Video capture device MF Windows frame rate setting.

-VideoCaptureCapabilityWin added two fields, frame_rate_numerator and frame_rate_denominator. These are supposed to be used internally to Windows, while keeping VideoCaptureCapability::frame_rate integer counterpart also updated.

- video_capture_device_mf_win.cc uses these two in FillCapabilitiesFromType(), GetFrameRate();
- video_capture_device_win.cc updates them in CreateCapabilityMap().
- CapabilityList::GetBestMatchedCapability() uses the numerator denominator frame_rate for calculating the best matched frame_rate.

Second try to fix this bug, first go was https://codereview.chromium.org/15792020/


BUG=246928

Review URL: https://chromiumcodereview.appspot.com/18991006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@210877 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 36 insertions, 10 deletions

diff --git a/media/video/capture/win/capability_list_win.cc b/media/video/capture/win/capability_list_win.cc
index 63bd69b..18325bb 100644
--- a/media/video/capture/win/capability_list_win.cc
+++ b/media/video/capture/win/capability_list_win.cc
@@ -67,7 +67,11 @@ const VideoCaptureCapabilityWin& CapabilityList::GetBestMatchedCapability(
     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;
+    // The 1000 allows using integer arithmetic for f.i. 29.971 fps.
+    diff.diff_frame_rate =
+        1000 * ((static_cast<float>(it->frame_rate_numerator) /
+                 it->frame_rate_denominator) -
+                requested_frame_rate);
     diff_list.push_back(diff);
   }
 
diff --git a/media/video/capture/win/capability_list_win.h b/media/video/capture/win/capability_list_win.h
index 6f96942..c07b220 100644
--- a/media/video/capture/win/capability_list_win.h
+++ b/media/video/capture/win/capability_list_win.h
@@ -17,8 +17,15 @@
 namespace media {
 
 struct VideoCaptureCapabilityWin : public VideoCaptureCapability {
-  explicit VideoCaptureCapabilityWin(int index) : stream_index(index) {}
+  explicit VideoCaptureCapabilityWin(int index)
+      : stream_index(index),
+        frame_rate_numerator(0),
+        frame_rate_denominator(1) {}
   int stream_index;
+  // Internally to Media Foundation Api type devices we use rational framerates
+  // so framerates can be properly represented, f.i. 29.971fps= 30000/1001.
+  int frame_rate_numerator;
+  int frame_rate_denominator;
 };
 
 class CapabilityList : public base::NonThreadSafe {
diff --git a/media/video/capture/win/video_capture_device_mf_win.cc b/media/video/capture/win/video_capture_device_mf_win.cc
index b2f47bc..fbfaf6a 100644
--- a/media/video/capture/win/video_capture_device_mf_win.cc
+++ b/media/video/capture/win/video_capture_device_mf_win.cc
@@ -97,30 +97,37 @@ bool GetFrameSize(IMFMediaType* type, int* width, int* height) {
   return true;
 }
 
-bool GetFrameRate(IMFMediaType* type, int* frame_rate) {
+bool GetFrameRate(IMFMediaType* type,
+                  int* frame_rate_numerator,
+                  int* frame_rate_denominator) {
   UINT32 numerator, denominator;
   if (FAILED(MFGetAttributeRatio(type, MF_MT_FRAME_RATE, &numerator,
-                                 &denominator))) {
+                                 &denominator))||
+      !denominator) {
     return false;
   }
-
-  *frame_rate = denominator ? numerator / denominator : 0;
-
+  *frame_rate_numerator = numerator;
+  *frame_rate_denominator = denominator;
   return true;
 }
 
 bool FillCapabilitiesFromType(IMFMediaType* type,
-                              VideoCaptureCapability* capability) {
+                              VideoCaptureCapabilityWin* capability) {
   GUID type_guid;
   if (FAILED(type->GetGUID(MF_MT_SUBTYPE, &type_guid)) ||
       !FormatFromGuid(type_guid, &capability->color) ||
       !GetFrameSize(type, &capability->width, &capability->height) ||
-      !GetFrameRate(type, &capability->frame_rate)) {
+      !GetFrameRate(type,
+                    &capability->frame_rate_numerator,
+                    &capability->frame_rate_denominator)) {
     return false;
   }
+  // Keep the integer version of the frame_rate for (potential) returns.
+  capability->frame_rate =
+      capability->frame_rate_numerator / capability->frame_rate_denominator;
 
   capability->expected_capture_delay = 0;  // Currently not used.
-  capability->interlaced = false;  // Currently not used.
+  capability->interlaced = false;          // Currently not used.
 
   return true;
 }
@@ -332,6 +339,10 @@ void VideoCaptureDeviceMFWin::Allocate(
 
   const VideoCaptureCapabilityWin& found_capability =
       capabilities.GetBestMatchedCapability(width, height, frame_rate);
+  DLOG(INFO) << "Chosen capture format= (" << found_capability.width << "x"
+             << found_capability.height << ")@("
+             << found_capability.frame_rate_numerator << "/"
+             << found_capability.frame_rate_denominator << ")fps";
 
   ScopedComPtr<IMFMediaType> type;
   if (FAILED(hr = reader_->GetNativeMediaType(
diff --git a/media/video/capture/win/video_capture_device_win.cc b/media/video/capture/win/video_capture_device_win.cc
index 32ac70c..e364aa2 100644
--- a/media/video/capture/win/video_capture_device_win.cc
+++ b/media/video/capture/win/video_capture_device_win.cc
@@ -576,6 +576,10 @@ bool VideoCaptureDeviceWin::CreateCapabilityMap() {
         capability.frame_rate = (time_per_frame > 0) ?
             static_cast<int>(kSecondsToReferenceTime / time_per_frame) : 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.frame_rate;
+      capability.frame_rate_denominator = 1;
 
       // We can't switch MEDIATYPE :~(.
       if (media_type->subtype == kMediaSubTypeI420) {