vvas_xvideodec

In Versal family of devices, there is an IP, VDU, for hardware accelerated video decodeo decoding. This IP supports decoding of H264/HEVC formats. Please refer to VDU PG414 for more information on the AMD/Xilinx VDU block.

vvas_xvideodec plugin controls the VDU IP for Video Decoding jobs. This plug-in is used only in PCIe/DC platform. For Embedded platforms, there is a separate plug-in that is covered in OMX Encoder/Decoder Plug-in. For implementation details, refer to vvas_xvideodec source code

Input and Output

This plugin supports H264 and HEVC encoded streams of various profile, level values as input. For complete list of supported profiles and levels, please refer to VDU PG414 The native output of this plugin is NV12 format. For any other desired output format, it should be software-converted and will affect performance.

Control Parameters and Plug-in Properties

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

Table 1: vvas_xvideodec Plug-in Properties

Property Name	Type	Range	Default	Description
avoid-output-copy	Boolean	true/false	False	Avoid output frames copy even when downstream does not support GstVideoMeta metadata
avoid-dynamic-alloc	Boolean	true/false	True	Avoid dynamic allocation of output buffers
dev-idx	Integer	0 to 31	0	Device index This is valid only in PCIe/ Data Center platforms.
i-frame-only	Boolean	true/false	false	Whether to decode ‘I’ frames only or not from the given input encoded stream
instance-id	Integer	0 to 1	0	Select one of the VDU hardware IP instances
disable-hdr10-sei	Boolean	true/false	false	Whether to passthrough HDR10/10+ SEI messages or not
interpolate-timestamps	Boolean	true/false	false	Whether to interpolate timestamps or not
kernel-name	String	N/A	decoder:{decoder_1}	Kernel name and instance separated by a colon.
low-latency	Boolean	true/false	false	Whether to enable low latency or not
num-entropy-buf	Unsigned Integer	2 - 10	2	Number of entropy buffers
splitbuff-mode	Boolean	true/false	false	Whether to enable splitbuff mode or not
xclbin-location	String	N/A	null	The location of xclbin.

Example Pipelines

The following pipeline takes MP4 file with H264 codec as an input and provides raw decoded output in NV12 format. Please refer above table for other parameters and values.

dev-idx represents the zero based index of the device on which this decoder to be launched. Please note that ‘dev-idx’ parameter range can vary from 0 to N-1 where N can be obtained with below command:

N=xbutil  examine | grep xilinx_v70 | wc -l

gst-launch-1.0 -v filesrc location=<input compressed H264 stream in MP4 container> \
! qtdemux ! h264parse \
! vvas_xvideodec kernel-name=kernel_vdu_decoder:{kernel_vdu_decoder_0} dev-idx=0 instance-id=0 avoid-output-copy=false xclbin-location=<xclbin file path> \
! fpsdisplaysink name=fpssink video-sink=fakesink text-overlay=false sync=false

kernel name is mandatory and the name represents both the name of the decoder kernel as well as its instance. In above example, “kernel-name=kernel_vdu_decoder:{kernel_vdu_decoder_0}” represents decoder kernel name as “kernel_vdu_decoder” and instance “0”. Instance Id range can be known from the below command:

xbutil examine -d <PCI bdf>

Currently, 2 instances of video decoder IP (VDU) is supported and can be selected with the plugin parameter ‘instance-id’. Above example uses instance id = 0.