BIG core logic rewrite

pkg/core/codec.go

@@ -0,0 +1,142 @@
+package core
+
+import (
+	"encoding/base64"
+	"fmt"
+	"github.com/pion/sdp/v3"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+type Codec struct {
+	Name        string // H264, PCMU, PCMA, opus...
+	ClockRate   uint32 // 90000, 8000, 16000...
+	Channels    uint16 // 0, 1, 2
+	FmtpLine    string
+	PayloadType uint8
+}
+
+func (c *Codec) String() string {
+	s := fmt.Sprintf("%d %s", c.PayloadType, c.Name)
+	if c.ClockRate != 0 && c.ClockRate != 90000 {
+		s = fmt.Sprintf("%s/%d", s, c.ClockRate)
+	}
+	if c.Channels > 0 {
+		s = fmt.Sprintf("%s/%d", s, c.Channels)
+	}
+	return s
+}
+
+func (c *Codec) Text() string {
+	switch c.Name {
+	case CodecH264:
+		if profile := DecodeH264(c.FmtpLine); profile != "" {
+			return "H.264 " + profile
+		}
+		return c.Name
+	}
+
+	s := c.Name
+	if c.ClockRate != 0 && c.ClockRate != 90000 {
+		s += "/" + strconv.Itoa(int(c.ClockRate))
+	}
+	if c.Channels > 0 {
+		s += "/" + strconv.Itoa(int(c.Channels))
+	}
+	return s
+}
+
+func (c *Codec) IsRTP() bool {
+	return c.PayloadType != PayloadTypeRAW
+}
+
+func (c *Codec) Clone() *Codec {
+	clone := *c
+	return &clone
+}
+
+func (c *Codec) Match(remote *Codec) bool {
+	switch remote.Name {
+	case CodecAll, CodecAny:
+		return true
+	}
+
+	return c.Name == remote.Name &&
+		(c.ClockRate == remote.ClockRate || remote.ClockRate == 0) &&
+		(c.Channels == remote.Channels || remote.Channels == 0)
+}
+
+func UnmarshalCodec(md *sdp.MediaDescription, payloadType string) *Codec {
+	c := &Codec{PayloadType: byte(atoi(payloadType))}
+
+	for _, attr := range md.Attributes {
+		switch {
+		case c.Name == "" && attr.Key == "rtpmap" && strings.HasPrefix(attr.Value, payloadType):
+			i := strings.IndexByte(attr.Value, ' ')
+			ss := strings.Split(attr.Value[i+1:], "/")
+
+			c.Name = strings.ToUpper(ss[0])
+			// fix tailing space: `a=rtpmap:96 H264/90000 `
+			c.ClockRate = uint32(atoi(strings.TrimRightFunc(ss[1], unicode.IsSpace)))
+
+			if len(ss) == 3 && ss[2] == "2" {
+				c.Channels = 2
+			}
+		case c.FmtpLine == "" && attr.Key == "fmtp" && strings.HasPrefix(attr.Value, payloadType):
+			if i := strings.IndexByte(attr.Value, ' '); i > 0 {
+				c.FmtpLine = attr.Value[i+1:]
+			}
+		}
+	}
+
+	if c.Name == "" {
+		// https://en.wikipedia.org/wiki/RTP_payload_formats
+		switch payloadType {
+		case "0":
+			c.Name = CodecPCMU
+			c.ClockRate = 8000
+		case "8":
+			c.Name = CodecPCMA
+			c.ClockRate = 8000
+		case "14":
+			c.Name = CodecMP3
+			c.ClockRate = 44100
+		case "26":
+			c.Name = CodecJPEG
+			c.ClockRate = 90000
+		default:
+			c.Name = payloadType
+		}
+	}
+
+	return c
+}
+
+func atoi(s string) (i int) {
+	i, _ = strconv.Atoi(s)
+	return
+}
+
+func DecodeH264(fmtp string) string {
+	if ps := Between(fmtp, "sprop-parameter-sets=", ","); ps != "" {
+		if sps, _ := base64.StdEncoding.DecodeString(ps); len(sps) >= 4 {
+			var profile string
+			switch sps[1] {
+			case 0x42:
+				profile = "Baseline"
+			case 0x4D:
+				profile = "Main"
+			case 0x58:
+				profile = "Extended"
+			case 0x64:
+				profile = "High"
+			default:
+				profile = fmt.Sprintf("0x%02X", sps[1])
+			}
+
+			return fmt.Sprintf("%s %d.%d", profile, sps[3]/10, sps[3]%10)
+		}
+	}
+	return ""
+}