So, like, is Star Blade does use teh FMV for its polygons or not, yo?

[tomaitheous]

I also always wondered why the framerate of the earth level was so low, if it was pre-rendered why wouldn't they have just rendered all the frames.

Because a fullscreen of tiles takes a lot of bandwidth from the CD unit (and transfer time to the VDP as well). The CD bandwidth is the bottleneck, so you start to see the frame rate go down/get choppier. Something has to give and pace of the video/stream is more important than the number of frames in a unit of time.

I just watched Silpheed's intro scene a few dozen times and now I'm watching the first level entrance cutscene. I cannot see any evidence of this being video either. The aliasing from the ultra low resolution polygons makes the ships almost look like they could be made of voxels. The backgrounds in these scenes are definitely something the Genesis CPU could o on its own. They're just flat walls like in Flashback and Out of This World. Then in the game certain aspects look more like they could just be a rotating 2D background, perhaps with some frames of animation, as much as they could be FMV. Other elements look more like FMV, but could just be animated as well.

It's already been known that Silpheed uses streaming for the background in game(you can crack open the files in the ISO and see the compressed video - albeit all messed up). Why would they do anything different for the intro? FMV, animation, streaming video - it's all the same thing.

The backgrounds in these scenes are definitely something the Genesis CPU could o on its own.

What? The Silpheed intro? I've never seen anything to indicate the Genesis CPU itself could render such an intro at that frame rate.

[sheath]

Because a fullscreen of tiles takes a lot of bandwidth from the CD unit (and transfer time to the VDP as well). The CD bandwidth is the bottleneck, so you start to see the frame rate go down/get choppier. Something has to give and pace of the video/stream is more important than the number of frames in a unit of time.

I meant that the level on earth, or the planet, with the mountains and tons of polygon detail is a lot slower than the rest of the game. For the VDP everything converts to tiles doesn't it?

It's already been known that Silpheed uses streaming for the background in game(you can crack open the files in the ISO and see the compressed video - albeit all messed up). Why would they do anything different for the intro? FMV, animation, streaming video - it's all the same thing.

I haven't seen the files opened up and viewed at all, sorry. Agostinho's pics using Gens is the first I've seen of an actual break down. I wasn't aware that Silpheeds could be viewed.

I have assumed, possibly incorrectly, that Full Motion Video, or streaming video, is significantly different from animated tiles or rotating/scaling backgrounds. I know on some level to the VDP they are all the same, but I was trying to figure out how the effects worked. The nebula in the first level of Silpheed that rotates in a broad circle, only half of which is viewable to the player, seems like it could be a static background effect using the Graphics CoProcessor.

What? The Silpheed intro? I've never seen anything to indicate the Genesis CPU itself could render such an intro at that frame rate.

The rolling cinematic that plays during the attact mode is what I am talking about, and the first level into with the big ships. Inside the hangar scenes in particular, but even the space scenes with far off ships that appear to be high polygon detail. This particular comment was directed purely at the backgrounds within the hangars, that consisted of a couple of lines and solid colors, not the ship model.

[Joe Redifer]

The background in the Silpheed opening (which is just stars, if I recall) still has a 3D shape to it. It's not simply scrolling left or right, but changing as the camera pans to and fro, changing the perspective a bit. Also, I'm pretty sure that there's not scaling and/or rotation going on like, say, Batman Returns. The Sega CD could scale a background on a 3D plane like I mentioned above with its scaling and rotation features, but I don't think that's happening here. The Sega CD's scaling and rotation was pretty cool, though. In Batman Returns you could see the sides of buildings and they're dynamic, changing perspective depending on your proximity to them. The Adventures of Batman & Robin did similar things with even more objects.

[Kamahl]

The Adventures of Batman & Robin did similar things with even more objects.

If only it had better gameplay, the graphics are just phenomenal. Same goes for Soulstar.
If every Sega-CD game looked like that you can bet the system would be more popular than it was.

[Team Andromeda]

The background in the Silpheed opening (which is just stars, if I recall) still has a 3D shape to it. It's not simply scrolling left or right, but changing as the camera pans to and fro, changing the perspective a bit. Also, I'm pretty sure that there's not scaling and/or rotation going on like, say, Batman Returns. The Sega CD could scale a background on a 3D plane like I mentioned above with its scaling and rotation features, but I don't think that's happening here. The Sega CD's scaling and rotation was pretty cool, though. In Batman Returns you could see the sides of buildings and they're dynamic, changing perspective depending on your proximity to them. The Adventures of Batman & Robin did similar things with even more objects.

