintf("Error: %d", n)
-	}
-	return string(buf[:n])
-
-}
-
 type Application int
 
 // TODO: Get from lib because #defines can change
@@ -54,19 +20,97 @@ const APPLICATION_VOIP Application = 2048
 const APPLICATION_AUDIO Application = 2049
 const APPLICATION_RESTRICTED_LOWDELAY Application = 2051
 
+const xMAX_BITRATE = 48000
+const xMAX_FRAME_SIZE_MS = 60
+const xMAX_FRAME_SIZE = xMAX_BITRATE * xMAX_FRAME_SIZE_MS / 1000
+
+func Version() string {
+	return C.GoString(C.opus_get_version_string())
+}
+
 type Encoder struct {
-	p unsafe.Pointer
+	p *C.struct_OpusEncoder
+}
+
+func opuserr(code int) error {
+	return fmt.Errorf("opus: %s", C.GoString(C.opus_strerror(C.int(code))))
 }
 
 func NewEncoder(sample_rate int, channels int, application Application) (*Encoder, error) {
 	var errno int
-	p := unsafe.Pointer(C.opus_encoder_create(C.opus_int32(sample_rate), C.int(channels), C.int(application), (*C.int)(unsafe.Pointer(&errno))))
+	p := C.opus_encoder_create(C.opus_int32(sample_rate), C.int(channels), C.int(application), (*C.int)(unsafe.Pointer(&errno)))
 	if errno != 0 {
-		return nil, fmt.Errorf("opus: %s", C.GoString(C.opus_strerror(C.int(errno))))
+		return nil, opuserr(errno)
 	}
 	return &Encoder{p: p}, nil
 }
 
-func Version() string {
-	return C.GoString(C.opus_get_version_string())
+func (enc *Encoder) EncodeFloat32(pcm []float32) ([]byte, error) {
+	// I never know how much to allocate
+	data := make([]byte, 10000)
+	n := int(C.opus_encode_float(
+		enc.p,
+		(*C.float)(&pcm[0]),
+		C.int(len(pcm)),
+		(*C.uchar)(&data[0]),
+		C.opus_int32(cap(data))))
+	if n < 0 {
+		return nil, opuserr(n)
+	}
+	return data[:n], nil
+}
+
+// Returns an error if the encoder was already closed
+func (enc *Encoder) Close() error {
+	if enc.p == nil {
+		return fmt.Errorf("opus: encoder already closed")
+	}
+	C.opus_encoder_destroy(enc.p)
+	enc.p = nil
+	return nil
+}
+
+type Decoder struct {
+	p           *C.struct_OpusDecoder
+	sample_rate int
+}
+
+func NewDecoder(sample_rate int, channels int) (*Decoder, error) {
+	var errno int
+	p := C.opus_decoder_create(C.opus_int32(sample_rate), C.int(channels), (*C.int)(unsafe.Pointer(&errno)))
+	if errno != 0 {
+		return nil, opuserr(errno)
+	}
+	dec := &Decoder{
+		p:           p,
+		sample_rate: sample_rate,
+	}
+	return dec, nil
+}
+
+func (dec *Decoder) DecodeFloat32(data []byte) ([]float32, error) {
+	var errno int
+	// I don't know how big this frame will be, but this is the limit
+	pcm := make([]float32, xMAX_FRAME_SIZE_MS*dec.sample_rate/1000)
+	n := int(C.opus_decode_float(
+		dec.p,
+		(*C.uchar)(&data[0]),
+		C.opus_int32(len(data)),
+		(*C.float)(&pcm[0]),
+		C.int(cap(pcm)),
+		0))
+	if n < 0 {
+		return nil, opuserr(errno)
+	}
+	return pcm[:n], nil
+}
+
+// Returns an error if the encoder was already closed
+func (dec *Decoder) Close() error {
+	if dec.p == nil {
+		return fmt.Errorf("opus: decoder already closed")
+	}
+	C.opus_decoder_destroy(dec.p)
+	dec.p = nil
+	return nil
 }
diff --git a/opus_test.go b/opus_test.go
index 97a775b..5109668 100644
--- a/opus_test.go
+++ b/opus_test.go
@@ -21,3 +21,23 @@ func Test_NewEncoder(t *testing.T) {
 		t.Errorf("Expected error for illegal samplerate 12345")
 	}
 }
+
+func Test_NewDecoder(t *testing.T) {
+	dec, err := NewDecoder(48000, 1)
+	if err != nil || dec == nil {
+		t.Errorf("Error creating new decoder: %v", err)
+	}
+	dec, err = NewDecoder(12345, 1)
+	if err == nil || dec != nil {
+		t.Errorf("Expected error for illegal samplerate 12345")
+	}
+}
+
+func Test_loop(t *testing.T) {
+	// Create bogus input sound
+	const SAMPLE_RATE = 48000
+	const FRAME_SIZE_MS = 10
+	const FRAME_SIZE = SAMPLE_RATE * FRAME_SIZE_MS / 1000
+	pcm := make([]float32, FRAME_SIZE)
+	//you know what I'll finish this later
+}
-- 
2.48.1