GP32 Loading A Jpg

[pea]

Hi all,

Is there a library (like gifLib) that lets you load and decode JPG files for the GP32? I have converted gifLib (16 bpp version) to use Mr Mirko SDK, so I'm on to JPG now...

Cheers,
Pea

 

[rtb7]

Flavor did one for his JPEG viewer.
Ask him.

 

[Orion_]

I found this, it's fast (asm) but it's for gba, since the gp32 as the same processor I think it could be compatible, not tested yet.
http://www.devrs.com/gba/asmcode.php#asmgraf

 

[Splinter]

Couldnt you just convert the jpeg into say bmp with your everyday photo editor although you will have probably thought of that and its not that simple.

But im simple, so thats my suggestion

 

[don]

Couldnt you just convert the jpeg into say bmp with your everyday photo editor although you will have probably thought of that and its not that simple.

But im simple, so thats my suggestion

​

That's a very good advise, especially if you're programming something like a picture viewer... "supports JPG, GIF, PNG, TGA and most other picture formats... be sure to convert them to BMP before."

 

[pea]

Couldnt you just convert the jpeg into say bmp with your everyday photo editor although you will have probably thought of that and its not that simple.

hehe, yeah, but that defeats the purpose of loading a jpeg, or not? I mean, if I wrote a jpeg viewer I couldn't just tell everyone to convert their jpeg to bmp, and then use the viewer Not that I'm writing a viewer mind...

Thanks Orion, I'll check it out.... probably after a slower c-based solution though (read: easier).

 

[Blah]

I found this, it's fast (asm) but it's for gba, since the gp32 as the same processor I think it could be compatible, not tested yet.
http://www.devrs.com/gba/asmcode.php#asmgraf

​

First of all they do not have the same processor. Second of all,
its not directly compatible. The graphics and I/O calls in the asm
would have to be changed to the proper DMA calls for the gp32.

@pea: Try something else. This one wouldn't work without a lot of
changes. It could be a good, fast way for when you need speed, but
you still would have to make a lot of changes to the code.

 

[pea]

Thanks blah. I agree. It was all pretty much greek to me anyway

 

[Orion_]

Blah > first of all the processor is compatible (arm7 -> arm9) that's why the gba emulator emulate so well and so fast the gba processor on the gp32
and second the io is not used in the function
you can pass in parameter the screen you want.
I tried (the C version only, not the asm one) and it worked, the only problem is that for picture larger than 255 it doesn't work (the gba screen is 240 so maybe it's an optimisation ?)
I will try to ask to the author how to correct this error.

 

[cyberic]

You could use epeg which is a very fast jpeg decompression/scaling routine.

It is here:
http://www.rasterman.com/code.html

Actually I did make some test with is and GP32Linux, it was so fast!

 

[pea]

epeg looks good on the surface, but it isn't stand alone - it uses the standard jpeg group libraries and builds on those.

I looked into the jpeg group code, and found an implementation that someone has made for ARM here http://www.bin-people.de/pnoJpegLib/. I'll be basing my code on this guys work. So far I think only loading (decompression) supported, but thats all I need at the moment anyway.