Hevc HM learning 02

In this section, we will learn about various coding modes and their cfg The meaning of parameters in the document ：

One 、cfg_HDR:

High dynamic range imaging （ English ：High Dynamic Range Imaging, abbreviation HDRI or HDR）, In computer graphics and cinematography , It is used to achieve a larger exposure dynamic range than ordinary digital image technology （ That is, a greater difference between light and shade ） A set of technologies . The purpose of high dynamic range imaging is to correctly represent the large range of brightness in the real world from direct sunlight to the darkest shadows . You can see in the configuration file that the bit depth is 12, Just for the time being .

Two 、misc

misc It's actually English miscellaneous The first four letters of , miscellaneous 、 A mixture 、 The meaning of a hodgepodge , skip

3、 ... and 、per-sequence

Place the media information file of the official test sequence ：

Such as BasketballDrill.cfg：

#======== File I/O ===============
InputFile              : BasketballDrill_832x480_50.yuv  file name 
InputBitDepth          : 8           #  Input bit depth 
InputChromaFormat      : 420         # YUV420 sampling 
FrameRate              : 50          #  Frame rate 
FrameSkip              : 0           #  Enter the number of frames to skip 
SourceWidth            : 832         #  wide 
SourceHeight           : 480         #  high 
FramesToBeEncoded      : 500   #  Number of frames to encode 

Level                  : 3.1   # What is this ？
Profile： Specifies the of the code stream profile. Values are ：main main10 main-still-picture main-RExt, high-throughput-RExt, main-SCC, wait .
Level： Specifies the of the code stream level. Value ：none、1, 2, 2.1, 3, 3.1, 4, 4.1, 5, 5.1, 5.2, 6, 6.1, 6.2, 8.5.

Four 、SEI

Add enhanced information Supplementary enhancement information, Don't understand, , Skip again QAQ

5、 ... and 、others

main and mian10 The main difference is profile Different from the internal bit depth .intra It means all I Frame encoding ,low delay and low delay_p Indicates that only the first frame is I Frame encoding , And the rest are P Frame or B Frame encoding .randomaccess Means batch B Frame structure , Periodically insert some random access frames ,rext It's a range extension ,high-throughput It's high throughput .
Combine the above , such as encoder_intra_main10.cfg by Profile by main10 Intra coding mode .

profile Is a description of video compression characteristics , Specifically, it refers to the coding algorithms and coding tools used in the code stream

stay HEVC Three grades are supported in （profile）, They are the main grades （main profile）、10bit Main grade （main 10 profile）、 Main level of still image （main still profile）, The relationship between them is shown in the figure below , The outer level can be compatible with the inner level

Main grade （mian profile） Characteristics

The bit depth is limited to 8bit

The sampling format is limited to 4：2：0

CTB The size is from 16 * 16 To 64 * 64

The buffer capacity of the decoded image is limited to 6 Images

It is allowed to select the wave front and plate division mode , But you can't choose at the same time

10 Bit master level （main 10 profile） Characteristics

Main features and main profile similar , But the difference is , It can support 10 Bit depth
Still images （main still profile） Characteristics

Main features and main profile similar , But the difference is that it does not support inter prediction coding , All video streams can only be encoded in one frame .

Reference resources ：https://blog.csdn.net/weixin_45615071/article/details/105460401

intra-only In the pattern

, All images to be encoded are treated as IDR The image is encoded by intra prediction . There is no time domain reference image . And in the image QP No change . The picture below is intra-only Schematic diagram of mode coding , The numbers on the image represent the coding order

#======== File I/O ===================== Input and output files 

BitstreamFile                 : str.bin  
ReconFile                     : rec.yuv 

#======== Unit definition ================ Unit definition （ It should mean LCU）

MaxCUWidth            : 64 # Maximum coding unit width in pixel
                           # Maximum coding unit LCU The width of 
                           
MaxCUHeight           : 64 # Maximum coding unit height in pixel
                           # Maximum coding unit LCU The height of 
                           
MaxPartitionDepth     : 4  # Maximum coding unit depth
           # Maximum depth 4, Depth range [0,1,2,3], The corresponding dimension is 64X64 To 8X8
           
