Amiga questions you've always been too embarrassed to ask

[Nobby_UK]

= 1,437,278 bytes as an IFF
or
153,736 bytes as a GIF

[demolition]

Originally Posted by Nobby_UK

= 1,437,278 bytes as an IFF
or
153,736 bytes as a GIF

Sure, but the GIF also has to be decompressed into something that resembles IFF (since IFF mimics the way pictures are stored in memory on the Amiga with bitplanes), so the only difference is how much HDD space it takes (and most people have plenty of that today).

[thomas]

Originally Posted by demolition

Convert your picture into a proper 8 color IFF file - it will also take some load off the Amiga and reduce its startup time since it won't have to do much processing of the background image to show it.

Actually my observations show exactly the opposite. The ILBM datatype seems to be so poorly programmed that dithering a 24bit JPEG is much faster than loading an IFF image.

[s2325]

Are Magic Pockets, Gods and Deep Core on same engine just with different graphics?

[lordofchaos]

Originally Posted by s2325

Are Magic Pockets, Gods and Deep Core on same engine just with different graphics?

I recon (guess) Magic Pockets and Gods share the same engine, with some minor alterations in it's code, Deep Core being a different developer and publisher probably just has an engine that looks and plays similar.




Q. What method is used to prevent the speeding up of music when switching from PAL to NTSC?

I noticed when playing Deluxe Galaga, switching frequencies doesn't effect the playback speed, yet when I do the same on Fury Of The Furries, the music playback is faster.

[Amiga1992]

Originally Posted by lordofchaos

Q. What method is used to prevent the speeding up of music when switching from PAL to NTSC?

I noticed when playing Deluxe Galaga, switching frequencies doesn't effect the playback speed, yet when I do the same on Fury Of The Furries, the music playback is faster.

This depends on how the audio player works, if it's tied to the CIAs or to the vertical blank rate.

If the routine is using vblank timing, switching from 50 to 60hz or viceversa would directly impact the speed.

[LuMan]

It's a good point, Akira. I noticed that using the Play Med feature in Blitz, you need to call the command every 50th second - which ties in to the PAL framerate. I wonder if this needs to be every 60th for an NTSC-based program...

But I would have thought that a professionally coded game would be in ASM or something and manage to work around this.

[Amiga1992]

Originally Posted by LuMan

But I would have thought that a professionally coded game would be in ASM or something and manage to work around this.

You're seeing it as a problem when it really isn't. I mean, most of the games for the Amiga were made in and targeted towards the European market where 50Hz Amigas were the norm. This happens in console games too, most Megadrive games are fricking slow in the European versions and their music sounds slow. Which one would you consider the "original" version? I'd say the one with the main market in mind. So for the Amiga, music at 50Hz is the way it's meant to be heard (if a 60Hz bump changes its speed or pitch, which could also vary due to each speed needing a different frequency table but I don't understand why or when the pitch changes or not), and for the Megadrive, a console whose main developer base and user base were in USA and Japan, 60Hz is the original way.

It has nothing to do with assembler or whatever. Your music needs a constant clock to tie to and here's two possibilities, one generated by the CIA or one created for the video. It's a choice rather than a bug. Sometimes CIA timing wasn't possible for who knows what reasons, or perhaps out of not knowing it could be used? This is where this gets more technical than I can explain and someone else with more knowledge should step in. In brief, there must be a good reason for use VBLANK timing over CIA timing or viceversa, but I am not knowledgeable enough to answer you that. MY GUESS is that MAYBE if you poll VBLANK for your clock, you could affect video display performance.

I would also say in most cases nobody gave a shit about the NTSC market, the games they were making wouldn't even run well on a 60Hz Amiga so why bother to make the music replay at the right speed?

