> When I watch TV in Linux using 2.6.0 and bttv (tvtime, but it happens in
> all tv-playing applications so it's a driver issue), there is a severe
> tearing effect. Like horizontal brown lines scanning and the text
> "shakes" and "jumps." Imagine having vsync set wrong in a game from the
> 1999 era -- it's like that, and very obnoxious. The tvtime people were
> very helpful but could not think of any solution and we tried every
> deinterlacing idea that could be conceived.
This looks like a PCI bus mastering problem. I've had it too. Because
the TV cards bus mastering ("DMA") engine cannot get access to the PCI
bus within a certain time (usually 10 - 40 ms) the buffer pipe get
overrun. This pipe is usually only a hundred to thousands of bytes
large.
The solution may be to increase the latency time of the capture card
(look for an option "latency" in your tv card's drivers). If you can set
it using the BIOS, then also set the latency for the other cards and
possibly integrated devices as low as possible.
If all this doesn't help, you either have a motherboard with broken PCI
implementation (not that rare...) or the hardware of the PCI bus is too
slow. I had this problem very severely on a 486/133 with a UMC chipset.
I had it very mildly on a MSI motherboard with an athlon xp 2000. Now
with my Tyan motherboard and dual athlon xp 2600 it's gone altogether.
BTW if I enable energy saving for Athlon MP chipsets (don't know the
name of the kernel option from the top of my head), this effect also
shows.
