Rewrite support MPEG-TS client

pkg/aac/aac.go

@@ -17,7 +17,10 @@ const (
 // streamtype=5 - audio stream
 const fmtp = "streamtype=5;profile-level-id=1;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3;config="
 
-var sampleRates = []uint32{96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 7350}
+var sampleRates = []uint32{
+	96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 7350,
+	0, 0, 0, // protection from request sampleRates[15]
+}
 
 func ConfigToCodec(conf []byte) *core.Codec {
 	// https://en.wikipedia.org/wiki/MPEG-4_Part_3#MPEG-4_Audio_Object_Types
@@ -40,9 +43,9 @@ func ConfigToCodec(conf []byte) *core.Codec {
 		codec.Name = fmt.Sprintf("AAC-%X", objType)
 	}
 
-	if sampleRateIdx := rd.ReadBits8(4); sampleRateIdx < 12 {
+	if sampleRateIdx := rd.ReadBits8(4); sampleRateIdx < 0x0F {
 		codec.ClockRate = sampleRates[sampleRateIdx]
-	} else if sampleRateIdx == 0x0F {
+	} else {
 		codec.ClockRate = rd.ReadBits(24)
 	}
 

pkg/aac/adts.go

@@ -0,0 +1,61 @@
+package aac
+
+import (
+	"encoding/hex"
+
+	"github.com/AlexxIT/go2rtc/pkg/bits"
+	"github.com/AlexxIT/go2rtc/pkg/core"
+)
+
+func IsADTS(b []byte) bool {
+	_ = b[1]
+	return len(b) > 7 && b[0] == 0xFF && b[1]&0xF0 == 0xF0
+}
+
+func ADTSToCodec(b []byte) *core.Codec {
+	// 1. Check ADTS header
+	if !IsADTS(b) {
+		return nil
+	}
+
+	// 2. Decode ADTS params
+	// https://wiki.multimedia.cx/index.php/ADTS
+	rd := bits.NewReader(b)
+	_ = rd.ReadBits(12)              // Syncword, all bits must be set to 1
+	_ = rd.ReadBit()                 // MPEG Version, set to 0 for MPEG-4 and 1 for MPEG-2
+	_ = rd.ReadBits(2)               // Layer, always set to 0
+	_ = rd.ReadBit()                 // Protection absence, set to 1 if there is no CRC and 0 if there is CRC
+	objType := rd.ReadBits8(2) + 1   // Profile, the MPEG-4 Audio Object Type minus 1
+	sampleRateIdx := rd.ReadBits8(4) // MPEG-4 Sampling Frequency Index
+	_ = rd.ReadBit()                 // Private bit, guaranteed never to be used by MPEG, set to 0 when encoding, ignore when decoding
+	channels := rd.ReadBits16(3)     // MPEG-4 Channel Configuration
+
+	//_ = rd.ReadBit()    // Originality, set to 1 to signal originality of the audio and 0 otherwise
+	//_ = rd.ReadBit()    // Home, set to 1 to signal home usage of the audio and 0 otherwise
+	//_ = rd.ReadBit()    // Copyright ID bit
+	//_ = rd.ReadBit()    // Copyright ID start
+	//_ = rd.ReadBits(13) // Frame length
+	//_ = rd.ReadBits(11) // Buffer fullness
+	//_ = rd.ReadBits(2)  // Number of AAC frames (Raw Data Blocks) in ADTS frame minus 1
+	//_ = rd.ReadBits(16) // CRC check
+
+	// 3. Encode RTP config
+	wr := bits.NewWriter()
+	wr.WriteBits8(objType, 5)
+	wr.WriteBits8(sampleRateIdx, 4)
+	wr.WriteBits16(channels, 4)
+	conf := wr.Bytes()
+
+	codec := &core.Codec{
+		Name:      core.CodecAAC,
+		ClockRate: sampleRates[sampleRateIdx],
+		Channels:  channels,
+		FmtpLine:  fmtp + hex.EncodeToString(conf),
+	}
+	return codec
+}
+
+func ReadADTSSize(b []byte) uint16 {
+	// AAAAAAAA AAAABCCD EEFFFFGH HHIJKLMM MMMMMMMM MMMOOOOO OOOOOOPP (QQQQQQQQ QQQQQQQQ)
+	return uint16(b[3]&0x03)<<(8+3) | uint16(b[4])<<3 | uint16(b[5]>>5)
+}

pkg/aac/rtp.go

@@ -2,11 +2,13 @@ package aac
 
 import (
 	"encoding/binary"
+
 	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/pion/rtp"
 )
 
 const RTPPacketVersionAAC = 0
+const ADTSHeaderSize = 7
 
 func RTPDepay(handler core.HandlerFunc) core.HandlerFunc {
 	var timestamp uint32
@@ -14,6 +16,7 @@ func RTPDepay(handler core.HandlerFunc) core.HandlerFunc {
 	return func(packet *rtp.Packet) {
 		// support ONLY 2 bytes header size!
 		// streamtype=5;profile-level-id=1;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3;config=1408
+		// https://datatracker.ietf.org/doc/html/rfc3640
 		headersSize := binary.BigEndian.Uint16(packet.Payload) >> 3
 
 		//log.Printf("[RTP/AAC] units: %d, size: %4d, ts: %10d, %t", headersSize/2, len(packet.Payload), packet.Timestamp, packet.Marker)
@@ -35,7 +38,7 @@ func RTPDepay(handler core.HandlerFunc) core.HandlerFunc {
 			clone.Version = RTPPacketVersionAAC
 			clone.Timestamp = timestamp
 			if IsADTS(unit) {
-				clone.Payload = unit[7:]
+				clone.Payload = unit[ADTSHeaderSize:]
 			} else {
 				clone.Payload = unit
 			}
@@ -54,11 +57,11 @@ func RTPPay(handler core.HandlerFunc) core.HandlerFunc {
 		}
 
 		// support ONLY one unit in payload
-		size := uint16(len(packet.Payload))
+		auSize := uint16(len(packet.Payload))
 		// 2 bytes header size + 2 bytes first payload size
-		payload := make([]byte, 2+2+size)
+		payload := make([]byte, 2+2+auSize)
 		payload[1] = 16 // header size in bits
-		binary.BigEndian.PutUint16(payload[2:], size<<3)
+		binary.BigEndian.PutUint16(payload[2:], auSize<<3)
 		copy(payload[4:], packet.Payload)
 
 		clone := rtp.Packet{
@@ -74,6 +77,19 @@ func RTPPay(handler core.HandlerFunc) core.HandlerFunc {
 	}
 }
 
-func IsADTS(b []byte) bool {
-	return len(b) > 7 && b[0] == 0xFF && b[1]&0xF0 == 0xF0
+func ADTStoRTP(b []byte) []byte {
+	header := make([]byte, 2)
+	for i := 0; i < len(b); {
+		auSize := ReadADTSSize(b[i:])
+		header = append(header, byte(auSize>>5), byte(auSize<<3)) // size in bits
+		i += int(auSize)
+	}
+	hdrSize := uint16(len(header) - 2)
+	binary.BigEndian.PutUint16(header, hdrSize<<3) // size in bits
+	return append(header, b...)
+}
+
+func RTPToCodec(b []byte) *core.Codec {
+	hdrSize := binary.BigEndian.Uint16(b) / 8
+	return ADTSToCodec(b[2+hdrSize:])
 }