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      1 /*
      2  *  Copyright (c) 2011 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 WEBRTC_MODULES_VIDEO_CODING_MAIN_SOURCE_TIMING_H_
     12 #define WEBRTC_MODULES_VIDEO_CODING_MAIN_SOURCE_TIMING_H_
     13 
     14 #include "webrtc/modules/video_coding/main/source/codec_timer.h"
     15 #include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
     16 #include "webrtc/typedefs.h"
     17 
     18 namespace webrtc {
     19 
     20 class Clock;
     21 class TimestampExtrapolator;
     22 
     23 class VCMTiming {
     24  public:
     25   // The primary timing component should be passed
     26   // if this is the dual timing component.
     27   VCMTiming(Clock* clock,
     28             VCMTiming* master_timing = NULL);
     29   ~VCMTiming();
     30 
     31   // Resets the timing to the initial state.
     32   void Reset();
     33   void ResetDecodeTime();
     34 
     35   // Set the amount of time needed to render an image. Defaults to 10 ms.
     36   void set_render_delay(uint32_t render_delay_ms);
     37 
     38   // Set the minimum time the video must be delayed on the receiver to
     39   // get the desired jitter buffer level.
     40   void SetJitterDelay(uint32_t required_delay_ms);
     41 
     42   // Set the minimum playout delay required to sync video with audio.
     43   void set_min_playout_delay(uint32_t min_playout_delay);
     44 
     45   // Increases or decreases the current delay to get closer to the target delay.
     46   // Calculates how long it has been since the previous call to this function,
     47   // and increases/decreases the delay in proportion to the time difference.
     48   void UpdateCurrentDelay(uint32_t frame_timestamp);
     49 
     50   // Increases or decreases the current delay to get closer to the target delay.
     51   // Given the actual decode time in ms and the render time in ms for a frame,
     52   // this function calculates how late the frame is and increases the delay
     53   // accordingly.
     54   void UpdateCurrentDelay(int64_t render_time_ms,
     55                           int64_t actual_decode_time_ms);
     56 
     57   // Stops the decoder timer, should be called when the decoder returns a frame
     58   // or when the decoded frame callback is called.
     59   int32_t StopDecodeTimer(uint32_t time_stamp,
     60                           int64_t start_time_ms,
     61                           int64_t now_ms);
     62 
     63   // Used to report that a frame is passed to decoding. Updates the timestamp
     64   // filter which is used to map between timestamps and receiver system time.
     65   void IncomingTimestamp(uint32_t time_stamp, int64_t last_packet_time_ms);
     66   // Returns the receiver system time when the frame with timestamp
     67   // frame_timestamp should be rendered, assuming that the system time currently
     68   // is now_ms.
     69   int64_t RenderTimeMs(uint32_t frame_timestamp, int64_t now_ms) const;
     70 
     71   // Returns the maximum time in ms that we can wait for a frame to become
     72   // complete before we must pass it to the decoder.
     73   uint32_t MaxWaitingTime(int64_t render_time_ms, int64_t now_ms) const;
     74 
     75   // Returns the current target delay which is required delay + decode time +
     76   // render delay.
     77   uint32_t TargetVideoDelay() const;
     78 
     79   // Calculates whether or not there is enough time to decode a frame given a
     80   // certain amount of processing time.
     81   bool EnoughTimeToDecode(uint32_t available_processing_time_ms) const;
     82 
     83   // Return current timing information.
     84   void GetTimings(int* decode_ms,
     85                   int* max_decode_ms,
     86                   int* current_delay_ms,
     87                   int* target_delay_ms,
     88                   int* jitter_buffer_ms,
     89                   int* min_playout_delay_ms,
     90                   int* render_delay_ms) const;
     91 
     92   enum { kDefaultRenderDelayMs = 10 };
     93   enum { kDelayMaxChangeMsPerS = 100 };
     94 
     95  protected:
     96   int32_t MaxDecodeTimeMs(FrameType frame_type = kVideoFrameDelta) const;
     97   int64_t RenderTimeMsInternal(uint32_t frame_timestamp, int64_t now_ms) const;
     98   uint32_t TargetDelayInternal() const;
     99 
    100  private:
    101   CriticalSectionWrapper* crit_sect_;
    102   Clock* clock_;
    103   bool master_;
    104   TimestampExtrapolator* ts_extrapolator_;
    105   VCMCodecTimer codec_timer_;
    106   uint32_t render_delay_ms_;
    107   uint32_t min_playout_delay_ms_;
    108   uint32_t jitter_delay_ms_;
    109   uint32_t current_delay_ms_;
    110   int last_decode_ms_;
    111   uint32_t prev_frame_timestamp_;
    112 };
    113 }  // namespace webrtc
    114 
    115 #endif  // WEBRTC_MODULES_VIDEO_CODING_MAIN_SOURCE_TIMING_H_
    116