This is the VideoCaptureDevice implementation for windows.

media/video/capture/win/pin_base_win.h

+// Copyright (c) 2011 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.
+
+// Implement a simple base class for a DirectShow input pin. It may only be
+// used in a single threaded apartment.
+
+#ifndef MEDIA_VIDEO_CAPTURE_WIN_PIN_BASE_WIN_H_
+#define MEDIA_VIDEO_CAPTURE_WIN_PIN_BASE_WIN_H_
+#pragma once
+
+// Avoid including strsafe.h via dshow as it will cause build warnings.
+#define NO_DSHOW_STRSAFE
+#include <dshow.h>
+
+#include "base/memory/ref_counted.h"
+#include "base/win/scoped_comptr.h"
+
+namespace media {
+
+class PinBase
+    : public IPin,
+      public IMemInputPin,
+      public base::RefCounted<PinBase> {
+ public:
+  explicit PinBase(IBaseFilter* owner);
+  virtual ~PinBase();
+
+  // Function used for changing the owner.
+  // If the owner is deleted the owner should first call this function
+  // with owner = NULL.
+  void SetOwner(IBaseFilter* owner);
+
+  // Checks if a media type is acceptable. This is called when this pin is
+  // connected to an output pin. Must return true if the media type is
+  // acceptable, false otherwise.
+  virtual bool IsMediaTypeValid(const AM_MEDIA_TYPE* media_type) = 0;
+
+  // Enumerates valid media types.
+  virtual bool GetValidMediaType(int index, AM_MEDIA_TYPE* media_type) = 0;
+
+  // Called when new media is received. Note that this is not on the same
+  // thread as where the pin is created.
+  STDMETHOD(Receive)(IMediaSample* sample) = 0;
+
+  STDMETHOD(Connect)(IPin* receive_pin, const AM_MEDIA_TYPE* media_type);
+
+  STDMETHOD(ReceiveConnection)(IPin* connector,
+                               const AM_MEDIA_TYPE* media_type);
+
+  STDMETHOD(Disconnect)();
+
+  STDMETHOD(ConnectedTo)(IPin** pin);
+
+  STDMETHOD(ConnectionMediaType)(AM_MEDIA_TYPE* media_type);
+
+  STDMETHOD(QueryPinInfo)(PIN_INFO* info);
+
+  STDMETHOD(QueryDirection)(PIN_DIRECTION* pin_dir);
+
+  STDMETHOD(QueryId)(LPWSTR* id);
+
+  STDMETHOD(QueryAccept)(const AM_MEDIA_TYPE* media_type);
+
+  STDMETHOD(EnumMediaTypes)(IEnumMediaTypes** types);
+
+  STDMETHOD(QueryInternalConnections)(IPin** pins, ULONG* no_pins);
+
+  STDMETHOD(EndOfStream)();
+
+  STDMETHOD(BeginFlush)();
+
+  STDMETHOD(EndFlush)();
+
+  STDMETHOD(NewSegment)(REFERENCE_TIME start,
+                        REFERENCE_TIME stop,
+                        double dRate);
+
+  // Inherited from IMemInputPin.
+  STDMETHOD(GetAllocator)(IMemAllocator** allocator);
+
+  STDMETHOD(NotifyAllocator)(IMemAllocator* allocator, BOOL read_only);
+
+  STDMETHOD(GetAllocatorRequirements)(ALLOCATOR_PROPERTIES* properties);
+
+  STDMETHOD(ReceiveMultiple)(IMediaSample** samples,
+                             long sample_count,
+                             long* processed);
+  STDMETHOD(ReceiveCanBlock)();
+
+  // Inherited from IUnknown.
+  STDMETHOD(QueryInterface)(REFIID id, void** object_ptr);
+
+  STDMETHOD_(ULONG, AddRef)();
+
+  STDMETHOD_(ULONG, Release)();
+
+ private:
+  AM_MEDIA_TYPE current_media_type_;
+  base::win::ScopedComPtr<IPin> connected_pin_;
+  // owner_ is the filter owning this pin. We don't reference count it since
+  // that would create a circular reference count.
+  IBaseFilter* owner_;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_VIDEO_CAPTURE_WIN_PIN_BASE_WIN_H_