[mythtv] Effect of Multi-rec on channel change times....?

Daniel Kristjansson danielk at cuymedia.net
Wed Jul 11 23:50:57 UTC 2007

On Thu, 2007-07-12 at 00:36 +0100, Colin Guthrie wrote:
> Daniel Kristjansson wrote:
> > Someone may implement the continuous record feature in
> > future, but implementing such a feature would in some
> > ways have been easier to implement before multirec and
> > no one ever bothered to do it, so I wouldn't bet on it.
> > (You just record as many other streams as your hardware
> > allows into small ring buffers and use them to initially
> > fill up your recording file when you switch to that
> > channel, then there is no need to wait for buffering
> > since you already have a few seconds of video..)
> Interesting.... Do you know if this is how VDR or commercial set top
> boxes do it?
I don't know. All STB's I've used had pretty darn awful
channel changing speed considering that they don't need
to do the buffering that a PVR does. A trick some of them
use is to start decoding the audio before they see a GOP
and start displaying video; which indicates that they don't
do this. We could do that trick fairly easily if we wanted
to in the multirec branch, but only because I patched the
avformatdecoder there do handle audio only files. STB
firmware doesn't have to work with the variety of hardware
that MythTV does; when I set a timing threshold for something
in MythTV I find a value that works on all my machines
then double or triple it (or if all it will cause is a
temporary glitch and it is critical that it is low, I add
30% and try to get as many people as possible to test it).
Comparing ourselves to VDR, BeyondTV, etc, is more realistic.

> I'd love to see this in Myth - it would make it really rock for live tv :)
> That said I rarely watch live tv anyway :p
And that's why this hasn't been implemented :]

-- Daniel

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