[MPlayer-users] Re: MPlayer-users Digest, Vol 27, Issue 59

[Gaute Strokkenes]

On 24 mar 2006, mosgalin at vm10124.spb.edu wrote:

> Hi pfile at pacbell.net!
>
> On 2006.03.24 at 09:55:22 -0800, pfile at pacbell.net wrote next:
>
>>> Thanks to you and everyone else who pitched in.  I have decided to get
>>> an Athlon 64 4000+.  I was considering an X2, but there aren't really
>>> any multi-threaded codecs out there yet, so I figured I should just
>>> get the fastest single-core CPU that I can.
>>
>> uh, really? lavc takes threads=n as an argument, and it definitely 
>> speeds up encoding on my A64 X2. like from 70fps to 80fps with 
>> threads=2 on pass1 of dvd transcoding to mpeg4.
>
> But generally I would suggest A64 X2 4200+ over A64 4000+ anyway.
> Getting powerful, but single core system today isn't wise, unless you'll
> be using system only for video encoding 100% of time. 

Actually, I'm not interested in _encoding_ at all.  I only really care
about playback.  I've never encoded any video before, and I don't see
myself doing it in the future either.  (I suppose this confusion is my
fault since I said "codec" rather than "decoder" above, but there you
are.)

> Even then, you can always encode two streams at once! In that case,
> X2 would easily outperform single-core systems. Just think about, X2
> 4200+ vs 4000+ is 2.4Ghz/1024Kb cache vs. 2x(2.2Ghz/512Kb
> cache). Not that big penalty in single-thread encoding, but a major
> win when running two encodings at once. Also if you have a lot of
> money to waste you can always buy 2x(2.4/1024) cpu (4800+) or just
> pick up a good MB, PSU and memory and overclock your 4200+ system...

That's interesting, but how does this relate to decoding?  I'm not
aware of h264 decoders being multithreaded, though I could easily be
wrong.

Now as it happens, I would actually rather like an X2.  (I don't
expect it would help me much with playback but there are other
reasons.)  However, my understanding is that:

 1) Decoding is pretty much single-threaded, so a dual core X2 system
    is effectively reduced to a single core when doing that sort of
    work.

 2) H.264 playback at a resolution like 1080p is pushing the envelope
    of what current CPUs are capable of.  (My current computer can't
    even handle 720p; this is in fact one of my (not very numerous)
    reasons for upgrading after 3.5 years with my present one.)
    People sound confident that the lavc h.264 decoder will only get
    better over time, but you never really how much or how it will
    play out on your system.  Besides which I don't really want to
    wait for that to happen, I want my 1080p goodness right now. :)
    Also, there will probably eventually be filters etc. that I might
    wish to use.

 3) The fastest X1 is the 4000+.  In order to get an X2 where an
    individual core is as fast as the single core in a 4000+, I have
    to get a 4800+, which is the fastest and most expensive X2.  The
    additional expense is GBP 365, which just doesn't seem worth it.

> Just don't forget to buy two memory modules (dual channel) for X2, it
> really needs it.

Interesting.  Is that a RAM feature, or a RAM-related motherboard
feature?  Searching for "dual channel" on <http://www.komplett.co.uk>
doesn't give any hits.

-- 
Gaute Strokkenes
I'm a fuschia bowling ball somewhere in Brittany