1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "media/formats/mp2t/es_adapter_video.h"
6
7 #include "media/base/buffers.h"
8 #include "media/base/stream_parser_buffer.h"
9 #include "media/base/video_decoder_config.h"
10 #include "media/formats/mp2t/mp2t_common.h"
11
12 namespace media {
13 namespace mp2t {
14
15 // Arbitrary decision about the frame duration when there is no previous
16 // hint about what could be the frame duration.
17 static const int kDefaultFrameDurationMs = 40;
18
19 // To calculate the frame duration, we make an assumption
20 // that the timestamp of the next frame in presentation order
21 // is no further than 5 frames away in decode order.
22 // TODO(damienv): the previous assumption should cover most of the practical
23 // cases. However, the right way to calculate the frame duration would be
24 // to emulate the H264 dpb bumping process.
25 static const size_t kHistorySize = 5;
26
EsAdapterVideo(const NewVideoConfigCB & new_video_config_cb,const EmitBufferCB & emit_buffer_cb)27 EsAdapterVideo::EsAdapterVideo(
28 const NewVideoConfigCB& new_video_config_cb,
29 const EmitBufferCB& emit_buffer_cb)
30 : new_video_config_cb_(new_video_config_cb),
31 emit_buffer_cb_(emit_buffer_cb),
32 has_valid_config_(false),
33 has_valid_frame_(false),
34 last_frame_duration_(
35 base::TimeDelta::FromMilliseconds(kDefaultFrameDurationMs)),
36 buffer_index_(0) {
37 }
38
~EsAdapterVideo()39 EsAdapterVideo::~EsAdapterVideo() {
40 }
41
Flush()42 void EsAdapterVideo::Flush() {
43 ProcessPendingBuffers(true);
44 }
45
Reset()46 void EsAdapterVideo::Reset() {
47 has_valid_config_ = false;
48 has_valid_frame_ = false;
49
50 last_frame_duration_ =
51 base::TimeDelta::FromMilliseconds(kDefaultFrameDurationMs);
52
53 config_list_.clear();
54 buffer_index_ = 0;
55 buffer_list_.clear();
56 emitted_pts_.clear();
57
58 discarded_frames_min_pts_ = base::TimeDelta();
59 discarded_frames_dts_.clear();
60 }
61
OnConfigChanged(const VideoDecoderConfig & video_decoder_config)62 void EsAdapterVideo::OnConfigChanged(
63 const VideoDecoderConfig& video_decoder_config) {
64 config_list_.push_back(
65 ConfigEntry(buffer_index_ + buffer_list_.size(), video_decoder_config));
66 has_valid_config_ = true;
67 ProcessPendingBuffers(false);
68 }
69
OnNewBuffer(const scoped_refptr<StreamParserBuffer> & stream_parser_buffer)70 void EsAdapterVideo::OnNewBuffer(
71 const scoped_refptr<StreamParserBuffer>& stream_parser_buffer) {
72 // Discard the incoming frame:
73 // - if it is not associated with any config,
74 // - or if only non-key frames have been added to a new segment.
75 if (!has_valid_config_ ||
76 (!has_valid_frame_ && !stream_parser_buffer->IsKeyframe())) {
77 if (discarded_frames_dts_.empty() ||
78 discarded_frames_min_pts_ > stream_parser_buffer->timestamp()) {
79 discarded_frames_min_pts_ = stream_parser_buffer->timestamp();
80 }
81 discarded_frames_dts_.push_back(
82 stream_parser_buffer->GetDecodeTimestamp());
83 return;
84 }
85
86 has_valid_frame_ = true;
87
88 if (!discarded_frames_dts_.empty())
89 ReplaceDiscardedFrames(stream_parser_buffer);
90
91 buffer_list_.push_back(stream_parser_buffer);
92 ProcessPendingBuffers(false);
93 }
94
ProcessPendingBuffers(bool flush)95 void EsAdapterVideo::ProcessPendingBuffers(bool flush) {
96 DCHECK(has_valid_config_);
97
98 while (!buffer_list_.empty() &&
99 (flush || buffer_list_.size() > kHistorySize)) {
100 // Signal a config change, just before emitting the corresponding frame.
