[mythtv-gta]: Re:Raspberry PI vs. VIA APC vs. ?

[Lennart Sorensen]

On Mon, Jun 18, 2012 at 01:25:04PM -0400, D. Hugh Redelmeier wrote:
> Beware things not covered by supplied CODECs.  I have a WDTV Live that
> doesn't get along with my Myth Backend and it won't even say why, just
> that the encoding isn't supported (probably).

Certainly a potential issue.

> In what way?
> 
> My impression is that modern x86 systems (possibly excipting
> Atom) do more per cycle than Arm systems.  It probably starts with a
> much higher-performance memory system (wider, larger, larger caches,
> better caching algorithms).  Note: "impression", not fact.

x86 has instructions that can do more, although how often the compiler
happens to have code that fits those instructions, who knows.  The ARM
is certainly quite efficient.  It is a very nice simple instruction set.

And yes the atom is amazingly slow.

Of course most ARM systems have NEON (similar to SSE) which can help
performance of a lot of code too.  Not all of them have it, but a lot do.

> After I wrote that, I googled a bit but didn't find anything great.
> Here's one useful article from the end of last year.  Not that it is
> comparing a new ARM system with ancient non-Atom X86 (Pentim M
> @ 1.86 GHz, Core Duo T2400 @ 1.83 GHz).
> 
> <http://www.phoronix.com/scan.php?page=article&item=pandaboard_es&num=1>
> 
> My tentative world view is:
> 
> ARM SOCs are cheap, low power, flexible, ubiquitous, well supported.
> A great choice for a lot of designs.  Great for embedding, great for
> appliances.
> 
> x86 systems are standardized, cheap, fast, well-supported, ubiquitous.
> A great choice for general purpose computing.
> 
> The disputed territory is mostly on the boundary of those two markets.
> 
> A Myth Box is actually a mixture of those two markets.  Myth is a
> funny beast: it is an appliance built by end users and intended to be
> built and customized by end users.  Replication is much looser than
> most appliances.
> 
> I want a Myth appliance.  But most appliances:
> 
> (a) resist end-user programming.  There are ARM systems that try, but
>     none is as easy as a PC.  In particular, the lack of
>     standardization reduces the leverage of a distro like MythBuntu.
>     This will become better if Myth developers gravitate towards
>     one particular ARM system.
> 
> (b) don't have as much Video, RAM, and disk space, and performance as
>     MythTV has become accustomed to.
> 
> Oh, and the video driver situation on ARM is mostly worse than on X86.

That is unfortunately true.  Although to only video cards that actually
work properly for mythtv use are nvidia cards, and pretty much only when
using the binary driver, so overall, it comes out about the same.

I still think an 800Mhz ARM with 1GB DDR3 ram and gigabit ethernet and
video decoding hardware ought to be OK for a mythfrontend.  Worth trying
at least.  Even has OpenGL|ES 2.0.

> Once you kit out an ARM to be comfortable for Myth, it starts to be in
> enemy territory.  I have a few X86 systems for running Myth front-ends
> and they each cost about $200 plus tax.  An ARM system useful for
> MythTV isn't likely to be much cheaper and convenient soon.  Note:
> nobody had to produce a distro specific to my X86 boxes since they are
> just PCs as far as the software is concerned.

Of course.  I still like the idea of a 3W 2" cube that does everything
a mythfrontend could possibly need for $135.

> I admit that I bought these at good prices, hard to duplicate.  But
> then again, I bought some of them three years ago so price/performance
> ought to have decreased.  It may not have -- the "nettop" seems to have
> lost favour.  Perhaps that is because they are approaching enemy
> territory (appliancehood).
> 
> Why are nettops unpopular?  Is it because they are seen as
> half-powered PCs?  After all, the somewhat similar Mac Mini does seem
> to be popular (full priced, full powered, but tiny and cute).  Or are
> they viewed as purposeless appliances (they come out of the box with
> no applications)?

Because they are atom powered and hence slugs?

-- 
Len Sorensen
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