[Amigajay]

Ok, stupid question time...why is it not possible for a computer to draw every pixel of say 320x256x50 =4,096,000 pixels/sec, if it could draw that many pixels which computers now can, why cant the graphics be what the designers want them to be?! Just imagine it like a TV refreshing television pictures changing every pixel into a different colour to make up a picture, the principle in my head should be the same!
Told you it was stupid, but im sure the answer is mind bogglingly obvious, ill take it on the chin though lol

[lordofchaos]

Originally Posted by Akira

This depends on how the audio player works, if it's tied to the CIAs or to the vertical blank rate.

If the routine is using vblank timing, switching from 50 to 60hz or viceversa would directly impact the speed.

Thanks for the explanation in layman's terms, for those of us without extensive knowledge in coding it's appreciated.

[volvo_0ne]

Originally Posted by Amigajay

Ok, stupid question time...why is it not possible for a computer to draw every pixel of say 320x256x50 =4,096,000 pixels/sec, if it could draw that many pixels which computers now can, why cant the graphics be what the designers want them to be?! Just imagine it like a TV refreshing television pictures changing every pixel into a different colour to make up a picture, the principle in my head should be the same!
Told you it was stupid, but im sure the answer is mind bogglingly obvious, ill take it on the chin though lol

Because it would have cost too much to develop/produce the machine
thus no-one would be able to afford it.

(I think the Amiga Blitter was boasted to blit "nearly a million pixels a second" which is a about a quarter of what you quote. But for the price, it didn't do bad )

[ajk]

Originally Posted by Amigajay

Ok, stupid question time...why is it not possible for a computer to draw every pixel of say 320x256x50 =4,096,000 pixels/sec, if it could draw that many pixels which computers now can, why cant the graphics be what the designers want them to be?! Just imagine it like a TV refreshing television pictures changing every pixel into a different colour to make up a picture, the principle in my head should be the same!

You can update the screen on the Amiga pretty fast, but the image to be displayed has to come from somewhere.

One extreme would be essentially video, with each frame painted by an artist - but this requires a massive amount of space to store, which obviously was not available on floppy based systems. Consider [ Show youtube player ].

The other extreme would be to generate all content on-the-fly, e.g. by using vector graphics - but this requires a lot of processing power, and only a limited amount was available. Consider [ Show youtube player ].

Most games fell somewhere in between.

[khph_re]

Originally Posted by volvo_0ne

Because it would have cost too much to develop/produce the machine
thus no-one would be able to afford it.

(I think the Amiga Blitter was boasted to blit "nearly a million pixels a second" which is a about a quarter of what you quote. But for the price, it didn't do bad )

Ok...if they had missed out HAM mode (Which Jay miner wasn't happy with anyway), and increased the chip space dedicated to the copper , could they have had a 4096 colour chunky mode? (though I guess more likely on AGA)...sort of a mode X for amiga.

[Vot]

Originally Posted by khph_re

Ok...if they had missed out HAM mode (Which Jay miner wasn't happy with anyway), and increased the chip space dedicated to the copper , could they have had a 4096 colour chunky mode? (though I guess more likely on AGA)...sort of a mode X for amiga.

Ram cost is the main reason for the design. Ram was expensive, the planar graphics was also to save ram.

[Amigajay]

Originally Posted by ajk

You can update the screen on the Amiga pretty fast, but the image to be displayed has to come from somewhere.

One extreme would be essentially video, with each frame painted by an artist - but this requires a massive amount of space to store, which obviously was not available on floppy based systems. Consider [ Show youtube player ].

The other extreme would be to generate all content on-the-fly, e.g. by using vector graphics - but this requires a lot of processing power, and only a limited amount was available. Consider [ Show youtube player ].

Most games fell somewhere in between.

I'm not talking if the Amiga was capable, I'm talking about why can't it be done now?

If it was real-time there would be no 'images' as such to display, the closest thing in my head would be photo-realistic graphics say like those train sims with pre-recorded footage that move and stop to the players commands, but forget the pre-recorded part lol this would be done in real-time, just changing every pixel into a different colour 50fps to make up a real time picture...