QuadtreeTULog2MaxSize  : 5 # Log2 of maximum transform size for
                    # quadtree-based TU coding (2...6)Log2(32)=5

QuadtreeTULog2MinSize  : 2 # Log2 of minimum transform size for
                  # quadtree-based TU coding (2...6)Log2(4)=2

QuadtreeTUMaxDepthInter : 3 （ Between frames TU Maximum depth ）

QuadtreeTUMaxDepthIntra : 3
 
#======== Coding Structure ============= Coding structure 

IntraPeriod          : 1  # Period of I-Frame ( -1 = only first)

DecodingRefreshType  : 0  # Random Accesss 0:none, 1:CDR, 2:IDR

 Random Accesss ： Decode update type , Random access type 

GOPSize               : 1  # GOP Size (number of B slice =           #GOPSize-1), Image group size 

# Type POC QPoffset QPfactor tcOffsetDiv2 betaOffsetDiv2 temporal_id #ref_pics_active #ref_pics reference pictures 

 

#=========== Motion Search ============= Sports search 

FastSearch           : 1 # 0:Full search  1:TZ search
                         # Quick search type ,0： Full search ;1：TZ Search for 

SearchRange          : 64   # (0: Search range is a Full frame)
                            # The scope of the search 

HadamardME        :1 # Use of hadamard measure for fractional ME
                     #fractional ME fraction （ Pixel position ） motion estimation 

FEN     : 1 # Fast encoder decision    Fast encoder decision 

FDM     : 1  # Fast Decision for Merge RD cost   Fast merge RD Cost decision 

#======== Quantization ============= quantitative 

QP      : 32      # Quantization parameter(0-51) Quantitative parameter range ：0－51

MaxDeltaQP  : 0  # CU-based multi-QP optimization be based on CU More QP Optimize 

MaxCuDQPDepth : 0   # Max depth of a minimum CuDQP for sub-LCU-level delta QP

DeltaQpRD     : 0    # Slice-based multi-QP optimization
                     # Slice based multi QP Optimize 
                     
RDOQ          : 1     # RDOQ Rate distortion optimized quantization 

RDOQTS        : 1     # RDOQ for transform skip
                      # Transform skipped rate distortion optimized quantization  

#=========== Deblock Filter ============ To block filter 

DeblockingFilterControlPresent: 0      # Dbl control params   #present (0=not present, 1=present) Db1 Controls whether a deblocking filter is used 

LoopFilterOffsetInPPS         : 0           # Dbl params: 0=varying params in SliceHeader, param = base_param + GOP_offset_param; 1=constant params in PPS, param = base_param)

LoopFilterDisable             : 0           # Disable deblocking filter (0=Filter, 1=No Filter)

LoopFilterBetaOffset_div2     : 0           # base_param: -13 ~ 13

LoopFilterTcOffset_div2       : 0           # base_param: -13 ~ 13

 

#=========== Misc. ============

InternalBitDepth       : 8    # codec operating bit-depth
# Codec control bit depth , Indicates the main grade , namely MAIN

 

#=========== Coding Tools ================= Coding tools 

SAO                           : 1           # Sample adaptive offset  (0: OFF, 1: ON)   Rate sample adaptive offset 

AMP                           : 1           # Asymmetric motion partitions (0: OFF, 1: ON)  Asymmetric motion segmentation 

TransformSkip                 : 1           # Transform skipping (0: OFF, 1: ON)

TransformSkipFast             : 1           # Fast Transform skipping (0: OFF, 1: ON)

SAOLcuBoundary                : 0           # SAOLcuBoundary using non-deblocked pixels (0: OFF, 1: ON) 

SAOLCU Boundary pixels are represented by pixel values that have not been subjected to past block filtering operations 

 

#============ Slices ================ slice 

SliceMode                : 0                # 0: Disable all slice options.

                                            # 1: Enforce maximum number of LCU in an slice,

                                            # 2: Enforce maximum number of bytes in an 'slice'

                                            # 3: Enforce maximum number of tiles in a slice

SliceArgument            : 1500             # Argument for 'SliceMode'.

