[theora-dev] Next step of Hardware Theora

Leonardo de Paula Rosa Piga lpiga at terra.com.br
Fri May 11 18:54:57 PDT 2007

On 5/11/07, André Costa <andre.lnc at gmail.com> wrote:
> 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
> controller.
> 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
> Hardware?
> Something like this:
> figure 3:
> http://www.students.ic.unicamp.br/~ra031198/fig3.JPG

I don't like the implementation above. As you said I think that it
might overload the AMBA bus.

> 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
> tested.
> 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

I think this is better because in this implementation the processor is
used just for the software part. And if we have throughput problem we
can easier convert to a pipelined implementation than the other one.

> 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.

Yes, I have studied the Lancelot VGA controller (this is the board we
have in our laboratory). I'm thinking in developing the VGA controller
as a separated module from Theora Hardware. In this manner the
integration will be done by a simple handshake protocol.
This would reduce the dependency between the VGA Controller  and the
Theora Hardware.

> 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
> http://www.brazilip.org.br/

Leonardo de Paula Rosa Piga
Undergraduate Computer Engineering Student

More information about the theora-dev mailing list