Spot on . It's all pre rendered Polygons just be played back and off the Disc hence the access light , Nothing real time about it at all . Batman looked ace and was all in real time quite amazing gfx for a system made in 1991 .

[sheath]

Well, yeah, I wasn't talking about real time 3D with a movable camera, but the cutscenes in Silpheed show all kinds of rendering artifacts but no video artifacts. I was speculating how they might have achieved that without streaming video.

[Kamahl]

Well, yeah, I wasn't talking about real time 3D with a movable camera, but the cutscenes in Silpheed show all kinds of rendering artifacts but no video artifacts. I was speculating how they might have achieved that without streaming video.

They could just stream rasterized vector coordinates and then paint the triangles. Personally I think it's just RLE video, the results would be pretty similar.

[Team Andromeda]

Well, yeah, I wasn't talking about real time 3D with a movable camera, but the cutscenes in Silpheed show all kinds of rendering artifacts but no video artifacts. I was speculating how they might have achieved that without streaming video.

It is streaming video and I don't know how Game Arts made it look all so clear . That said I was very impressed with cadillac and dinosaurs in game streaming video too and the Chuck Rock II intro

[sheath]

The background in the Silpheed opening (which is just stars, if I recall) still has a 3D shape to it. It's not simply scrolling left or right, but changing as the camera pans to and fro, changing the perspective a bit. Also, I'm pretty sure that there's not scaling and/or rotation going on like, say, Batman Returns. The Sega CD could scale a background on a 3D plane like I mentioned above with its scaling and rotation features, but I don't think that's happening here. The Sega CD's scaling and rotation was pretty cool, though. In Batman Returns you could see the sides of buildings and they're dynamic, changing perspective depending on your proximity to them. The Adventures of Batman & Robin did similar things with even more objects.

I forgot to reply to this first point more thoroughly. I think there are Genesis space sims that have the fisheye effect on the stars in the background. Shadow Squadron on 32X looks to be using the Genesis for the backgrounds and it fisheyes everything. I'm not sure if that is what you meant by the stars having a 3D aspect to them. What I was suggesting about Silpheeds backgrounds is a composite of Genesis CPU/VDP effects with heavily animated background tiles and a smattering of that technobabble 3D vector stuff people have been suggesting.

I think some of the better FMV games do some of this already, cutting out "FMV" objects and placing them on a regular tile background to eliminate the free floating video artifacts all over the screen. Load Star and Rebel Assault are two that spring to mind, in addition to Stellar Assault's intro.

[Team Andromeda]

I think it also helped that most of the ships in the game were untextured polygons with simple colours of grey ect , you can see the FMV grain at times on the sk/space backrounds though

[kool kitty89]

They could just stream rasterized vector coordinates and then paint the triangles. Personally I think it's just RLE video, the results would be pretty similar.

Exactly . . . this would apply to all the Sega CD games with fixed PoV polygonal models in the background. But for the resolutions/color depths/framerates involved in Starblade and Silpheed, RLE compressed video would make perfect sense. (and you could easily have RLE allow for dithering as well, just use 8-bits to define the color instead of 4 . . . or less than 8 if you didn't need all 256 possible combinations of 16 colors -use the extra bits for RLE information)

Rasterizing vector animation would require more overhead than simple RLE compressed frames, and it's not needed for what's generally being done here. It's also not even useful for the various non "low detail" polygonal stuff in Silpheed's case. (there's a lot of more detailed prerendered 3D stuff in there -planets in BG and terrrain in the surface levels, along with some explosion effects -aside from sprites-) The slowdown in areas of non polygonal stuff would also make sense for RLE compression since that sort of detail would compress much more poorly than the large areas of solid color (or checkerboard dither) with the space levels. (unless they applied a fillter when encoding to reduce quality for higher compression ratio using RLE -ie lossy compression; just because RLE is a lossless format doesn't mean you cant use lossy compression on the encoding end -converting to 4-bit color alone would be quality reduction too Sega's Cinepak is technically lossless too, though you'll typically get pretty limited compression without lossy filtering applied that caters to Cinepak -super posterized video will compress pretty well though, which is true for LZ style compression and RLE too)




Continued from: http://www.sega-16.com/forum/showthr...752#post562752

No, it's not. I think you missed this while you're off: http://www.sega-16.com/forum/showthr...gons-or-not-yo
Yes, it's a technique with limited use, but, still, you could render Starfox background's animated "objects" (not the enemies with AI, of course) using that to save a lot of processing resources IMO.

