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Scalable Video Technology for AV1 Encoder (SVT-AV1 Encoder) User Guide

Table of Contents

  1. Introduction
  2. Sample Application Guide
  3. Legal Disclaimer

Introduction

This document describes how to use the Scalable Video Technology for AV1 Encoder (SVT-AV1). In particular, this user guide describes how to run the sample application with the respective dynamically linked library.

Sample Application Guide

This section describes how to run the sample encoder application that uses the SVT-AV1 Encoder library. It describes the input video format, the command line input parameters and the resulting outputs.

Input Video Format

The SVT-AV1 Encoder supports the following input formats:

8-bit yuv420p
8-bit yuv420p

10-bit yuv420p10le
10-bit yuv420p10le

Compressed 10-bit format

In order to reduce the size of the input original YUV file, the SVT-AV1 Encoder uses a compressed 10-bit format allowing the software to achieve a higher speed and channel density levels. The conversion between the 10-bit yuv420p10le and the compressed 10-bit format is a lossless operation and is performed using the following steps.

Unpack the 10-bit picture

This step consists of separating the 10 bit video samples into 8 bit and 2 bit planes so that each 10-bit picture will be represented as two separate pictures as shown in the figure below. As a result of the operation, the 2 least significant bits of the 10 bits will be written into a full byte.

10-bit yuv420p10le unpacked
10-bit yuv420p10le unpacked

Compress the 2 bit Plane

The unpacking steps separates the 10bits into a group of 8 bits and a group of 2 bits, where the 2 bits are stored in a byte. In this step, every group of consecutive 4 bytes, each containing 2bits from the unpacking step, are compressed into one byte. As a result, each 10bit picture will be represented as two separate pictures as shown in the figure below.

10-bit yuv420p10le compressed
10-bit yuv420p10le compressed

Unroll the 64x64

Now for a faster read of the samples, every 64x64 block of the 2 bit picture should be written into a one dimensional array. Therefore, the top left 64x64 sample block which is now written into a 16 bytes x 64 bytes after the compression of the 2bit samples, will be written into a 1024 bytes x 1 byte array as shown in the picture below.

64x64 block after 2 bit compression
64x64 block after 2 bit compression

64x64 block after unrolling
64x64 block after unrolling

Running the encoder

This section describes how to run the sample encoder application SvtAv1EncApp.exe (on Windows*) or SvtAv1EncApp (on Linux*) from the command line, including descriptions of the most commonly used input parameters and outputs.

The sample application typically takes the following command line parameters:

-c filename [Optional]

A text file that contains encoder parameters such as input file name, quantization parameter etc. Refer to the comments in the Config/Sample.cfg for specific details. The list of encoder parameters are also listed below. Note that command line parameters take precedence over the parameters included in the configuration file when there is a conflict.

-i filename [Required]

A YUV file (e.g. 8 bit 4:2:0 planar) containing the video sequence that will be encoded. The dimensions of each image are specified by –w and –h as indicated below.

-b filename [Optional]

The resulting encoded bit stream file in binary format. If none specified, no output bit stream will be produced by the encoder.

-w integer [Required]

The width of each input image in units of picture luma pixels, e.g. 1920

-h integer [Required]]

The height of each input image in units of picture luma pixels, e.g. 1080

-n integer [Optional]

The number of frames of the sequence to encode. e.g. 100. If the input frame count is larger than the number of frames in the input video, the encoder will loopback to the first frame when it is done.

-intra-period integer [Optional]

The intra period defines the interval of frames after which you insert an Intra refresh. It is strongly recommended to use (multiple of 8) -1 the closest to 1 second (e.g. 55, 47, 31, 23 should be used for 60, 50, 30, (24 or 25) respectively). When using closed gop (-irefresh-type 2) add 1 to the value above (e.g. 56 instead of 55).

-rc integer [Optional]

This token sets the bitrate control encoding mode [1: Variable Bitrate, 0: Constant QP]. When -rc is set to 1, it is best to match the –lad (lookahead distance described in the next section) parameter to the -intra-period. When –rc is set to 0, a qp value is expected with the use of the –q command line option otherwise a default value is assigned (25).

For example, the following command encodes 100 frames of the YUV video sequence into the bin bit stream file. The picture is 1920 luma pixels wide and 1080 pixels high using the Sample.cfg configuration. The QP equals 30 and the md5 checksum is not included in the bit stream.

