IAMVideoCompression interface (strmif.h)
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The IAMVideoCompression interface sets and retrieves video compression properties. It is supported by some video compression filters, and also by some video capture filters that output compressed video. Filters that support this interface expose it through their output pins.
An application can use this interface to control how video is compressed, including characteristics such as the key-frame rate or the compression quality.
A filter that supports this interface might not support every method. Use the IAMVideoCompression::GetInfo method to determine which methods the filter supports.
Inheritance
The IAMVideoCompression interface inherits from the IUnknown interface. IAMVideoCompression also has these types of members:
Methods
The IAMVideoCompression interface has these methods.
| IAMVideoCompression::get_KeyFrameRate The get_KeyFrameRate method retrieves the current key-frame rate. |
| IAMVideoCompression::get_PFramesPerKeyFrame The get_PFramesPerKeyFrame method retrieves the rate of predicted (P) frames per key frame. |
| IAMVideoCompression::get_Quality The get_Quality method retrieves the current compression quality. |
| IAMVideoCompression::get_WindowSize The get_WindowSize method retrieves the number of frames over which the compressor will maintain the average data rate. |
| IAMVideoCompression::GetInfo The GetInfo method retrieves information about the filter's compression properties, including capabilities and default values. |
| IAMVideoCompression::OverrideFrameSize The OverrideFrameSize method overrides the frame size of a specified frame. |
| IAMVideoCompression::OverrideKeyFrame The OverrideKeyFrame method instructs the filter to compress a particular frame as a key frame. |
| IAMVideoCompression::put_KeyFrameRate The put_KeyFrameRate method sets the key-frame rate. |
| IAMVideoCompression::put_PFramesPerKeyFrame The put_PFramesPerKeyFrame method sets the rate of predicted (P) frames per key frame. |
| IAMVideoCompression::put_Quality The put_Quality method sets the compression quality. |
| IAMVideoCompression::put_WindowSize The put_WindowSize method sets the number of frames over which the compressor must maintain an average data rate. |
Remarks
For Windows Driver Model (WDM) devices, the WDM Video Capture Filter automatically exposes this interface if the WDM driver supports the PROPSETID_VIDCAP_VIDEOCOMPRESSION property set. For more information, see the Windows Driver Kit (WDK) documentation.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | strmif.h (include Dshow.h) |