It's FMV . . . just because it's not streaming bitmaps or using bitmap style graphics compression (RLE, LZ77/LZSS/etc, vector quantization -cinepak, etc) doesn't mean it's not FMV.
I'm not sure that it was definitively established that streaming vector graphics animation was used (using software rasterization), but the same method could have been used in Silpheed for its compression format. (with the framerates involved and the large areas of solid color, RLE compression would be perfectly applicable as well though, and a lot less computationally intensive -plus it allows compression of other things in the BGs like the terrain, explosions, and planets in Silpheed)

"precalculated points" projected into 2D space is pretty much vector animation, and it's basically the same method Another World (out of this world) used for its animations. (some similar games used posterized rotoscoped compressed -probably RLE- animation -I believe Flasback used that method) You'd get a higher compression ratio for pure vector animation vs RLE in these examples, but with the framerates and resolutions (and color depths) involved, it would really seem like RLE would work fine. (you only need like 2:1 compression over raw 4-bit bitmap frames)
Like all other FMV railshooters (or scrolling style FMV BG games), the video involves full screen animation frames, not individual objects moving around the screen. (you could have vector animated objects too -like Another World- and that's still not 3D, but it's also not FMV)

And in either case, you're stuck with fixed perspective on the animations, realtime perspective can't be produced like realtime 3D rendering since the points are all fixed for prerendered vectors. So you'd need a lot of animation frames for most of Star Fox's objects . . . it could work for a CD based system, but cart or even floppy disk would generally rule that out since it takes way too much space. (I was thinking Star Fox might use it for some objects with fixed perspective, but side from the actual 2D scaled sprites, I don't think that was done)

In any case, this is all aside of the point for the context I intended with "reailtime 3D" . . . and even Stellar Fire isn't very 3D due to the fixed Battlezone style perspective. (it uses realtime 3D objects, but the gameplay itself is pretty close to plain 2D)

What is "true 3D"?

Realtime calculation of points in 3D space projected to a 2D vector or raster display . . . technically you'd have 3D without the latter, but you couldn't physically see it.
The simplest form of 3D is just projected points (tiny dots on screen, and this is sometimes used for simple 3D representations and even demo/game effects). The next step beyond that is drawing vector lines between the points to create frames, and then there's hidden line removal or solid filling of the shapes created by the vector lines to represent 3D solids.

You could also take a step back from that and stick with the 3D points, and then use those not to draw vector lines or polygons, but draw 2D objects instead, but with the game engine itself still technically being in 3D. (think Wing Commander 1 or 2 style animation . . . I have no idea whether WC actually does the game engine that way, but that sort of graphics could certainly be applied to a game engine working in real 3D space, and you'd only need 3 points for each object, with the distance/position defining what animation frame, rotation position, and scaling size to apply -or animation alone if not doing scaling or rotation effects)

You can also have games that use tricks to depict 3D space visually, but use no actual 3D elements in the game engine whatsoever . . . that could involve polygonal models with prerendered animation and a 2D game engine or things like ray casting and scaling effects.
Wolf 3D style games have no Y-space (height/vertical position) at all, so that's an obvious example of 2D "looking" like 3D, but cases like Doom or Duke Nukem 3D (or voxel style height maps) are a bit odd, since they don't technically project 3D space but they do involve some form of movement/position in Y-space, but it's strictly limited to a height map (like a topographical map) where terrain or buildings have a very strict/limited structure. (the fact that it's so convincing is that real world architecture conforms to that somewhat -and more so terrain- and the level design of the game does a good job hiding it from the player as well)

I think you're pretty wrong. It can be really using pre-calculated geometry like some other games used for the backgrounds or "on rails" segments and that also takes up a lot of memory.
Probably this is the same trick that is used during Silpheed's intro and in that sequence before the first stage. That isn't FMV.
There are no video artifacts or grainy signs in the backgrounds like in Silpheed, how do you explain that?

Lossless video compression could look absolutely identical to precalculated vector animation, no artifacts whatsoever. (well, technically, a LOT of Sega CD FMV is lossless or even uncompressed, but the artifacts come from the conversion methods and how detailed the graphics are in general -shaded polygons already formated for the color restrictions of the MD can be truely losslessly compressed, as can 2D cartoon animation . . . hell, Cinepak can even be used as a lossless compression scheme, it's all a matter of the encoding process)

Artifacts (especially dithering and posterization) say nothing specific about whether any compression has been used at all. A ton of Sega CD FMV is uncompressed but still has tons of artifacts from postierzation, dithering, etc.

