[mythtv] HDTV Random Blockiness

[Brandon Beattie]

> The close() fix that John Patrick Poet submitted has taken care of the
> random blockiness problem for HDTV recordings off my HD-2000 card, but I
> still see that occurring (along with several buffer overruns from the card)
> if I change channels while watching Live TV.  Subsequent channel changes
> continue to exhibit the symptom as well, and I usually lose sound, too.
> Switching to another capture card and then back to the HD-2000 gives me a
> clean stream, so I assume a similar type of fix is needed after a channel
> change.
> 
> I don't think I see the same thing occurring on my HD-3000 card, but it
> might just be because that's the only card in a different backend server.
> The HD-2000 is in my master backend, which is also where my /myth/store
> (live TV ringbuffer) is shared out of, while the HD-3000 is on a slave
> backend that I only seldom use.  Could the extra DMA activity of the HDD's
> be exacerbating this?

The HD-3000 is slightly better/nicer with surviving longer when there
are limited pci resources availible for it to transfer data.  You bet
any PCI card, HDD, or anything that uses the system bus will cause more
buffer overrun errors -- Regardless of it being an HD-2000 or HD-3000.
Motherboards and CPU speed also play a minor role.  .. If you don't have
enough resources to send data, you see overruns.  In the future if the
driver can be modified to work better, hopefully we'll see less or none
of the overruns.  Don't get stuck on them though.  The amount of data
loss typically is very very minor, for most people.

--Brandon