[mythtv] Padding of recordings

[Peter Schachte]

Michael T. Dean wrote:

> Channel record for a specific program times how ever many channels may 
> air that program.  No one says you can only have one rule to record, 
> "The Simpsons."  Each rule can have different start early/end late times.

That would work, but it's not very convenient, since you have to specify all
the info multiple times, and have to explicitly enter the start early and end
late values for each one.  And you have to know what channels a show may be on.
 It also means that if you change any of the parameters of one rule, you
probably want (but will probably forget) to change all the rules.

Compare that to once, at set-up time, specifying how bad each channel is at
following their own schedule, and deciding whether you'd rather record a
program without its padding, or not record it at all.  Thereafter, when you
schedule a program, you don't have to worry about padding at all.  And best of
all, if you discover that a channel deviates from its schedule more than you
expected, you just correct the set-up for that channel once, rather than having
to edit every recording rule that might involve that channel (I had to do that
a few months back, and I'm still finding rules I missed).

> Where do we draw the line?  I still think the only way Myth can read 
> your mind is if you write the contents of your mind into the 
> database--i.e. tell Myth what you want and it will do it...

Absolutely.  That's what I'd like it to let me do.

> Now if you're just talking about a one-click (or possibly two because of 
> the Amazon patent) "create an override that records this episode without 
> start early/end late times," that might be somewhat useful.

I'm talking about no clicks (let's see Amazon patent that!).

> As far as adding new functionality for allowing but not requiring 
> padding, show me a use case where scheduling becomes easier than start 
> early/end late and recording overrides--as opposed to some magical 
> formula _plus_ start early/end late and recording overrides--and I might 
> see it as an improvement.  The only way that's likely to happen is if 
> the magical formula is truly magical--if it always does the right thing 
> for everyone.

It really only needs to do the right thing more often than the current
implementation, and I think this would.  Basically, this approach works better
for anyone who needs different amounts of padding on different channels
(because they don't have to set the padding for each recording rule), and for
anyone who would rather record a program without padding than not record it at
all, because it automatically does this for them.  And I can't see how anyone
would be worse off with this change.

> Otherwise, overrides will still be necessary.  True, it 
> may be possible to make the overrides less common, but doing so would 
> add significant complexity (from a user perspective) to the system, 
> making it much harder for the user to tell Myth what he wants--if the 
> user doesn't understand the /interaction/ between all these settings, 
> he's likely to program the Myth box incorrectly.

There will always be times when overrides are necessary, but I think this would
actually simplify myth for most users.  There are a few more set-up options,
but they can be set and forgotten.  When scheduling a program, there are two
fewer options to set, and conflicts happen less often.

I'm envisioning a scheduling algorithm something like this:

	schedule all overrides
	for each priority level p from highest to lowest {
		for each rule r at priority level p {
			for each distinct episode e matching rule r {
				for each airing a of e {
					if a can be recorded respecting
					   the padding configured for the
					   channel a is aired on {
						schedule a with padding
						next e
					}
				if the user has configured myth
				   to drop padding {
					for each airing a of e {
						if a can be recorded ignoring
						   padding {
							schedule a without
							padding
							next e
						}
					}
				}
			}
		}
	}

This isn't complete, because I've ignored tuner priority, but this should be
pretty close.

-- 
Peter Schachte              In the post-Cold War era, the United States
schachte at cs.mu.OZ.AU        needs to promote the development of democracy
www.cs.mu.oz.au/~schachte/  and human rights, not militaries that view their
Phone: +61 3 8344 1338      own citizens as the enemy. -- Richard Durbin