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Diffstat (limited to 'third_party/libwebrtc/modules/video_coding/timing/inter_frame_delay.cc')
-rw-r--r-- | third_party/libwebrtc/modules/video_coding/timing/inter_frame_delay.cc | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/timing/inter_frame_delay.cc b/third_party/libwebrtc/modules/video_coding/timing/inter_frame_delay.cc new file mode 100644 index 0000000000..bed9f875ee --- /dev/null +++ b/third_party/libwebrtc/modules/video_coding/timing/inter_frame_delay.cc @@ -0,0 +1,71 @@ +/* + * Copyright (c) 2011 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. + */ + +#include "modules/video_coding/timing/inter_frame_delay.h" + +#include "absl/types/optional.h" +#include "api/units/frequency.h" +#include "api/units/time_delta.h" +#include "modules/include/module_common_types_public.h" + +namespace webrtc { + +namespace { +constexpr Frequency k90kHz = Frequency::KiloHertz(90); +} + +InterFrameDelay::InterFrameDelay() { + Reset(); +} + +// Resets the delay estimate. +void InterFrameDelay::Reset() { + prev_wall_clock_ = absl::nullopt; + prev_rtp_timestamp_unwrapped_ = 0; +} + +// Calculates the delay of a frame with the given timestamp. +// This method is called when the frame is complete. +absl::optional<TimeDelta> InterFrameDelay::CalculateDelay( + uint32_t rtp_timestamp, + Timestamp now) { + int64_t rtp_timestamp_unwrapped = unwrapper_.Unwrap(rtp_timestamp); + if (!prev_wall_clock_) { + // First set of data, initialization, wait for next frame. + prev_wall_clock_ = now; + prev_rtp_timestamp_unwrapped_ = rtp_timestamp_unwrapped; + return TimeDelta::Zero(); + } + + // Account for reordering in jitter variance estimate in the future? + // Note that this also captures incomplete frames which are grabbed for + // decoding after a later frame has been complete, i.e. real packet losses. + uint32_t cropped_last = static_cast<uint32_t>(prev_rtp_timestamp_unwrapped_); + if (rtp_timestamp_unwrapped < prev_rtp_timestamp_unwrapped_ || + !IsNewerTimestamp(rtp_timestamp, cropped_last)) { + return absl::nullopt; + } + + // Compute the compensated timestamp difference. + int64_t d_rtp_ticks = rtp_timestamp_unwrapped - prev_rtp_timestamp_unwrapped_; + TimeDelta dts = d_rtp_ticks / k90kHz; + TimeDelta dt = now - *prev_wall_clock_; + + // frameDelay is the difference of dT and dTS -- i.e. the difference of the + // wall clock time difference and the timestamp difference between two + // following frames. + TimeDelta delay = dt - dts; + + prev_rtp_timestamp_unwrapped_ = rtp_timestamp_unwrapped; + prev_wall_clock_ = now; + return delay; +} + +} // namespace webrtc |