And I maintain that vector animation is still streaming video . . . so long as it's full-frame animation and not individual vector animated sprites/objects that are then manipulated in realtime. Then it becomes a hybrid realtime animation technique. (like streaming/buffered animation in some multiemdia PC games with animated objects moved across the screen independent of the animation frames themselves -like the Cutscenes in X-Wing or Tie Fighter, or Wing Commander 2 . . . among others -Lunar II and Popful Mail on MCD would also be good examples)

[sheath]

So, kool kitty, what did you make of the artifact free but 3D warped effects in Sega CD Star Blade that barone pointed out? Also, the VDP and Word RAM dump in this post. Ah heck, I'll just repost them, I wish the PS1 and 3DO videos were still online.





Word RAM:

[madmax2069]

I wish the PS1 and 3DO videos were still online.

There's still videos of them on YouTube but the video quality is questionable.

[kool kitty89]

So, kool kitty, what did you make of the artifact free but 3D warped effects in Sega CD Star Blade that barone pointed out? Also, the VDP and Word RAM dump in this post. Ah heck, I'll just repost them, I wish the PS1 and 3DO videos were still online.

I'll have to keep looking, but all the "FMV" examples they showed had the tiles decoded by the Sub-CPU into word RAM . . . so you could use the Sega CD debug to view the data.

However, if Starblade is having the MD CPU decode part or all of the data (stream RLE code/data to word RAM or have sub-CPU decode to a bitmap framebuffer and use main CPU to convert to tiles on the fly), then you wouldn't see any graphics in tile format until you got to VRAM. You can also have the ASIC convert 8-bit unpacked (4 bits per byte used) bitmap images to 4-bit tile format, but that (like all ASIC operations) only works in 2Mbit word RAM mode, not dual 1mbit mode. (and the latter allows the sub-CPU to keep working full time, and page flipping the next frame by flipping the word RAM banks)
Likewise it could be vector animation that the main CPU rasterizes in realtime or (more plausible) vector animation that the sub-CPU rasterizes to a framebuffer in word RAM and the main CPU converts to tiles and writes to VRAM. (in any case, since data isn't in tile format within word RAM, the debugger shouldn't show it as such)

This would also be the reason for the "similarity" to software rendered graphics in cart games. And, word RAM aside, I'll bet any other framebuffer rendered FMV will show up similarly in VRAM. (assuming they don't tile-sort as well, Dune, Novastorm, Microcosm, Stellar Fire, MegaRace, and the tons of uncompressed stuff like the Wolf Team games and Sonic CD's FMV should show up as lots of individual tiles in VRAM -whether or not they're tiles in word RAM would depend whether the sub CPU or main CPU handles tile conversion) Technically, Cinepak based stuff should be "the same" as those examples too, as far as the VRAM end of things goes, since it doesn't tile sort either and so an entire frame (window) worth of unique (and redundant) tiles should be found in VRAM. (plus it's double buffered, which isn't the case for all FMV or software rendering)

Edit: saw your post on Stellar Fire: the lack of tiles in word RAM would imply that the main CPU is handling bitmap to tile conversion or (less likely) that the main CPU is handling the decompression itself. (particularly unlikely since that game uses 2 320x128 windows for 31 colors and some form of lossless compression -possibly RLE- so a lot of overhead for the main CPU to handle on top of tile conversion)

On another note, it does seem like Silpheed's video format removes redundant tiles rather than compressing full-frame bitmap images (Dragon's lair seems to do that too). I know Cinepak doesn't do that, though it decodes to tiles directly into word RAM rather than a bitmap framebuffer. Tile sorting works well for super posterized stuff . . . and that probably would have been a simple compression method that would have helped with the choppy uncompressed Japanese FMV games too. (really though, RLE compression shouldn't have taken a lot of work either and would cater very well too . . . or tile sort and use RLE or LZ lossless compression -Silpheed probably does both tile sorting and lossless compression of some sort, I wonder if some western FMV does that too -like Novastorm or Dune)

[Saturn Fan]

The Sega CD CPU isn't blazingly faster than the Genesis CPU.

Have no idea what you guys are talking about but, Sega CPU was MUCH faster. 12.5 Mhz Vs 7.6 Mhz. About 5 Mhz difference was huge back in the day!

Pretty sure the Neo Geo cpu was 12 Mhz also.