This base class is used for building video renderer filters.
Protected Data Members
| Name | Description |
| m_bDrawLateFrames | Flag to signal that no frames are to be dropped. Debug only. This destroys synchronization. |
| m_bSupplierHandlingQuality | TRUE indicates quality control messages are being handled. This lets the renderer know to wait until as late as possible to drop frames itself, and to display the next frame very early after the supplier has dropped a frame. |
| m_cFramesDrawn | Total number of frames that have been drawn since streaming started. |
| m_cFramesDropped | Cumulative frames that have been dropped in the renderer since streaming started. Frames can also be dropped upstream without the renderer recognizing them. |
| m_idDecision | MSR_id for the decision code of ShouldDrawSampleNow. |
| m_idDuration | MSR_id for the duration of a frame. |
| m_idFrameAccuracy | Performance log identifier for the time in milliseconds that the frame was late. |
| m_idFrameAvg | Performance log identifier for the average frame time that is used for synchronization and quality control. |
| m_idQualityRate | MSR_id for the quality rate requested. |
| m_idQualityTime | MSR_id for the quality time requested. |
| m_idRenderAvg | Performance log identifier for the average renderer time recorded. |
| m_idSchLateTime | MSR_id for how late the frame was when scheduled. |
| m_idSendQuality | MSR_id for timing the notifications (unused). |
| m_idTimeStamp | MSR_id for a frame time stamp. |
| m_idWait | Performance log identifier for the recorded wait time (unused). |
| m_idWaitReal | Performance log identifier for the true wait time. |
| m_iSumFrameTime | Sum of the interframe times; needed for the property page. |
| m_iSumSqAcc | Sum of the squares of the accuracies (in milliseconds) needed for the property page. |
| m_iSumSqFrameTime | Sum of the squares of interframe times; needed for the property page. |
| m_iTotAcc | Sum of the accuracies (in milliseconds) needed for the property page. |
| m_nNormal | Number of consecutive frames drawn at their scheduled time. A negative number indicates that a frame has just been dropped by the renderer. |
| m_trDuration | Duration of the last frame (difference between the start and end times). |
| m_trFrame | Most recently recorded time between frames. Used in statistical measurements. |
| m_trFrameAvg | Average interframe time in reference time units. |
| m_trEarliness | How early a frame is allowed to be played when a frame has just been dropped. |
| m_trLastDraw | Time of previous frame. Used for interframe time references. |
| m_trLate | Amount of time that the current frame was late. Used in statistical measurements. |
| m_trThrottle | Period to insert after rendering each frame, typically used when audio quality has been increased and video performance must be decreased to allow this. |
| m_trRenderAvg | Time that frames are taking to perform the bit-block transfer. |
| m_trRenderLast | Time for the last frame bit-block transfer. |
| m_trRenderStart | Time the bit-block transfer started. Used to get m_trRenderLast. |
| m_trWaitAvg | Average wait time in reference time units. |
| m_tStreamingStart | Used for property page statistics. Represents the start time of the current streaming process or the previous streaming process if not currently streaming. |
Member Functions
| Name | Description |
| CBaseVideoRenderer | Constructs a CBaseVideoRenderer object. |
| GetStdDev | Estimates the standard deviation in milliseconds between when each frame is due and when it is actually rendered, for per-frame statistics. |
| PreparePerformanceData | Sets the m_trLate and m_trFrame values of the current frame. |
| ThrottleWait | Inserts a wait period after each frame. |
Overridable Member Functions
| Name | Description |
| JoinFilterGraph | Sends EC_WINDOW_DESTROYED event notification when filter is removed from the filter graph. |
| OnDirectRender | Collects timing information that controls synchronization and quality control. |
| OnRenderEnd | Records information for quality control and synchronization. |
| OnRenderStart | Records information for quality control and synchronization. |
| OnStartStreaming | Resets all times that control streaming. |
| OnStopStreaming | Called at the end of streaming to fix times for the property page report. |
| OnWaitEnd | Called when a wait time ends. Performance logging only. |
| OnWaitStart | Updates times spent waiting and not waiting. Performance logging only. |
| RecordFrameLateness | Records how timely the rendering occurred and gathers statistics for the property page. |
| ResetStreamingTimes | Resets all times that control the streaming. |
| ScheduleSample | Sets up an advise link with the clock. |
| SendQuality | Sends a quality message to indicate what the supplier should do about quality. |
| ShouldDrawSampleNow | Determines if the video should be drawn when it is due, without setting a timer advise link with the clock. |
Implemented IQualProp Methods
| Name | Description |
| get_AvgFrameRate | Retrieves the average frame rate since streaming started in frames per 100 seconds. |
| get_AvgSyncOffset | Retrieves the average of the time in milliseconds between when each frame was due and when it was actually rendered. This applies to all frames since streaming started. |
| get_DevSyncOffset | Retrieves the standard deviation of the time in milliseconds between when each frame was due and when it was actually rendered for all frames since streaming started. |
| get_FramesDrawn | Retrieves the number of frames drawn since streaming started. |
| get_FramesDroppedInRenderer | Retrieves the number of frames dropped by the renderer. Frames can also be dropped upstream. |
| get_Jitter | Retrieves the standard deviation of the time in milliseconds between each frame and the next. This applies to all frames since streaming started. |
Implemented INonDelegatingUnknown Methods
| Name | Description |
| NonDelegatingQueryInterface | Provides access to other interfaces, particularly the property page. |
Implemented IQualityControl Methods
| Name | Description |
| Notify | Notifies the recipient that a quality change is requested. |
| SetSink | Sets the IQualityControl object that will receive quality messages. |
Constructs a CBaseVideoRenderer object.
