The video refresh rate is controlled by stretching the video front porch value. In AXI4-Stream mode, the following API is provided to adjust the video frame rate by configuring the video front porch values. Based on the VFP value, v_tc generates the new timing data.
void XV_HdmiTxSS1_SetVrrVfpStretch(XV_HdmiTxSs1 *InstancePtr,u16 StretchValue)