Anyone care to comment in-depth on the PC-FX hardware design?

[SamIAm]

I personally cannot stand 2D games that use 3D rendered nonsense.  hand-drawn or GTFO.

You know what I think would be cool? A 2D Castlevania game where all the backgrounds are hi-color, hi-res scans of actual 17th century-style paintings. They could hire a bunch of art students and make original material or whatever. There's so many ideas...

[Arkhan]

f*ck that lets just go scan a bunch of art books and shit and diddle up the colors so it looks video-game-like.

[Keranu]

I personally cannot stand 2D games that use 3D rendered nonsense.  hand-drawn or GTFO.

You know what I think would be cool? A 2D Castlevania game where all the backgrounds are hi-color, hi-res scans of actual 17th century-style paintings. They could hire a bunch of art students and make original material or whatever. There's so many ideas...

That's a really good idea! Like that one a lot, could add lighting effects via hardware too to add some liveliness.

[SamIAm]

^^^I guarantee that nobody has seen anything quite like a painting coming alive with parallax, palette shifts and transparencies.

Anyway, back on topic, I thought of another question. Does anyone have any speculation about why the PC-FX uses so much PCE hardware? To my understanding, it's got basically all the sound and video hardware in there. Do you think it was because they were hoping to achieve backwards compatibility but abandoned it partway through the design process, like the SNES going with the 65c816 because it was b/c with the NES CPU? Or do you think it's because they were hoping to take advantage of developers' familiarity with the hardware?

If it wasn't that kind of decision, could it have just been a cost-cutting measure? Or something else?

As I think about it, I can understand using the PCE sound chip as a quick solution and a cost-cutter, but the two 7ups and KING combo seems a little odd. Surely they could have found another video solution that was similarly priced, more simple and, if only for 2D, more powerful.

[SignOfZeta]

The absolute state of the art in 2D gaming these days is actually coming from...Bandai.

It's true. Check out Super Robot Wars Z2 (PSP) and Kamen Rider Generations (DS).

[Arkhan]

They chose to stick with the same kind of PSG because it sounds f*cking amazing.  True story.

[saturndual32]

I agree with Arkhan, about the PCE soundchip being awesome, but at least they should have used 2 for the PCFX, like they did by using 2 7UP videochips instead of one.
Anyway, i see that the FX has 3.75MB of RAM, does anyone know how it is divided. I wonder if it had enough video RAM to do a port of Street Fighter Zero 2 comparable with the Playstation and Saturn.

[Arkhan]

DUAL PSG?

omg I just peed myself.

[Nando]

yeah, drawing in any form is laborious for me.

I don't know if there is anyone who would really want to do something like that.   It's too much goddamn work.

"Hey draw, a 3 hour show for me, cmon"

labour intensive to say the least, but well looped animation bits could work. It would come down to a really Type-A grip on the art direction, to make sure it works. Then finding an OCD team to do the animations

[SamIAm]

All right, after spending boatloads of time messing with Zeroigar's MPEG videos, I think I can comment a little on the PC-FX's FMV playback.

Zeroigar's movies are 256x208 pixels, with approximately 30 horizontal lines and 8 vertical lines of blackness around the real video. They run at 12 frames per second, have 31.5kHz stereo sound, and average about a 227kB/sec data rate for playback. Note that this is not a totally constant data rate; there's actually quite a lot of variation over time.

Within these parameters, the PC-FX appears to have fairly decent and versatile video playback. I'm just speculating, but because the drive can go up to 300kB/sec, I suspect that you could maintain similar quality going 15 FPS at the same resolution and sound quality, even with no black areas. With no room for variability, though, some things might not encode well.

With the sound set to 22.1kHz mono, I'd imagine that 20 FPS would work fine, assuming that the system can re-portion the bandwidth.

The tool I'm using for encoding the Zeroigar videos has a maximum of 256x240 resolution. Whether the system itself can go higher than that, I can't say. Also, while the maximum sound quality appears to be 44.1kHz stereo, it can go all the way down to 15.8, 11, 7.9 or 3.9kHz mono. FPS rates include 30, 20, 15, 12, 10, 6, 3, 2, and 1.

Finally, one thing to note is that visually active footage at 30 FPS is probably going to look terrible when coupled with any kind of decent sound and resolution. I would be surprised if any games used 30 FPS at all.

[KiddoCabbusses]

Are you sure the PC-FX doesn't have a 25 FPS rate? I mean, I would've thought that'd have been a normal framerate by that time... hrm...


Anyhow, I always thought Battle Heat's OP looked incredibly visually active, even compared to other PC-FX games;


Since that seems like it pushes the limits of what the PC-FX's FMV playback can do, would you mine telling me what it's specifications are?

