[mythtv-users] Mythtv .19 live watching

Osma Ahvenlampi oa at iki.fi
Fri Jul 14 13:18:23 UTC 2006


On pe, 2006-07-14 at 12:29 +0100, Steve Daniels wrote:
> > On Fri, Jul 14, 2006 at 10:41:40AM +0300, Osma Ahvenlampi wrote:
> > > d) display live tv, but show a message over the OSD that storage space
> > > is not available, so time-shift capability and recording are disabled.
> >
> > The intuitive solution when you don't have any room to record live
> > TV is simply to not record live TV.
> >
> However if you've been using your system for any length of time you have
> long filled your storage space and *rely* on myth to delete the oldest stuff
> to allow you to continue recording new stuff. So there will never be free
> space for live tv, so you will never be able to just go to live tv, you
> would always be informed that you can't enter live tv because you have no
> storage space... Which would be a pita.

Steve, I don't think you actually read what me and Chris said above.
Please read it again. I did not suggest that entering live tv would be
blocked. I suggested that perhaps it would be logical that automatic
RECORDING of live tv would be blocked if there's no room for that. It
does not preclude a user for VIEWING live tv, unless you happen to think
that "what MythTV does right now is the only way things can work". I
don't think so.

And, once you follow this line of thought, it automatically follows that
unless you've set auto-expiry off on all recordings (lets not even
discuss here how unreasonable that is...), you can also record FROM live
tv quite simply by pressing the REC key on your remote. Huh? Didn't I
just write that recording was unavailable? Yes, I did. 

But, see - once you press that REC key, you're switching from "we'd like
to implicitly record because the user is watching tv, but there's no
space to do so" to "the user just asked us to record, so this is a
recording - follow normal autoexpiry process to make space available".

And, as is normal under those circumstances, if there's simply no space
to be made available due to all previous recordings being non-expirable,
then the recording will be aborted. Ideally, at this point the user
would be presented the option (via the *OSD*, since we do not want to
abort the *viewing of tv*, which is a separate activity from recording
it) to manually delete the show which would be the first under the
hammer if autoexpiry was on.

To make it possible for the user to decide mid-show that they would in
fact like to record it, and have MythTV magically store it from the
beginning, the right choice under this mental model is for the
autoexpiry system to keep room for one hour of buffer. This is
reasonable, because the feature you are presenting to the user is:

"While watching TV, you can choose to save the entire show you've been
watching from up to one hour since its beginning. For this feature, you
only give up maximum one hour from your entire DVR storage space of x
(typically 50+) hours."

This feature is distinctly different from the current implementation
because (pay attention here): you do not lose previous recordings until
you choose to record. The live tv never causes expiry of anything. It
simply uses the "extra" space the auto-expiry process keeps around.
There's never more than one hour of "unrecorded" live tv on the disk
unless your system has gobs and gobs of space that wasn't taken by
actual recordings.

> If you're using MythTV you *know* that when your storage is full any new
> recordings will overwrite the oldest recordings (simplified view).
  ^^^^^^^^^^                           ^^^^^^^^^^
> If you're using MythTV you *know* that when you watch LiveTV it is in fact a
> recording that can be ff/rw paused saved in it's entirety from the point you

It's not a recording until the user has made it a recording. Until then,
it's a time-shift ringbuffer that was in 0.19 converted to technically
use the same code as recording for implementation reasons. That
implementation detail does not make live tv conceptually the same as
recordings.

-- 
Osma Ahvenlampi   <oa at iki.fi>    http://www.fishpool.org



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