NVIDIA H265 Encoding Configurations

Introduction

This wiki is intended to show some common configurations used to tune the H265 encoding that NVIDIA provides using the V4L2 controls. You can visit the official documentation for more details.

H265 Controls Mapping

NVIDIA provides different ways to control and use the H265 encoder through V4l2 controls. Some of them are the NvVideoEncoder class from the Video API, and the Gstreamer element. To show how to modify the different H265 controls we have created the following table containing a mapping between these two options and the actual control.

V4L2 Control	Description	Gstreamer nvv4l2h265enc Property	NvVideoEncoder Class Method (Video API)
Profile	H265 encoder profile	profile	setProfile
I-frame Interval or GOP Size	Interval between two I-frames, in number of frames	iframeinterval	setIFrameInterval
IDR Interval	Encoder IDR frame interval	idrinterval	setIDRInterval
Number of B-frames	Number of B-frames between P-frames	num-B-frames	setNumBFrames
Bitrate	Bits per second of the encoded stream	bitrate	setBitrate
Maximum Bitrate	Peak bitrate of the encoded stream in bits per second	peak-bitrate	setPeakBitrate
Rate Mode	Type of rate control (constant or variable)	control-rate	setRateControlMode
Intra Refresh Slice Interval	Slice intra refresh interval, in number of slices	SliceIntraRefreshInterval	setSliceIntrarefresh
Quantization Parameters	Quantization parameter for constant QP mode	quant-i*, quant-p*, quant-b*	setConstantQp
Quantization Range	Minimum and maximum for each frame quantization parameter	qp-range	setQpRange
Virtual Buffer Size	Virtual buffer size in bits	vbv-size	setVirtualBufferSize
Number of Reference Frames	Maximum number of reference frames that can be used	num-Ref-Frames	setNumReferenceFrames
Insert SPS and PPS at IDR Interval	Configuration to enable/disable inserting SPS and PPS explicitly at IDR interval	insert-sps-pps	setInsertSpsPpsAtIdrEnabled
Insert VUI	Enable or disable inserting video usability information in SPS.	insert-vui	setInsertVuiEnabled
Insert AUD	Enable or disable inserting access unit delimiter.	insert-aud	setInsertAudEnabled
Enable Motion Vector Metadata	Enable or disable encoder motion vector reporting	EnableMVBufferMeta	enableMotionVectorReporting
Hardware Preset	Hardware encoder preset type	preset-level	setHWPresetType
Temporal Trade-off Level	Encoder level to drop frames while encoding	N/A	setTemporalTradeoff
Slice Length	Slice length either in terms of MBs or bits	N/A	setSliceLength
Reconstructed CBR	Configure Reconstructed CRC for a session	N/A	enableReconCRC
ROI Encoding	Configure ROI encoding for a session	N/A	enableROI
ROI Params	Configuration to encode a particular region of a frame in high quality	N/A	setROIParams
Metadata	Get encoder output metadata	N/A	getMetadata
Motion Vector Metadata	Get encoder output motion vector metadata	N/A	getMotionVectors
Input Metadata	Provide input metadata for the encoder buffer	N/A	SetInputMetaParams
External RPS	Configure encoder for external RPS control	N/A	enableExternalRPS
External Rate Control	Configure encoder for external rate control	N/A	enableExternalRC
Extended Color Format	Enable or disable setting for extended color format	N/A	setExtendedColorFormat
All I-frame Encoding	Enable or disable all I-Frame encoding	N/A	setAlliFramesEncode
All I-frame Encoding	Enable or disable all I-Frame encoding	N/A	setAlliFramesEncode
H265 Level	Set the H265 encoding level	N/A	setLevel
Slice Level Encode	Enable or disable slice level encoding	N/A	setSliceLevelEncode

Notes:

• Require ratecontrol-enable=0 and preset-level=0 properties.

Common Rate Control Modes

The rate control option shown above only allows the constant or variable bitrate options, however with certain combinations of properties other modes can be achieved, for example:

Mode	Required Properties
Constant QP	ratecontrol-enable=0, preset-level=0, quant-i-frames, quant-p-frames, quant-b-frames
CBR Single-Pass	control-rate=constant_bitrate, bitrate
VBR	control-rate=variable_bitrate, bitrate, peak-bitrate
VBR with Minimum QP	control-rate=variable_bitrate, ratecontrol-enable=1, bitrate, peak-bitrate, qp-range

Examples

Camera Capture + UDP Streaming

For this example we are using OV5693 Xavier AGX camera at 120 FPS, however we want our stream to be at 60 FPS, so we use a videorate to drop frames.

IP=127.0.0.1
PORT=12345
gst-launch-1.0 nvarguscamerasrc ! "video/x-raw(memory:NVMM),width=1280,height=720,framerate=120/1" ! videorate max-rate=60 drop-only=true ! queue max-size-buffers=3 leaky=downstream ! nvv4l2h265enc bitrate=2000000 iframeinterval=300 vbv-size=33333 insert-sps-pps=true control-rate=constant_bitrate profile=Main num-B-Frames=0 ratecontrol-enable=true preset-level=UltraFastPreset EnableTwopassCBR=false maxperf-enable=true ! h265parse ! mpegtsmux alignment=7 ! queue ! udpsink clients="${IP}:${PORT}"

This is an optimized pipeline with a maximum latency (from nvarguscamerasrc to udpsink) of 8 ms, as shown in the following diagram created with GstShark.

Example of encoder latency from video source to UDP sink

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