----------  Original message  ----------
Subject: Re: Which is a faster option?
Date:    Donnerstag, 10. September 2009N
From:    "Mac User #330250" <[email protected]>
To:      [email protected]

> Like coding a video, the decoding of it is also mostly CPU work at first,
> the decoded data gets then distributed to the graphics card via, as you say
> rightly, the memory over the system bus over to the graphics card.
>
> But that's normally not the bottleneck.
> The conventional PCI bus can transfer 133 MB/s of data.  PC100 SDRAM has a
> peak transfer rate of 800 MB/s.
>
> According to
> http://www.blackmagic-design.com/de/support/detail.asp?techID=30 the the
> most out of a HD video (1920x1080, 10-bit, 60fps) would require 237 MB/s.
> Thus, for transferring decodeded HD material, you need a faster system bus.

I forgot to check: AGP (original AGPx1) has a transfer rate of 266 MB/s, so 
getting the decoded pictures to your AGP graphics card shouldn't be a 
problem.

> So, yes, it's not always the CPU. But I bet that a PowerPC below 1 GHz is
> not even able to decode a HD video with this resolution out of an
> MPEG-4/AVC or H.264 stream.

So, the CPU remains the bottleneck.

> Cheers,
> Andreas.

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