[mythtv-users] Feature request: realtime commercial flagging

[Patrick Reynolds]

On Wed, 18 Feb 2004 papenfuss at juneau.me.vt.edu wrote:

> > FYI, part of the reason the commercial flagging takes so long is that it
> > is run as a nice-d process and sleeps a little for every frame it
> > processes.  I didn't want the commercial flagging thread to cause any
> > problems with running recordings so it tries to be as nice as possible
> > (no pun intended) to the other processes on the machine.
>
> 	If the CPU's idle, why doesn't it burn it up?  Makes sense to have a
> very low priority on it to keep it for more time-critical tasks, but I don't
> see why it can't take more cpu if it's available.

The CPU isn't the only constrained resource.  Commercial flagging does a
_lot_ of disk reads, which can keep more important reads (or even writes)
from completing when needed.  I've definitely noticed some playback
hiccups when commercials are getting flagged, even with mythcommflag in
its nice-and-also-sleeping mode.

A related question: do the frontend and backend do readahead on playback,
and how much?  That is, how long can the disk block on playback without
causing stutters?  It seems like a little more readahead (like skip
protection on a portable CD player) would eliminate a lot of stutters.

--Patrick