VJ runs at 60 FPS in NTSC mode, 30 in PAL mode

djipi / Virtual-Jaguar-Rx

Virtual Jaguar, an Atari Jaguar emulator, with integrated debugger

GNU General Public License v3.0

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Open ericde45 opened 2 years ago

ericde45 commented 2 years ago

when running virtualjaguar --ntsc, fps are 60 running virtualjaguar --pal give 30 fps even when running virtualjaguar without any program/rom

djipi commented 2 years ago

Thank you to have report this issue. It is also present in the original VJ (checked with vj-20160613-win64, and 2.1.2).

djipi commented 8 months ago

Investigation provided additional clues.

The fps reports slightly more than 60 fps in NTSC -- This is due to the timer in charge of the main loop, value should be 16.6 but timer needs an integer, so 16 is used as value.
The test in PAL shows main loop takes a significant amount of time in each loop -- Ticks calculus should use a value of 20 but, got a values range between 0x1a to 0x24 instead.