When you are done using the Direct3D device, call to unlock the device.

If the method returns MF_E_DXGI_NEW_VIDEO_DEVICE, call to close the handle and then call OpenDeviceHandle again to get a new handle. The method invalidates all open device handles.

If fBlock is TRUE, this method can potentially deadlock. For example, it will deadlock if a thread calls LockDevice and then waits on another thread that calls LockDevice. It will also deadlock if a thread calls LockDevice twice without calling UnlockDevice in between.

When you first create the DXGI Device Manager, call this method with a reference to the Direct3D device. (The device manager does not create the device; the caller must provide the device reference initially.) Also call this method if the Direct3D device becomes lost and you need to reset the device or create a new device.

The resetToken parameter ensures that only the component that originally created the device manager can invalidate the current device.

If this method succeeds, all open device handles become invalid.

Call this method to release the device after calling .

Call this method to release a device handle that was retrieved by the method.

If the method returns MF_E_DXGI_NEW_VIDEO_DEVICE, call to close the handle and then call OpenDeviceHandle again to get a new handle. The method invalidates all open device handles.

When you are done using the Direct3D device, call to unlock the device.

If the method returns MF_E_DXGI_NEW_VIDEO_DEVICE, call to close the handle and then call OpenDeviceHandle again to get a new handle. The method invalidates all open device handles.

If fBlock is TRUE, this method can potentially deadlock. For example, it will deadlock if a thread calls LockDevice and then waits on another thread that calls LockDevice. It will also deadlock if a thread calls LockDevice twice without calling UnlockDevice in between.

When you first create the DXGI Device Manager, call this method with a reference to the Direct3D device. (The device manager does not create the device; the caller must provide the device reference initially.) Also call this method if the Direct3D device becomes lost and you need to reset the device or create a new device.

The resetToken parameter ensures that only the component that originally created the device manager can invalidate the current device.

If this method succeeds, all open device handles become invalid.

If the method returns MF_E_DXGI_NEW_VIDEO_DEVICE, call to close the handle and then call OpenDeviceHandle again to get a new handle. The method invalidates all open device handles.

Call this method to release the device after calling .

Before using this interface, call CoInitializeEx and .

To get a reference to this interface, call CoCreateInstance. The class identifier is .

Before calling this method, call .

The Media Engine supports three distinct modes:

?

The following attributes are defined for the pAttr parameter. Some are required, and some are optional, depending on the mode you want.

?

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

This method corresponds to the canPlayType attribute of the HTMLMediaElement interface in HTML5.

The canPlayType attribute defines the following values.

?

The value "probably" is used because a MIME type for a media resource is generally not a complete description of the resource. For example, "video/mp4" specifies an MP4 file with video, but does not describe the codec. Even with the optional codecs parameter, the MIME type omits some information, such as the actual coded bit rate. Therefore, it is usually impossible to be certain that playback is possible until the actual media resource is opened.

The values greater than zero correspond to error codes defined for the MediaError object in HTML5.

The application receives Media Engine events through the method. The EventNotify method includes two event parameters, param1 and param2. The meaning of the parameters depends on the event code. If the event description does not list any parameters, ignore the values of param1 and param2.

Values below 1000 correspond to events defined in HTML 5 for media elements.

The transfer matrices are defined as follows.

BT.709 transfer matrices:

BT.601 transfer matrices:

SMPTE 240M (SMPTE RP 145) transfer matrices:

This enumeration is equivalent to the DXVA_VideoTransferMatrix enumeration used in DXVA 1.0.

If you are using the interface to describe the video format, the video transfer matrix is specified in the attribute.

This method corresponds to the networkState attribute of the HTMLMediaElement interface in HTML5.

The transfer matrices are defined as follows.

BT.709 transfer matrices:

BT.601 transfer matrices:

SMPTE 240M (SMPTE RP 145) transfer matrices:

This enumeration is equivalent to the DXVA_VideoTransferMatrix enumeration used in DXVA 1.0.

If you are using the interface to describe the video format, the video transfer matrix is specified in the attribute.

These flags are used with the attribute.

These values correspond to constants defined for the HTMLMediaElement.readyState attribute in HTML5.

The transfer matrices are defined as follows.

BT.709 transfer matrices:

BT.601 transfer matrices:

SMPTE 240M (SMPTE RP 145) transfer matrices:

This enumeration is equivalent to the DXVA_VideoTransferMatrix enumeration used in DXVA 1.0.

