media/capture/content/thread_safe_capture_oracle.cc

   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/capture/content/thread_safe_capture_oracle.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/bind.h"
   9 #include "base/logging.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/synchronization/lock.h"
  12 #include "base/time/time.h"
  13 #include "base/trace_event/trace_event.h"
  14 #include "media/base/video_capture_types.h"
  15 #include "media/base/video_frame.h"
  16 #include "media/base/video_frame_metadata.h"
  17 #include "media/base/video_util.h"
  18 #include "ui/gfx/geometry/rect.h"
  19
  20 namespace media {
  21
  22 namespace {
  23
  24 // The target maximum amount of the buffer pool to utilize.  Actual buffer pool
  25 // utilization is attenuated by this amount before being reported to the
  26 // VideoCaptureOracle.  This value takes into account the maximum number of
  27 // buffer pool buffers and a desired safety margin.
  28 const int kTargetMaxPoolUtilizationPercent = 60;
  29
  30 }  // namespace
  31
  32 ThreadSafeCaptureOracle::ThreadSafeCaptureOracle(
  33     scoped_ptr<VideoCaptureDevice::Client> client,
  34     const VideoCaptureParams& params,
  35     bool enable_auto_throttling)
  36     : client_(client.Pass()),
  37       oracle_(base::TimeDelta::FromMicroseconds(static_cast<int64>(
  38                   1000000.0 / params.requested_format.frame_rate +
  39                   0.5 /* to round to nearest int */)),
  40               params.requested_format.frame_size,
  41               params.resolution_change_policy,
  42               enable_auto_throttling),
  43       params_(params) {
  44 }
  45
  46 ThreadSafeCaptureOracle::~ThreadSafeCaptureOracle() {
  47 }
  48
  49 bool ThreadSafeCaptureOracle::ObserveEventAndDecideCapture(
  50     VideoCaptureOracle::Event event,
  51     const gfx::Rect& damage_rect,
  52     base::TimeTicks event_time,
  53     scoped_refptr<VideoFrame>* storage,
  54     CaptureFrameCallback* callback) {
  55   // Grab the current time before waiting to acquire the |lock_|.
  56   const base::TimeTicks capture_begin_time = base::TimeTicks::Now();
  57
  58   base::AutoLock guard(lock_);
  59
  60   if (!client_)
  61     return false;  // Capture is stopped.
  62
  63   const bool should_capture =
  64       oracle_.ObserveEventAndDecideCapture(event, damage_rect, event_time);
  65   const gfx::Size visible_size = oracle_.capture_size();
  66   // Always round up the coded size to multiple of 16 pixels.
  67   // See http://crbug.com/402151.
  68   const gfx::Size coded_size((visible_size.width() + 15) & ~15,
  69                              (visible_size.height() + 15) & ~15);
  70
  71   scoped_ptr<media::VideoCaptureDevice::Client::Buffer> output_buffer(
  72       client_->ReserveOutputBuffer(coded_size,
  73                                    (params_.requested_format.pixel_storage !=
  74                                     media::PIXEL_STORAGE_TEXTURE)
  75                                        ? media::VIDEO_CAPTURE_PIXEL_FORMAT_I420
  76                                        : media::VIDEO_CAPTURE_PIXEL_FORMAT_ARGB,
  77                                    params_.requested_format.pixel_storage));
  78   // Get the current buffer pool utilization and attenuate it: The utilization
  79   // reported to the oracle is in terms of a maximum sustainable amount (not the
  80   // absolute maximum).
  81   const double attenuated_utilization =
  82       client_->GetBufferPoolUtilization() *
  83       (100.0 / kTargetMaxPoolUtilizationPercent);
  84
  85   const char* event_name =
  86       (event == VideoCaptureOracle::kTimerPoll
  87            ? "poll"
  88            : (event == VideoCaptureOracle::kCompositorUpdate ? "gpu"
  89                                                              : "unknown"));
  90
  91   // Consider the various reasons not to initiate a capture.
  92   if (should_capture && !output_buffer.get()) {
  93     TRACE_EVENT_INSTANT1("gpu.capture", "PipelineLimited",
  94                          TRACE_EVENT_SCOPE_THREAD, "trigger", event_name);
  95     oracle_.RecordWillNotCapture(attenuated_utilization);
  96     return false;
  97   } else if (!should_capture && output_buffer.get()) {
  98     if (event == VideoCaptureOracle::kCompositorUpdate) {
  99       // This is a normal and acceptable way to drop a frame. We've hit our
 100       // capture rate limit: for example, the content is animating at 60fps but
 101       // we're capturing at 30fps.
 102       TRACE_EVENT_INSTANT1("gpu.capture", "FpsRateLimited",
 103                            TRACE_EVENT_SCOPE_THREAD, "trigger", event_name);
 104     }
 105     return false;
 106   } else if (!should_capture && !output_buffer.get()) {
 107     // We decided not to capture, but we wouldn't have been able to if we wanted
 108     // to because no output buffer was available.
