(07-06-2020, 06:00 AM)Bombastisch Wrote: [ -> ]I sometimes lurk on Github and I was wondering if maybe LZ4 https://github.com/lz4/lz4 would also be a good compression alogrithm to implement, since it can decompress so fast and maybe reduce stuttering even further.
Or is Zstandard good enough and LZ4 is not worth the hassle?
Yes, Zstandard is good enough performance-wise.
Another question about RVZ: if I use LZMA2 with 128 KB block size at the maximum compression level, will it affect performance when emulating those games? I just ran some test conversions with some games on my library and LZMA2 seems to give fairly better results, depending of the game. From a quick play with them, I didn't notice any performance impact, but decided it was better to ask before converting everything...
(07-06-2020, 10:37 AM)mbc07 Wrote: [ -> ]Another question about RVZ: if I use LZMA2 with 128 KB block size at the maximum compression level, will it affect performance when emulating those games? I just ran some test conversions with some games on my library and LZMA2 seems to give fairly better results, depending of the game. From a quick play with them, I didn't notice any performance impact, but decided it was better to ask before converting everything...
LZMA2 with 128 KiB might be fine, I haven't really tested it. But avoid LZMA/LZMA2 with 2 MiB.
What does RVZ actually stand for? I took a quick peek at the documentation but couldn't find anything.
(07-07-2020, 12:17 AM)Miksel12 Wrote: [ -> ]What does RVZ actually stand for? I took a quick peek at the documentation but couldn't find anything.
It's like GCZ, but with Revolution instead of GameCube. (And no, I'm not sure what the Z in all compressed formats actually stands for...)
I keep forgetting to ask this, but considering that the blogpost regarding RVZ recommending having at least a third CPU core for decompression, I'm guessing that the two extra CPU cores of the Wii U would not be anywhere near fast enough to decompress a Zstandard-based RVZ disc image?
Which does make me wonder how the aforementioned LZ4 would fair on those same two extra Wii U CPU cores...
To clarify, my thinking here is that
I recall early Wii U homebrew attempts resulting in normal Wii homebrew running with all three CPU cores albeit at Wii clocks of 729MHz, and I had been theorizing how realistic it would be for an updated USB loader Wii homebrew app to take advantage of those two extra CPU cores for use decompressing RVZ images.
The thing is, the various GameCube game loaders (particularly Nintendont and Devolution) only support FAT32 which is obviously limited to 4096MB for a single file, but a CleanRip'd Wii ISO is at minimum 4.7GB which prevents you from storing unmodified ISOs of GameCube and Wii games on the same partition, but lossy formats like wbfs gets around this by being able to use split files at 4096MB increments.
One of the Wii U's cores might do an okay job with it, as long as you can get some RAM from the Wii U side to go along with it, because there is very little RAM left on the Wii side that could be used for this. But whether the code for this would be easy or hard to create (or whether you even can access the extra RAM at all) is something I don't know.
The RVZ decompression doesn't actually need an entire modern PC core (at least not if the block size is reasonable). The reason why an extra core is recommended is simply because this lets Dolphin avoid putting any additional load on the cores that already are busy doing other things.
(08-05-2020, 09:16 AM)JosJuice Wrote: [ -> ]The RVZ decompression doesn't actually need an entire modern PC core (at least not if the block size is reasonable). The reason why an extra core is recommended is simply because this lets Dolphin avoid putting any additional load on the cores that already are busy doing other things.
So you're saying there's a chance even the
243MHz ARM9 "Starlet" could somehow be repurposed on a Wii (not Wii U) to handle RVZ decompression?
(or maybe that'd once again require LZ4 instead)
(08-05-2020, 09:16 AM)JosJuice Wrote: [ -> ]whether you even can access the extra RAM at all
It's my impression that co-opting the Wii U's official Wii "VC" mode (what eShop Wii games used) can take advantage of the higher CPU clock and therefore presumably the extra RAM considering such mode also supports using the gamepad as an actual controller as well, but such method is extremely hacky (in a piracy manner) to the point that I would expect the much more legitimate Dolphin devs to want nothing to do with such things.