SvtAv1EncApp.exe -c Sample.cfg -i CrowdRun\_1920x1080.yuv -w 1920 -h 1080 -n 100 -q 30 -intra-period 31 -b CrowdRun\_1920x1080\_qp30.bin

It should be noted that not all the encoder parameters present in the Sample.cfg can be changed using the command line.

List of all configuration parameters

The encoder parameters present in the Sample.cfg file are listed in this table below along with their status of support, command line parameter and the range of values that the parameters can take.

Configuration file parameter Command line Range Default Description
ChannelNumber -nch [1 - 6] 1 Number of encode instances
ConfigFile -c any string null Configuration file path
InputFile -i any string None Input file path
StreamFile -b any string null output bitstream file path
ErrorFile -errlog any string stderr error log displaying configuration or encode errors
UseQpFile -use-q-file [0 - 1] 0 When set to 1, overwrite the picture qp assignment using qp values in QpFile
QpFile -qp-file any string Null Path to qp file
StatReport -stat-report [0 - 1] 0 When set to 1, calculate and display PSNR values
StatFile -stat-file any string Null Path to statistics file if specified and StatReport is set to 1, per picture statistics are outputted in the file
EncoderMode -enc-mode [0 - 8] 8 Encoder Preset [0,1,2,3,4,5,6,7,8] 0 = highest quality, 8 = highest speed
EncoderBitDepth -bit-depth [8 , 10] 8 specifies the bit depth of the input video
CompressedTenBitFormat -compressed-ten-bit-format [0 - 1] 0 Offline packing of the 2bits: requires two bits packed input (0: OFF, 1: ON)
SourceWidth -w [64 - 4096] None Input source width
SourceHeight -h [0 - 2304] None Input source height
FrameToBeEncoded -n [0 - 2^64 -1] 0 Number of frames to be encoded, if number of frames is > number of frames in file, the encoder will loop to the beginning and continue the encode. Use -1 to not buffer.
BufferedInput -nb [-1, 1 to 2^31 -1] -1 number of frames to preload to the RAM before the start of the encode If -nb = 100 and –n 1000 -- > the encoder will encode the first 100 frames of the video 10 times
FrameRate -fps [0 - 2^64 -1] 25 If the number is less than 1000, the input frame rate is an integer number between 1 and 60, else the input number is in Q16 format (shifted by 16 bits) [Max allowed is 240 fps]
FrameRateNumerator -fps-num [0 - 2^64 -1] 0 Frame rate numerator e.g. 6000
FrameRateDenominator -fps-denom [0 - 2^64 -1] 0 Frame rate denominator e.g. 100
HierarchicalLevels -hierarchical-levels [3 – 4] 4 0 : Flat4: 5-Level HierarchyMinigop Size = (2^HierarchicalLevels) (e.g. 3 == > 7B pyramid, 4 == > 15B Pyramid)
IntraPeriod -intra-period [-2 - 255] -2 Distance Between Intra Frame inserted. -1 denotes no intra update. -2 denotes auto.
IntraRefreshType -irefresh-type [1 – 2] 1 1: CRA (Open GOP)2: IDR (Closed GOP)
QP -q [0 - 63] 50 Quantization parameter used when RateControl is set to 0
RateControlMode -rc [0 - 3] 0 0 = CQP , 1 = ABR , 2 = ABR , 3 = CVBR
UseDefaultMeHme -use-default-me-hme [0 - 1] 1 0 : Overwrite Default ME HME parameters1 : Use default ME HME parameters, dependent on width and height
HME -hme [0 - 1] 1 Enable HME, 0 = OFF, 1 = ON
HMELevel0 -hme-l0 [0 - 1] 1 Enable HME Level 0 , 0 = OFF, 1 = ON
HMELevel1 -hme-l1 [0 - 1] Depends on input resolution Enable HME Level 1 , 0 = OFF, 1 = ON
HMELevel2 -hme-l2 [0 - 1] Depends on input resolution Enable HME Level 2 , 0 = OFF, 1 = ON
InLoopMeFlag -in-loop-me [0 - 1] Depends on –enc-mode 0=ME on source samples, 1= ME on recon samples
LocalWarpedMotion -local-warp [0 - 1] 0 Enable warped motion use , 0 = OFF, 1 = ON
ExtBlockFlag -ext-block [0 - 1] Depends on –enc-mode Enable the non-square block 0=OFF, 1= ON
ScreenContentMode -scm [0 - 2] 2 Enable Screen Content Optimization mode (0: OFF, 1: ON, 2: Content Based Detection)
SearchAreaWidth -search-w [1 - 256] Depends on input resolution Search Area in Width
SearchAreaHeight -search-h [1 - 256] Depends on input resolution Search Area in Height
NumberHmeSearchRegionInWidth -num-hme-w [1 - 2] Depends on input resolution Search Regions in Width
NumberHmeSearchRegionInHeight -num-hme-h [1 - 2] Depends on input resolution Search Regions in Height
HmeLevel0TotalSearchAreaWidth -hme-tot-l0-w [1 - 256] Depends on input resolution Total HME Level 0 Search Area in Width
HmeLevel0TotalSearchAreaHeight -hme-tot-l0-h [1 - 256] Depends on input resolution Total HME Level 1 Search Area in Width
HmeLevel0SearchAreaInWidth -hme-l0-w [1 - 256] Depends on input resolution HME Level 0 Search Area in Width for each region, separated in spaces, the number of input search areas must equal to NumberHmeSearchRegionInWidth, and the sum must equal toHmeLevel0TotalSearchAreaWidth
HmeLevel0SearchAreaInHeight -hme-l0-h [1 - 256] Depends on input resolution HME Level 0 Search Area in Height for each region, separated in spaces, the number of input search areas must equal to NumberHmeSearchRegionInHeight, and the sum must equal toHmeLevel0TotalSearchAreaHeight
HmeLevel1SearchAreaInWidth -hme-l1-w [1 - 256] Depends on input resolution HME Level 1 Search Area in Width for each region, separated in spaces, the number of input search areas must equal to NumberHmeSearchRegionInWidth
HmeLevel1SearchAreaInHeight -hme-l1-h [1 - 256] Depends on input resolution HME Level 1 Search Area in Height for each region, separated in spaces, the number of input search areas must equal to NumberHmeSearchRegionInHeight
HmeLevel2SearchAreaInWidth -hme-l2-w [1 - 256] Depends on input resolution HME Level 2 Search Area in Width for each region, separated in spaces, the number of input search areas must equal to NumberHmeSearchRegionInWidth
HmeLevel2SearchAreaInHeight -hme-l2-h [1 - 256] Depends on input resolution HME Level 2 Search Area in Height for each region, separated in spaces, the number of input search areas must equal to NumberHmeSearchRegionInHeight
LookAheadDistance -lad [0 - 120] 33 When Rate Control is set to 1 it's best to set this parameter to be equal to the Intra period value (such is the default set by the encoder) [this value is capped by the encoder to its maximum need e.g. 33 for CQP, 2*fps for rate control]
SceneChangeDetection -scd [0 - 1] 1 Enables or disables the scene change detection algorithm
AsmType -asm [0 - 1] 1 Assembly instruction set (0: Automatically select lowest assembly instruction set supported, 1: Automatically select highest assembly instruction set supported,)
LogicalProcessorNumber -lp [0, total number of logical processor] 0 The number of logical processor which encoder threads run on.Refer to Appendix A.1
TargetSocket -ss [-1,1] -1 For dual socket systems, this can specify which socket the encoder runs on.Refer to Appendix A.1
ReconFile -o any string null Recon file path. Optional output of recon.
ImproveSharpness -sharp [0-1] 0 Improve sharpness (0= OFF, 1=ON )
TileRow -tile-rows [0-6] 0 log2 of tile rows
TileCol -tile-columns [0-6] 0 log2 of tile columns