If you are using the interface to describe the video format, the video transfer matrix is specified in the attribute.

To skip forward or backward in a playlist, call or IMFMediaSession::Start with the MF_TIME_FORMAT_ENTRY_RELATIVE time-format . This capability applies only when the flag is present.

The values in this enumeration are not bit flags, so they should not be combined with a bitwise OR. Also, the caller should test for these flags with the equality operator, not a bitwise AND:

The values in this enumeration are not bit flags, so they should not be combined with a bitwise OR. Also, the caller should test for these flags with the equality operator, not a bitwise AND:

The values in this enumeration are not bit flags, so they should not be combined with a bitwise OR. Also, the caller should test for these flags with the equality operator, not a bitwise AND:

Before the client sets the media types on the MFT, the only flag guaranteed to be accurate is the flag. For all other flags, the client should first set the media type on every non-optional stream.

The and flags define different behaviors for how the MFT can discard output data.

• MFT_OUTPUT_STREAM_DISCARDABLE: The MFT discards output data only if the client calls ProcessOutput with the flag. The MFT never discards data when the client calls ProcessInput.

• MFT_OUTPUT_STREAM_LAZY_READ: If the client continues to call ProcessInput without collecting the output from this stream, the MFT eventually discards the output. If all output streams have the flag, the MFT never refuses more input data.

If neither of these flags is set, the MFT never discards output data.

The values in this enumeration are not bit flags, so they should not be combined with a bitwise OR. Also, the caller should test for these flags with the equality operator, not a bitwise AND:

If the MFT sets this flag, the ProcessOutput method returns MF_E_TRANSFORM_STREAM_CHANGE and no output data is produced. The client should respond as follows:

1. Call to get the new number of streams.

2. Call to get the new stream identifiers.

3. Call and to set the media types on the new streams.

Until these steps are completed, all further calls to ProcessOutput return MF_E_TRANSFORM_STREAM_CHANGE.

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

If the decoder sets the flag, the quality manager tries to reduce latency through the media source and the media sink. For example, it might request the Enhanced Video Renderer (EVR) to drop frames. During this period, the quality manager stops calling the decoder's method, until samples are no longer arriving late at the sink. At that point, the quality manager resumes calling NotifyQualityEvent on the decoder.

In drop mode, a component drops samples, more or less aggressively depending on the level of the drop mode. The specific algorithm used depends on the component. Mode 1 is the least aggressive mode, and mode 5 is the most aggressive. A component is not required to implement all five levels.

For example, suppose an encoded video stream has three B-frames between each pair of P-frames. A decoder might implement the following drop modes:

• Mode 1: Drop one out of every three B frames.

• Mode 2: Drop one out of every two B frames.

• Mode 3: Drop all delta frames.

• Modes 4 and 5: Unsupported.

The enhanced video renderer (EVR) can drop video frames before sending them to the EVR mixer.

Each successive quality level decreases the amount of processing that is needed, while also reducing the resulting quality of the audio or video. The specific algorithm used to reduce quality depends on the component. Mode 1 is the least aggressive mode, and mode 5 is the most aggressive. A component is not required to implement all five levels. Also, the same quality level might not be comparable between two different components.

Video decoders can often reduce quality by leaving out certain post-processing steps. The enhanced video renderer (EVR) can sometimes reduce quality by switching to a different deinterlacing mode.

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

For certain version numbers of sample protection, the downstream component must provide a certificate. Components that do not support these version numbers can return E_NOTIMPL.

This method causes the stream sink to send an event after the stream sink consumes all of the samples that were delivered up to this point (before the call to PlaceMarker).

Before calling this method, set the media types on all input and output streams.

The MFT might ignore certain message types. If so, the method returns . An error code indicates that the transform handles this message type but was unable to process the message in this instance.

If MFT_UNIQUE_METHOD_NAMES is defined before including mftransform.h, this method is renamed MFTProcessMessage. See Creating Hybrid DMO/MFT Objects.

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

An instance of the video processor can be created in one of the following ways:

• By calling MFTEnumEx. The video processor is registered under the MFT_CATEGORY_VIDEO_PROCESSOR category.
• By calling the COM function CoCreateInstance passing it the CLSID CLSID_VideoProcessorMFT.

The video processor supports GPU-accelerated video processing, using Microsoft Direct3D?11. For more information, see .

