On 1/25/2011 5:33 AM, Invisible wrote:

> Spec claims it comes with a 4 GB flash card, but that's going to fill in
> seconds I would imagine.

Nah... My 7D records 1080p HD video and can store probably about 15 
minutes on a flash card that size.

>
>>> The product spec also claims it stores video as H.264, which surprises
>>> me. I was under the impression that this requires some pretty serious
>>> computer power (most especially for encoding).
>>

Not uncommon, especially for HD video. The encoding is usually done by a 
purpose-built chip, rather that software on a general-purpose CPU.

>
> I was under the impression that the compression algorithm remains the
> same regardless of what bitrate you select. Higher compression just
> means that more of the data is discarded. The difference between, say,
> Ogg Theora and WMV is the algorithm. Once you select an algorithm,
> changing the bitrate just changes how much of the data gets kept.

Right, but the algorithm invariably has a trade-off for quality v.s. 
speed. It can spend more cycles determining which bits are best kept, or 
spend less time and dump the bits to storage, not always getting the 
most important ones.

>
> Then again, I would think there's probably silicon for directly
> computing DCTs and so forth by now...

Been that way for a while. DVD players, portable media players, mobil 
phones, etc ... all have hardware to do this, now.

-- 
~Mike

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