Appendix A Encoder Parameters

1. Thread management parameters

LogicalProcessorNumber (-lp) and TargetSocket (-ss) parameters are used to management thread affinity on Windows and Ubuntu OS. These are some examples how you use them together.

If LogicalProcessorNumber and TargetSocket are not set, threads are managed by OS thread scheduler.

SvtAv1EncApp.exe -i in.yuv -w 3840 -h 2160 –lp 40

If only LogicalProcessorNumber is set, threads run on 40 logical processors. Threads may run on dual sockets if 40 is larger than logical processor number of a socket.

NOTE: On Windows, thread affinity can be set only by group on system with more than 64 logical processors. So, if 40 is larger than logical processor number of a single socket, threads run on all logical processors of both sockets.

SvtAv1EncApp.exe -i in.yuv -w 3840 -h 2160 –ss 1

If only TargetSocket is set, threads run on all the logical processors of socket 1.

SvtAv1EncApp.exe -i in.yuv -w 3840 -h 2160 –lp 20 –ss 0

If both LogicalProcessorNumber and TargetSocket are set, threads run on 20 logical processors of socket 0. Threads guaranteed to run only on socket 0 if 20 is larger than logical processor number of socket 0.

Legal Disclaimer

Optimization Notice

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Notice Revision #20110804

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