OpenShot Library | libopenshot 0.2.7
PlayerPrivate.cpp
Go to the documentation of this file.
1/**
2 * @file
3 * @brief Source file for PlayerPrivate class
4 * @author Duzy Chan <code@duzy.info>
5 * @author Jonathan Thomas <jonathan@openshot.org>
6 *
7 * @ref License
8 */
9
10/* LICENSE
11 *
12 * Copyright (c) 2008-2019 OpenShot Studios, LLC
13 * <http://www.openshotstudios.com/>. This file is part of
14 * OpenShot Library (libopenshot), an open-source project dedicated to
15 * delivering high quality video editing and animation solutions to the
16 * world. For more information visit <http://www.openshot.org/>.
17 *
18 * OpenShot Library (libopenshot) is free software: you can redistribute it
19 * and/or modify it under the terms of the GNU Lesser General Public License
20 * as published by the Free Software Foundation, either version 3 of the
21 * License, or (at your option) any later version.
22 *
23 * OpenShot Library (libopenshot) is distributed in the hope that it will be
24 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
25 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
26 * GNU Lesser General Public License for more details.
27 *
28 * You should have received a copy of the GNU Lesser General Public License
29 * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
30 */
31
32#include "PlayerPrivate.h"
33#include "Exceptions.h"
34
35#include <thread> // for std::this_thread::sleep_for
36#include <chrono> // for std::chrono milliseconds, high_resolution_clock
37
38namespace openshot
39{
40 // Constructor
41 PlayerPrivate::PlayerPrivate(openshot::RendererBase *rb)
42 : renderer(rb), Thread("player"), video_position(1), audio_position(0)
43 , audioPlayback(new openshot::AudioPlaybackThread())
44 , videoPlayback(new openshot::VideoPlaybackThread(rb))
45 , videoCache(new openshot::VideoCacheThread())
46 , speed(1), reader(NULL), last_video_position(1)
47 { }
48
49 // Destructor
50 PlayerPrivate::~PlayerPrivate()
51 {
52 stopPlayback(1000);
53 delete audioPlayback;
54 delete videoCache;
55 delete videoPlayback;
56 }
57
58 // Start thread
59 void PlayerPrivate::run()
60 {
61 // bail if no reader set
62 if (!reader)
63 return;
64
65 // Start the threads
66 if (reader->info.has_audio)
67 audioPlayback->startThread(8);
68 if (reader->info.has_video) {
69 videoCache->startThread(2);
70 videoPlayback->startThread(4);
71 }
72
73 using std::chrono::duration_cast;
74
75 // Types for storing time durations in whole and fractional milliseconds
76 using ms = std::chrono::milliseconds;
77 using double_ms = std::chrono::duration<double, ms::period>;
78
79 // Calculate on-screen time for a single frame in milliseconds
80 const auto frame_duration = double_ms(1000.0 / reader->info.fps.ToDouble());
81
82 while (!threadShouldExit()) {
83 // Get the start time (to track how long a frame takes to render)
84 const auto time1 = std::chrono::high_resolution_clock::now();
85
86 // Get the current video frame (if it's different)
87 frame = getFrame();
88
89 // Experimental Pausing Code (if frame has not changed)
90 if ((speed == 0 && video_position == last_video_position)
91 || (video_position > reader->info.video_length)
92 ) {
93 speed = 0;
94 std::this_thread::sleep_for(frame_duration);
95 continue;
96 }
97
98 // Set the video frame on the video thread and render frame
99 videoPlayback->frame = frame;
100 videoPlayback->render.signal();
101
102 // Keep track of the last displayed frame
103 last_video_position = video_position;
104
105 // How many frames ahead or behind is the video thread?
