commit 98bae7beffa702ed22bdce49c53e3fe8f738e446
parent 15c30d27f9f07b66b4ccbf48bdb7186c34adec0b
Author: Oliver Lowe <o@olowe.co>
Date: Sat, 22 Jun 2024 14:57:48 +1000
rtp: add dynamic payload type generator
We need this to be able to generate text RTP packets. But it's also
useful for everyone else working with common payloads like H.264
video.
Diffstat:
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/rtp/rtp.go b/rtp/rtp.go
@@ -6,13 +6,14 @@ import (
"encoding/binary"
"errors"
"fmt"
+ "math/rand"
)
// Packet represents a single RTP data packet.
type Packet struct {
// Header is the RTP fixed header present at the beginning of
// every packet.
- Header Header
+ Header Header
// Payload contains the raw bytes, excluding the header,
// transported in a packet.
Payload []byte
@@ -25,22 +26,22 @@ type Header struct {
Version uint8
// TODO(otl): do we store padding bytes? how many?
- padding bool
+ padding bool
// Marker indicates the marker bit is set. The payload type
// determines how this value is interpreted.
- Marker bool
+ Marker bool
// Type specifies the format of the payload transported in the Packet.
// In general, each type has its own IETF RFC specifying how the payload is encoded.
// For example, PayloadMP2T is detailed in RFC 2250.
- Type PayloadType
+ Type PayloadType
// Sequence is a monotonically incremented number used by
// receivers to manage packet loss. The first packet's Sequence
// should be randomly assigned, then incremented by one for each
// RTP packet transmitted.
- Sequence uint16
+ Sequence uint16
// Timestamp is the instant sampled of the first byte of the packet.
// The first packet in a session should have a randomly assigned
@@ -50,13 +51,13 @@ type Header struct {
// instance, the Timestamp field of RTP packets with MPEG payloads
// represents the number of ticks of a 90KHz clock. Timestamps of GSM
// audio RTP packets represent ticks of a 8KHz clock.
- Timestamp uint32
+ Timestamp uint32
// SyncSource identifies the synchronisation source of the RTP
// session. It should be randomly assigned at the start of a
// session and remain unchanged throughout to prevent
// collisions with other sessions.
- SyncSource uint32
+ SyncSource uint32
// ContribSource lists a maximum of 15 contribution sources
// used to generate the payload. For example, a RTP session for
@@ -67,7 +68,7 @@ type Header struct {
// payloads to transmit extra information. The RTP specification
// discourages the use of Extension. Instead it recommendeds to
// store extra information in leading bytes of the payload.
- Extension *Extension
+ Extension *Extension
}
const (
@@ -83,7 +84,20 @@ const (
// ...
)
+// DynamicPayloadType returns a randomly generated PayloadType from
+// the range of allowed values for payloads with non-static PayloadType
+// values. For example, transporting text and JPEG XS with RTP requires
+// the use of a dynamic payload type.
+func DynamicPayloadType() PayloadType {
+ floor := 96
+ ceil := 127
+ return PayloadType(floor + rand.Intn(ceil-floor))
+}
+
func (t PayloadType) String() string {
+ if t >= 96 && t <= 127 {
+ return "dynamic"
+ }
switch t {
case PayloadMP2T:
return "MP2T"