The video processor supports the view unpacking operation on 3D video frames:

If the input frame contains two views packed in the same frame, the video processor can split the views into separate buffers, or extract the base view and discard the second view. To enable view unpacking, set the attribute to or .

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

These flags are used with the attribute.

For more information about these values, see the remarks for the DXVA2_VideoChromaSubSampling enumeration, which is the DirectX Video Acceleration (DXVA) equivalent of this enumeration.

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

Scan lines in the lower field are 0.5 scan line lower than those in the upper field. In NTSC television, a frame consists of a lower field followed by an upper field. In PAL television, a frame consists of an upper field followed by a lower field.

The upper field is also called the even field, the top field, or field 2. The lower field is also called the odd field, the bottom field, or field 1.

If the interlace mode is or , each sample contains a single field, so each buffer contains only half the number of field lines given in the media type.

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

The application implements the credential manager, which must expose the IMFNetCredentialManager interface. If the REQUIRE_PROMPT flag is set, the credential manager should prompt the user for his or her name and password.

The credential cache object sets the REQUIRE_PROMPT flag if the cache does not yet contain valid credentials. It also sets this flag if the credentials will be sent as plain text, unless the credential manager previously set the MFNET_CREDENTIAL_ALLOW_CLEAR_TEXT option. (See IMFNetCredentialCache::SetUserOptions.)

An application must call this function before using Media Foundation. Before your application quits, call once for every previous call to .

Do not call or from work queue threads. For more information about work queues, see Work Queues.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

The maximum size of the wrapper buffer is limited to the size of the valid data in the original buffer. This might be less than the allocated size of the original buffer. To set the size of the valid data, call .

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

The application must call once for every call to .

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

Attributes are used throughout Microsoft Media Foundation to configure objects, describe media formats, query object properties, and other purposes. For more information, see Attributes in Media Foundation.

For a complete list of all the defined attribute GUIDs in Media Foundation, see Media Foundation Attributes.

The function allocates a buffer with a 1-byte memory alignment. To allocate a buffer that is aligned to a larger memory boundary, call .

When the media buffer object is destroyed, it releases the allocated memory.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

The application must call once for every call to MFAllocateWorkQueue and then once for every call to .

The returned buffer object also exposes the interface.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

To create the Windows Runtime object, call or IClassFactory::CreateInstance.

This function creates an allocator for DXGI video surfaces. The buffers created by this allocator expose the interface. To create an allocator for Microsoft Direct3D?9 video surfaces, call MFCreateVideoSampleAllocator.

If the wFormatTag member of the returned structure is , you can cast the reference to a structure.

An application must call this function before using Media Foundation. Before your application quits, call once for every previous call to .

Do not call or from work queue threads. For more information about work queues, see Work Queues.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

This function copies a single plane of the image. For planar YUV formats, you must call the function once for each plane. In this case, pDest and pSrc must point to the start of each plane.

This function is optimized if the MMX, SSE, or SSE2 instruction sets are available on the processor. The function performs a non-temporal store (the data is written to memory directly without polluting the cache).

Note??Prior to Windows?7, this function was exported from evr.dll. Starting in Windows?7, this function is exported from mfplat.dll, and evr.dll exports a stub function that calls into mfplat.dll. For more information, see Library Changes in Windows?7.

This function enables a component to wait for an event without blocking the current thread.

The function puts a work item on the specified work queue. This work item waits for the event given in hEvent to be signaled. When the event is signaled, the work item invokes a callback. (The callback is contained in the result object given in pResult. For more information, see ).

The work item is dispatched on a work queue by the method of the callback. The work queue can be any of the following:

• The default work queue (MFASYNC_CALLBACK_QUEUE_STANDARD).
• The platform multithreaded queue (MFASYNC_CALLBACK_QUEUE_MULTITHREADED).
• A multithreaded queue returned by the function.
• A serial queue created by the function.

Do not use any of the following work queues: MFASYNC_CALLBACK_QUEUE_IO, MFASYNC_CALLBACK_QUEUE_LONG_FUNCTION, MFASYNC_CALLBACK_QUEUE_RT, or MFASYNC_CALLBACK_QUEUE_TIMER.

To invoke the callback specified in pCallback, call the function.

The returned buffer object supports the following interfaces:

Initially the sample does not contain any media buffers.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

Call this function after a successful call to the function.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

Use this function to find the size of the array that is needed for the function.

