AVEncMPVGOPSize property

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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.]

Specifies the maximum number of pictures from one group-of-pictures (GOP) header to the next GOP header.

This property is read/write.

Data type


Property GUID


Property value

Encoders can implement this property as an enumerated set or as a linear range.


Set this property before starting a recording.

Applies to Windows 8: The encoded GOP size shall be smaller than or equal to the specified number through this property, in order to keep the same B frame pattern set by CODECAPI_AVEncMPVDefaultBPictureCount throughout the GOP or due to scene change. For example, when the number of B frames in a GOP is specified to be 2, and GOP size is 11, then encoder shall produce GOP size of 10 frames or less. When scene change happens in the middle of a GOP, encoder might also insert key frame and produce smaller GOP.

GOP size 0 is encoder dependent and encoders can choose different GOP sizes based on their implementation/quality/performance. Encoders should honor the GOP size and truncate B frames in this case.


Requirement Value
Minimum supported client
Windows 2000 Professional [desktop apps | UWP apps]
Minimum supported server
Windows 2000 Server [desktop apps | UWP apps]

See also

Codec API Properties

ICodecAPI Interface