Win Video Capture: add DirectShow WDM devices capabilities enumeration.

media/video/capture/win/video_capture_device_factory_win.cc

 // Copyright 2014 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/video_capture_device_factory_win.h"
 
 #include <mfapi.h>
 #include <mferror.h>
 
 #include "base/command_line.h"
@@ skipping 74 matching lines @@
                                                  UINT32* count) {
   ScopedComPtr<IMFAttributes> attributes;
   if (!PrepareVideoCaptureAttributesMediaFoundation(attributes.Receive(), 1))
     return false;
 
   return SUCCEEDED(MFEnumDeviceSources(attributes, devices, count));
 }
 
 static void GetDeviceNamesDirectShow(Names* device_names) {
   DCHECK(device_names);
+  DCHECK(device_names->empty());
   DVLOG(1) << " GetDeviceNamesDirectShow";
 
   ScopedComPtr<ICreateDevEnum> dev_enum;
   HRESULT hr = dev_enum.CreateInstance(CLSID_SystemDeviceEnum, NULL,
                                        CLSCTX_INPROC);
   if (FAILED(hr))
     return;
 
   static const struct{
     CLSID class_id;
     Name::CaptureApiType capture_api_type;
   } kDirectShowFilterClasses[] = {
     { CLSID_VideoInputDeviceCategory, Name::DIRECT_SHOW },
-    { AM_KSCATEGORY_CROSSBAR, Name::DIRECT_SHOW_WDM}
+    { AM_KSCATEGORY_CROSSBAR, Name::DIRECT_SHOW_WDM}  // Must be the last entry.

[perkj_chrome, 2014/09/02 09:22:03]

http://msdn.microsoft.com/en-us/library/windows/desktop/dd373520(v=vs.85).aspx
suggest that there are other types of WDM types as well and that
AM_KSCATEGORY_CROSSBAR is just for analog video input. 

Should Name::DIRECT_SHOW_WDM be changed to NAME::DIRECT_SHOW_AMCROSSBAR ? 

http://msdn.microsoft.com/en-us/library/windows/desktop/dd388914(v=vs.85).aspx

[mcasas, 2014/09/02 15:13:41]

Done.

   };
 
-
-  device_names->clear();
   for (int class_index = 0; class_index < arraysize(kDirectShowFilterClasses);

[perkj_chrome, 2014/09/02 09:22:03]

instead of a for loop- would it make sence to put line 113 to 166 in a separate
method?

static void GetDeviceNamesDirectShow(xxx class_id, Names* device_names);

Then GetDeviceNamesDirectShow(Names* device_names)
Could call 
 {
GetDeviceNamesDirectShow(CLSID_VideoInputDeviceCategory, device_names) 
GetDeviceNamesDirectShow(AM_KSCATEGORY_CROSSBAR, device_names) 
... Special handle the AM_KSCATEGORY_CROSSBAR.
That would simplify reading the code a bit and clarify why the order matters. 

[mcasas, 2014/09/02 15:13:41]

Done.

       ++class_index) {
     ScopedComPtr<IEnumMoniker> enum_moniker;
     hr = dev_enum->CreateClassEnumerator(
         kDirectShowFilterClasses[class_index].class_id,
         enum_moniker.Receive(),
         0);
     // CreateClassEnumerator returns S_FALSE on some Windows OS
     // when no camera exist. Therefore the FAILED macro can't be used.
     if (hr != S_OK)
       continue;
@@ skipping 20 matching lines @@
       if (FAILED(hr))
         hr = prop_bag->Read(L"FriendlyName", name.Receive(), 0);
 
       if (SUCCEEDED(hr) && name.type() == VT_BSTR) {
         // Ignore all VFW drivers and the special Google Camera Adapter.
         // Google Camera Adapter is not a real DirectShow camera device.
         // VFW are very old Video for Windows drivers that can not be used.
         const wchar_t* str_ptr = V_BSTR(&name);
         const int name_length = arraysize(kGoogleCameraAdapter) - 1;
 
         if ((wcsstr(str_ptr, L"(VFW)") == NULL) &&

[magjed_chromium, 2014/09/02 15:14:41]

These parentheses are wrong. && has higher precedence, so the current condition
is actually:
(wcsstr(str_ptr, L"(VFW)") == NULL && lstrlenW(str_ptr) < name_length) ||
LowerCaseEqualsASCII(...)

