as i understand it beam racing/chasing is basically a very clever and more “the right way” solution / replacement for what frame delay currently provides in retroarch, its main purpose would be to cut down on that last frames worth of latency that’s inherent when pushing full frames with vsync on the host via standard api’s (opengl, vulkan, drm, etc. and when i say last frame i mean compared to methods like using hard sync/fences in opengl, which can achieve approximately just 1 frame additional latency over original hardware)
however, wouldn’t it be a lot of work for relatively little pay off? the libretro api, retroarch and its shader pipeline, and all the libretro modules of emulators are all currently based on full frames. not only that but the core logic in many of these emulators are too. (well, to varying degrees. the point being most emulators would need their core logic tweaked as well as the libretro implementation)
it’s also not compatible with run ahead, which while not a silver bullet, provides at least as good if not better results where supported. (run ahead requires that the emulator has reasonably efficient, fully complete, and side affect free serialization support, which not all emulators do or even can provide. and it’s also game dependent) I get that there are pros and cons to each approach, but run ahead at least made a lot of sense for retroarch since it was mostly built upon features that already existed.
personally i think medanfen would be a much better testing ground for this than retroarch. for one thing it would most likely be easier and less disruptive to implement there, and for another doing so would lay the ground work for getting all the libretro mednafen cores ready to support this if and when beam chasing ever gets added to retroarch + libretro api. (note: i would advise against requesting/pestering mednafen author to implement this)
edit: fixed some terminology
edit 2: nevermind, don’t bother responding to this post, mdrejhon has already addressed pretty much everything i’ve brought up at some point or another in one of his many posts here, there were just sooo many about this i didn’t catch all of it at first. anyway, i still stand by my statement that mednafen is more suited for this