[SamIAm]

The framerate kind of needs to multiply evenly into 60, so 25 FPS doesn't really work. Movies filmed at 24 frames per second go through 3:2 pulldown to work in 60Hz interlaced TVs. Modern games that don't use frame-based timings update the screen with whatever the latest image is that the GPU has drawn, and so they can have pretty much any rate imaginable.

EDIT: OK, looking at a rip of that youtube Battle Heat video was confusing. Since I don't have a copy of that game, I popped the Tengai Makyou fighter into Mednafen instead and set it on frame-advance mode for the intro to make sure I knew what the system was doing. This and Battle Heat are similar enough. What I found is very strange.

The framerate for Tengai Makyo in particular is highly variable. Most of the time it alternates between 15 and 30 FPS, but usually the rate changes so rapidly that you can't really call it a rate. The system has to draw to the TV at a locked 60 FPS, but you'll see the image updated in 2 frames, then 4 frames, then 2, then 2, then 4 and 4 and 4, and then occasionally 3. That's what Battle Heat appeared to be doing as well, although with a little less variation. They must be using a unique format and encoding method.

Usually the moments when the image was updated in 2 frames/60 (30 FPS for that instant) were parts with relatively less change in the frame, presumably for compression reasons. They must have planned the hell out of this.

The video is 256x232, which beats Battle Heat if the youtube video is any indication. I can't quite hear if the sound is mono or stereo with my current setup, but it doesn't quite sound like 22.1kHz. I'd be stunned if it was 44.1kHz stereo with this quality. It would mean that somewhere out there is encoding software for the PC-FX that beats the pants off the software included with the GMAKER/PC-FXGA publicly released stuff.

It's not really possible to know the details about the sound for sure without accessing the video at the source, though.

[Mednafen]

The possible PC-FX ADPCM playback rates are ~31468 Hz, ~15734 Hz, ~7867 Hz, ~3934 Hz.  (Of the pattern 31468 / (2 ** n), which allows for very computationally-inexpensive linear interpolation at the < 31468 playback rates, by right-shifting the delta step by 1 to 3, while still adding the shifted delta step value to the predictor at 31468 Hz).

The ADPCM encoder that (most?) commercial games used is buggy(the GMAKER one is buggy too IIRC); it uses an algorithm that is mismatched to how the PC-FX actually decodes, which results in the audio being noisier than it should be.

For practical purposes, the JPEGish decoder chip can only display at 256x240 maximum.

The decoding is semi-real-time, with a 256x16 automatic double-buffer setup(decodes into 256x16 buffer A while displaying buffer B, then displays buffer A while decoding into buffer B, etc).  Kind of overkill as far as computational power required goes, but makes more efficient use of RAM I guess.  This means that 60FPS FMV is no problem as far as the decoder chip is concerned, at least.

[SamIAm]

Thanks for the post, Mednafen.

I was thinking 44.1kHz was an option because it's available in GMAKER, but sure enough, trying to encode a video with that doesn't work at all, regardless of what the source is.

Having said that, I just tried making a PC-FX video with 30 FPS source material and output settings of 30 FPS, stereo 31.5kHz sound, and a 300KB/sec limit. It wasn't as bad as I was expecting. I must have overestimated things after spending so much time re-encoding videos that were lossy to begin with.

EDIT: Oh, and if anyone is interested, Megami Paradise II is a solid 12 FPS with 256x232 resolution, minus about 12 horizontal lines total of blackness.
Also:
Sparkling Feather is 256x232 @ 12 FPS, about 8 vertical lines of black on the borders
First Kiss Monogatari has a 30 FPS bit for the company logo at the beginning, but then goes back to 12. Forgot to check the res.
Zenki is like Tengai Makyo, with highly variable rates averaging around 20, as well as 256x232 resolution with no borders. For now, it appears that these two games have the best video on the system.
Finally, Battle Heat is 256x232, but its huge black borders make it 256x160. Like the previous two, the rates are highly variable, but with an interesting twist. There are long sections of 30 FPS, but they are preceded by moments of 10 FPS, maybe to fill up some buffer.

[KiddoCabbusses]

It's not really possible to know the details about the sound for sure without accessing the video at the source, though.

I got a legit copy of Battle Heat (wish I could say the same for the Tengai Makyo game) and would be more than willing to do a rip for analysis sake. (Although more than likely if I'd have to transfer an ISO image around I'd may as well download one..)

I wouldn't really have the ears for being able to gauge the quality of the music in the games, except I'd think Tengai Makyo's music generally doesn't sound like it was as encoded in as high a quality. (Although this may just be the ol' "OMG LYRICS N' VOCALS" mindset here, but then again, if the audio quality had any really noticable decay comparing the FMV file and the CDDA audio version on the disc, it'd probably be most notable -in- the vocals... ... my lord, am I overthinking this.)