From 54c8ca0112dc8ecdef587f2e62ec23ccfbf958f7 Mon Sep 17 00:00:00 2001
From: Alex X <alexey.khit@gmail.com>
Date: Tue, 21 May 2024 17:48:22 +0300
Subject: [PATCH] Add wav format to magic producer

---
 pkg/magic/producer.go |   4 ++
 pkg/wav/wav.go        | 127 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 131 insertions(+)
 create mode 100644 pkg/wav/wav.go

diff --git a/pkg/magic/producer.go b/pkg/magic/producer.go
index 5728da33e..c49fe8bfe 100644
--- a/pkg/magic/producer.go
+++ b/pkg/magic/producer.go
@@ -14,6 +14,7 @@ import (
 	"github.com/AlexxIT/go2rtc/pkg/magic/mjpeg"
 	"github.com/AlexxIT/go2rtc/pkg/mpegts"
 	"github.com/AlexxIT/go2rtc/pkg/multipart"
+	"github.com/AlexxIT/go2rtc/pkg/wav"
 )
 
 func Open(r io.Reader) (core.Producer, error) {
@@ -28,6 +29,9 @@ func Open(r io.Reader) (core.Producer, error) {
 	case string(b) == annexb.StartCode:
 		return bitstream.Open(rd)
 
+	case string(b) == wav.FourCC:
+		return wav.Open(rd)
+
 	case bytes.HasPrefix(b, []byte{0xFF, 0xD8}):
 		return mjpeg.Open(rd)
 
diff --git a/pkg/wav/wav.go b/pkg/wav/wav.go
new file mode 100644
index 000000000..5f572bd64
--- /dev/null
+++ b/pkg/wav/wav.go
@@ -0,0 +1,127 @@
+package wav
+
+import (
+	"bufio"
+	"encoding/binary"
+	"errors"
+	"io"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/pion/rtp"
+)
+
+const FourCC = "RIFF"
+
+func Open(r io.Reader) (*Producer, error) {
+	// https://en.wikipedia.org/wiki/WAV
+	// https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html
+	rd := bufio.NewReaderSize(r, core.BufferSize)
+
+	// skip Master RIFF chunk
+	if _, err := rd.Discard(12); err != nil {
+		return nil, err
+	}
+
+	codec := &core.Codec{}
+
+	for {
+		chunkID, data, err := readChunk(rd)
+		if err != nil {
+			return nil, err
+		}
+
+		if chunkID == "data" {
+			break
+		}
+
+		if chunkID == "fmt " {
+			// https://audiocoding.cc/articles/2008-05-22-wav-file-structure/wav_formats.txt
+			switch data[0] {
+			case 1:
+				codec.Name = core.CodecPCML
+			case 6:
+				codec.Name = core.CodecPCMA
+			case 7:
+				codec.Name = core.CodecPCMU
+			}
+
+			codec.Channels = uint16(data[2])
+			codec.ClockRate = binary.LittleEndian.Uint32(data[4:])
+		}
+	}
+
+	if codec.Name == "" {
+		return nil, errors.New("waw: unsupported codec")
+	}
+
+	prod := &Producer{rd: rd, cl: r.(io.Closer)}
+	prod.Type = "WAV producer"
+	prod.Medias = []*core.Media{
+		{
+			Kind:      core.KindAudio,
+			Direction: core.DirectionRecvonly,
+			Codecs:    []*core.Codec{codec},
+		},
+	}
+	return prod, nil
+}
+
+type Producer struct {
+	core.SuperProducer
+	rd *bufio.Reader
+	cl io.Closer
+}
+
+func (c *Producer) Start() error {
+	var seq uint16
+	var ts uint32
+
+	const PacketSize = 0.040 * 8000 // 40ms
+
+	for {
+		payload := make([]byte, PacketSize)
+		if _, err := io.ReadFull(c.rd, payload); err != nil {
+			return err
+		}
+
+		c.Recv += PacketSize
+
+		if len(c.Receivers) == 0 {
+			continue
+		}
+
+		pkt := &rtp.Packet{
+			Header: rtp.Header{
+				Version:        2,
+				Marker:         true,
+				SequenceNumber: seq,
+				Timestamp:      ts,
+			},
+			Payload: payload,
+		}
+		c.Receivers[0].WriteRTP(pkt)
+
+		seq++
+		ts += PacketSize
+	}
+}
+
+func (c *Producer) Stop() error {
+	_ = c.SuperProducer.Close()
+	return c.cl.Close()
+}
+
+func readChunk(r io.Reader) (chunkID string, data []byte, err error) {
+	b := make([]byte, 8)
+	if _, err = io.ReadFull(r, b); err != nil {
+		return
+	}
+
+	if chunkID = string(b[:4]); chunkID != "data" {
+		size := binary.LittleEndian.Uint32(b[4:])
+		data = make([]byte, size)
+		_, err = io.ReadFull(r, data)
+	}
+
+	return
+}