Amiga Animation and CHIP RAM versus FAST RAM

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What were you using to measure the frame rate?

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Rowbeartoe wrote:
On the ST, each function key represented differn't frame speeds.f9 was 30fps and f10 was 60fps.  So when I had the same demons up, the Amiga was always doing either f8 or f9.  The Software on the ST always claimed 60fps as well.

Ok... So you didn't actually measure the frame rate?

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Rowbeartoe wrote:
It was obvious to me.  For example, I could count the frames of an animation.  It wasn't rocket science.  If it was 15 frames, the ST would flip thru all of them 4 times every second at F10 or 2twice at f9.   And it was easy to match the exact speed on the Amiga Demos I had at the time.  Albeit only a few.  I had the machines side by side and the customers loved it.  

Ok, I'm not really sure what you are basing this on... Both machines were more than capable of running at the refresh rate of the display device, the Amiga with more colours and at a higher resolution than the ST... simple really.

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JetRacer wrote:

Fun fact: even modern PC's have major difficulties working under similar conditions (read: massive MB 320x200 raw animation replayed with flawless 60hz fps). It's ofcourse the OS of Win/Linux/Mac that bogs down performance and nothing else.

It does? Perhaps 10 years ago... but not now...

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Rowbeartoe wrote:
Ok, so from the bandwidth point of view, the Amiga could in theory.  But what about the software I mentioned?  Why was the Scult 3D, juggler, and Antic Cad-3d 2.0 never page flipping at 60fps? I may never have had a frame counter, but clearly the Amiga demos converted to the ST could run at least twice as fast on the ST, suggesting to me either 24fps or 30fps.  Now, I want to make it clear, I'm not saying the graphics were better on the ST, they were downgraded slightly in Spectrum 512, but I'm just talking about good old fashion page flipping.  The Atari ST used 16MHz RAM, 8 MHZ for Video and 8 MHz for the 68000- it was cheap and effective for this kind of stuff. I'm just curious as to why the demos I saw, and the software reviews never mentioned up to 60fps animations and if in fact the Amiga software allowed it's user to reach such a speed?

 

As a programmer, I could flip a page far faster than 60fps... simply by changing the bitmap pointer... But to do so would look terrible, so I would always synchronise it with the VBL of the display this would limit the frame rate to whatever the refresh rate of your display device was.

-Edit- I should point out that the GFX chips have priority over the CPU with Chipram access on the Amiga.

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JetRacer wrote:
@ bloodline: notice how I didn't write compressed video replay but raw video (more accurately: animation).

An attemt to make a modern OS display and loop a +16MB raw feed flawlessly in 60fps will in 99.9% of all cases fail miserably. If not at replay then when it "loops" and halt for 0.5 sec to re-loading the whole thing or some similar dumbass behavior.

I would seriously have to disagree here, since I can run 50 stereo tracks of 24bit audio all at 48Khz on my MacBook Pro... right from its slow laptop drive without problems in Logic Pro... That is something like 25MB/s... not to mention the number of effects and automations running at the same time...

I have friends who are film students, one is able to edit uncompressed HD films in FinalCut on His MacBook Pro... and the other uses Adobe something-or-other on a fairly old WinXP machine...

Even the humble laptop has had this level of performance for many years.

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Rowbeartoe wrote:


Zac67 wrote:
I'd venture the replay routines on the Amiga were optimized/designed to allow replay of interlaced frames. There are only 30 interlaced fps, so the coders didn't include a special faster non-interlace mode replay of up to 60 fps.
The Ataris lack interlace mode, so you'd code for 60 fps from the start.

Maybe as simple as that.

Interesting- so you have a theory that say those Anim files were limited to 30fps because the programers scripted them for interlaced modes?  

This does get to the heart of my question.  Most software by 1989 that allowed non programers such as myself to make animation using programs such as Scupt 3d, or photon paint II, saved the files as ANIM files (?).  So these players much like the Atari ST SPC players, could page flip up to only 30fps?  Unitl that AGA chipset and ANIM6 or ANIM7 came out?  

Thank you everyone for your help.  I'm always much more fascinating is what software allowed the user to do versus the specifications.  If a paint program was faster on an ST, did didn't matter if the Amiga had a Blitter, the software buyer was at the mercy of the programmers.  [/quote]

It could be that Amiga software was almost always beam synchronised to ensure that the graphics wouldn't tear during redraws... I guess the Amiga was therefore at the mercy of the display device, if that was a TV, then it would be 25fps (PAL) or 30fps (NTSC).

