We have code with very similar structure to the draft standard pseudocode. This pseudocode in the text seems incorrect:

inferSigCoeffFlag = 0 if( ( i < lastSubBlock ) && ( i > 0 ) ) {

coded_sub_block_flag[ xS ][ yS ] inferSigCoeffFlag = 1

}

To make our implementation agree with HM, we had to do this instead:

inferSigCoeffFlag = 0 if( ( i < lastSubBlock ) && ( i > 0 ) ) {

coded_sub_block_flag[ xS ][ yS ] inferSigCoeffFlag = coded_sub_block_flag[ xS ][ yS ]

}

Now this could be indicative of a problem elsewhere in the draft standard description or possibly in a mistake our own implementation but we thought it worth flagging up.

If I want to know ctxIdxInc for last_significant_coeff_x_prefix or last_significant_coeff_y_prefix, I am directed to subclause 9.2.1.2 Memorization process for context variables. The correct subclause for the crossreference is 9.2.3.1.2 Derivation process of ctxIdxInc for the syntax elements last_significant_coeff_x_prefix and last_significant_coeff_y_prefix

There is a loop in the VPS syntax that opens thusly:

  for( i = ( vps_sub_layer_ordering_info_present_flag ?
                0 : vps_max_sub_layers_minus1 );
                i <= vps_max_sub_layers_minus1; i++ ) {

This takes longer to understand that it should because it does not use idiomatic C-style constructs. It looks "hackish". To improve clarity suggest changing to:

  for( i = 0; vps_sub_layer_ordering_info_present_flag &&
                i <= vps_max_sub_layers_minus1; i++ ) {

or

  if (vps_sub_layer_ordering_info_present_flag)
      for( i = 0; i <= vps_max_sub_layers_minus1; i++ ) {