Video capture implementation using the Media Foundation API.

media/video/capture/win/capability_list_win.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/video/capture/win/capability_list_win.h"
+
+#include <algorithm>
+
+#include "base/logging.h"
+
+namespace media {
+namespace {
+
+// Help structure used for comparing video capture capabilities.
+struct ResolutionDiff {
+  const VideoCaptureCapabilityWin* capability;
+  int diff_height;
+  int diff_width;
+  int diff_frame_rate;
+};
+
+bool CompareHeight(const ResolutionDiff& item1, const ResolutionDiff& item2) {
+  return abs(item1.diff_height) < abs(item2.diff_height);
+}
+
+bool CompareWidth(const ResolutionDiff& item1, const ResolutionDiff& item2) {
+  return abs(item1.diff_width) < abs(item2.diff_width);
+}
+
+bool CompareFrameRate(const ResolutionDiff& item1,
+                      const ResolutionDiff& item2) {
+  return abs(item1.diff_frame_rate) < abs(item2.diff_frame_rate);
+}
+
+bool CompareColor(const ResolutionDiff& item1, const ResolutionDiff& item2) {
+  return item1.capability->color < item2.capability->color;
+}
+
+}  // namespace.
+
+CapabilityList::CapabilityList() {
+  DetachFromThread();
+}
+
+CapabilityList::~CapabilityList() {}
+
+// Appends an entry to the list.
+void CapabilityList::Add(const VideoCaptureCapabilityWin& capability) {
+  DCHECK(CalledOnValidThread());
+  capabilities_.push_back(capability);
+}
+
+const VideoCaptureCapabilityWin& CapabilityList::GetBestMatchedCapability(
+    int requested_width,
+    int requested_height,
+    int requested_frame_rate) const {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!capabilities_.empty());
+
+  std::list<ResolutionDiff> diff_list;
+
+  // Loop through the candidates to create a list of differentials between the
+  // requested resolution and the camera capability.
+  for (Capabilities::const_iterator it = capabilities_.begin();
+       it != capabilities_.end(); ++it) {
+    ResolutionDiff diff;
+    diff.capability = &(*it);
+    diff.diff_width = it->width - requested_width;
+    diff.diff_height = it->height - requested_height;
+    diff.diff_frame_rate = it->frame_rate - requested_frame_rate;
+    diff_list.push_back(diff);
+  }
+
+  // Sort the best height candidates.
+  diff_list.sort(&CompareHeight);
+  int best_diff = diff_list.front().diff_height;
+  for (std::list<ResolutionDiff>::iterator it = diff_list.begin();
+       it != diff_list.end(); ++it) {
+    if (it->diff_height != best_diff) {
+      // Remove all candidates but the best.
+      diff_list.erase(it, diff_list.end());
+      break;
+    }
+  }
+
+  // Sort the best width candidates.
+  diff_list.sort(&CompareWidth);
+  best_diff = diff_list.front().diff_width;
+  for (std::list<ResolutionDiff>::iterator it = diff_list.begin();
+       it != diff_list.end(); ++it) {
+    if (it->diff_width != best_diff) {
+      // Remove all candidates but the best.
+      diff_list.erase(it, diff_list.end());
+      break;
+    }
+  }
+
+  // Sort the best frame rate candidates.
+  diff_list.sort(&CompareFrameRate);
+  best_diff = diff_list.front().diff_frame_rate;
+  for (std::list<ResolutionDiff>::iterator it = diff_list.begin();
+       it != diff_list.end(); ++it) {
+    if (it->diff_frame_rate != best_diff) {
+      diff_list.erase(it, diff_list.end());
+      break;
+    }
+  }
+
+  // Decide the best color format.
+  diff_list.sort(&CompareColor);
+  return *diff_list.front().capability;
+}
+
+}  // namespace media