Because work items are asynchronous, the work-item callback might still be invoked after is called.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

When the media buffer object is destroyed, it releases the allocated memory.

Use this function to find the size of the array that is needed for the function.

The original media type (pOrig) is stored in the new media type under the attribute. To extract the original media type, call .

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

This function creates a helper object that you can use to implement the interface.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

This function prevents the function from shutting down the work queue. Use this function to ensure that asynchronous operations on the work queue complete gracefully before the platform shuts down. The function blocks until the work queue is unlocked, or until a fixed wait period has elapsed. (The wait period is a few seconds.)

Call to unlock the work queue. Each call to must be matched by a corresponding call to .

Note??The MFAllocateWorkQueue function implicitly locks the work queue that it creates.

This function prevents work queue threads from being shut down when is called. Use this function to ensure that asynchronous operations complete gracefully before the platform shuts down.

This function holds a lock on the Media Foundation platform. To unlock the platform, call . The application must call once for every call to .

The function blocks until the platform is unlocked, or until a fixed wait period has elapsed. (The wait period is a few seconds.) To avoid memory leaks, the application should unlock the platform before the wait period ends. For example, cancel any asynchronous operations that are waiting to complete and are holding a lock on the platform.

The default implementation of the interface automatically locks the Media Foundation platform when the result object is created. Releasing the interface unlocks the platform. Therefore, in most cases your application does not need to lock the platform directly. For more information, see Work Queues.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

An application must call this function before using Media Foundation. Before your application quits, call once for every previous call to .

Do not call or from work queue threads. For more information about work queues, see Work Queues.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

When you are done using the work queue, call .

Multithreaded queues use a thread pool, which can reduce the total number of threads in the pipeline. However, they do not serialize work items. A serial work queue enables the application to get the benefits of the thread pool, without needing to perform manual serialization of its own work items.

A serializer queue can also work in "reply" mode. If the caller?s method returns the MFASYNC_REPLY_CALLBACK flag, the serializer queue does not automatically advance to the next work item. Instead, the queue waits for a reply from the caller. The caller signals the reply by invoking the asynchronous result object that the work queue passes to the Invoke method. The following code illustrates how the caller signals the work queue.

 CCallback::Invoke( *pResult)	
            { DoSomeWork(); // Reply to the work queue that you are done. (pResult); // Note: This call to  does not have to occur inside the // Invoke method. You could call  at a later time.  return ;	
            }	
             CCallback::GetParameters(DWORD *pdwFlags, DWORD *pdwQueue)	
            { *pdwFlags = MFASYNC_REPLY_CALLBACK; *pdwQueue = m_QueueId; return ;	
            }	
            

Note??A previous version of this topic described the parameters incorrectly. The divisor is c and the rounding factor is d.

A multithreaded work queue uses a thread pool to dispatch work items. Whenever a thread becomes available, it dequeues the next work item from the queue. Work items are dequeued in first-in-first-out order, but work items are not serialized. In other words, the work queue does not wait for a work item to complete before it starts the next work item.

Within a single process, the Microsoft Media Foundation platform creates up to one multithreaded queue for each Multimedia Class Scheduler Service (MMCSS) task. The function checks whether a matching work queue already exists. If not, the function creates a new work queue and registers the work queue with MMCSS. The function returns the MMCSS task identifier (pdwTaskId) and the work queue identifier (pID). To queue a work item, pass the work queue identifier to any of the following functions:

• MFPutWorkItem
• MFPutWorkItemEx

The function also locks the queue. Before the process exits, call to unlock the work queue.

If the regular priority queue is being used (wszClass=""), then null must be passed in to pdwTaskId and the value 0 must be passed into BasePriority.

Call this function after a successful call to the function.

The original media type (pOrig) is stored in the new media type under the attribute. To extract the original media type, call .

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

If you are implementing an asynchronous method, use this function to invoke the caller's method.

The callback is invoked from a Media Foundation work queue. For more information, see Writing an Asynchronous Method.

The function shuts down the work queue threads, so the callback is not guaranteed to be invoked after is called.

The media type is created without any attributes.

To invoke the work item, this function passes pResult to the function. The callback is specified when you create the result object specified by pResult.

Note??Prior to Windows?7, this function was exported from mf.dll. Starting in Windows?7, this function is exported from mfplat.dll, and mf.dll exports a stub function that calls into mfplat.dll. For more information, see Library Changes in Windows?7.