Obviously the actual game 'data' would be still be programmed but all the graphics are pixel generated on the fly.

Another example good or bad again its painfully obvious i have no idea lol would be cloud gaming, these pictures get streamed to your TV and the games controlled by you in real time (giving the example of every pixel on the screen changing 50fps to make up a picture), but instead of being streamed through your broadband, the streaming would be through the local computer?

I'll stop now, its one of those things i have in my head that i can't fully explain, but if you can help please do!

[demolition]

In theory you could hook up some PC or other heavy computer to render the raw pixels and then just using the Amiga to show the pixels on the screen. But what would be the point? Then you are just using the Amiga as a video DAC or simple graphics adapter.

The video chip takes the content from chip memory and shows it on the display and it doesn't need the CPU to do this. The CPU, blitter etc. is then used to update those memory contents, and that is where the bottleneck lies.

[Daedalus]

Yep, there are far more operations required to modify what's on the screen than to simply display it. Displaying it is generally what a RAMDAC does - it simply reads out the pixels from a particular area of video memory and outputs them to video. The CPU doesn't have anything to do with it, which is why drawing so many pixels doesn't take up lots of CPU time. See the old ZX80 for an example of what computers would be like if the CPU actually did the drawing to screen In fact, for heavy calculations you could turn off the screen updates to get a significant speed boost, though that was of little use for games...

The operation of moving graphics in a meaningful way is the real stressful part for a computer. There are many calculations involved, including copying the graphics into the area of the memory where the display pixels are read from. If an object is moved or removed from the display memory, it must be replaced with the original background pixels, which also takes time. In the Amiga, these sorts of operations are carried out by the blitter, which is specially designed to copy around chunks of memory without the CPU having to do it itself, and modern GPUs work in a similar fashion. But copying that memory around is far slower than simply reading the value of the pixel and converting it into a colour for the video, which is why things are generally done the way they are.

[clebin]

Originally Posted by Amigajay

I'm not talking if the Amiga was capable, I'm talking about why can't it be done now?

If it was real-time there would be no 'images' as such to display, the closest thing in my head would be photo-realistic graphics say like those train sims with pre-recorded footage that move and stop to the players commands, but forget the pre-recorded part lol this would be done in real-time, just changing every pixel into a different colour 50fps to make up a real time picture...

Obviously the actual game 'data' would be still be programmed but all the graphics are pixel generated on the fly.

Another example good or bad again its painfully obvious i have no idea lol would be cloud gaming, these pictures get streamed to your TV and the games controlled by you in real time (giving the example of every pixel on the screen changing 50fps to make up a picture), but instead of being streamed through your broadband, the streaming would be through the local computer?

I'll stop now, its one of those things i have in my head that i can't fully explain, but if you can help please do!

A classic Amiga won't be fast enough to slurp up that amount of data in the required time unfortunately. Try downloading a few megabytes over FTP on an average Amiga and you can see how painfully slow the connection is by today's standards. Try the same on a modern machine and you'll see that the bottleneck is the Amiga itself not the network.

On top of that, the Amiga would need to deal with any compression that you're applying to the video stream and it would just choke on it. Most classic Amigas are too slow even to play a local MP3 file because of the decompression that needs to happen in real-time.

[ajk]

@Amigajay

Well the problem remains the same. Today, movies can have very close to realistic computer generated imagery. But a two hour movie takes many months to make. There's no way you can generate comparable imagery real-time based on the input from the player.

So either you have real-time rendered game graphics, which are these days very good but not life-like, OR you have pre-rendered videos which look great but won't be very interactive.

[gimbal]

Originally Posted by ajk

So either you have real-time rendered game graphics, which are these days very good but not life-like, OR you have pre-rendered videos which look great but won't be very interactive.

Yeah you can say that again.

[ Show youtube player ]

This game blew me away. BUT, it still looks awkwardly wrong at times.