[SunRescue] MP3s

[James Lockwood]

On Mon, 22 Nov 1999, Martin Frost wrote:

> James Lockwood wrote:
> 
> > The LX goes up to 48KHz 16 bit stereo.  It plays MP3's quite well.  Both
> > use the same CPU, a 50MHz microSPARC-I.
> 
> Hmmmm. A microSPARC-I is roughly 486-class, yes? Does this mean that

The Sun systems most comparable to 80486's are the sun4c machines.  They
have relatively small caches by modern standards and comparable memory
subsystems (32 bits wide running at around 25MHz is typical).  They
generally have a higher performance than comparable 

The microSPARC CPU's aren't directly comparable to any PC system
architecture.  The basic design includes a fast main memory bus and a very
small cache.  The cache isn't much of a bottleneck as there is an
extremely low cache miss cost.  Compare this to the SuperSPARC line which
is comparable to the Pentium in many ways, large caches with a higher
cache miss cost. 

Performance wise the Classic/LX will generally fall between the 80486 and
the Pentium, but it's difficult to estimate relative performance due to
the different memory architectures.

> a 486/66 should be able to do this (assuming a real OS and not much
> else going on)? I ask because it's a current project of mine to
> network my entire flat and pipe music over Ethernet to computers
> equipped with sound, possibly a VT220-based jukebox system and

I would recommend having a main server "play" the MP3's and send raw data
through the network to a local audio receiver (like NAS).  A 486 would be
able to do this with no problem, and you need under 2mbps of bandwidth for
each stereo audio stream at full quality.  A lower bandwidth alternative
would be to have the "server" decode the MP3's and run them through a
simple compression filter (an RLE like Huffman would be my first choice
for a slow CPU though you might find that other alternatives are
satisfactory).

> enough? Is the LX's ability down to superior SPARC floating point?

The LX has probably twice the SpecFP marks as the 486/66.  This is due
partially to the faster FP core of the CPU, but to the fast memory bus.  A
cache miss on the LX takes less time to service than a cache hit on the
486!  If you try to compare the two architectures, imagine that the LX has
as much cache as RAM.

> overkill... Also, ISTR that SS5 audio is worse than LX.

SS5 audio is CS4231, LX is DBRI/CS4215.  They both have the same
capabilities (48MHz 16bit stereo), the SS5 doesn't include ISDN and is
cheaper to manufacture.

All of the Ultras with audio also include CS4231 audio and they work fine.

-James