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server/vendor/github.com/pion/rtp/audiolevelextension.go

@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package rtp
+
+import (
+	"errors"
+)
+
+const (
+	// audioLevelExtensionSize One byte header size
+	audioLevelExtensionSize = 1
+)
+
+var errAudioLevelOverflow = errors.New("audio level overflow")
+
+// AudioLevelExtension is a extension payload format described in
+// https://tools.ietf.org/html/rfc6464
+//
+// Implementation based on:
+// https://chromium.googlesource.com/external/webrtc/+/e2a017725570ead5946a4ca8235af27470ca0df9/webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc#49
+//
+// One byte format:
+// 0                   1
+// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |  ID   | len=0 |V| level       |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// Two byte format:
+// 0                   1                   2                   3
+// 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=1     |V|    level    |    0 (pad)    |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+type AudioLevelExtension struct {
+	Level uint8
+	Voice bool
+}
+
+// Marshal serializes the members to buffer
+func (a AudioLevelExtension) Marshal() ([]byte, error) {
+	if a.Level > 127 {
+		return nil, errAudioLevelOverflow
+	}
+	voice := uint8(0x00)
+	if a.Voice {
+		voice = 0x80
+	}
+	buf := make([]byte, audioLevelExtensionSize)
+	buf[0] = voice | a.Level
+	return buf, nil
+}
+
+// Unmarshal parses the passed byte slice and stores the result in the members
+func (a *AudioLevelExtension) Unmarshal(rawData []byte) error {
+	if len(rawData) < audioLevelExtensionSize {
+		return errTooSmall
+	}
+	a.Level = rawData[0] & 0x7F
+	a.Voice = rawData[0]&0x80 != 0
+	return nil
+}