1 /* 2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef VIDEO_STREAM_SYNCHRONIZATION_H_ 12 #define VIDEO_STREAM_SYNCHRONIZATION_H_ 13 14 #include <stdint.h> 15 16 #include "system_wrappers/include/rtp_to_ntp_estimator.h" 17 18 namespace webrtc { 19 20 class StreamSynchronization { 21 public: 22 struct Measurements { MeasurementsMeasurements23 Measurements() : latest_receive_time_ms(0), latest_timestamp(0) {} 24 RtpToNtpEstimator rtp_to_ntp; 25 int64_t latest_receive_time_ms; 26 uint32_t latest_timestamp; 27 }; 28 29 StreamSynchronization(uint32_t video_stream_id, uint32_t audio_stream_id); 30 31 bool ComputeDelays(int relative_delay_ms, 32 int current_audio_delay_ms, 33 int* total_audio_delay_target_ms, 34 int* total_video_delay_target_ms); 35 36 // On success `relative_delay_ms` contains the number of milliseconds later 37 // video is rendered relative audio. If audio is played back later than video 38 // `relative_delay_ms` will be negative. 39 static bool ComputeRelativeDelay(const Measurements& audio_measurement, 40 const Measurements& video_measurement, 41 int* relative_delay_ms); 42 43 // Set target buffering delay. Audio and video will be delayed by at least 44 // `target_delay_ms`. 45 void SetTargetBufferingDelay(int target_delay_ms); 46 47 // Lowers the audio delay by 10%. Can be used to recover from errors. 48 void ReduceAudioDelay(); 49 50 // Lowers the video delay by 10%. Can be used to recover from errors. 51 void ReduceVideoDelay(); 52 audio_stream_id()53 uint32_t audio_stream_id() const { return audio_stream_id_; } video_stream_id()54 uint32_t video_stream_id() const { return video_stream_id_; } 55 56 private: 57 struct SynchronizationDelays { 58 int extra_ms = 0; 59 int last_ms = 0; 60 }; 61 62 const uint32_t video_stream_id_; 63 const uint32_t audio_stream_id_; 64 SynchronizationDelays audio_delay_; 65 SynchronizationDelays video_delay_; 66 int base_target_delay_ms_; 67 int avg_diff_ms_; 68 }; 69 } // namespace webrtc 70 71 #endif // VIDEO_STREAM_SYNCHRONIZATION_H_ 72