Functions
The VPSS module receives images sent by the VI/VDEC module, and performs cropping, resizing, and fisheye correction on the images. In addition, the VPSS module outputs dual-channel images with different resolutions from the same source for encoding, previewing, or snapshot.
hi_mpi_sys_bind can be called to bind the VI/VDEC video streams to the VPSS for further processing. The VPSS provides the corresponding processing capability by using groups and channels in the groups, and finally outputs images to users or the next-level module (such as VO).
Concepts related to the VPSS are described as follows:
- Group
Each group shares VPSS hardware resources in time division multiplexing (TDM) mode.
- Channel
A VPSS group provides multiple channels, and each channel has independent functions such as resizing and fisheye correction.
- FRC
Stands for frame rate control and is classified into group frame rate control and channel frame rate control based on the control point.
- Group frame rate control: When hi_mpi_vpss_create_grp is used to create a group, FRC can be used to control the reception of input images of each group.
- Channel frame rate control: When hi_mpi_vpss_set_chn_attr is used to configure the group channel attributes, FRC can be used to control the image processing of each channel.
- CROP
- 3DNR
Used for three-dimensional noise reduction. The Gaussian noises are removed from images by configuring parameters, making images smoother and reducing the encoding bit rate.
- Mosaic
Overlays a Mosaic region on a VPSS output image. This function must be used together with the region management function.
- Cover
A Cover region can be used to fill the output image of the VPSS with a pure color block. This function must be used together with the region management function.
The coordinates of a Cover region can be absolute coordinates or relative coordinates.
- Aspect Ratio
The aspect ratio specifies the ratio of the width to height of the output image relative to the input image.