                                            # If SliceMode==1 it represents max. SliceGranularity-sized blocks per slice.

                                            # If SliceMode==2 it represents max. bytes per slice.

                                            # If SliceMode==3 it represents max. tiles per slice.

 

LFCrossSliceBoundaryFlag : 1                # In-loop filtering, including ALF and DB, is across or not across slice boundary.

ALF And DB Whether the two filters intersect at the chip boundary 

                                            # 0:not across, 1: across

 

#============ PCM ================ PCM Pattern 

PCMEnabledFlag                      : 0                # 0: No PCM mode

PCMLog2MaxSize                      : 5                # Log2 of maximum PCM block size.

PCMLog2MinSize                      : 3                # Log2 of minimum PCM block size.

PCM The maximum block size is 32X32, The minimum is 8X8

PCMInputBitDepthFlag                : 1                # 0: PCM bit-depth is internal bit-depth. 1: PCM bit-depth is input bit-depth.

PCMFilterDisableFlag                : 0                # 0: Enable loop filtering on I_PCM samples. 1: Disable loop filtering on I_PCM samples.

 

#============ Tiles ================ strip 

UniformSpacingIdc                   : 0                # 0: the column boundaries are indicated by ColumnWidth array, the row boundaries are indicated by RowHeight array

Tiles The column boundary of is determined by the column width array 

                                                       # 1: the column and row boundaries are distributed uniformly

NumTileColumnsMinus1                : 0                # Number of columns in a picture minus 1

ColumnWidthArray                    : 2 3              # Array containing ColumnWidth values in units of LCU (from left to right in picture)   

NumTileRowsMinus1                   : 0                # Number of rows in a picture minus 1

RowHeightArray                      : 2                # Array containing RowHeight values in units of LCU (from top to bottom in picture)

 

LFCrossTileBoundaryFlag           : 1                  # In-loop filtering is across or not across tile boundary.

                                                       # 0:not across, 1: across 

 

#============ WaveFront ================ Wave front 

WaveFrontSynchro                    : 0                # 0:  No WaveFront synchronisation (WaveFrontSubstreams must be 1 in this case).

 Wavefront parallel processing synchronization 

                                                       # >0: WaveFront synchronises with the LCU above and to the right by this many LCUs.

 

#=========== Quantization Matrix ================= Quantization matrix 

ScalingList                   : 0                      # ScalingList 0 : off, 1 : default, 2 : file read

ScalingListFile               : scaling_list.txt       # Scaling List file name. If file is not exist, use Default Matrix.

 

#============ Lossless ================ The distortion 

TransquantBypassEnableFlag: 0  # Value of PPS flag.

CUTransquantBypassFlagValue: 0 # Constant lossless-value signaling per CU, if TransquantBypassEnableFlag is 1.

                                                       

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Its GOPSize by 1, Is full of I frame

Low-delay To configure

low-delay Yes low-delay P and low-delay B Two modes . about low-delay Pattern , The first image is IDR Images . stay low-delay P All but the first frame in the mode are P Images . stay low-delay B All but the first frame in the mode are B Images . For both models , Whether it's P The image is still B Images only refer to the image before the playback order . And in low-delay B Reference image list in mode RefPicList0 and RefPicList1 identical . Of each inter prediction image QP Is in the frame of the image QP Add a compensation value , The compensation value is determined by the time domain layer .

The picture below is Low-delay Schematic diagram of mode coding , The numbers on the image represent the coding order .

Random-access To configure

stay random-access In the pattern , Coding uses layering B structure （hierarchical B structure）. The picture below is random-access Schematic diagram of mode coding , The numbers on the image represent the coding order .

Code one at regular intervals I frame , The interval is determined by the configuration item IntraPeriod decision , It is generally configured as... According to the frame rate 1 One second I frame . first I The frame is IDR Images , other I Frame is not IDR Images （Open GOP）. The display sequence is continuous I The inter frame image is encoded as B frame .

The inter prediction image at the lowest level in the time domain （GPB）, You can refer to an intra image or an inter image . The second and third time domain layers are composed of referenced B pictures Image composition . The highest time domain layer contains only non-referenced B picture Images . Of each inter prediction image QP Is in the frame of the image QP Add a compensation value , The compensation value is determined by the time domain layer .

Reference resources ：https://blog.csdn.net/Dillon2015/article/details/104212995/