Re: Astonishing technological achievement

From: Eamer (eamer_at_digitalme.com)
Date: 06/16/04 

Date: 16 Jun 2004 10:00:13 GMT

Travers Naran wrote:

> Kevin Wayne Williams wrote:
>
>> Travers Naran wrote:
>>
>>> But that doesn't tell me what its place was. Was it the price of the
>>> codec hardware or the CPU horsepower required? I suspect it was the
>>> hardware because I can't imagine JPEG requiring less CPU power than
>>> MPEG, but MPEG compressors requires more on-board memory, no?
>>
>>
>>
>> You need to imagine harder. MPEG encoding is much more CPU and memory
>> intensive than Motion JPEG. The decoding is roughly equivalent. We had
>> a more expensive box as a result, and the network technology made it
>> difficult to take advantage of the bandwidth savings.
>
90$BG/$NH>$P:"$K(BMPEG2$B$N%j%"%k%?%$%`05=L$,=PMh$k5!3#$,$"$k$HJ9$$$F!"!V$X!A(B
$B@$$NCf$K$O$=$s$J$9$4$$J*$,$"$k$s$@$M$(!#0lHL2HDm$N#P#C$G=PMh$k$h$&$K$J$k(B
$B$N$O2?G/@h$@$m$&!W$H;W$C$?$N$r;W$$=P$7$^$7$?!#;d$OEv;~#P#C$7$+;H$C$?$3$H(B
$B$J$+$C$?$N$G!#2{$+$7$$$G$9!#(B

>
> That's understandable. I figured JPEG was just as computationally hard
> as MPEG to compress, but then again, MPEG has a temporal component JPEG
> doesn't have to care about.

As I understand it, it's actually the temporal component (specifically,
motion compensation) that is the most CPU intensive (CPU$B$@$1$G$J$/$F%a%b(B
$B%j4X78$b(B). After all the temporal computation, the data are run through
the DCT, quantization, entropy coding and the like anyway, just like a
bunch of JPEG images. Well not quite, but the idea is the same.

eamer

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