![]() ![]() Shadow wrote:Why did Sony even make a VCD system. Doesn't look good under emulation, but on a real PSX with a CRT it looks fine. I made a "FRIENDS" short which I used as a test about 4 years ago. A whole movie could be played on the PSX without any delays or pauses from the SD Card What's cool though is with PSIO, you can easily swap between multiple ISO's instantly, so it means after 40 odd minutes of playtime from one ISO, the program code would tell PSIO to switch to the next ISO and continue playback of the next 40 odd minutes minutes seamlessly. Only thing would be you would have to swap discs or if they used a double-sided CD-ROM, turn it over like a Laser Disc. Isn't the STR format decent enough? I mean, sure, maybe they were trying to market a whole format (in this case, Video CD's), but I'm sure Sony could have come out with their own movie format for the PlayStation which used the STR format and regular MDEC in the R3000A. I don't if anybody has ever used that feature, but it was really useful to figure out which functions did eat up how many clock cycles (and to optimize the code as best as possible). Oh, and side note: There's some profiler in no$psx. But then, reducing the sample rate, dropping stereo, unrolling some loops, and optimizing some stuff helped to reduce the audio load. Okay, maybe I had underestimated something. ![]() I didn't believe it, and mounted to audio engine the next day - which dropped the frame rate back to around 5fps. The funny part was when I got it working at 10fps, and then TriMesh mentioned that audio decoding might also consume a lot of cpu load. Changing byte operations to process four bytes at once via 32bit memory access, in some cases also doing multiple 8bit operations via 32bit registers (for color additions & saturations). Squeezing most variables & cpu stack into the 1Kbyte scratchpad (=fast RAM) memory. So I've blown up some more weeks on optimizations: Using the MDEC hardware. Next, I've ported the 80x86 code to MIPS, aiming at 10fps/mono, and the first built did actually reach around 5fps, which wasn't too bad, considering that it wasn't yet really optimized for the PSX hardware. Then I've blown up a bunch of weeks on learning how to implement the MP2 audio and MPEG1 video decoding, and first implemented it as 80x86 asm code (which is now also included in no$psx, somewhat emulating the SCPH-5903 hardware with 30fps/color/stereo). I finally got two sample VCDs, and -shortly after - four real movies on pressed discs from TriMesh. The first problem has been finding VCDs which are nearly unknown in western world. 5thElementSwDecoder.jpg Some Making Of notes ![]()
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