 109     TRACE_EVENT_INSTANT1("gpu.capture", "NearlyPipelineLimited",
 110                          TRACE_EVENT_SCOPE_THREAD, "trigger", event_name);
 111     return false;
 112   }
 113   const int frame_number = oracle_.RecordCapture(attenuated_utilization);
 114   TRACE_EVENT_ASYNC_BEGIN2("gpu.capture", "Capture", output_buffer.get(),
 115                            "frame_number", frame_number, "trigger", event_name);
 116   // Texture frames wrap a texture mailbox, which we don't have at the moment.
 117   // We do not construct those frames.
 118   if (params_.requested_format.pixel_storage != media::PIXEL_STORAGE_TEXTURE) {
 119     *storage = VideoFrame::WrapExternalData(
 120         media::PIXEL_FORMAT_I420, coded_size, gfx::Rect(visible_size),
 121         visible_size, static_cast<uint8*>(output_buffer->data()),
 122         output_buffer->size(), base::TimeDelta());
 123     DCHECK(*storage);
 124   }
 125   *callback =
 126       base::Bind(&ThreadSafeCaptureOracle::DidCaptureFrame, this, frame_number,
 127                  base::Passed(&output_buffer), capture_begin_time,
 128                  oracle_.estimated_frame_duration());
 129   return true;
 130 }
 131
 132 gfx::Size ThreadSafeCaptureOracle::GetCaptureSize() const {
 133   base::AutoLock guard(lock_);
 134   return oracle_.capture_size();
 135 }
 136
 137 void ThreadSafeCaptureOracle::UpdateCaptureSize(const gfx::Size& source_size) {
 138   base::AutoLock guard(lock_);
 139   VLOG(1) << "Source size changed to " << source_size.ToString();
 140   oracle_.SetSourceSize(source_size);
 141 }
 142
 143 void ThreadSafeCaptureOracle::Stop() {
 144   base::AutoLock guard(lock_);
 145   client_.reset();
 146 }
 147
 148 void ThreadSafeCaptureOracle::ReportError(const std::string& reason) {
 149   base::AutoLock guard(lock_);
 150   if (client_)
 151     client_->OnError(reason);
 152 }
 153
 154 void ThreadSafeCaptureOracle::DidCaptureFrame(
 155     int frame_number,
 156     scoped_ptr<VideoCaptureDevice::Client::Buffer> buffer,
 157     base::TimeTicks capture_begin_time,
 158     base::TimeDelta estimated_frame_duration,
 159     const scoped_refptr<VideoFrame>& frame,
 160     base::TimeTicks timestamp,
 161     bool success) {
 162   base::AutoLock guard(lock_);
 163   TRACE_EVENT_ASYNC_END2("gpu.capture", "Capture", buffer.get(), "success",
 164                          success, "timestamp", timestamp.ToInternalValue());
 165
 166   if (oracle_.CompleteCapture(frame_number, success, &timestamp)) {
 167     TRACE_EVENT_INSTANT0("gpu.capture", "CaptureSucceeded",
 168                          TRACE_EVENT_SCOPE_THREAD);
 169
 170     if (!client_)
 171       return;  // Capture is stopped.
 172
 173     frame->metadata()->SetDouble(VideoFrameMetadata::FRAME_RATE,
 174                                  params_.requested_format.frame_rate);
 175     frame->metadata()->SetTimeTicks(VideoFrameMetadata::CAPTURE_BEGIN_TIME,
 176                                     capture_begin_time);
 177     frame->metadata()->SetTimeTicks(VideoFrameMetadata::CAPTURE_END_TIME,
 178                                     base::TimeTicks::Now());
 179     frame->metadata()->SetTimeDelta(VideoFrameMetadata::FRAME_DURATION,
 180                                     estimated_frame_duration);
 181
 182     frame->AddDestructionObserver(
 183         base::Bind(&ThreadSafeCaptureOracle::DidConsumeFrame, this,
 184                    frame_number, frame->metadata()));
 185
 186     client_->OnIncomingCapturedVideoFrame(buffer.Pass(), frame, timestamp);
 187   }
 188 }
 189
 190 void ThreadSafeCaptureOracle::DidConsumeFrame(
 191     int frame_number,
 192     const media::VideoFrameMetadata* metadata) {
 193   // Note: This function may be called on any thread by the VideoFrame
 194   // destructor.  |metadata| is still valid for read-access at this point.
 195   double utilization = -1.0;
 196   if (metadata->GetDouble(media::VideoFrameMetadata::RESOURCE_UTILIZATION,
 197                           &utilization)) {
 198     base::AutoLock guard(lock_);
 199     oracle_.RecordConsumerFeedback(frame_number, utilization);
 200   }
 201 }
 202
 203 }  // namespace media