add MP4A-LATM format (#237)

pkg/formats/mpeg4_audio_latm.go

@@ -0,0 +1,164 @@
+package formats
+
+import (
+	"encoding/hex"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/pion/rtp"
+)
+
+// MPEG4AudioLATM is a RTP format that uses a MPEG-4 audio codec.
+// Specification: https://datatracker.ietf.org/doc/html/rfc6416#section-7.3
+type MPEG4AudioLATM struct {
+	PayloadTyp     uint8
+	SampleRate     int
+	Channels       int
+	ProfileLevelID int
+	Bitrate        *int
+	Object         int
+	CPresent       *bool
+	Config         []byte
+	SBREnabled     *bool
+}
+
+// String implements Format.
+func (f *MPEG4AudioLATM) String() string {
+	return "MPEG4-audio-latm"
+}
+
+// ClockRate implements Format.
+func (f *MPEG4AudioLATM) ClockRate() int {
+	return f.SampleRate
+}
+
+// PayloadType implements Format.
+func (f *MPEG4AudioLATM) PayloadType() uint8 {
+	return f.PayloadTyp
+}
+
+func (f *MPEG4AudioLATM) unmarshal(
+	payloadType uint8, clock string, codec string,
+	rtpmap string, fmtp map[string]string,
+) error {
+	tmp := strings.SplitN(clock, "/", 2)
+	if len(tmp) != 2 {
+		return fmt.Errorf("invalid clock: %v", clock)
+	}
+
+	tmp2, err := strconv.ParseInt(tmp[0], 10, 64)
+	if err != nil {
+		return err
+	}
+	f.SampleRate = int(tmp2)
+
+	tmp2, err = strconv.ParseInt(tmp[1], 10, 64)
+	if err != nil {
+		return err
+	}
+	f.Channels = int(tmp2)
+
+	f.PayloadTyp = payloadType
+	f.ProfileLevelID = 30 // default value defined by specification
+
+	for key, val := range fmtp {
+		switch key {
+		case "profile-level-id":
+			tmp, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				return fmt.Errorf("invalid profile-level-id: %v", val)
+			}
+
+			f.ProfileLevelID = int(tmp)
+
+		case "bitrate":
+			tmp, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				return fmt.Errorf("invalid bitrate: %v", val)
+			}
+
+			v := int(tmp)
+			f.Bitrate = &v
+
+		case "object":
+			tmp, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				return fmt.Errorf("invalid object: %v", val)
+			}
+
+			f.Object = int(tmp)
+
+		case "cpresent":
+			tmp, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				return fmt.Errorf("invalid cpresent: %v", val)
+			}
+
+			v := (tmp == 1)
+			f.CPresent = &v
+
+		case "config":
+			var err error
+			f.Config, err = hex.DecodeString(val)
+			if err != nil {
+				return fmt.Errorf("invalid AAC config: %v", val)
+			}
+
+		case "sbr-enabled":
+			tmp, err := strconv.ParseInt(val, 10, 64)
+			if err != nil {
+				return fmt.Errorf("invalid SBR-enabled: %v", val)
+			}
+
+			v := (tmp == 1)
+			f.SBREnabled = &v
+		}
+	}
+
+	if f.Object == 0 {
+		return fmt.Errorf("object is missing")
+	}
+	if f.Config == nil {
+		return fmt.Errorf("config is missing")
+	}
+
+	return nil
+}
+
+// Marshal implements Format.
+func (f *MPEG4AudioLATM) Marshal() (string, map[string]string) {
+	fmtp := map[string]string{
+		"profile-level-id": strconv.FormatInt(int64(f.ProfileLevelID), 10),
+		"config":           hex.EncodeToString(f.Config),
+		"object":           strconv.FormatInt(int64(f.Object), 10),
+	}
+
+	if f.Bitrate != nil {
+		fmtp["bitrate"] = strconv.FormatInt(int64(*f.Bitrate), 10)
+	}
+
+	if f.CPresent != nil {
+		if *f.CPresent {
+			fmtp["cpresent"] = "1"
+		} else {
+			fmtp["cpresent"] = "0"
+		}
+	}
+
+	if f.SBREnabled != nil {
+		if *f.CPresent {
+			fmtp["SBR-enabled"] = "1"
+		} else {
+			fmtp["SBR-enabled"] = "0"
+		}
+	}
+
+	return "MP4A-LATM/" + strconv.FormatInt(int64(f.SampleRate), 10) +
+		"/" + strconv.FormatInt(int64(f.Channels), 10), fmtp
+}
+
+// PTSEqualsDTS implements Format.
+func (f *MPEG4AudioLATM) PTSEqualsDTS(*rtp.Packet) bool {
+	return true
+}