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#4387 - 11/06/1999 02:26 DAB
sirbod
new poster

Registered: 11/06/1999
Posts: 5
Loc: Essex
This isn't really for this forum, but the other forums seem to be read only - so here goes!

I'm really tempted to get an empeg, although the lack of DAB (or DAB control) does put me off. Will there be a DAB version?

On the programming side, does it have to be done for Linux in C++ etc, I'd much prefer to use assembler to code some nifty fractal routines for the display! On that note, is the display a single colour or can it do brightness levels?

Jon Abbott

ps Hugo - don't now if you remember me (dare I mention SoundSynth!) It's good to see your still pushing the ARM chip.


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#4388 - 11/06/1999 05:14 Assembler visuals (was DAB) [Re: sirbod]
mac
addict

Registered: 20/05/1999
Posts: 411
Loc: Cambridge, UK
I'll leave the DAB bit for Hugo to answer.

Most of the visuals are already written in ARM assembler. It's only the interface to the player that's in C++ - you can write the actual visuals in whatever you like (and can persuade to work on the empeg - VB is probably out).

Each pixel on the display is capable of four intensity levels including off.

--
Mike Crowe
I may not be speaking on behalf of empeg above :-)
_________________________
--
Mike Crowe

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#4389 - 13/06/1999 08:06 Re: Assembler visuals (was DAB) [Re: mac]
sirbod
new poster

Registered: 11/06/1999
Posts: 5
Loc: Essex
Four levels - good. What's the frame update rate? And, how much CPU bandwidth is there left after the DSP and MP3 decoding are done?

I was thinking along the lines of a Fractal zoomer routine and 3D scene animation.


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#4390 - 14/06/1999 02:47 Re: Assembler visuals (was DAB) [Re: sirbod]
mac
addict

Registered: 20/05/1999
Posts: 411
Loc: Cambridge, UK
Although only four colours are supported by the hardware the screen map accessed by user processes has sixteen different "colours" available hence each byte holds two pixels. The screen memory is made available through mmap(2) and is 2K long. The kernel handles converting this format into the much more complex format used by the hardware.

The display is updated approximately 38 times a second because it is synchronised to the audio.

The player software _generally_ uses less than 40% of CPU power while playing at the moment (including displaying one visual). However, at some points (e.g. during caching, track skipping etc.) it can use much more.

I'd like to see a fractal zoomer, particularly if zooming was dependent on the music too. I'm sure you already know not to use floating point since there is no FP hardware :-)

--
Mike Crowe
I may not be speaking on behalf of empeg above :-)
_________________________
--
Mike Crowe

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#4391 - 23/06/1999 16:22 Re: Assembler visuals (was DAB) [Re: mac]
bowerman
new poster

Registered: 21/06/1999
Posts: 4
Loc: Indianapolis, IN, USA
Hey All,
Will you be able to change the display like that through the locked down player, or the developer diskset?? Also, what are the means of adding this code?? Is the player told what screen sequence to play in order or something??
Just curious as to how it works.
Doug


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#4392 - 24/06/1999 14:30 Re: Assembler visuals (was DAB) [Re: mac]
sirbod
new poster

Registered: 11/06/1999
Posts: 5
Loc: Essex
Floating Point! I never had that luxury when I was doing ARM coding.

Which chip are you using then, I though all the new ARM chips had floating point.

Jon


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#4393 - 29/06/1999 17:01 Re: Assembler visuals (was DAB) [Re: sirbod]
altman
carpal tunnel

Registered: 19/05/1999
Posts: 3457
Loc: Palo Alto, CA
We use a SA1100. None of the ARM chips, except for the ARM7500FE, have got floating point - that was the only one. I have a feeling that the SA1500 had some sort of attached media processor for doing FP intensive stuff (well, DSP type stuff) but it wasn't actually a FP.

Hugo



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