mfxExtLAControl

Definition

 

 

typedef struct

{

    mfxExtBuffer    Header;

    mfxU16  LookAheadDepth;

    mfxU16  DependencyDepth;

    mfxU16  DownScaleFactor;

    mfxU16  BPyramid;

 

    mfxU16  reserved1[23];

   

    mfxU16  NumOutStream;

    struct  mfxStream{

        mfxU16  Width;

        mfxU16  Height;

        mfxU16  reserved2[14];

    } OutStream[16];

}mfxExtLAControl;

 

Description

 

 

The mfxExtLAControl structure is used to control standalone look ahead behavior. This LA is performed by ENC class of functions and its results are used later by ENCODE class of functions to improve coding efficiency.

This LA is intended for one to N transcoding scenario, where one input bitstream is transcoded to several output ones with different bitrates and resolutions. Usage of integrated into the SDK encoder LA in this scenario is also possible but not efficient in term of performance and memory consumption. Standalone LA by ENC class of functions is executed only once for input bitstream in contrast to the integrated LA where LA is executed for each of output streams.

This structure is used at ENC initialization time and should be attached to the mfxVideoParam structure.

 

Members

 

 

Header.BufferId

Must be MFX_EXTBUFF_LOOKAHEAD_CTRL.

 

 

LookAheadDepth

Look ahead depth. This parameter has exactly the same meaning as LookAheadDepth in the mfxExtCodingOption2 structure.

 

 

DependencyDepth

Dependency depth. This parameter specifies the number of frames that SDK analyzes to calculate inter-frame dependency. It should be less than LookAheadDepth filed.

 

 

DownScaleFactor

Down scale factor. This parameter has exactly the same meaning as LookAheadDS in the mfxExtCodingOption2 structure. It is recommended to execute LA on downscaled image to improve performance without significant quality degradation.

 

 

BPyramid

Turn ON this flag to enable BPyramid feature (this mode is not supported by h264 encoder). See the CodingOptionValue enumerator for values of this option.

 

 

NumOutStream

Number of output streams in one to N transcode scenario.

 

 

OutStream

Output stream parameters.

 

 

    Width

Output stream width.

 

 

    Height

Output stream height.

 

Change History

 

This structure is available since SDK API 1.10.

 

 

The SDK API 1.15 adds BPyramid field.

 

 

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