vvas_xabrscaler

There are several use cases where the available frame resolution and color formats may not be suitable for the consumption by the next component. For example, in case of Machine Learning applications, input can be from different sources, resolutions, but ML models work on a fixed resolution. In such cases, the input image needs to be re-sized to a different resolution. Also, the input image color format may be YUV/NV12, but the ML models require image to be in BGR format. In this case we need to do the color space conversion as well. ML model may also require some pre-processing, like Mean Subtraction, Normalization etc. on the input image.

In adaptive bit rate (ABR) use cases, one video is encoded at different bit rates so that it can be streamed in different network bandwidth conditions without any artifacts. To achieve this, input frame is decoded, resized to different resolutions and then re-encoded. vvas_xabrscaler is a plug-in that takes one input frame and can produce several outputs frames having different resolutions and color formats. The vvas_xabrscaler is a GStreamer plug-in developed to accelerate the resize and color space conversion, Mean Subtraction, Normalization, and cropping. For more implementation details, refer to vvas_xabrscaler source code.

This plug-in supports:

• Single input, multiple output pads

• Color space conversion

• Resize

• Each output pad has independent resolution and color space conversion capability.

• Crop of input buffer

Prerequisite

This plug-in requires the image_processing kernel to be available in the hardware design and the kernel is configured with required color formats and maximum resolution as per your application needs. image_processing kernel configuration, like maximum resolution supported, color formats etc. can be found in image-processing kernel config

Input and Output

This plug-in accepts buffers with the following color format standards:

• RGBx

• YUY2

• r210

• Y410

• NV16

• NV12

• RGB

• v308

• I422_10LE

• GRAY8

• NV12_10LE32

• BGRx

• GRAY10_LE32

• BGRx

• UYVY

• BGR

• RGBA

• BGRA

• I420

• GBR

Important

Make sure that the color formats needed for your application are supported by the image-processing hardware kernel.

image_processing kernel configuration, like maximum resolution supported, color formats etc. can be found in image-processing kernel config

Control Parameters and Plug-in Properties

The following table lists the GStreamer plug-in properties supported by the vvas_xabrscaler plug-in.

Table 3: vvas_xabrscaler Plug-in Properties

Property Name	Type	Range	Default	Description
avoid-output-copy	Boolean	true/false	False	Avoid output frames copy on all source pads even when downstream does not support GstVideoMeta metadata
enable-pipeline	Boolean	true/false	false	Enable buffer pipelining to improve performance in non zero-copy use cases
in-mem-bank	Unsigned int	0 - 65535	0	VVAS input memory bank to allocate memory
out-mem-bank	Unsigned int	0 - 65535	0	VVAS o/p memory bank to allocate memory
xclbin-location	string	N/A	./binary_container_1 xclbin	The location of xclbin.
kernel-name	string	N/A	image_processing: {image_processing_1}	Kernel name and instance separated by a colon.
dev-idx	integer	0 to 31	0	Device index This is valid only in PCIe/ Data Center platforms.
ppc	integer	1, 2, 4	2	Pixel per clock supported by a multi- scaler kernel
scale-mode	integer	0, 1, 2	0	Scale algorithm to use: 0:BILINEAR 1:BICUBIC 2:POLYPHASE
coef-load-type	integer	0 => Fixed 1 => Auto	1	Type of filter Coefficients to be used: Fixed or Auto generated
num-taps	integer	6=>6 taps 8=>8 taps 10=>10 taps 12=>12 taps	1	Number of filter taps to be used for scaling
alpha-b	float	0 to 128	0	Mean subtraction for blue channel , needed for PPE
alpha-g	float	0 to 128	0	Mean subtraction for green channel , needed for PPE
alpha-r	float	0 to 128	0	Mean subtraction for red channel , needed for PPE
beta-b	float	0 to 1	1	Scaling for blue channel, needed for PPE
beta-g	float	0 to 1	1	scaling for green channel, needed for PPE
beta-r	float	0 to 1	1	scaling for red channel, needed for PPE
crop-x	unsigned integer	0 to 4294967295	0	Crop X coordinate
crop-y	unsigned integer	0 to 4294967295	0	Crop Y coordinate
crop-width	unsigned integer	0 to 4294967295	0	Crop width ( minimum: 64), if this is 0 or not set, it will be calculated as input width - crop-x
crop-height	unsigned integer	0 to 4294967295	0	Crop height ( minimum: 64), if this is 0 or not set, it will be calculated as input height - crop-y
software-scaling	Boolean	true/false	false	Enable software scaling instead of accelerated scaling.