             lstrlenW(str_ptr) < name_length ||
             (!(LowerCaseEqualsASCII(str_ptr, str_ptr + name_length,
                                     kGoogleCameraAdapter)))) {
           std::string id;
           std::string device_name(base::SysWideToUTF8(str_ptr));

[magjed_chromium, 2014/09/02 15:14:41]

device_name can be made const

           name.Reset();
           hr = prop_bag->Read(L"DevicePath", name.Receive(), 0);
           if (FAILED(hr) || name.type() != VT_BSTR) {
             id = device_name;
           } else {
             DCHECK_EQ(name.type(), VT_BSTR);
             id = base::SysWideToUTF8(V_BSTR(&name));
           }
-          device_names->push_back(Name(device_name, id,
-              kDirectShowFilterClasses[class_index].capture_api_type));
+          Name device(device_name, id,

[magjed_chromium, 2014/09/02 15:14:41]

device can be made const

+                kDirectShowFilterClasses[class_index].capture_api_type);
+          // For WDM devices, we need to search in the listed |device_names| to
+          // find a device with matching USB ID.

[perkj_chrome, 2014/09/02 09:22:03]

you are comparing GetModel()  to find the USB id of the first device - of that
model. 

[mcasas, 2014/09/02 15:13:41]

Clarified.

+          if (device.capture_api_type() == Name::DIRECT_SHOW_WDM) {
+            const std::string& device_model = device.GetModel();
+            Names::const_iterator iter = device_names->begin();
+            for (; iter != device_names->end(); ++iter) {
+              if (device_model.compare(iter->GetModel()) == 0) {

[perkj_chrome, 2014/09/02 09:22:03]

prefer == 

[mcasas, 2014/09/02 15:13:41]

Not sure I understand. Can you please clarify?

+                device.set_capabilities_unique_id(iter->id());

[perkj_chrome, 2014/09/02 09:22:03]

Do you know what happens if you have two capture cards of the same model? Would
they have the same set of capabilities?

[mcasas, 2014/09/02 15:13:41]

Yes.

+                break;
+              }
+            }
+          }
+          device_names->push_back(device);
         }
       }
       moniker.Release();
     }
   }
 }
 
 static void GetDeviceNamesMediaFoundation(Names* device_names) {
   DVLOG(1) << " GetDeviceNamesMediaFoundation";
   ScopedCoMem<IMFActivate*> devices;
@@ skipping 35 matching lines @@
     return;
 
   ScopedComPtr<IEnumMoniker> enum_moniker;
   hr = dev_enum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,
                                        enum_moniker.Receive(), 0);
   // CreateClassEnumerator returns S_FALSE on some Windows OS when no camera
   // exists. Therefore the FAILED macro can't be used.
   if (hr != S_OK)
     return;
 
-  // Walk the capture devices. No need to check for device presence again, that
-  // is caught in GetDeviceFilter(). "google camera adapter" and old VFW devices
-  // are already skipped in the previous GetDeviceNames() enumeration.
+  // Walk the capture devices. No need to check for device presence again since
+  // that is anyway needed in GetDeviceFilter(). "google camera adapter" and old
+  // VFW devices are already skipped previously in GetDeviceNames() enumeration.
   base::win::ScopedComPtr<IBaseFilter> capture_filter;
-  hr = VideoCaptureDeviceWin::GetDeviceFilter(device,
+  hr = VideoCaptureDeviceWin::GetDeviceFilter(device.capabilities_unique_id(),
                                               capture_filter.Receive());
   if (!capture_filter) {
-    DVLOG(2) << "Failed to create capture filter.";
+    DVLOG(2) << "Failed to create capture filter." ;

[magjed_chromium, 2014/09/02 15:14:41]

Unnecessary space after string :)

     return;
   }
 
   base::win::ScopedComPtr<IPin> output_capture_pin(
       VideoCaptureDeviceWin::GetPin(capture_filter,
                                     PINDIR_OUTPUT,
                                     PIN_CATEGORY_CAPTURE));
   if (!output_capture_pin) {
     DVLOG(2) << "Failed to get capture output pin";
     return;
@@ skipping 175 matching lines @@
     const Name& device,
     VideoCaptureFormats* formats) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (use_media_foundation_)
     GetDeviceSupportedFormatsMediaFoundation(device, formats);
   else
     GetDeviceSupportedFormatsDirectShow(device, formats);
 }
 
 }  // namespace media