Bit-stream switching causes encoder-decoder mismatches

[crhelmrich]

observed with VTM 2.0 but likely to affect VTM 2.0.1 and BMS as well

I took regular VTM 2.0 coded bit-steams at QP 32 and 37 (attached)
and, with the VTM 2 encoder, created a bit-stream switching between
the two. The command-line was

./\[vcgit.hhi.fraunhofer.de\]\[jvet\]\[VVCSoftware_BMS.git\]\[e617dff\]\[enc\] -c encoder_randomaccess_vtm2.cfg -q 32 -wdt 1920 -hgt 1080 -fr 50 -ip 48 -f 500 --InputBitDepth=8 -i BasketballDrive_1920x1080_50.yuv -o BasketballDrive_qpa32.5_sw_e.yuv -b BasketballDrive_qpa32.5_sw.bit --DecodeBitstream1=[RA][BasketballDrive][QP32].bit --DecodeBitstream2=[RA][BasketballDrive][QP37].bit --SwitchPOC=240 --SwitchDQP=5

The resulting BasketballDrive_qpa32.5_sw_e.yuv looks fine. Decoding
the BasketballDrive_qpa32.5_sw.bit with the VTM 2 decoder, however,

./\[vcgit.hhi.fraunhofer.de\]\[jvet\]\[VVCSoftware_BMS.git\]\[e617dff\]\[dec\] -b BasketballDrive_qpa32.5_sw.bit -o ...

causes visible errors e.g. in frame 4. Screenshots are attached.

Christian

[crhelmrich]

Screenshots showing the mismatch (see green player on left and red player on right side)

[ksuehring]

fixed in VTM