mirror of
https://github.com/mollyim/webrtc.git
synced 2025-05-15 14:50:39 +01:00
63b3095d2b
This also changes the meaning of |estimated_capture_clock_offset| in |absolute_capture_time_| to become a remote to capturer clock offset. Bug: chromium:1056230, webrtc:10739 Change-Id: Id658590e027bbe77ae0834ea224e1dc977a305f2 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/219163 Commit-Queue: Minyue Li <minyue@webrtc.org> Reviewed-by: Åsa Persson <asapersson@webrtc.org> Reviewed-by: Erik Språng <sprang@webrtc.org> Reviewed-by: Alessio Bazzica <alessiob@webrtc.org> Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org> Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org> Reviewed-by: Chen Xing <chxg@google.com> Cr-Commit-Position: refs/heads/master@{#34067}
86 lines
3.2 KiB
C++
86 lines
3.2 KiB
C++
/*
|
|
* Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license
|
|
* that can be found in the LICENSE file in the root of the source
|
|
* tree. An additional intellectual property rights grant can be found
|
|
* in the file PATENTS. All contributing project authors may
|
|
* be found in the AUTHORS file in the root of the source tree.
|
|
*/
|
|
|
|
#ifndef MODULES_RTP_RTCP_SOURCE_ABSOLUTE_CAPTURE_TIME_INTERPOLATOR_H_
|
|
#define MODULES_RTP_RTCP_SOURCE_ABSOLUTE_CAPTURE_TIME_INTERPOLATOR_H_
|
|
|
|
#include "api/array_view.h"
|
|
#include "api/rtp_headers.h"
|
|
#include "api/units/time_delta.h"
|
|
#include "api/units/timestamp.h"
|
|
#include "rtc_base/synchronization/mutex.h"
|
|
#include "rtc_base/thread_annotations.h"
|
|
#include "system_wrappers/include/clock.h"
|
|
|
|
namespace webrtc {
|
|
|
|
//
|
|
// Helper class for interpolating the |AbsoluteCaptureTime| header extension.
|
|
//
|
|
// Supports the "timestamp interpolation" optimization:
|
|
// A receiver SHOULD memorize the capture system (i.e. CSRC/SSRC), capture
|
|
// timestamp, and RTP timestamp of the most recently received abs-capture-time
|
|
// packet on each received stream. It can then use that information, in
|
|
// combination with RTP timestamps of packets without abs-capture-time, to
|
|
// extrapolate missing capture timestamps.
|
|
//
|
|
// See: https://webrtc.org/experiments/rtp-hdrext/abs-capture-time/
|
|
//
|
|
class AbsoluteCaptureTimeInterpolator {
|
|
public:
|
|
static constexpr TimeDelta kInterpolationMaxInterval =
|
|
TimeDelta::Millis(5000);
|
|
|
|
explicit AbsoluteCaptureTimeInterpolator(Clock* clock);
|
|
|
|
// Returns the source (i.e. SSRC or CSRC) of the capture system.
|
|
static uint32_t GetSource(uint32_t ssrc,
|
|
rtc::ArrayView<const uint32_t> csrcs);
|
|
|
|
// Returns a received header extension, an interpolated header extension, or
|
|
// |absl::nullopt| if it's not possible to interpolate a header extension.
|
|
absl::optional<AbsoluteCaptureTime> OnReceivePacket(
|
|
uint32_t source,
|
|
uint32_t rtp_timestamp,
|
|
uint32_t rtp_clock_frequency,
|
|
const absl::optional<AbsoluteCaptureTime>& received_extension);
|
|
|
|
private:
|
|
friend class AbsoluteCaptureTimeSender;
|
|
|
|
static uint64_t InterpolateAbsoluteCaptureTimestamp(
|
|
uint32_t rtp_timestamp,
|
|
uint32_t rtp_clock_frequency,
|
|
uint32_t last_rtp_timestamp,
|
|
uint64_t last_absolute_capture_timestamp);
|
|
|
|
bool ShouldInterpolateExtension(Timestamp receive_time,
|
|
uint32_t source,
|
|
uint32_t rtp_timestamp,
|
|
uint32_t rtp_clock_frequency) const
|
|
RTC_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
|
|
|
|
Clock* const clock_;
|
|
|
|
Mutex mutex_;
|
|
|
|
Timestamp last_receive_time_ RTC_GUARDED_BY(mutex_);
|
|
|
|
uint32_t last_source_ RTC_GUARDED_BY(mutex_);
|
|
uint32_t last_rtp_timestamp_ RTC_GUARDED_BY(mutex_);
|
|
uint32_t last_rtp_clock_frequency_ RTC_GUARDED_BY(mutex_);
|
|
uint64_t last_absolute_capture_timestamp_ RTC_GUARDED_BY(mutex_);
|
|
absl::optional<int64_t> last_estimated_capture_clock_offset_
|
|
RTC_GUARDED_BY(mutex_);
|
|
}; // AbsoluteCaptureTimeInterpolator
|
|
|
|
} // namespace webrtc
|
|
|
|
#endif // MODULES_RTP_RTCP_SOURCE_ABSOLUTE_CAPTURE_TIME_INTERPOLATOR_H_
|