RGBA to NV12 - 2023.2 English

Vitis Libraries

Release Date
2023-12-20
Version
2023.2 English

The rgba2nv12 function converts a 4-channel RGBA image to NV12 (4:2:0) format. The function outputs Y plane and interleaved UV plane separately. NV12 holds the subsampled data, Y is sampled for every RGBA pixel and U, V are sampled once for 2row and 2columns (2x2) pixels. UV plane is of (rows/2)*(columns/2) size as U and V values are interleaved.

API Syntax

template <int SRC_T, int Y_T, int UV_T, int ROWS, int COLS, int NPC=1, int XFCVDEPTH_IN = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT_0 = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT_1 = _XFCVDEPTH_DEFAULT>
void rgba2nv12(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN> & _src, xf::cv::Mat<Y_T, ROWS, COLS, NPC, XFCVDEPTH_OUT_0> & _y, xf::cv::Mat<UV_T, ROWS/2, COLS/2, NPC, XFCVDEPTH_OUT_1> & _uv)

Parameter Descriptions

The following table describes the template and the function parameters.

Table 356 Table rgba2nv12 Parameter Description
Parameter Description
SRC_T Input pixel type. Only 8-bit,unsigned, 4-channel is supported (XF_8UC4).
Y_T Output pixel type. Only 8-bit,unsigned, 1-channel is supported (XF_8UC1).
UV_T Output pixel type. Only 8-bit,unsigned, 2-channel is supported (XF_8UC2).
ROWS Maximum height of input and output image.
COLS Maximum width of input and output image. Must be a multiple of 8 for 8 pixel mode.
NPC Number of pixels to be processed per cycle; possible options are XF_NPPC1 and XF_NPPC8 for 1 pixel and 8 pixel operations respectively.
XFCVDEPTH_IN Depth of input image
XFCVDEPTH_OUT_0 Depth of output image
XFCVDEPTH_OUT_1 Depth of output image
_src Input RGBA image of size (ROWS, COLS).
_y Output Y image of size (ROWS, COLS).
_uv Output UV image of size (ROWS/2, COLS/2).

Resource Utilization

The following table summarizes the resource utilization of RGBA to NV12 for different configurations, generated using Vivado HLS 2019.1 tool for the Xczu9eg-ffvb1156-1-i-es1 FPGA, to process a HD (1080x1920) image.

Table 357 Table rgba2nv12 Function Resource Utilization Summary
Operating Mode Operating Frequency (MHz) Utilization Estimate
BRAM_18K DSP_48Es FF LUT CLB
1 Pixel 300 0 9 802 452 128

Performance Estimate

The following table summarizes the performance of RGBA to NV12 for different configurations, as generated using Vivado HLS 2019.1 tool for the Xczu9eg-ffvb1156-1-i-es1, to process a grayscale HD (1080x1920) image.

Table 358 Table rgba2nv12 Function Performance Estimate Summary
Operating Mode Latency Estimate
Max Latency (ms)
1 pixel operation (300 MHz) 1.8