CBaseVideoRenderer(
REFCLSID RenderClass,
TCHAR *pName,
LPUNKNOWN pUnk,
HRESULT *phr
);
No return value.
Calculates and retrieves the average frame rate achieved.
HRESULT get_AvgFrameRate(
int *piAvgFrameRate
);
Returns an HRESULT value.
This member function implements the IQualProp::get_AvgFrameRate method.
Retrieves the average of the time in milliseconds between when each frame was due and when it was actually rendered for all frames since streaming started.
HRESULT get_AvgSyncOffset(
int *piAvg
);
Returns an HRESULT value.
This member function implements the IQualProp::get_AvgSyncOffset method.
Retrieves the standard deviation of the time in milliseconds between when each frame was due and when it was actually rendered, for all frames since streaming started.
HRESULT get_DevSyncOffset(
int *piDev
);
Returns an HRESULT value.
This member function implements the IQualProp::get_DevSyncOffset method.
Retrieves the m_cFramesDrawn member variable, giving the number of frames drawn since streaming started.
HRESULT get_FramesDrawn(
int *pcFramesDrawn
);
Returns an HRESULT value.
This member function implements the IQualProp::get_FramesDrawn method.
Retrieves the number of frames dropped by the renderer.
HRESULT get_FramesDroppedInRenderer(
int *pcFramesDropped
);
Returns an HRESULT value.
This member function implements the IQualProp::get_FramesDroppedInRenderer method. This is how the property page retrieves the data from the scheduler. Note that frames can also be dropped upstream without the renderer even seeing them.
Retrieves the standard deviation of time in milliseconds between each frame and the next for all frames since streaming started.
HRESULT get_Jitter(
int *piJitter
);
Returns an HRESULT value.
This member function implements the IQualProp::get_Jitter method.
Estimates the standard deviation in milliseconds between when each frame is due and when it is actually rendered, for per-frame statistics.
HRESULT GetStdDev(
int nSamples,
int *piResult,
LONGLONG llSumSq,
LONGLONG iTot
);
Returns NOERROR.
Sends EC_WINDOW_DESTROYED event notification when a filter is removed from the filter graph.
HRESULT JoinFilterGraph(
IBaseFilterGraph * pGraph,
LPCWSTR pName
);
No return value.
This member function overrides the CBaseFilter::JoinFilterGraph member function. If this function determines that the filter is being notified that it is leaving the filter graph (pGraph is null, but m_pGraph is not), it sends an EC_WINDOW_DESTROYED event notification so that the resource manager does not hold on to the renderer as a focus object.
Returns an interface and increments the reference count.
HRESULT NonDelegatingQueryInterface(
REFIID riid,
VOID **ppv
);
Returns a pointer to the interface.
Override this member function to publish the interface.
This member function implements the INonDelegatingUnknown::NonDelegatingQueryInterface method. It exposes the IQualProp interface and then calls CBaseRenderer::NonDelegatingQueryInterface to expose interfaces implemented in the base classes.
Receives a notification that a quality change is requested.
HRESULT Notify(
IBaseFilter * pSelf,
Quality q
);
Returns an HRESULT value.
