Video capture: Refactor GetBestMatchedFormat from Win to OS independent

media/video/capture/win/video_capture_device_win.cc

Index: media/video/capture/win/video_capture_device_win.cc
diff --git a/media/video/capture/win/video_capture_device_win.cc b/media/video/capture/win/video_capture_device_win.cc
index 7dfd834b2614e7c5c5e75953b5ba25d08459a944..d1ee6fc5e181e86cc2c9b7efe8fb785df9a16e34 100644
--- a/media/video/capture/win/video_capture_device_win.cc
+++ b/media/video/capture/win/video_capture_device_win.cc
@@ -318,18 +318,15 @@ void VideoCaptureDeviceWin::AllocateAndStart(
 
   client_ = client.Pass();
 
-  // Get the camera capability that best match the requested resolution.
-  const VideoCaptureCapabilityWin& found_capability =
-      capabilities_.GetBestMatchedFormat(
-          params.requested_format.frame_size.width(),
-          params.requested_format.frame_size.height(),
-          params.requested_format.frame_rate);
+  // Get the camera capability that best match the requested format.
+  const CapabilityWin found_capability =
+      GetBestMatchedCapability(params.requested_format, capabilities_);
   VideoCaptureFormat format = found_capability.supported_format;
 
   // Reduce the frame rate if the requested frame rate is lower
   // than the capability.
-  if (format.frame_rate > params.requested_format.frame_rate)
-    format.frame_rate = params.requested_format.frame_rate;
+  format.frame_rate =
+      std::min(format.frame_rate, params.requested_format.frame_rate);
 
   ScopedComPtr<IAMStreamConfig> stream_config;
   HRESULT hr = output_capture_pin_.QueryInterface(stream_config.Receive());
@@ -501,9 +498,10 @@ bool VideoCaptureDeviceWin::CreateCapabilityMap() {
   }
 
   scoped_ptr<BYTE[]> caps(new BYTE[size]);
-  for (int i = 0; i < count; ++i) {
+  for (int stream_index = 0; stream_index < count; ++stream_index) {
     ScopedMediaType media_type;
-    hr = stream_config->GetStreamCaps(i, media_type.Receive(), caps.get());
+    hr = stream_config->GetStreamCaps(
+        stream_index, media_type.Receive(), caps.get());
     // GetStreamCaps() may return S_FALSE, so don't use FAILED() or SUCCEED()
     // macros here since they'll trigger incorrectly.
     if (hr != S_OK) {
@@ -514,53 +512,42 @@ bool VideoCaptureDeviceWin::CreateCapabilityMap() {
 
     if (media_type->majortype == MEDIATYPE_Video &&
         media_type->formattype == FORMAT_VideoInfo) {
-      VideoCaptureCapabilityWin capability(i);
-      capability.supported_format.pixel_format =
+      VideoCaptureFormat format;
+      format.pixel_format =
           TranslateMediaSubtypeToPixelFormat(media_type->subtype);
-      if (capability.supported_format.pixel_format == PIXEL_FORMAT_UNKNOWN)
+      if (format.pixel_format == PIXEL_FORMAT_UNKNOWN)
         continue;
 
       VIDEOINFOHEADER* h =
           reinterpret_cast<VIDEOINFOHEADER*>(media_type->pbFormat);
-      capability.supported_format.frame_size.SetSize(h->bmiHeader.biWidth,
-                                                     h->bmiHeader.biHeight);
+      format.frame_size.SetSize(h->bmiHeader.biWidth, h->bmiHeader.biHeight);
 
-      // Try to get a better |time_per_frame| from IAMVideoControl.  If not, use
+      // Try to get a better |time_per_frame| from IAMVideoControl. If not, use
       // the value from VIDEOINFOHEADER.
       REFERENCE_TIME time_per_frame = h->AvgTimePerFrame;
       if (video_control) {
         ScopedCoMem<LONGLONG> max_fps;
         LONG list_size = 0;
-        SIZE size = {capability.supported_format.frame_size.width(),
-                     capability.supported_format.frame_size.height()};
-
-        // GetFrameRateList doesn't return max frame rate always
-        // eg: Logitech Notebook. This may be due to a bug in that API
-        // because GetFrameRateList array is reversed in the above camera. So
-        // a util method written. Can't assume the first value will return
-        // the max fps.
-        hr = video_control->GetFrameRateList(output_capture_pin_, i, size,
-                                             &list_size, &max_fps);
-        // Sometimes |list_size| will be > 0, but max_fps will be NULL.  Some
+        const SIZE size = {format.frame_size.width(),
+                           format.frame_size.height()};
+        hr = video_control->GetFrameRateList(
+            output_capture_pin_, stream_index, size, &list_size, &max_fps);
+        // Can't assume the first value will return the max fps.
+        // Sometimes |list_size| will be > 0, but max_fps will be NULL. Some
         // drivers may return an HRESULT of S_FALSE which SUCCEEDED() translates
-        // into success, so explicitly check S_OK.  See http://crbug.com/306237.
+        // into success, so explicitly check S_OK. See http://crbug.com/306237.
         if (hr == S_OK && list_size > 0 && max_fps) {
           time_per_frame = *std::min_element(max_fps.get(),
                                              max_fps.get() + list_size);
         }
       }
 
-      capability.supported_format.frame_rate =
+      format.frame_rate =
           (time_per_frame > 0)
               ? (kSecondsToReferenceTime / static_cast<float>(time_per_frame))
               : 0.0;
 
-      // DirectShow works at the moment only on integer frame_rate but the
-      // best capability matching class works on rational frame rates.
-      capability.frame_rate_numerator = capability.supported_format.frame_rate;
-      capability.frame_rate_denominator = 1;
-
-      capabilities_.Add(capability);
+      capabilities_.emplace_back(stream_index, format);
     }
   }