916170ae46
If a frame is dropped and re-encoded because it exceeded the target bitrate by a large factor, the next frame will be encoded at max qp (worst quality) in order to get a frame through in a timely manner. The next frame after this will still have lower quality since the rate controller essentially gets reset. In order to mitigate that we boost the qp for that next frame, which brings the stream back to a good quality quicker. However, if the network conditions are _really_ bad, this boosted qp may be too large, causing the frame again to be dropped an re-encoded. This CL set's a minimum bitrate available in order to enabling the boosting in the first place. It also adjusts a timeout (max time between frames in TL0), since a too small value and very difficult frames in conjunction with the mentioned bad network could actually cause bad network over-utilization in turn leading to packet loss and bad follow-on effects to that. There was also some slop in the rate keeping for the two layers. This has been tightened up and affected test cases have been fixed. BUG=webrtc:7694 Review-Url: https://codereview.webrtc.org/2897983002 Cr-Commit-Position: refs/heads/master@{#18236}
131 lines
4.1 KiB
C++
131 lines
4.1 KiB
C++
/* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_MODULES_VIDEO_CODING_CODECS_VP8_SCREENSHARE_LAYERS_H_
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#define WEBRTC_MODULES_VIDEO_CODING_CODECS_VP8_SCREENSHARE_LAYERS_H_
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#include <vector>
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#include "webrtc/base/rate_statistics.h"
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#include "webrtc/base/timeutils.h"
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#include "webrtc/modules/video_coding/codecs/vp8/temporal_layers.h"
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#include "webrtc/modules/video_coding/utility/frame_dropper.h"
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#include "webrtc/typedefs.h"
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namespace webrtc {
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struct CodecSpecificInfoVP8;
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class Clock;
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class ScreenshareLayers : public TemporalLayers {
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public:
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static const double kMaxTL0FpsReduction;
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static const double kAcceptableTargetOvershoot;
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static const int kMaxFrameIntervalMs;
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ScreenshareLayers(int num_temporal_layers,
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uint8_t initial_tl0_pic_idx,
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Clock* clock);
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virtual ~ScreenshareLayers();
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// Returns the recommended VP8 encode flags needed. May refresh the decoder
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// and/or update the reference buffers.
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TemporalLayers::FrameConfig UpdateLayerConfig(uint32_t timestamp) override;
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// Update state based on new bitrate target and incoming framerate.
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// Returns the bitrate allocation for the active temporal layers.
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std::vector<uint32_t> OnRatesUpdated(int bitrate_kbps,
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int max_bitrate_kbps,
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int framerate) override;
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// Update the encoder configuration with target bitrates or other parameters.
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// Returns true iff the configuration was actually modified.
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bool UpdateConfiguration(vpx_codec_enc_cfg_t* cfg) override;
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void PopulateCodecSpecific(bool base_layer_sync,
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const TemporalLayers::FrameConfig& tl_config,
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CodecSpecificInfoVP8* vp8_info,
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uint32_t timestamp) override;
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void FrameEncoded(unsigned int size, int qp) override;
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int GetTemporalLayerId(
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const TemporalLayers::FrameConfig& tl_config) const override;
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uint8_t Tl0PicIdx() const override;
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private:
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enum class TemporalLayerState : int { kDrop, kTl0, kTl1, kTl1Sync };
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bool TimeToSync(int64_t timestamp) const;
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uint32_t GetCodecTargetBitrateKbps() const;
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Clock* const clock_;
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int number_of_temporal_layers_;
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bool last_base_layer_sync_;
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uint8_t tl0_pic_idx_;
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int active_layer_;
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int64_t last_timestamp_;
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int64_t last_sync_timestamp_;
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int64_t last_emitted_tl0_timestamp_;
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rtc::TimestampWrapAroundHandler time_wrap_handler_;
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int min_qp_;
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int max_qp_;
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uint32_t max_debt_bytes_;
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// Configured max framerate.
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rtc::Optional<uint32_t> target_framerate_;
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// Incoming framerate from capturer.
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rtc::Optional<uint32_t> capture_framerate_;
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// Tracks what framerate we actually encode, and drops frames on overshoot.
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RateStatistics encode_framerate_;
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bool bitrate_updated_;
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static constexpr int kMaxNumTemporalLayers = 2;
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struct TemporalLayer {
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TemporalLayer()
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: state(State::kNormal),
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enhanced_max_qp(-1),
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last_qp(-1),
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debt_bytes_(0),
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target_rate_kbps_(0) {}
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enum class State {
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kNormal,
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kDropped,
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kReencoded,
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kQualityBoost,
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} state;
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int enhanced_max_qp;
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int last_qp;
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uint32_t debt_bytes_;
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uint32_t target_rate_kbps_;
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void UpdateDebt(int64_t delta_ms);
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} layers_[kMaxNumTemporalLayers];
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void UpdateHistograms();
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// Data for histogram statistics.
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struct Stats {
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int64_t first_frame_time_ms_ = -1;
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int64_t num_tl0_frames_ = 0;
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int64_t num_tl1_frames_ = 0;
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int64_t num_dropped_frames_ = 0;
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int64_t num_overshoots_ = 0;
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int64_t tl0_qp_sum_ = 0;
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int64_t tl1_qp_sum_ = 0;
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int64_t tl0_target_bitrate_sum_ = 0;
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int64_t tl1_target_bitrate_sum_ = 0;
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} stats_;
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};
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} // namespace webrtc
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#endif // WEBRTC_MODULES_VIDEO_CODING_CODECS_VP8_SCREENSHARE_LAYERS_H_
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