This member function implements the IQualityControl::Notify method on the video renderer. This is called, typically by the filter graph manager, when the quality must be cut back. This might occur when the quality of audio playback has been increased to the point that the video playback quality must be decreased.
Notify sets the m_trThrottle data member to a delay value to be inserted between frames by ThrottleWait.
Collects timing information that controls synchronization and quality control.
virtual void OnDirectRender(
IMediaSample *pMediaSample
);
Returns an HRESULT value.
Call this member function instead of OnRenderStart and OnRenderEnd. This is used by the Microsoft® DirectDraw® video renderer.
Performs smoothing for cases where the rendering time varies due to interruptions.
void OnRenderEnd(
IMediaSample *pMediaSample
);
No return value.
This member function should be called just after drawing an image.
This member function overrides CBaseRenderer::OnRenderEnd.
Sets information for rendering.
void OnRenderStart(
IMediaSample *pMediaSample
);
No return value.
This member function retrieves the current clock time from the system and stores it in a member variable to be used when the drawing is complete. The function also performs performance logging. This member function should be called just before drawing starts.
This member function overrides CBaseRenderer::OnRenderStart.
Resets all times that control streaming.
HRESULT OnStartStreaming(void);
Returns an HRESULT value.
This member function overrides CBaseRenderer::OnStartStreaming.
Called at the end of streaming to fix times for the property page report.
HRESULT OnStopStreaming(void);
Returns an HRESULT value.
This member function is called twice, once when pausing and again when the stream is actually stopped.
This member function overrides CBaseRenderer::OnStopStreaming.
Called when a wait time ends.
void OnWaitEnd(void);
No return value.
This member function does only performance logging. It is called when the thread is awoken from waiting in the window, or when the next sample is due to be rendered. It could eventually be used to gather information that controls synchronization.
Updates times spent waiting and not waiting.
void OnWaitStart(void);
No return value.
This member function is called when starting to wait for a rendering event. It is used only for performance measurements.
Sets the m_trLate and m_trFrame values of the current frame.
void PreparePerformanceData(
int trLate,
int trFrame
);
No return value.
This member function sets m_trLate to the value of trLate and m_trFrame to the value of trFrame.
When the CBaseVideoRenderer::RecordFrameLateness member function is called from either CBaseVideoRenderer::OnRenderStart or CBaseVideoRenderer::OnDirectRender, it passes the values of m_trLate and m_trFrame for it to update the statistics. PreparePerformanceData is called from CBaseVideoRenderer::OnWaitEnd to set these data member values.
Records how timely the rendering occurred and gathers statistics for the property page.
virtual void RecordFrameLateness(
int trLate,
int trFrame
);
No return value.
Resets all times that control the streaming.
virtual HRESULT ResetStreamingTimes(void);
Returns an HRESULT value.
The times are set so that frames will not be initially dropped and so that the first frame will be drawn.
Overrides the base class that does the main work to keep a count of samples drawn and dropped (which are used by the IQualProp implementation).
BOOL ScheduleSample(
IMediaSample *pMediaSample
);
Returns TRUE if the sample is scheduled; otherwise, returns FALSE.
Sends a quality message to indicate what the supplier should do about quality.
virtual HRESULT SendQuality(
REFERENCE_TIME trLate,
REFERENCE_TIME trRealStream
);
Returns an HRESULT value.
This member function sends a quality control message upstream to control quality management. The nature of the quality message (that is, whether to reduce or increase the number of samples) is determined in the quality management implementation in this derived class (see CBaseVideoRenderer::ShouldDrawSampleNow).
Sets the IQualityControl object that will receive quality messages.
HRESULT SetSink(
IQualityControl *piqc
);
Returns an HRESULT value.
This member function implements the IQualityControl::SetSink method on the video renderer.
Determines if the video should be drawn without setting a timer advise link with the clock.
virtual HRESULT ShouldDrawSampleNow(
IMediaSample *pMediaSample,
REFERENCE_TIME *ptrStart,
REFERENCE_TIME *ptrEnd
);
Returns an HRESULT value. Returns S_OK to mean draw at once without waiting, S_FALSE to mean draw at time ptrStart, or error to mean do not draw the sample; that is, skip it to save time.
This member function overrides CBaseRenderer::ShouldDrawSampleNow.
Inserts a wait period after each frame.
void ThrottleWait(void);
No return value.
This member function waits for a time period obtained from the m_trThrottle data member.
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