[x265] H265 classes in TComSlice.h

[dave]

Hi All,

I have been working on a file, h265.h, of classes to replace the H265 
classes in TComSlice.h.  I would like some feedback on a few things 
before I submit it for review.

First, a decent number of fields either have default values or are 
optional and are not currently added to encoded video generated by 
x265.  I am duplicating the functionality of what is in TComSlice.h 
while cutting out its cruft with the goal of not breaking current x265 
code.  Please remember this as some of the code that I will be 
submitting probably doesn't look to good as it is meant to replace HM 
code without breaking x265 code.  As functionality is added to x265 it 
should be easier to work with the unused fields.

Some of the TComSlice.h H265 classes have fields that are not part of 
their equivalent H265 data structures but are used in the encoding 
process.  Some are duplicates of what is in Encoder and could be used 
from there.  Others could be moved somewhere else.  Or they could just 
be used as they currently are.  My preference would be for H265 classes 
to only have H265 fields.

Generally, I have been naming/renaming fields after what they are in the 
H265 while adding x265 naming convention standards.  Basically, m_<H265 
field>.

Some fields are obviously booleans and have the form <H265 field>Flag 
which makes adding the boolean m_b seem a bit redundant.  I could drop 
the b or Flag, my preference is to drop the b.

Some fields had to be renamed because the HM code called them something 
slightly different.  Most of the time this renaming simply shortened the 
name in some way, a few almost seem to be obfuscating something.  
Generally I prefer to stick to the H265 standard for clarity.

Having said that, not all of the H265 names are all that clear to begin 
with.  fpsNum and fpsDenom being one example.  My preference would be to 
use H265 names but if unclear, then document in comments a more clear 
definition.

    /* Numerator of frame rate(fpsNum) */
     uint32_t  numUnitsInTick;

    /* Denominator of frame rate(fpsDenom) */
     uint32_t  timeScale;

The obvious alternative would be to have the documentation contain the 
H265 name and use the alternative field name for the variable.

I debated putting h265.h in source/common or source/encoder. Currently I 
have it in common.

Currently, I have classes for VPS, SPS, PPS, VUI, HRD, Window, 
TimingInfo, SubLayerOrderingInfo and HrdSubLayerInfo.

Todo classes are PTL(ProfileTierLevel), ScalingList and RPSList.  If 
anything else needs to be added let me know.

The TComSlice class looks pretty big.  I haven't had a chance to go over 
it yet but if it isn't mostly cruft then it probably should have its own 
file or perhaps be merged into a current x265 file.