Minor TrafoSkip Residual Coding Issues

[bbross]

1. In 9.5.4.2.6, the context derivation process for coded_sub_block_flag for TSRC, the left shift operation in 9-42 is not aligned in the software, as the csbfs in the left and above blocks are just added to csbfCtx, not shifting in initSubblock() in the software.

Fix:
If transform_skip_flag[ xS ][ yS ] is equal to 1, the following applies:

• When xS is greater than 0, csbfCtx is modified as follows:

csbfCtx += coded_sub_block_flag[ xS − 1 ][ yS ] (9‑41)

• When yS is greater than 0, csbfCtx is modified as follows:

csbfCtx += coded_sub_block_flag[ xS ][ yS − 1 ] (9‑42)

2. The variable counter MaxCcbs is set only in residual_ts_coding( ) and checked in ctx derivation for the syntax elements coded_sub_block_flag, sig_coeff_flag, par_flag, etc., also for the non-TS residual coding process.

Fix:
Set MaxCcbs also for residual_coding() syntax.

3. Typos in residual_ts_coding() syntax:

• The brace for the if condition right above coded_sub_block_flag seems missing.
• The initialization of index n in the first scan pass has a bug.
• In the Greater than X scan pass, the index i is already used for the current subblock index, which seems to be replaced such as j. The followings using this index have to be changed as well.

Thanks Sunmi for pointing this out.

[bbross]

Fixed in D5 v8