From 38e75cb5cf29f8e66c36f5e228a12c7821137a85 Mon Sep 17 00:00:00 2001
From: Sean DuBois <duboisea@justin.tv>
Date: Tue, 20 Sep 2022 22:29:27 -0400
Subject: [PATCH] Upgrade oggreader to be segment aware

---
 examples/decode/main.go    | 41 ++++++++++++++++++++-------------
 pkg/oggreader/oggreader.go | 46 +++++++++++++++++++++-----------------
 2 files changed, 51 insertions(+), 36 deletions(-)

diff --git a/examples/decode/main.go b/examples/decode/main.go
index 658f0dd..4595609 100644
--- a/examples/decode/main.go
+++ b/examples/decode/main.go
@@ -2,8 +2,8 @@ package main
 
 import (
 	"bytes"
+	"encoding/binary"
 	"errors"
-	"fmt"
 	"io"
 	"os"
 
@@ -11,15 +11,18 @@ import (
 	"github.com/pion/opus/pkg/oggreader"
 )
 
-func main() {
-	decoder := opus.NewDecoder()
+func convertFloatToByteSlice(i []float32) []byte {
+	buf := new(bytes.Buffer)
+	binary.Write(buf, binary.LittleEndian, i)
+	return buf.Bytes()
+}
 
-	homeDir, err := os.UserHomeDir()
-	if err != nil {
-		panic(err)
+func main() {
+	if len(os.Args) != 3 {
+		panic("Usage: <in-file> <out-file>")
 	}
 
-	file, err := os.Open(homeDir + "/opus/silk.ogg")
+	file, err := os.Open(os.Args[1])
 	if err != nil {
 		panic(err)
 	}
@@ -29,12 +32,19 @@ func main() {
 		panic(err)
 	}
 
-	out := make([]float64, 320)
+	out := make([]float32, 320)
+	f, err := os.Create(os.Args[2])
+	if err != nil {
+		panic(err)
+	}
+
+	decoder := opus.NewDecoder()
 	for {
-		pageData, _, err := ogg.ParseNextPage()
+		segments, _, err := ogg.ParseNextPage()
+
 		if errors.Is(err, io.EOF) {
 			break
-		} else if bytes.HasPrefix(pageData, []byte("OpusTags")) {
+		} else if bytes.HasPrefix(segments[0], []byte("OpusTags")) {
 			continue
 		}
 
@@ -42,11 +52,12 @@ func main() {
 			panic(err)
 		}
 
-		bandwidth, isStereo, err := decoder.Decode(pageData, out)
-		if err != nil {
-			panic(err)
-		}
+		for i := range segments {
+			if _, _, err = decoder.Decode(segments[i], out); err != nil {
+				panic(err)
+			}
 
-		fmt.Printf("bandwidth(%s) isStereo(%t) framesCount(%d)\n", bandwidth.String(), isStereo, len(out))
+			f.Write(floatarrtobytes(out))
+		}
 	}
 }
diff --git a/pkg/oggreader/oggreader.go b/pkg/oggreader/oggreader.go
index cd14a01..67fce7c 100644
--- a/pkg/oggreader/oggreader.go
+++ b/pkg/oggreader/oggreader.go
@@ -89,7 +89,7 @@ func newWith(in io.Reader, doChecksum bool) (*OggReader, *OggHeader, error) {
 }
 
 func (o *OggReader) readHeaders() (*OggHeader, error) {
-	payload, pageHeader, err := o.ParseNextPage()
+	segments, pageHeader, err := o.ParseNextPage()
 	if err != nil {
 		return nil, err
 	}
@@ -103,27 +103,27 @@ func (o *OggReader) readHeaders() (*OggHeader, error) {
 		return nil, errBadIDPageType
 	}
 
-	if len(payload) != idPagePayloadLength {
+	if len(segments[0]) != idPagePayloadLength {
 		return nil, errBadIDPageLength
 	}
 
-	if s := string(payload[:8]); s != idPageSignature {
+	if s := string(segments[0][:8]); s != idPageSignature {
 		return nil, errBadIDPagePayloadSignature
 	}
 
-	header.Version = payload[8]
-	header.Channels = payload[9]
-	header.PreSkip = binary.LittleEndian.Uint16(payload[10:12])
-	header.SampleRate = binary.LittleEndian.Uint32(payload[12:16])
-	header.OutputGain = binary.LittleEndian.Uint16(payload[16:18])
-	header.ChannelMap = payload[18]
+	header.Version = segments[0][8]
+	header.Channels = segments[0][9]
+	header.PreSkip = binary.LittleEndian.Uint16(segments[0][10:12])
+	header.SampleRate = binary.LittleEndian.Uint32(segments[0][12:16])
+	header.OutputGain = binary.LittleEndian.Uint16(segments[0][16:18])
+	header.ChannelMap = segments[0][18]
 
 	return header, nil
 }
 
-// ParseNextPage reads from stream and returns Ogg page payload, header,
+// ParseNextPage reads from stream and returns Ogg page segments, header,
 // and an error if there is incomplete page data.
-func (o *OggReader) ParseNextPage() ([]byte, *OggPageHeader, error) {
+func (o *OggReader) ParseNextPage() ([][]byte, *OggPageHeader, error) {
 	h := make([]byte, pageHeaderLen)
 
 	n, err := io.ReadFull(o.stream, h)
@@ -149,14 +149,15 @@ func (o *OggReader) ParseNextPage() ([]byte, *OggPageHeader, error) {
 		return nil, nil, err
 	}
 
-	payloadSize := 0
-	for _, s := range sizeBuffer {
-		payloadSize += int(s)
-	}
+	segments := [][]byte{}
 
-	payload := make([]byte, payloadSize)
-	if _, err = io.ReadFull(o.stream, payload); err != nil {
-		return nil, nil, err
+	for _, s := range sizeBuffer {
+		segment := make([]byte, int(s))
+		if _, err = io.ReadFull(o.stream, segment); err != nil {
+			return nil, nil, err
+		}
+
+		segments = append(segments, segment)
 	}
 
 	if o.doChecksum {
@@ -177,8 +178,11 @@ func (o *OggReader) ParseNextPage() ([]byte, *OggPageHeader, error) {
 		for _, s := range sizeBuffer {
 			updateChecksum(s)
 		}
-		for index := range payload {
-			updateChecksum(payload[index])
+
+		for i := range segments {
+			for index := range segments[i] {
+				updateChecksum(segments[i][index])
+			}
 		}
 
 		if binary.LittleEndian.Uint32(h[22:22+4]) != checksum {
@@ -186,7 +190,7 @@ func (o *OggReader) ParseNextPage() ([]byte, *OggPageHeader, error) {
 		}
 	}
 
-	return payload, pageHeader, nil
+	return segments, pageHeader, nil
 }
 
 // ResetReader resets the internal stream of OggReader. This is useful