101 if (!config_list_.empty() && config_list_.front().first == buffer_index_) {
102 new_video_config_cb_.Run(config_list_.front().second);
103 config_list_.pop_front();
104 }
105
106 scoped_refptr<StreamParserBuffer> buffer = buffer_list_.front();
107 buffer_list_.pop_front();
108 buffer_index_++;
109
110 if (buffer->duration() == kNoTimestamp()) {
111 base::TimeDelta next_frame_pts = GetNextFramePts(buffer->timestamp());
112 if (next_frame_pts == kNoTimestamp()) {
113 // This can happen when emitting the very last buffer
114 // or if the stream do not meet the assumption behind |kHistorySize|.
115 DVLOG(LOG_LEVEL_ES) << "Using last frame duration: "
116 << last_frame_duration_.InMilliseconds();
117 buffer->set_duration(last_frame_duration_);
118 } else {
119 base::TimeDelta duration = next_frame_pts - buffer->timestamp();
120 DVLOG(LOG_LEVEL_ES) << "Frame duration: " << duration.InMilliseconds();
121 buffer->set_duration(duration);
122 }
123 }
124
125 emitted_pts_.push_back(buffer->timestamp());
126 if (emitted_pts_.size() > kHistorySize)
127 emitted_pts_.pop_front();
128
129 last_frame_duration_ = buffer->duration();
130 emit_buffer_cb_.Run(buffer);
131 }
132 }
133
GetNextFramePts(base::TimeDelta current_pts)134 base::TimeDelta EsAdapterVideo::GetNextFramePts(base::TimeDelta current_pts) {
135 base::TimeDelta next_pts = kNoTimestamp();
136
137 // Consider the timestamps of future frames (in decode order).
138 // Note: the next frame is not enough when the GOP includes some B frames.
139 for (BufferQueue::const_iterator it = buffer_list_.begin();
140 it != buffer_list_.end(); ++it) {
141 if ((*it)->timestamp() < current_pts)
142 continue;
143 if (next_pts == kNoTimestamp() || next_pts > (*it)->timestamp())
144 next_pts = (*it)->timestamp();
145 }
146
147 // Consider the timestamps of previous frames (in decode order).
148 // In a simple GOP structure with B frames, the frame next to the last B
149 // frame (in presentation order) is located before in decode order.
150 for (std::list<base::TimeDelta>::const_iterator it = emitted_pts_.begin();
151 it != emitted_pts_.end(); ++it) {
152 if (*it < current_pts)
153 continue;
154 if (next_pts == kNoTimestamp() || next_pts > *it)
155 next_pts = *it;
156 }
157
158 return next_pts;
159 }
160
ReplaceDiscardedFrames(const scoped_refptr<StreamParserBuffer> & stream_parser_buffer)161 void EsAdapterVideo::ReplaceDiscardedFrames(
162 const scoped_refptr<StreamParserBuffer>& stream_parser_buffer) {
163 DCHECK(!discarded_frames_dts_.empty());
164 DCHECK(stream_parser_buffer->IsKeyframe());
165
166 // PTS is interpolated between the min PTS of discarded frames
167 // and the PTS of the first valid buffer.
168 base::TimeDelta pts = discarded_frames_min_pts_;
169 base::TimeDelta pts_delta =
170 (stream_parser_buffer->timestamp() - pts) / discarded_frames_dts_.size();
171
172 while (!discarded_frames_dts_.empty()) {
173 scoped_refptr<StreamParserBuffer> frame =
174 StreamParserBuffer::CopyFrom(
175 stream_parser_buffer->data(),
176 stream_parser_buffer->data_size(),
177 stream_parser_buffer->IsKeyframe(),
178 stream_parser_buffer->type(),
179 stream_parser_buffer->track_id());
180 frame->SetDecodeTimestamp(discarded_frames_dts_.front());
181 frame->set_timestamp(pts);
182 frame->set_duration(pts_delta);
183 buffer_list_.push_back(frame);
184 pts += pts_delta;
185 discarded_frames_dts_.pop_front();
186 }
187 }
188
189 } // namespace mp2t
190 } // namespace media
191