install go2rtc on bob

installs_on_host/go2rtc/pkg/wav/backchannel.go

@@ -0,0 +1,67 @@
+package wav
+
+import (
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/shell"
+	"github.com/pion/rtp"
+)
+
+type Backchannel struct {
+	core.Connection
+	cmd *shell.Command
+}
+
+func NewBackchannel(cmd *shell.Command) (core.Producer, error) {
+	medias := []*core.Media{
+		{
+			Kind:      core.KindAudio,
+			Direction: core.DirectionSendonly,
+			Codecs: []*core.Codec{
+				//{Name: core.CodecPCML},
+				{Name: core.CodecPCMA},
+				{Name: core.CodecPCMU},
+			},
+		},
+	}
+
+	return &Backchannel{
+		Connection: core.Connection{
+			ID:         core.NewID(),
+			FormatName: "wav",
+			Protocol:   "pipe",
+			Medias:     medias,
+			Transport:  cmd,
+		},
+		cmd: cmd,
+	}, nil
+}
+
+func (c *Backchannel) GetTrack(media *core.Media, codec *core.Codec) (*core.Receiver, error) {
+	return nil, core.ErrCantGetTrack
+}
+
+func (c *Backchannel) AddTrack(media *core.Media, codec *core.Codec, track *core.Receiver) error {
+	wr, err := c.cmd.StdinPipe()
+	if err != nil {
+		return err
+	}
+
+	b := Header(track.Codec)
+	if _, err = wr.Write(b); err != nil {
+		return err
+	}
+
+	sender := core.NewSender(media, track.Codec)
+	sender.Handler = func(packet *rtp.Packet) {
+		if n, err := wr.Write(packet.Payload); err != nil {
+			c.Send += n
+		}
+	}
+	sender.HandleRTP(track)
+	c.Senders = append(c.Senders, sender)
+	return nil
+}
+
+func (c *Backchannel) Start() error {
+	return c.cmd.Run()
+}

installs_on_host/go2rtc/pkg/wav/producer.go

@@ -0,0 +1,83 @@
+package wav
+
+import (
+	"bufio"
+	"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)
+
+	codec, err := ReadHeader(r)
+	if err != nil {
+		return nil, err
+	}
+
+	if codec.Name == "" {
+		return nil, errors.New("waw: unsupported codec")
+	}
+
+	medias := []*core.Media{
+		{
+			Kind:      core.KindAudio,
+			Direction: core.DirectionRecvonly,
+			Codecs:    []*core.Codec{codec},
+		},
+	}
+	return &Producer{
+		Connection: core.Connection{
+			ID:         core.NewID(),
+			FormatName: "wav",
+			Medias:     medias,
+			Transport:  r,
+		},
+		rd: rd,
+	}, nil
+}
+
+type Producer struct {
+	core.Connection
+	rd *bufio.Reader
+}
+
+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
+	}
+}

installs_on_host/go2rtc/pkg/wav/wav.go

@@ -0,0 +1,103 @@
+package wav
+
+import (
+	"encoding/binary"
+	"io"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+)
+
+func Header(codec *core.Codec) []byte {
+	var fmt, size, extra byte
+
+	switch codec.Name {
+	case core.CodecPCML:
+		fmt = 1
+		size = 2
+	case core.CodecPCMA:
+		fmt = 6
+		size = 1
+		extra = 2
+	case core.CodecPCMU:
+		fmt = 7
+		size = 1
+		extra = 2
+	default:
+		return nil
+	}
+
+	channels := byte(codec.Channels)
+	if channels == 0 {
+		channels = 1
+	}
+
+	b := make([]byte, 0, 46) // cap with extra
+	b = append(b, "RIFF\xFF\xFF\xFF\xFFWAVEfmt "...)
+
+	b = append(b, 0x10+extra, 0, 0, 0)
+	b = append(b, fmt, 0)
+	b = append(b, channels, 0)
+	b = binary.LittleEndian.AppendUint32(b, codec.ClockRate)
+	b = binary.LittleEndian.AppendUint32(b, uint32(size*channels)*codec.ClockRate)
+	b = append(b, size*channels, 0)
+	b = append(b, size*8, 0)
+	if extra > 0 {
+		b = append(b, 0, 0) // ExtraParamSize (if PCM, then doesn't exist)
+	}
+
+	b = append(b, "data\xFF\xFF\xFF\xFF"...)
+
+	return b
+}
+
+func ReadHeader(r io.Reader) (*core.Codec, error) {
+	// skip Master RIFF chunk
+	if _, err := io.ReadFull(r, make([]byte, 12)); err != nil {
+		return nil, err
+	}
+
+	var codec core.Codec
+
+	for {
+		chunkID, data, err := readChunk(r)
+		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 = data[2]
+			codec.ClockRate = binary.LittleEndian.Uint32(data[4:])
+		}
+	}
+
+	return &codec, nil
+}
+
+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
+}