Total rework FLV client

pkg/aac/aac.go

@@ -0,0 +1,52 @@
+package aac
+
+import (
+	"encoding/hex"
+	"fmt"
+
+	"github.com/AlexxIT/go2rtc/pkg/bits"
+	"github.com/AlexxIT/go2rtc/pkg/core"
+)
+
+const (
+	TypeAACMain = 1
+	TypeAACLC   = 2
+	TypeESCAPE  = 31
+)
+
+// 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}
+
+func ConfigToCodec(conf []byte) *core.Codec {
+	// https://en.wikipedia.org/wiki/MPEG-4_Part_3#MPEG-4_Audio_Object_Types
+	rd := bits.NewReader(conf)
+
+	codec := &core.Codec{
+		FmtpLine:    fmtp + hex.EncodeToString(conf),
+		PayloadType: core.PayloadTypeRAW,
+	}
+
+	objType := rd.ReadBits(5)
+	if objType == TypeESCAPE {
+		objType = 32 + rd.ReadBits(6)
+	}
+
+	switch objType {
+	case TypeAACLC:
+		codec.Name = core.CodecAAC
+	default:
+		codec.Name = fmt.Sprintf("AAC-%X", objType)
+	}
+
+	if sampleRateIdx := rd.ReadBits8(4); sampleRateIdx < 12 {
+		codec.ClockRate = sampleRates[sampleRateIdx]
+	} else if sampleRateIdx == 0x0F {
+		codec.ClockRate = rd.ReadBits(24)
+	}
+
+	codec.Channels = rd.ReadBits16(4)
+
+	return codec
+}