107 lines
3.4 KiB
Go
107 lines
3.4 KiB
Go
// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
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// SPDX-License-Identifier: MIT
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package rtp
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import (
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"encoding/binary"
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"time"
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)
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const (
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absCaptureTimeExtensionSize = 8
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absCaptureTimeExtendedExtensionSize = 16
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)
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// AbsCaptureTimeExtension is a extension payload format in
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// http://www.webrtc.org/experiments/rtp-hdrext/abs-capture-time
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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=7 | absolute capture timestamp (bit 0-23) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | absolute capture timestamp (bit 24-55) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | ... (56-63) |
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// +-+-+-+-+-+-+-+-+
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type AbsCaptureTimeExtension struct {
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Timestamp uint64
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EstimatedCaptureClockOffset *int64
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}
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// Marshal serializes the members to buffer.
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func (t AbsCaptureTimeExtension) Marshal() ([]byte, error) {
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if t.EstimatedCaptureClockOffset != nil {
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buf := make([]byte, 16)
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binary.BigEndian.PutUint64(buf[0:8], t.Timestamp)
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binary.BigEndian.PutUint64(buf[8:16], uint64(*t.EstimatedCaptureClockOffset))
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return buf, nil
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}
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buf := make([]byte, 8)
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binary.BigEndian.PutUint64(buf[0:8], t.Timestamp)
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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 (t *AbsCaptureTimeExtension) Unmarshal(rawData []byte) error {
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if len(rawData) < absCaptureTimeExtensionSize {
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return errTooSmall
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}
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t.Timestamp = binary.BigEndian.Uint64(rawData[0:8])
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if len(rawData) >= absCaptureTimeExtendedExtensionSize {
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offset := int64(binary.BigEndian.Uint64(rawData[8:16]))
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t.EstimatedCaptureClockOffset = &offset
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}
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return nil
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}
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// CaptureTime produces the estimated time.Time represented by this extension.
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func (t AbsCaptureTimeExtension) CaptureTime() time.Time {
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return toTime(t.Timestamp)
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}
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// EstimatedCaptureClockOffsetDuration produces the estimated time.Duration represented by this extension.
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func (t AbsCaptureTimeExtension) EstimatedCaptureClockOffsetDuration() *time.Duration {
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if t.EstimatedCaptureClockOffset == nil {
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return nil
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}
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offset := *t.EstimatedCaptureClockOffset
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negative := false
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if offset < 0 {
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offset = -offset
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negative = true
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}
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duration := time.Duration(offset/(1<<32))*time.Second + time.Duration((offset&0xFFFFFFFF)*1e9/(1<<32))*time.Nanosecond
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if negative {
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duration = -duration
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}
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return &duration
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}
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// NewAbsCaptureTimeExtension makes new AbsCaptureTimeExtension from time.Time.
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func NewAbsCaptureTimeExtension(captureTime time.Time) *AbsCaptureTimeExtension {
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return &AbsCaptureTimeExtension{
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Timestamp: toNtpTime(captureTime),
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}
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}
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// NewAbsCaptureTimeExtensionWithCaptureClockOffset makes new AbsCaptureTimeExtension from time.Time and a clock offset.
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func NewAbsCaptureTimeExtensionWithCaptureClockOffset(captureTime time.Time, captureClockOffset time.Duration) *AbsCaptureTimeExtension {
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ns := captureClockOffset.Nanoseconds()
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negative := false
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if ns < 0 {
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ns = -ns
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negative = true
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}
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lsb := (ns / 1e9) & 0xFFFFFFFF
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msb := (((ns % 1e9) * (1 << 32)) / 1e9) & 0xFFFFFFFF
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offset := (lsb << 32) | msb
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if negative {
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offset = -offset
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}
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return &AbsCaptureTimeExtension{
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Timestamp: toNtpTime(captureTime),
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EstimatedCaptureClockOffset: &offset,
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}
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}
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