Porting libjpeg to bare boards

I think you mean "can I port C code to my microcontroller" and the answer is yes.

It depends on your coding ability and the complexity of the software.

It might be easier to just read bitmaps :)

ttyl,

--buddy

I don't know about libjpeg, I'm sure it's possible to port with enought effort, but there are other JPEG decoders that certainly are easy to port. I ported this decoder: ftp://137.193.64.130/pub/jpeg/pfp.zip to a NIOS processor. I'm not sure how good this decoder is compared to the reference implementation or libjpeg but it did work on several of my test images and it's a breeze to port. Just replace win.c with your main program and you're done. The code in pfp.c will try to open a file stored in the "filename" string and return pixels in the "bgr" array. "hdim and "vdim" is the size of the result image in the bgr array.

I found a couple other libs but this one was so small and easy to grasp that I went with it.

Andrew

I'd be interested in this code too but the site seems to have gone. Any chance of posting it somewhere?

Peter

No it doesn't. It's simply a piece of C code. I've ported the standard JPEG6A source (which comprises libjpeg) to many OS-less platforms.

However, the mega128 doesn't have enough RAM to do this job. It's also too slow (though it would eventually get there, of course). And how do you display the result?

Use an ARM7.

Peter,

Check your email, I sent you a copy of what I downloaded since I don't have a website to put it on. The FTP site still seems to work, though.

Andrew

Ouw..I dont know that.

I though 18MIPS is enough to display static picture.

Do you have any reference on MIPS vs JPEG decoding speed ? Is there any equation that I should know ?

Let's just say, the photo frame should be able to display 3MB JPEG

But you're right on the memory. I'm planning to add SRAM to the board.

But if the MIPS is too far (from decoding speed), I'll take your suggestion to take it to ARM7.

Thank you for your help.

-daniel

Actually, anything larger than 0.0 MIPS will be a waste of CPU speed on a static picture, what with there being exactly _nothing_ left to do for the CPU once the picture's on the screen ;-)