DirectShow Registry Settings

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

The DirectShow registry settings allow you to configure Windows Media codec playback performance, maintain a smooth audio or video playback, control the settings of the video renderer, establish quality levels and associated parameters for image encoding, control the number and size of the buffers that are available on the input pin, and specify the number and size of MediaSamples that are allocated for the connection between the MPEG-2 Program Stream Multiplexer Filter and the DVR Engine Sink filter.

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

Audio and Video Thread Priorities

If DirectShow is using a high percentage of the available CPU on a device when the device is decoding video, the audio and video performance may be uneven if other threads with higher priorities also need to use the CPU.

To maintain a smooth audio or smooth video playback at all times, you can use the following registry subkey to fine tune the priorities for the audio and video threads: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ThreadPriority

The following table describes the named values for this subkey.

The named values Highest, AboveNormal, Normal, and BelowNormal are all associated with standard operating system thread priority levels.

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

For more information about Windows Mobile thread priorities, see Priority Levels.

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ThreadPriority.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ThreadPriority]
    "Highest"=DWORD:F9
    "AboveNormal"= DWORD:FA
    "Normal"= DWORD:FB
    "BelowNormal"= DWORD:FC
    "Video"= DWORD:FB

Notes

• The default settings for DirectShow thread priorities provide satisfactory results for almost all devices; these values should not be changed unless absolutely necessary.
• Changing values for DirectShow thread priorities from their default values can be very risky because the new values can cause unexpected performance problems for other applications that are running concurrently with DirectShow. It can be difficult to test for, diagnose, and resolve these types of problems.
• If you must adjust the DirectShow audio and video thread priorities, make sure that the DirectShow priorities are higher than the audio and video driver priorities in your operating system design. Also, make sure that the audio priority is higher than the priority of the software mixer. Failing to take these steps almost always results in audio and video playback performance problems.

Video Renderer Settings

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

The following table shows the named values for this subkey.

The following table describes the AMDDS flag values to use with the SurfaceTypes named value.

Encoder Quality Settings

You can establish quality levels and associated parameters for image encoding with the following registry subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectShow\ImageSink\Quality\ <Quality Level> \ <File Extension> \ <Parameter Name>

The IImageSinkFilter Interface interface uses this subkey to obtain parameter values that are passed on to the image encoding factory. The designated encoder quality level, the file extension, and the parameter name are all integral to the path of the registry subkey.

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 a value for the Compression parameter when the device is encoding a .jpg 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 Use and Performance During Streaming

You can use the following registry key 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 key allows you to choose between memory use and performance. For high bit-rate, High Definition video files, you must allow a large amount of memory to prevent the device from running out of buffer space when a long stream of hard frames arrives.

The registry key named values are multipliers of the pre-roll values that are set in the file. The values should be specified as percentage numbers. For example, a number of 300 denotes a multiplier of 3x, and 1 denotes a multiplier of 0.01X.

Settings for the MPEG-2 Program Stream Multiplexer Filter

You can specify the number and size of MediaSamples that are allocated for the connection between the MPEG-2 Program Stream Multiplexer Filter and the DVR Engine Sink filter by using the following subkey:

HKEY_LOCAL_MACHINE\Software\Microsoft\Dvr\DvrPsMux

The following table shows the named values for this subkey. These values are not set by default.

See Also

Reference

DMO Wrapper Filter

Other Resources

DirectShow Application Development