[Libre-soc-dev] daily kan-ban update 20aug2020

Alain D D Williams addw at phcomp.co.uk
Thu Aug 20 20:31:12 BST 2020

On Thu, Aug 20, 2020 at 08:13:58PM +0100, Luke Kenneth Casson Leighton wrote:
> On Thu, Aug 20, 2020 at 7:44 PM Alain D D Williams <addw at phcomp.co.uk> wrote:
> >
> > On Thu, Aug 20, 2020 at 07:35:00PM +0100, Luke Kenneth Casson Leighton wrote:
> > > On Thu, Aug 20, 2020 at 7:25 PM Jacob Lifshay <programmerjake at gmail.com> wrote:
> > >
> > > > my assumption has been video processing unit, since we're adding
> > > > instructions to accelerate video decode (and maybe encode too).
> > >
> > > yep VPU.  we're including audio in that as well, because lauri pointed
> > > out that audio processing can be really quite CPU-intensive.
> >
> > So how does our VPU differ from a GPU ?
> there is some crossover.
> for example: both a GPU and a VPU might have certain types of pixel
> conversion instructions (RGB24 to RGB32 conversion instruction,
> YUV2RGB conversion instruction, and so on).
> what a GPU will *not* typically have is: "a special instruction
> exclusively dedicated to DCT (discrete cosine transformation) in a
> format exclusively targetted at video processing and not at all really
> suited to 3D graphics processing".
> if you  *only* have GPU tasks, you absolutely do not bother to design
> or put in hardware instructions that accelerate the decoding and
> encoding of H.265, or VP9.
> you "normally" leave that to a *dedicated* VPU.  or a hard macro that
> is incapable of anything other than actual H.265.  or actual MP4.
> we are not doing that.

For the avoidance of doubt: by saying "we are not doing that." what you mean is
that we are not "leaving that to a *dedicated* VPU", ie we will be doing those
things [[ H.265 & VP9 ]] in our CPU-GPU-VPU commercial product.

> we are *specifically* augmenting a *general-purpose* ISA so that it
> has the capacity to perform reasonable video decoding *without*
> requiring a completely separate VPU hard macro.

So you will say 'yes' to my interpretation above [[ which was my original
understanding ]].

Alain Williams
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