CODECAPI_AVEncVideoLTRBufferControl property

Article
08/19/2021

Specifies the maximum number of Long Term Reference (LTR) frames controlled by application.

Data type

ULONG (VT_UI4)

Property GUID

CODECAPI_AVEncVideoLTRBufferControl

Property value

The value of this control includes two fields, where each field has 16 bits.

Value	Meaning
The first field Bits[0..15]	The number of LTR frames controlled by the application. H.264/AVC encoders: Assuming the value is N and N is non-zero value, at each IDR frame the encoder must automatically mark the frames following the IDR frame (and including the IDR frame) as LTR frames as long as all 3 of the following apply: The frame is not already set to be marked as a long term reference frame. The frame is a base layer frame. For example, syntax element temporal_id equal to 0. The number of frames currently marked as LTR is less than N.
The second field Bits[16..31]	The trust mode of LTR control. H.264/AVC encoders: 1 (Trust Until) means the encoder may use an LTR frame unless the app explicitly invalidates it through the CODECAPI_AVEncVideoUseLTRFrame control. Other values are invalid and reserved for future use.

Value

Meaning

The first field
Bits[0..15]

The number of LTR frames controlled by the application.
H.264/AVC encoders:
Assuming the value is N and N is non-zero value, at each IDR frame the encoder must automatically mark the frames following the IDR frame (and including the IDR frame) as LTR frames as long as all 3 of the following apply:

The frame is not already set to be marked as a long term reference frame.
The frame is a base layer frame. For example, syntax element temporal_id equal to 0.
The number of frames currently marked as LTR is less than N.

The second field
Bits[16..31]

The trust mode of LTR control.
H.264/AVC encoders:
1 (Trust Until) means the encoder may use an LTR frame unless the app explicitly invalidates it through the CODECAPI_AVEncVideoUseLTRFrame control.
Other values are invalid and reserved for future use.

Remarks

This is a static API.

Default value shall be 0

Requirements

Requirement	Value
Minimum supported client	Windows 8.1 [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2012 R2 [desktop apps \| UWP apps]
Header	Codecapi.h