snapshot of https://github.com/livekit/livekit.git @ 08c5433449c106943231037d0b892895f6e92d3b (2026-09-15)

pkg/sfu/rtpextension/playoutdelay/playoutdelay.go

@@ -0,0 +1,72 @@
+// Copyright 2024 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package playoutdelay
+
+import (
+	"encoding/binary"
+	"errors"
+)
+
+const (
+	PlayoutDelayURI        = "http://www.webrtc.org/experiments/rtp-hdrext/playout-delay"
+	MaxPlayoutDelayDefault = 10000            // 10s, equal to chrome's default max playout delay
+	PlayoutDelayMaxValue   = 10 * (1<<12 - 1) // max value for playout delay can be represented
+
+	playoutDelayExtensionSize = 3
+)
+
+var (
+	errPlayoutDelayOverflow = errors.New("playout delay overflow")
+	errTooSmall             = errors.New("buffer too small")
+)
+
+//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |  ID   | len=2 |       MIN delay       |       MAX delay       |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// The wired MIN/MAX delay is in 10ms unit
+
+type PlayOutDelay struct {
+	Min, Max uint16 // delay in ms
+}
+
+func PlayoutDelayFromValue(min, max uint16) PlayOutDelay {
+	if min > PlayoutDelayMaxValue {
+		min = PlayoutDelayMaxValue
+	}
+	if max > PlayoutDelayMaxValue {
+		max = PlayoutDelayMaxValue
+	}
+	return PlayOutDelay{Min: min, Max: max}
+}
+
+func (p PlayOutDelay) Marshal() ([]byte, error) {
+	min, max := p.Min/10, p.Max/10
+	if min >= 1<<12 || max >= 1<<12 {
+		return nil, errPlayoutDelayOverflow
+	}
+
+	return []byte{byte(min >> 4), byte(min<<4) | byte(max>>8), byte(max)}, nil
+}
+
+func (p *PlayOutDelay) Unmarshal(rawData []byte) error {
+	if len(rawData) < playoutDelayExtensionSize {
+		return errTooSmall
+	}
+
+	p.Min = (binary.BigEndian.Uint16(rawData) >> 4) * 10
+	p.Max = (binary.BigEndian.Uint16(rawData[1:]) & 0x0FFF) * 10
+	return nil
+}

pkg/sfu/rtpextension/playoutdelay/playoutdelay_test.go

@@ -0,0 +1,57 @@
+// Copyright 2024 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package playoutdelay
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPlayoutDelay(t *testing.T) {
+	p1 := PlayOutDelay{Min: 100, Max: 200}
+	b, err := p1.Marshal()
+	require.NoError(t, err)
+	require.Len(t, b, playoutDelayExtensionSize)
+	var p2 PlayOutDelay
+	err = p2.Unmarshal(b)
+	require.NoError(t, err)
+	require.Equal(t, p1, p2)
+
+	// overflow
+	p3 := PlayOutDelay{Min: 100, Max: (1 << 12) * 10}
+	_, err = p3.Marshal()
+	require.ErrorIs(t, err, errPlayoutDelayOverflow)
+
+	// too small
+	p4 := PlayOutDelay{}
+	err = p4.Unmarshal([]byte{0x00, 0x00})
+	require.ErrorIs(t, err, errTooSmall)
+
+	// from value
+	p5 := PlayoutDelayFromValue(1<<12*10, 1<<12*10+10)
+	_, err = p5.Marshal()
+	require.NoError(t, err)
+	require.Equal(t, uint16((1<<12)-1)*10, p5.Min)
+	require.Equal(t, uint16((1<<12)-1)*10, p5.Max)
+
+	p6 := PlayOutDelay{Min: 100, Max: PlayoutDelayMaxValue}
+	bytes, err := p6.Marshal()
+	require.NoError(t, err)
+	p6Unmarshal := PlayOutDelay{}
+	err = p6Unmarshal.Unmarshal(bytes)
+	require.NoError(t, err)
+	require.Equal(t, p6, p6Unmarshal)
+}