MFPKEY_DESIRED_VBRQUALITY Property

Specifies the desired quality level for quality based (1-pass) variable-bit-rate (VBR) encoding of audio streams.

Available only by using IPropertyStore.

VT_UI4

This value can be from 0 to 100, where 100 is maximum quality. A value of 0 indicates that the quality-based VBR encoding method is not to be used.

To enumerate VBR modes that meet a certain quality requirement, set the following encoder properties.

Set MFPKEY_VBRENABLED to VARIANT_TRUE.
Set MFPKEY_CONSTRAIN_ENUMERATED_VBRQUALITY to VARIANT_TRUE.
Set MFPKEY_DESIRED_VBRQUALITY to the desired quality. For Lossless modes, set the desired quality to 100.

Additional resources