[theora-dev] Next step of Hardware Theora

André Costa andre.lnc at gmail.com
Fri May 11 14:53:03 PDT 2007

Thanks for Feedback,

I have been talked with some people, we (I, Felipe and Leonardo) know a
group (that worked with us) that did a MPEG decoder in hardware at Brazil
and they have been helped us with some tips in others list. Also, I had a
chat with my professor and now I think it is more clear about LEON and SDRAM

First, I agree with you, the priority should be the LEON. How Ralph said,
until this is done, no one else can play with the code.

figure 1: http://www.students.ic.unicamp.br/~ra031198/leon3.JPG

It is a excellent nonproprietay processor, very flexible and has a lot of
components that can be pluged (like Memory controller, jTag, AMBA).

The steps would be:

- To find a configuration that be able to decode the Theora.
- Synthesis of LEON3
- To compile only de initial part of Theora for LEON and to run this inside
of the LEON.
- To change the handshake of Theora Hardware of AVALON to AMBA protocol.
- Integrate the processor and theora hardware

In think the hard part would be to debug this, construct a testbench to test
this. To learn the LEON3 features/configuration and the protocols would be
dificult too.

SDRAM Controller and FlashCard
Yes. To do it in Hardware would be much complicate, because there are many
constrains and the SDRAM is very rigid with timing. For this, I would need
to have a good study of the datasheet before to start the developing.

In the other list we had the ideia of work with a Flash Card, but It is very
slow. The Flash card would be nice to store the Videos encoded.

LEON3/Memory Controller

How you can see in figure 1, the LEON3 has a Memory Controller of SDRAM.
The LEON will use this to execute the functions of the intial decoding.
figure 2: http://www.students.ic.unicamp.br/~ra031198/fig2.JPG

Ok, then we can use this SDRAM memory controller to buffer of the Theora
Something like this:
figure 3: http://www.students.ic.unicamp.br/~ra031198/fig3.JPG

This answer I still don't, because it's depende of the AMBA, frequecie of
operation and data throuput. AMBA is a little slow, I think it will not get
to answer the LEON and Theora Hardware requests in time. But It is could be

If it is not ok, the alternative would be copy the memory controller to use
with the SRAM
figure 4: http://www.students.ic.unicamp.br/~ra031198/fig4.JPG

LEON3/VGA controller
Beyond this, LEON3 has a VGA controller, but I don't know if it would be
necessary to plug with Theora Hardware. But I think that could happen the
same problem of the SDRAM, It could overload the AMBA. And then, I think It
should be unpluged of AMBA and to plug directly with the Theora Hardware.
The group that we know did a Video Controller (for MPEG) in hardware. It
seems to be not much dificult to do, maybe it is more interesting to
Leonardo to do one.

What do you think?

André Costa

On 5/9/07, Timothy B. Terriberry <tterribe at vt.edu> wrote:
> >> Derf, what do you think?
> I don't know enough about the complexity implementing an SDRAM
> controller to say whether it should be one of the "primary goals" or a
> "secondary goal, time permitting". However, I think it would be nice to
> shoot for completing integration with Leon by the midterm date (the week
> of July 9; in approximately two months).  Then you will have the entire
> second half of the project to focus on the SDRAM controller. That may
> not be enough to finish it if it is really as complex as last year's
> entire GSoC project, but I would think you could make some good
> progress. When you talk to your professor tomorrow, he may be able to
> give you a better idea whether or not this is reasonable.

André Costa
Gerente Técnico
Projeto BrazilIP

Cel: + 55 13 9201 1870
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