VTM encoder command: EncoderAppStatic -c BasketballDrill.cfg -c encoder_randomaccess_vtm_IM.cfg -c test_rect_slice-2-2-1-1.cfg -i test.yuv -wdt 128 -hgt 192 -f 1

VTM decoder command and error: DecoderAppStatic -b str.bin -o dec_str.yuv

VVCSoftware: VTM Decoder Version 15.2 [Linux][GCC 5.5.0][64 bit] [SIMD=AVX2]

ERROR: In function "getTileRowBd" in /users/HOME/iole/VTM/VVCSoftware_VTM_15.2/VVCSoftware_VTM/source/Lib/CommonLib/Slice.h:2178: Tile row index exceeds valid range

Possible root cause: we suspect a bug in VLCWriter.cpp when calculating numExpSliceInTile.

In the attached config files CTU = 32 and frame size=128x192, so frame size in CTU unit is 4x6. In test_rect_slice-2-2-1-1.cfg 4 slices’ height in CTU unit is 2,2,1,1. So, numExpSliceInTile should be 3, and the encoder should encode pps_exp_slice_height_in_ctus_minus1[0] = 1 pps_exp_slice_height_in_ctus_minus1[1] = 1 pps_exp_slice_height_in_ctus_minus1[2] = 0 in pps header, the height of the last slice is derived by decoder

It seems the VTM Encoder compute numExpSliceInTile as 2, and encodes pps_exp_slice_height_in_ctus_minus1[0] = 1 pps_exp_slice_height_in_ctus_minus1[1] = 1 into pps header

Therefore VTM decoder's slice layout is 3 slices with 2 CTU height each, and an error is detected.

One possible fix is to add “else {break;}” under line 380.

​https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104591

Section 8.4.5.2.9 reference substition process has a bulleted list describing the process for handling when "at least one but not all samples refUnfilt[ x ][ y ] are marked as "not available for intra prediction"".

There appears to be an error in bullet 2:

2. For x = −1 − refIdx, y = −( refH − 2 )..1 + refIdx, when refUnfilt[ −x ][ −y ] is marked as "not available for intra prediction", the value of refUnfilt[ −x ][ −y ] is set equal to the value of refUnfilt[ −x ][ −y + 1 ].

x is defined as the left boundary pixel position (x = -1-refIdx). However, both the "not available for intra prediction" and substitution processes use "-x" indexing. ie: after x is converted to -x, it is pointing within the TU rather than the intended left boundary.

I believe the intention is for all the indexing in this bullet to use "x" rather than "-x".