[mythtv-users] is mythtv smart enough to do this (overlap/back-to-back) with recordings?

[Michael T. Dean]

On 07/26/06 12:10, Peter Watkins wrote:

>On Wed, Jul 26, 2006 at 11:43:51AM -0400, Michael T. Dean wrote:
>  
>
>>On 07/26/06 10:31, George Nychis wrote:
>>
>>>I have 2 shows recording back to back...
>>>
>>>First show: 5:00pm-5:30pm
>>>Second show: 5:30pm-6:00pm
>>>
>>>Both shows are on the *same* channel.
>>>
>>>If I set the first show to end 1 minute late, and I have only 1 tuner,
>>>is mythtv smart enough to put the [overlapping] minute into both recordings?
>>>
>>Nope.
>>
...

>If Myth should expect the same data for both recordings (e.g., both are
>HDTV, or both use the same recording profile), then I think Myth ought to be
>smart enough to copy/splice the overlap video into both recordings and only use
>one tuner. At least for schedules that are driven by program guide data (vs.
>VCR-style hard-coded date/time schedules), this should work really well.
>

OK.  So let's say I'm recording a high-priority (+99) movie from 
3:30-5:30.  From 5:00-5:30 and 5:30-6:00 are two episodes of a 
medium-priority (+50) show.  Since the TV show often goes a few seconds 
beyond the scheduled time, I set an end late of 1 minute on the TV 
show's recording rule.  So, assuming these are the only shows I'm 
recording during this time period and I have two capture cards, I would 
have recordings as shown:

Card 0 - Movie - 3:30-5:30
Card 1 - Show - 5:00-5:31
Card 0 - Show - 5:30-6:01

Notice that the two episodes of my show are being recorded on different 
capture cards.  So, you may ask, "Well, why isn't Myth smart enough to 
record both episodes of the show on the same card?"  Well, Myth /always/ 
uses the preferred input for capturing--assuming if you record it, you 
want it to be high quality.  If multiple shows are being recorded at the 
same time, the highest priority show is recorded on the most-preferred 
input.  If all your inputs have the same specified priority, the 
lowest-numbered input wins the tie.  If we randomly shuffle around 
capture cards, we might get the high-priority movie recorded on a BTTV 
card and the episodes of a medium-priority show recorded on a 
high-definition card.  Myth shouldn't be making this decision--the user 
should do so by rearranging priorities (possibly with a recording 
override for the show).

So, as Peter suggested, why not /if/ the cards are identical (i.e. both 
PVR-x50's) still record the overlap to both files even though it will be 
on different cards?  OK, imagine now a system with 2 PVR-x50's and a 
BTTV card.  Can you say, "Non-intuitive behavior that's hard for the 
user to predict."

Now, keeping all this in mind, let's say we have 2 PVR-x50's and a 
distributed Myth system with 2 backends.  At this point, how would we 
get the data from a capture card on one backend to the filesystem on the 
other backend?  Even if both backends write to a common networked 
filesystem, we still have to ensure one of them handles writing the file.

This is /not/ the "principal of least surprise."  Imagine all the 
questions we would see about why /sometimes/ (in the general sense 
because no one has been able to determine the pattern from empirical 
evidence) Myth records the overlap successfully, but sometimes it doesn't.

Just because it /seems/ easy to do on a simple MythTV system, don't 
forget that Myth supports many more configurations.

Also, if I put a start early of 1 minute on my TV show's recording rule, 
I have a conflict:

Card 0 - Movie - 3:30-5:30
Card 1 - Show - 4:59-5:31
Conflict - Show - 5:29-6:01

At this point, the /only/ things I can do are:
    - adjust my recording rules (i.e. with a recording override)
    - get more capture cards

Which means, that for both situations (recording an overlap or 
preventing conflicts due to overlaps), the /right/ solution is to add 
more capture cards.

Mike