vendor.github.com.pion.rtp.audiolevelextension.go Maven / Gradle / Ivy
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// SPDX-FileCopyrightText: 2023 The Pion community
// 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
}