DirectShow Registry Settings (Compact 2013)

3/26/2014

The following topics describe programming elements that can add, delete, enumerate, or represent DirectShow registry settings:

• AMovieDllRegisterServer function
• DMORegister function
• IFilterMapper Interface interface
• IFilterMapper::RegisterFilter method
• IFilterMapper::RegisterPin method
• IFilterMapper::UnregisterFilter method
• IFilterMapper::UnregisterFilterInstance method
• IFilterMapper::UnregisterPin method
• REGFILTER structure

Windows Media Video Codec Performance

The HKLM\Software\Microsoft\DirectX\DirectShow\WMVDecoder registry key allows you to adjust Windows Media video codec playback performance and quality for x86 processors only. This entry is not available for other architectures.

[HKEY_LOCAL_MACHINE\Software\Microsoft\DirectX\DirectShow\WMVDecoder]
    "PostProcessing"=dword:FFFFFFFF

By default, each frame from a Windows Media video stream undergoes some level of post-processing after it is decoded.

The level of post-processing depends on the level of CPU performance. This post-processing smoothes the video frame by deblocking the image to smooth artifacts that are inherent to the digital compression process, and by deringing the image to correct for certain motion artifacts. Adjusting the amount of post-processing directly affects your target device's CPU usage.

The following table shows the allowable settings for the PostProcessing named entry.

• FFFFFFFF
  Automatic. The Windows Media codec automatically sets the level of post-processing based on the incoming data and the CPU of your device.

• 0
  Disabled. All post-processing is disabled. This setting produces the highest frame rates during playback, but at the expense of video quality.

• 1
  Fast deblocking. The codec runs each frame through a coarse deblocking filter.

• 2
  Full deblocking. The codec runs each frame through a fine deblocking filter.

• 3
  Fast deblocking and deringing. The codec runs each frame through a coarse deblocking filter and through a deringing filter.

• 4
  Full deblocking and deringing. The codec runs each frame through a fine deblocking filter and also through a deringing filter. This setting has the highest CPU usage. It produces the highest quality image for each individual frame; however, the overall frame rate may be degraded.

Audio and Video Thread Priorities

If DirectShow uses a very high percentage of your device's CPU when decoding video, you may experience choppy audio and video performance if other threads with higher priorities need to use the CPU.

If you must maintain smooth audio or smooth video playback at all times, you can use the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ThreadPriority to fine tune the priorities for the audio and video threads.

The following table shows the named entries and the associated registry values for this key.

All of the named values, except for Video, are associated with standard operating system thread priority levels. For more information, see SetThreadPriority.

DirectShow threads that are identified with the standard operating system thread priorities run at the priority levels specified by these registry settings instead of the normal values. These settings only affect threads that are owned by DirectShow. They do not affect the global OS priority levels and they do not affect threads owned by Windows Media Player.

The following registry key example shows the default values for this registry subkey.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ThreadPriority]
    "Critical"=DWORD:F8
    "Highest"=DWORD:F9
    "AboveNormal"= DWORD:FA
    "Normal"= DWORD:FB
    "BelowNormal"= DWORD:FC
    "Lowest"= DWORD:FD
    "AboveIdle"= DWORD:FE
    "Idle"= DWORD:FF
    "Video"= DWORD:FB

Adjusting the thread priorities from their default values can be risky because the adjustments can cause unexpected performance issues for other applications running concurrently with your DirectShow application. Such issues can be very difficult to test, diagnose, and resolve.

If you need to adjust the DirectShow audio and video thread priorities, make sure the DirectShow priorities are higher than the audio and video driver priorities in your OS design. Also make sure the audio priority is higher than that of the software mixer. If you do not perform these actions, the result will be in audio and video playback performance issues.

Video Renderer Settings

You can control the settings of the video renderer with the registry key HKEY_LOCAL_MACHINE\Software\Microsoft\DirectX\DirectShow\Video Renderer.

The following table shows the named entries for this key.

The following table shows the DirectShow DirectDraw Surface (AMDDS) values for use with the SurfaceTypes named entry.

Encoder Quality Settings

You can establish quality levels and associated parameters for image encoding with the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ImageSink\Quality\<Quality Level>\<File Extension>\<Parameter Name>. The IImageSinkFilter Interface uses this key to obtain parameter values that pass to the image encoding factory.

The quality level, file extension, and parameter name are all integral to the path of the registry key. The following table shows the named values for a parameter. Each of these values corresponds to a member of a StructEncoderParameter structure.

The following example shows a registry entry that sets one value for the Compression parameter when encoding a JPEG file at quality level 0.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ImageSink\Quality\0\jpg\Compression]
"GUID"="0xe09d739d-ccd4-44ee-8eba-3fbf8be4fc58"
"Value"=dword:00000003
"Type"=dword:00000004
"NumberOfValues"=dword:00000001

Memory Usage and Performance During Streaming

The following registry key can be used to control how much memory is allowed for the buffer during streamed playback of media by using Windows Media technologies:

HKEY_CURRENT_USER\Software\Microsoft\Netshow\Player\

This entry gives you a choice between memory usage and performance. For very high bit-rate, high definition video files, you need to allow a very large amount of memory to avoid running out of buffer when a long stream of hard frames arrive.

The registry keys are just multipliers of the pre-roll value set in the file. They should be specified as percentage numbers. Therefore, a number of 300 means a multiplier of 3x. 1 means 0.01X.

Settings for the MPEG-2 Program Stream Multiplexer Filter

You can use the following registry key to recommend for the number and size of MediaSamples allocated for the connection between the MPEG-2 Program Stream Multiplexer Filter and the DVR Engine Sink filter:

[HKEY_LOCAL_MACHINE\Software\Microsoft\Dvr\DvrPsMux]

These values are not set by default. They assist in recommending the number and size of media samples allocated for the connection between the MPEG-2 Program Stream Multiplexer Filter and the DVR Engine Sink filter.

The following list contains programming elements that can add, delete, enumerate, or represent DirectShow registry settings:

• CBaseFilter Class class
• CBaseFilter::Register method
• CBaseFilter::Unregister method
• IAMovieSetup interface
• IAMovieSetup::Register method
• IAMovieSetup::Unregister method
• IEnumRegFilters interface

MPEG Splitter Settings

You can control the number and size of the buffers available on the input pin of the MPEG-1 Parser/Splitter with the registry key HKEY_LOCAL_MACHINE\Software\Microsoft\Multimedia\DirectShow\MPEG Splitter.

The upstream asynchronous file source filter uses this key during pin negotiation; see File Source (Async) Filter.

The following table shows the named entries for this key.

See Also

Reference

DirectShow Reference
DMO Wrapper Filter