Add UnmarshalHeader func to OPUS codec

pkg/opus/.opus.go

@@ -1,68 +0,0 @@
-package opus
-
-import (
-	"time"
-
-	"github.com/AlexxIT/go2rtc/pkg/core"
-	"github.com/pion/rtp"
-)
-
-func Log(handler core.HandlerFunc) core.HandlerFunc {
-	var ts uint32
-
-	return func(pkt *rtp.Packet) {
-		if ts == 0 {
-			ts = pkt.Timestamp
-		}
-
-		toc := pkt.Payload[0]
-		//config := toc >> 3
-		code := toc & 0b11
-
-		frame := parseFrameSize(toc)
-		rate := parseSampleRate(toc)
-
-		log.Printf(
-			"[RTP/OPUS] frame=%s rate=%5d code=%d size=%6d ts=%10d dt=%5d pt=%2d ssrc=%d seq=%d mark=%t",
-			frame, rate, code, len(pkt.Payload), pkt.Timestamp, pkt.Timestamp-ts, pkt.PayloadType, pkt.SSRC, pkt.SequenceNumber, pkt.Marker,
-		)
-
-		ts = pkt.Timestamp
-
-		handler(pkt)
-	}
-}
-
-func parseFrameSize(toc byte) time.Duration {
-	switch toc >> 3 {
-	case 0, 4, 8, 12, 14, 18, 22, 26, 30:
-		return 10_000_000
-	case 1, 5, 9, 13, 15, 19, 23, 27, 31:
-		return 20_000_000
-	case 2, 6, 10:
-		return 40_000_000
-	case 3, 7, 11:
-		return 60_000_000
-	case 16, 20, 24, 28:
-		return 2_500_000
-	case 17, 21, 25, 29:
-		return 5_000_000
-	}
-	return 0
-}
-
-func parseSampleRate(toc byte) uint16 {
-	switch toc >> 3 {
-	case 0, 1, 2, 3, 16, 17, 18, 19:
-		return 8000
-	case 4, 5, 6, 7:
-		return 12000
-	case 8, 9, 10, 11, 20, 21, 22, 23:
-		return 16000
-	case 12, 13, 24, 25, 26, 27:
-		return 24000
-	case 14, 15, 28, 29, 30, 31:
-		return 48000
-	}
-	return 0
-}

pkg/opus/opus.go

@@ -0,0 +1,87 @@
+package opus
+
+import (
+	"time"
+)
+
+type Header struct {
+	Mode       string
+	SampleRate uint16
+	FrameSize  time.Duration
+	Channels   byte
+	Frames     byte
+}
+
+func UnmarshalHeader(b []byte) *Header {
+	// https://datatracker.ietf.org/doc/html/rfc6716#section-3.1
+	b0 := b[0]
+	config := b0 >> 3
+	return &Header{
+		Mode:       parseMode(config),
+		SampleRate: parseSampleRate(config),
+		FrameSize:  parseFrameSize(config),
+		Channels:   parseChannels(b0 >> 2 & 0b1),
+		Frames:     parseFrames(b0 & 0b11),
+	}
+}
+
+func parseMode(config byte) string {
+	if config <= 11 {
+		return "silk"
+	}
+	if config <= 15 {
+		return "hybrid"
+	}
+	return "celt"
+}
+
+func parseSampleRate(config byte) uint16 {
+	switch config {
+	case 0, 1, 2, 3, 16, 17, 18, 19:
+		return 8000 // NB (narrowband)
+	case 4, 5, 6, 7:
+		return 12000 // MB (medium-band)
+	case 8, 9, 10, 11, 20, 21, 22, 23:
+		return 16000 // WB (wideband)
+	case 12, 13, 24, 25, 26, 27:
+		return 24000 // SWB (super-wideband)
+	case 14, 15, 28, 29, 30, 31:
+		return 48000 // FB (fullband)
+	}
+	return 0
+}
+
+func parseFrameSize(config byte) time.Duration {
+	switch config {
+	case 0, 4, 8, 12, 14, 18, 22, 26, 30:
+		return 10_000_000
+	case 1, 5, 9, 13, 15, 19, 23, 27, 31:
+		return 20_000_000
+	case 2, 6, 10:
+		return 40_000_000
+	case 3, 7, 11:
+		return 60_000_000
+	case 16, 20, 24, 28:
+		return 2_500_000
+	case 17, 21, 25, 29:
+		return 5_000_000
+	}
+	return 0
+}
+
+func parseChannels(s byte) byte {
+	if s == 1 {
+		return 2
+	}
+	return 1
+}
+
+func parseFrames(c byte) byte {
+	switch c {
+	case 0:
+		return 1
+	case 1, 2:
+		return 2
+	}
+	return 0xFF
+}