Note??Prior to Windows?7, this function was exported from mf.dll. Starting in Windows?7, this function is exported from mfplat.dll, and mf.dll exports a stub function that calls into mfplat.dll. For more information, see Library Changes in Windows?7.

An application must call this function before using Media Foundation. Before your application quits, call once for every previous call to .

Do not call or from work queue threads. For more information about work queues, see Work Queues.

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

If you are writing a custom media source, you can use this function to create stream descriptors for the source. This function automatically creates the stream descriptor media type handler and initializes it with the list of types given in apMediaTypes. The function does not set the current media type on the handler, however. To set the type, call .

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

If you are writing a custom media source, you can use this function to create the source presentation descriptor. The presentation descriptor is created with no streams selected. Generally, a media source should select at least one stream by default. To select a stream, call .

This function is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

• Windows?XP with Service Pack?2 (SP2) and later.
• Windows?XP Media Center Edition?2005 with KB900325 (Windows?XP Media Center Edition?2005) and KB925766 (October 2006 Update Rollup for Windows?XP Media Center Edition) installed.

The aggregated media source is useful for combining streams from separate media sources. For example, you can use it to combine a video capture source and an audio capture source.

Use this function to deserialize an attribute store that was serialized with the function.

If dwOptions contains the flag, the function deserializes references from the stream, as follows:

• If the reference exposes the IMFObjectReferenceStream interface (through QueryInterface), the function calls IMFObjectReferenceStream::LoadReference to deserialize each reference.

• Otherwise, the function calls CoUnmarshalInterface to deserialize a proxy for the object.

This function deletes any attributes that were previously stored in pAttr.

Use this function to deserialize an attribute store that was serialized with the function.

If dwOptions contains the flag, the function deserializes references from the stream, as follows:

• If the reference exposes the IMFObjectReferenceStream interface (through QueryInterface), the function calls IMFObjectReferenceStream::LoadReference to deserialize each reference.

• Otherwise, the function calls CoUnmarshalInterface to deserialize a proxy for the object.

This function deletes any attributes that were previously stored in pAttr.

Call CoInitialize(Ex) and before calling this function.

Internally, the source reader calls the method to create a media source from the URL.

This function is available on Windows?Vista if Platform Update Supplement for Windows?Vista is installed.

Call CoInitialize(Ex) and before calling this function.

When you are done using the media sink, call the media sink's method. (The sink writer does not shut down the media sink.) Release the sink writer before calling Shutdown on the media sink.

This function is available on Windows?Vista if Platform Update Supplement for Windows?Vista is installed.

Call CoInitialize(Ex) and before calling this function.

The first three parameters to this function can be null; however, only certain combinations are valid:

?

The pAttributes parameter is required in the first case and optional in the others.

• Case 1: Specify a byte stream without a URL. The pAttributes parameter must point to an attribute store that contains the MF_TRANSCODE_CONTAINERTYPE attribute. The sink writer uses the MF_TRANSCODE_CONTAINERTYPE attribute to determine the type of file container to write, such as ASF or MP4.
• Case 2: Specify a URL without a byte stream. The sink writer creates a new file named pwszOutputURL. If pAttributes specifies an attribute store with the MF_TRANSCODE_CONTAINERTYPE attribute, the sink writer uses that attribute to determine the type of file container. Otherwise, if the MF_TRANSCODE_CONTAINERTYPE attribute is absent or pAttributes is null, the sink writer uses the file name extension to select the container type; for example, ".asf" for an ASF file.
• Case 3: Specify both a URL and a byte stream. The sink writer writes to the byte stream. The URL provided in pwszOutputURL is informational only; the sink writer does not create a new file. If pAttributes specifies an attribute store with the MF_TRANSCODE_CONTAINERTYPE attribute, the sink writer uses that attribute to determine the type of file container. Otherwise, the sink writer uses the file name extension to select the container type. The MF_TRANSCODE_CONTAINERTYPE attribute overrides the URL file name extension in this case.

This function is available on Windows?Vista if Platform Update Supplement for Windows?Vista is installed.

Call CoInitialize(Ex) and before calling this function.

By default, when the application releases the source reader, the source reader shuts down the media source by calling on the media source. At that point, the application can no longer use the media source.

To change this default behavior, set the attribute in the pAttributes parameter. If this attribute is TRUE, the application is responsible for shutting down the media source.