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Zac67 wrote:

bloodline wrote:

It could be that Amiga software was almost always beam synchronised to ensure that the graphics wouldn't tear during redraws... I guess the Amiga was therefore at the mercy of the display device, if that was a TV, then it would be 25fps (PAL) or 30fps (NTSC).

Good point, but non-interlaced runs at 50 resp. 60 fps. However, the synchronized 'Amiga' way is what I was pointing at.

All TV displays are interlaced, regardless of what the Amiga is putting out. :-)

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Zac67 wrote:
Well, TV displays are interlaced since TV signals{/i] are.  The Amiga's video signal may be non-interlaced, so that's what the monitor has to output.

My old Mitsubishi EUM even showed black lines between scan lines in non-interlace mode due to its low dot pitch.

Exactly! http://en.wikipedia.org/wiki/Technology_of_television#Display_technology
Anything synced with a TV will referesh at either 25 or 30 fps.

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Rowbeartoe wrote:

bloodline wrote:

Zac67 wrote:

bloodline wrote:

It could be that Amiga software was almost always beam synchronised to ensure that the graphics wouldn't tear during redraws... I guess the Amiga was therefore at the mercy of the display device, if that was a TV, then it would be 25fps (PAL) or 30fps (NTSC).

Good point, but non-interlaced runs at 50 resp. 60 fps. However, the synchronized 'Amiga' way is what I was pointing at.

All TV displays are interlaced, regardless of what the Amiga is putting out. :-)

The Atari ST color monitor wasn't interlaced.  I'm sure the Amiga monitor wasn't interlaced as well.  Correct.

Without knowing which model of monitor you are refering to, how are we to know? :-)

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Rowbeartoe wrote:

Below is a link to see some Spectrum 512 examples- some were Amiga HAM-6 pictures converted to Spectrum 512.  The other is a picture I made showing all of the Atari ST's colors and the conversion to HAM-6.  I realize and acknoledge however, that some HAM-6 pictures looked really bad converted to Spectrum 512- the point is, HAM-6 wasn't always better.

But the "Spectrum 512" trick requires CPU time, a significant amount since you need to interrupt at the end of every scanline... HAM-6 requires no CPU time... HAM-6 is better, in every regard... it is more complex to set up the picture to look good, but it is better.

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Rowbeartoe wrote:

By 1990- Atari released the STE (4,096 colors, blitter, better sound) and the TT- the first true next generation Atari after the ST.

Note that while the STE palette was 12bit (like the OCS Amiga) upgraded from the ST's 9bit palette, it was still only able to display 16 colours at any one time on the screen without the interrupt tricks we have already mentioned.

You must not confuse the palette width with the display depth.

If the palette width of the STE is 12bit, that means each colour gun has 4 shades associated with it... But the STE's RAMDAC can only hold 16 of these 12bit colour registers, this means that the display has a 4bit depth... So each of the 16 colours that can be displayed can be any one of 4096 colours.

And the addition of 2 PCM audio channels isn't really much of an improvement over the original ST... Certainly nothing on the Amiga's 4 PCMs :-)

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shoggoth wrote:

bloodline wrote:
And the addition of 2 PCM audio channels isn't really much of an improvement over the original ST... Certainly nothing on the Amiga's 4 PCMs :-)

Most true, no offence, didn't you sort of miss the point with the original post?

Ok, then... on topic...

The Original poster states, from memory, he felt that the Amiga seemed to only play at 30fps when the Atari ST appeared to play at 60fps.


First off, this statement is based on apparent observation, not a testable examination, of an event that happened 18 years or more in the past.

Secondly, no one seems to be able to test this... are there really that few Atari ST's around? Does no one have the software in question?

Thirdly, in answer to the OP question... Yes the Amiga can display animations at 60fps with out problems. In fact, these animations can even be in HAM-6 mode and use very little CPU time. I or in fact anyone with a modicum of programming ability can easily write a program to prove this, if need be.

Fourthly, The ST used an alternate bus cycle design, to share the memory between the CPU and the Display chips. This means that on a 16Mhz bus, each chip only gets access to the memory half the time, ie 8MHz. On the Amiga the GFX chips could steal (dynamically allocate) cycles from the CPU if needed (beneficial since the GFX chip do most of the work on the Amiga). On a related note the Atari Scanline Interrupt trick, to increase the effective number of colours displayable (essentially a new 16 colour palette every scanline) was also available on the Amiga (and probably every other 68k based machine of the time), but it uses a huge amount of CPU time, leaving nothing left for any other code to run.

I hope that sums everything up.

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If you link to me 30 frames of an animation, I will write a program to play back in HAM6 at a user selectable speed on an A500. Will that help?

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I just fired up DPaint4... you can set the frame rate in that... I can happily run an animation 60fps.