Note

Image-processing IP has some alignment requirement, hence user given parameters for crop are aligned as per the IP requirement, alignment ensures that it covers the region of crop specified by user, hence final cropped image may have extra pixels cropped.

Example Pipelines

One input one output

The following example configures vvas_xabrscaler in one input and one output mode. The input to the scaler is 1280 x 720, NV12 frames that are resized to 640 x 360 resolution, and the color format is changed from NV12 to BGR.

gst-launch-1.0 videotestsrc num-buffers=100 \
! "video/x-raw, width=1280, height=720, format=NV12" \
! vvas_xabrscaler xclbin-location="/run/media/mmcblk0p1/dpu.xclbin" kernel-name=image_processing:{image_processing_1} \
! "video/x-raw, width=640, height=360, format=BGR" ! fakesink -v

One input multiple output

The following example configures vvas_xabrscaler for one input and three outputs. The input is 1920 x 1080 resolution in NV12 format. There are three output formats:

• 1280 x 720 in BGR format

• 300 x 300 in RGB format

• 640 x 480 in NV12 format

gst-launch-1.0 videotestsrc num-buffers=100 \
! "video/x-raw, width=1920, height=1080, format=NV12, framerate=60/1" \
! vvas_xabrscaler xclbin-location="/run/media/mmcblk0p1/dpu.xclbin" kernel-name=image_processing:{image_processing_1} name=sc sc.src_0 \
! queue \
! "video/x-raw, width=1280, height=720, format=BGR" \
! fakesink sc.src_1 \
! queue \
! "video/x-raw, width=300, height=300, format=RGB" \
! fakesink sc.src_2 \
! queue \
! "video/x-raw, width=640, height=480, format=NV12" \
! fakesink -v

Crop with multiple output:

The following example configures vvas_xabrscaler for one input and three outputs. The input is 1920 x 1080 resolution in NV12 format. This input is cropped at X:140, Y:300, Width:640, Height:480.

Cropped input is scaled and converted to below format:

• 640 * 480 in RGB format

• 320 * 240 in RGB format

• 256 * 256 in NV12 format

gst-launch-1.0 -v \
videotestsrc num-buffers=10 ! video/x-raw,format=NV12,width=1920,height=1080 \
! vvas_xabrscaler xclbin-location="/run/media/mmcblk0p1/dpu.xclbin" kernel-name=image_processing:{image_processing_1} crop-x=140 crop-y=300 crop-width=640 crop-height=480 name=sc \
sc.src_0 ! queue ! video/x-raw,format=RGB,width=640,height=480 ! filesink location=480p.yuv \
sc.src_1 ! queue ! video/x-raw,format=RGB,width=320,height=240 ! filesink location=240p.yuv \
sc.src_2 ! queue ! video/x-raw,format=NV12,width=256,height=256 ! filesink location=256p.yuv -v

vvas_xabrscaler with software scaling kernel

VVAS plugin “vvas_xabrscaler” can also work with software implementation of the IP. The same plugin can be used to invoke the software scaling functionality. User needs to set few properties on “vvas_xabrscaler” plugin to invoke the software scaling, please refer the example pipeline mentioned below. The current release version supports only fixed and 12 tap filter coefficients. Below are the formats supported by the current release version.

• NV12

• RGB

• GRAY8

• BGR

• I420

Note: For GRAY8, only scaling is supported, cross format conversion is not supported.

Example pipeline:

gst-launch-1.0  videotestsrc num-buffers=10  \
! video/x-raw, width=1920, height=1080, format=NV12  \
! vvas_xabrscaler kernel-name="image_processing_sw:{image_processing_sw_1}" software-scaling=true coef-load-type=0 num-taps=12 \
! video/x-raw, width=1280, height=720, format=NV12 !  filesink location=output_sw_scale.nv12 -v