Add WithPayloader to TrackLocalStatic

Allow custom payloader depending on the mime type

Fixes #2928

Author: LeeTeng2001

track_local_static.go

@@ -31,6 +31,7 @@ type TrackLocalStaticRTP struct {
 	mu                sync.RWMutex
 	bindings          []trackBinding
 	codec             RTPCodecCapability
+	payloader         func(RTPCodecCapability) (rtp.Payloader, error)
 	id, rid, streamID string
 }
 
@@ -57,6 +58,13 @@ func WithRTPStreamID(rid string) func(*TrackLocalStaticRTP) {
 	}
 }
 
+// WithPayloader allows the user to override the Payloader
+func WithPayloader(h func(RTPCodecCapability) (rtp.Payloader, error)) func(*TrackLocalStaticRTP) {
+	return func(s *TrackLocalStaticRTP) {
+		s.payloader = h
+	}
+}
+
 // Bind is called by the PeerConnection after negotiation is complete
 // This asserts that the code requested is supported by the remote peer.
 // If so it sets up all the state (SSRC and PayloadType) to have a call
@@ -250,7 +258,12 @@ func (s *TrackLocalStaticSample) Bind(t TrackLocalContext) (RTPCodecParameters,
 		return codec, nil
 	}
 
-	payloader, err := payloaderForCodec(codec.RTPCodecCapability)
+	payloadHandler := s.rtpTrack.payloader
+	if payloadHandler == nil {
+		payloadHandler = payloaderForCodec
+	}
+
+	payloader, err := payloadHandler(codec.RTPCodecCapability)
 	if err != nil {
 		return codec, err
 	}

track_local_static_test.go

@@ -9,12 +9,14 @@ package webrtc
 import (
 	"context"
 	"errors"
+	"sync/atomic"
 	"testing"
 	"time"
 
 	"github.com/pion/rtp"
 	"github.com/pion/transport/v3/test"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // If a remote doesn't support a Codec used by a `TrackLocalStatic`
@@ -336,3 +338,49 @@ func Test_TrackLocalStatic_RTX(t *testing.T) {
 
 	closePairNow(t, offerer, answerer)
 }
+
+type customCodecPayloader struct {
+	invokeCount atomic.Int32
+}
+
+func (c *customCodecPayloader) Payload(_ uint16, payload []byte) [][]byte {
+	c.invokeCount.Add(1)
+	return [][]byte{payload}
+}
+
+func Test_TrackLocalStatic_Payloader(t *testing.T) {
+	const mimeTypeCustomCodec = "video/custom-codec"
+
+	mediaEngine := &MediaEngine{}
+	assert.NoError(t, mediaEngine.RegisterCodec(RTPCodecParameters{
+		RTPCodecCapability: RTPCodecCapability{MimeType: mimeTypeCustomCodec, ClockRate: 90000, Channels: 0, SDPFmtpLine: "", RTCPFeedback: nil},
+		PayloadType:        96,
+	}, RTPCodecTypeVideo))
+
+	offerer, err := NewAPI(WithMediaEngine(mediaEngine)).NewPeerConnection(Configuration{})
+	assert.NoError(t, err)
+
+	answerer, err := NewAPI(WithMediaEngine(mediaEngine)).NewPeerConnection(Configuration{})
+	assert.NoError(t, err)
+
+	customPayloader := &customCodecPayloader{}
+	track, err := NewTrackLocalStaticSample(RTPCodecCapability{MimeType: mimeTypeCustomCodec}, "video", "pion", WithPayloader(func(c RTPCodecCapability) (rtp.Payloader, error) {
+		require.Equal(t, c.MimeType, mimeTypeCustomCodec)
+		return customPayloader, nil
+	}))
+	assert.NoError(t, err)
+
+	_, err = offerer.AddTrack(track)
+	assert.NoError(t, err)
+
+	assert.NoError(t, signalPair(offerer, answerer))
+
+	onTrackFired, onTrackFiredFunc := context.WithCancel(context.Background())
+	answerer.OnTrack(func(*TrackRemote, *RTPReceiver) {
+		onTrackFiredFunc()
+	})
+
+	sendVideoUntilDone(onTrackFired.Done(), t, []*TrackLocalStaticSample{track})
+
+	closePairNow(t, offerer, answerer)
+}