[mythtv] Memory bandwith

Bruce Markey mythtv-dev@snowman.net
Sat Jan 4 02:34:00 EST 2003

Monty Walls wrote:
> The KT133 chip set max's out at about 69mb/s without the latency patches,
> some raid benchmarks last year tripped over VIA pci/dma bandwidth limitations.
> Doing RTjpeg, I can reduce the quality and stop the stuttering.  So for my
> old board it looks like a pci/latency issue. 
> Try using RTjpeg to the increase data-rates over the bus, instead of
> mpeg4.  Mpeg4 gets your pci data rates low enough that it's not a problem.
> You may find stuttering under RTjpeg. At least that was my experience.

Software compression happens after the raw video data from
the capture card has been sent across the bus. If changing
the quality settings (at the same resolution) reduces dropped
frames, you're probably CPU bound. If PCI bus contention is
the problem, then shrinking the resolution would help.

--  bjm

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