[mythtv-users] Oddity with keep max and overlapping recordings

[John Veness]

John Veness wrote:
> Hi,
> 
> I have discovered an oddity (I think it's a bug, but want to check 
> first), regarding recording rules which specify to keep a maximum number 
> of episodes and to not record if that would exceed the max, and 
> situations where multiple recordings happen at once.
> 
> Background and example:
> 
> Let's say I have a rule to record The Simpsons, keeping a max of 3 
> episodes, and not to record if that would exceed. Allow expire is set to 
> Yes, but I have plenty of disk space. I do not use the Deleted group. My 
> recording rule is set to include 3 minutes before and 3 minutes after.
> 
> Here's the important thing: Sometimes multiple episodes of The Simpsons 
> are broadcast back-to-back. With my recording rules, that would mean 
> that for 6 minutes there are actually two episodes of The Simpsons being 
> recorded at once.
> 
> If I have three episodes recorded (the max) then everything is fine - no 
> new episodes get recorded, nothing gets expired.
> 
> If I then watch and delete an episode, I have 2 left, and so another 
> episode of The Simpsons should be recorded. However, if two episodes are 
> broadcast back-to-back what actually happens is the first episode is 
> recorded (making 2 recorded eps and 1 recording in progress), and then 
> near the end the 2nd episode starts recording (making 2 recorded eps and 
> 2 recordings in progress).
> 
> When both eps finish, I have 4 recorded eps, exceeding the max. The 
> autoexpiry code soon kicks in and deletes the oldest ep, leaving 3, 
> namely the two new ones and one of the old ones.
> 
> So, this means that in this situation, I watch and delete one ep, then 2 
> get recorded and 1 gets expired. This is inefficient, e.g. on tuners, 
> and a bit annoying as I might have been looking forward to watching a 
> particular episode which I could see had been recorded.
> 
> I think the crux of the problem is that the second recording should not 
> have started if it noticed that there are already 2 recorded eps and 1 
> recording in progress, as that adds up to the max of 3 in my mind. I 
> guess this is a scheduler issue.
> 
> Anyone else seen this and can confirm?
> 
> Cheers,
> 
> John

Has anyone else seen the above or is it just me?

Looking further into the problem, I notice that if, say, only 2 episodes 
of The Simpsons are currently recorded and max episodes is set to 3, 
then the Upcoming Recordings screen shows all future episodes set to 
record (as long as they aren't dupes). In other words, the scheduler 
doesn't just set the next X number to record, where X is the number of 
free 'slots' left. Once the max number of episodes has been recorded, 
all upcoming eps are set to not record.

I think that this does explain the behaviour I was seeing. Presumably 
the scheduler doesn't reschedule until a episode stops recording, hence 
it can record two episodes simultaneously in the circumstances mentioned 
above.

I can imagine two fixes - 1) run the scheduler when a recording starts, 
which might not be a good idea, as I think it's better if reschedules 
don't happen during recordings, isn't it? 2) Make the scheduler more 
accurately schedule the correct number of episodes to fill up to the max 
episodes count in the recording rule, so that in the circumstances 
described above only the first ep would be allowed to record, not the 
second.

Anyone agree or disagree with my analysis? Shall I try to file a bug 
(not done that before)?

Cheers,

John

-- 
John Veness, MythTV user, UK, DVB-T