There is a lot of duplicated code due to handling random access and trailing
pictures separately. I merged the code for these two branches so it would be
easier to modify.
According to spec the end_of_slice_segment_flag is always coded, but in the
code it looked like it was not coded for the last LCU in picture. This was
due to the end_of_slice_segment_flag being coded inside cabac_flush, like it
is in HM. This is a bit silly so I moved it out of cabac_flush.
The relation between coefficients positions and coefficient group positions
was a big confusing due to the use of 16x16 diagonal coefficient mappings
also as coefficient group mappings.
- Moved all coefficient group mappings to their own const arrays and added
a new array the select the correct coefficient group mapping. This removes
special cases for 8x8 and 32x32 transform sizes.
- Removed all coefficient group mapping initialization from init_sig_last_scan.
- Removed 128x128 and 64x64 from regular coefficient group array as those
transform sizes don't exist anymore in HEVC.
- Moved NxN search to be done on the same level as other searches, as it's
really not any different from 2Nx2N.
- Produces working bitstream but reconstruction is different.
- Also set default width and height to 0 because it makes no sense to assume
dimensions. It's kind of like defaulting to the most common altitude when
the altimeter is broken.
- Add config_validate to have a place for checks on overall cfg state.
Related to issue #12.
Motivation for adding this is that the syntax for frame accurate seeking in
ffmpeg is a little cumbersome. Also it's kind of a standard feature I guess.
Moves CABAC context initialization to take place before search. This fixes
an issue with RDOQ returning different coefficients for identical adjacent
frames.
- This actually probably worsens BD-rate a little for all frames except the
first one because we were using last frames final CABAC context for every
LCU and now we are using initialized CABAC contexts. The fix is to encode
the LCU before we start compressing the next LCU so we can update CABAC
contexts.
Moves CABAC context initialization to take place before search. This fixes
an issue with RDOQ returning different coefficients for identical adjacent
frames.
- This actually probably worsens BD-rate a little for all frames except the
first one because we were using last frames final CABAC context for every
LCU and now we are using initialized CABAC contexts. The fix is to encode
the LCU before we start compressing the next LCU so we can update CABAC
contexts.
