vvas_xabrscaler¶
There are certain situations where the available frame resolution and color format may not be suitable for the next component’s consumption. For instance, in machine learning applications, inputs can be sourced from different resolutions and color formats, but the ML models require fixed resolution and specific color formats. Thus, it becomes necessary to resize the input image to a different resolution and convert its color space, for example, to BGR.
In some adaptive bit rate (ABR) use cases, a single video is encoded at different bit rates to allow streaming under different network bandwidth conditions without artifacts. This requires the input frame to be decoded, resized to different resolutions, and then re-encoded. To accelerate these processes, vvas_xabrscaler is a GStreamer plug-in that can take one input frame and produce multiple output frames with different resolutions and color formats. This plug-in can also perform the pre-processing operations like mean subtraction, normalization, and cropping. For implementation details, please 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¶
To use this plug-in, your hardware design must have the image_processing kernel available and it must be configured to support the required color formats and maximum resolution for your application. You can find the configuration details for the image_processing kernel, including the supported maximum resolution and color formats, 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 1: 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 |
NULL |
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 |
-1 to 31 |
-1 |
Device index This is valid only in PCIe/ Data Center platforms. Default value is set to -1 intentionally so that user provides the correct device index. |
ppc |
integer |
1, 2, 4 |
4 |
Pixel per clock supported by the image_processing 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 |
12 |
Number of filter taps to be used for scaling. BILINEAR scale-mode uses 2 taps. |
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: 16), 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: 16), 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. |
maintain-aspect- ratio |
Boolean |
true/false |
false |
Maintains aspect ratio in output with the aspect ratio of input video. |
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.
The supported video formats being displayed in sink/src caps are the formats supported by vvas-core hardware(Image-processing) scaler.
This plugin queries pre-processing parameters (alpha and beta) from the downstream vvas_xinfer plugin (if available) and applies those pre-processing values. User can override the vvas_xinfer suggested values by setting the pre-processing gstreamer properties (alpha and beta properties).
Example Pipelines¶
The pipelines mentioned below is for PCIe/Data Center platform. For Embedded platform remove dev-idx property from the pipelines mentioned below.
One input one output¶
The below 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 dev-idx=<device-index> xclbin-location=<xclbin-path> 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 dev-idx=<device-index> xclbin-location=<xclbin-path> 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 dev-idx=<device-index> xclbin-location=<xclbin-path> 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