Mismatch between SW and Spec on assigning intra reference sample array

[chiaming]

In "8.4.5.2.12 Specification of INTRA_ANGULAR2..INTRA_ANGULAR66 intra prediction modes", when assigning intra reference sample array according to predModeIntra:

– If predModeIntra is greater than or equal to 34, the following ordered steps apply:

...

– Otherwise (predModeIntra is less than 34), the following ordered steps apply:

1.The reference sample array ref[ x ] is specified as follows:
– The following applies:

ref[ x ] = p[ −1 − refIdx ][ −1 − refIdx + x ], with x = 0..nTbH + refIdx + 1 (8-140)

– If intraPredAngle is less than 0, the main reference sample array is extended as follows:

ref[ x ] = p[ −1 − refIdx + Min( ( x * invAngle + 256 ) >> 9, nTbW ) ][ −1 − refIdx ], with x = −nTbW..−1 (8-141)

– Otherwise,

ref[ x ] = p[ −1 − refIdx ][ −1 − refIdx + x ], with x = nTbH + 2 + refIdx..refH + refIdx (8-142)

– The additional samples ref[ refH + refIdx +x ] with x = 1..( Max( 1, nTbW / nTbH ) * refIdx + 2) are derived as follows:

ref[ refH + refIdx +x ] = p[ −1 + refH ][ −1 − refIdx ] (8-143)

It should be corrected to:

– If predModeIntra is greater than or equal to 34, the following ordered steps apply:

...

– Otherwise (predModeIntra is less than 34), the following ordered steps apply:

1.The reference sample array ref[ x ] is specified as follows:
– The following applies:

ref[ x ] = p[ −1 − refIdx ][ −1 − refIdx + x ], with x = 0..nTbH + refIdx + 1 (8-140)

– If intraPredAngle is less than 0, the main reference sample array is extended as follows:

ref[ x ] = p[ −1 − refIdx + Min( ( x * invAngle + 256 ) >> 9, nTbW ) ][ −1 − refIdx ], with x = −nTbW..−1 (8-141)

– Otherwise,

ref[ x ] = p[ −1 − refIdx ][ −1 − refIdx + x ], with x = nTbH + 2 + refIdx..refH + refIdx (8-142)

– The additional samples ref[ refH + refIdx +x ] with x = 1..( Max( 1, nTbH / nTbW ) * refIdx + 2) are derived as follows:

ref[ refH + refIdx +x ] = p[ −1 + refH ][ −1 − refIdx ] (8-143)

[bbross]

Thanks for reporting.

This will be fixed JVET-P2001-vC.