106 int64_t video_frame_diff = 0;
107 if (reader->info.has_audio && reader->info.has_video) {
108 if (speed != 1)
109 // Set audio frame again (since we are not in normal speed, and not paused)
110 audioPlayback->Seek(video_position);
111
112 // Only calculate this if a reader contains both an audio and video thread
113 audio_position = audioPlayback->getCurrentFramePosition();
114 video_frame_diff = video_position - audio_position;
115 }
116
117 // Get the end time (to track how long a frame takes to render)
118 const auto time2 = std::chrono::high_resolution_clock::now();
119
120 // Determine how many milliseconds it took to render the frame
121 const auto render_time = double_ms(time2 - time1);
122
123 // Calculate the amount of time to sleep (by subtracting the render time)
124 auto sleep_time = duration_cast<ms>(frame_duration - render_time);
125
126 // Debug
127 ZmqLogger::Instance()->AppendDebugMethod("PlayerPrivate::run (determine sleep)", "video_frame_diff", video_frame_diff, "video_position", video_position, "audio_position", audio_position, "speed", speed, "render_time(ms)", render_time.count(), "sleep_time(ms)", sleep_time.count());
128
129 // Adjust drift (if more than a few frames off between audio and video)
130 if (video_frame_diff > 0 && reader->info.has_audio && reader->info.has_video) {
131 // Since the audio and video threads are running independently,
132 // they will quickly get out of sync. To fix this, we calculate
133 // how far ahead or behind the video frame is, and adjust the amount
134 // of time the frame is displayed on the screen (i.e. the sleep time).
135 // If a frame is ahead of the audio, we sleep for longer.
136 // If a frame is behind the audio, we sleep less (or not at all),
137 // in order for the video to catch up.
138 sleep_time += duration_cast<ms>(video_frame_diff * frame_duration);
139 }
140
141 else if (video_frame_diff < -10 && reader->info.has_audio && reader->info.has_video) {
142 // Skip frame(s) to catch up to the audio (if more than 10 frames behind)
143 video_position += std::fabs(video_frame_diff) / 2; // Seek forward 1/2 the difference
144 sleep_time = sleep_time.zero(); // Don't sleep now... immediately go to next position
145 }
146
147 // Sleep (leaving the video frame on the screen for the correct amount of time)
148 if (sleep_time > sleep_time.zero()) {
149 std::this_thread::sleep_for(sleep_time);
150 }
151
152 }
153 }
154
155 // Get the next displayed frame (based on speed and direction)
156 std::shared_ptr<openshot::Frame> PlayerPrivate::getFrame()
157 {
158 try {
159 // Get the next frame (based on speed)
160 if (video_position + speed >= 1 && video_position + speed <= reader->info.video_length)
161 video_position = video_position + speed;
162
163 if (frame && frame->number == video_position && video_position == last_video_position) {
164 // return cached frame
165 return frame;
166 }
167 else
168 {
169 // Update cache on which frame was retrieved
170 videoCache->setCurrentFramePosition(video_position);
171
172 // return frame from reader
173 return reader->GetFrame(video_position);
174 }
175
176 } catch (const ReaderClosed & e) {
177 // ...
178 } catch (const OutOfBoundsFrame & e) {
179 // ...
180 }
181 return std::shared_ptr<openshot::Frame>();
182 }
183
184 // Start video/audio playback
185 bool PlayerPrivate::startPlayback()
186 {
187 if (video_position < 0) return false;
188
189 stopPlayback(-1);
190 startThread(1);
191 return true;
192 }
193
194 // Stop video/audio playback
195 void PlayerPrivate::stopPlayback(int timeOutMilliseconds)
196 {
197 if (audioPlayback->isThreadRunning() && reader->info.has_audio) audioPlayback->stopThread(timeOutMilliseconds);
198 if (videoCache->isThreadRunning() && reader->info.has_video) videoCache->stopThread(timeOutMilliseconds);
199 if (videoPlayback->isThreadRunning() && reader->info.has_video) videoPlayback->stopThread(timeOutMilliseconds);
200 if (isThreadRunning()) stopThread(timeOutMilliseconds);
201 }
202
203}
Header file for all Exception classes.
Source file for PlayerPrivate class.
This is the base class of all Renderers in libopenshot.
Definition: RendererBase.h:49
This namespace is the default namespace for all code in the openshot library.
Definition: Compressor.h:47