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