Scheduling Conflict - define all conditions of one?

Basq

OK... i had absolutely no idea where to put this!

In terms of either TV scheduling or project management, what would you consider to be conditions of a scheduling conflict between two tasks?

For example, one such condition of a scheduling conflict would be when the start of the next task begins before one task has finished.

Strange question i know but am working on a project right now and i can't seem to get all conditions of a scheduling conflict correct.

PS - mods, please move elsewhere if you can think of somewhere else!

Karoma

Explain your project & context.

From software development project management perspective:
Break down what a project requires: time, personnell, money, etc.
+ how they're spent (Phases,etc.)
Wherever these overlap due to other phases of a lifecycle or whatever = conflict...

Basq

Sorry.. i shouldn't have used the project management analogy.

I'm basically making an PVR for my project and i'm currently working through some tweaks to hand it up along with documentation in a fortnight.

But one of the things i can't seem to get right is scheduling tv shows to record in the TV Guide. You add programs from there which go into a scheduler.

It will check for a conflict with all existing shows set to record on that day if you add a show. The scheduling conflict will work on some occasions but not all. The only real condition i have preventing a conflict is i check if the start time of one show is before the end time of another show? Can't really make it much clearer though i wish i could.

What i'm essentially asking asking is: what (in terms of time constraints) constitutes one TV show overlapping with another?

Adam

I've read and re-read your post and I'm still slightly confused... One programs end time being after the next programs start time would also contitute a conflict surely...

Basq

fade_to_grey wrote:

I've read and re-read your post and I'm still slightly confused... One programs end time being after the next programs start time would also contitute a conflict surely...

Yeah.. that's exactly what i need! I need to cover all possible conditions of when a conflict occurs. The one you mentioned is another one so now i've:

One programs end time being after the next programs start time
One programs start time is before the previous programs end time

Or are they (/\) the same thing? Is there any more possibilities i'm missing here?

Karoma

From a programming/systems perspective, you should be using a semaphore... Or some proper form of synchronization mechanism to inform all processes of the occurrence of that particular event and prevent overlap.

The only real condition i have preventing a conflict is i check if the start time of one show is before the end time of another show?

Will this work for several programs, entered in a non-sequential manner?
I assume that you're really checking date+time of one show against another...


Another condition is that Program A's end time might be after the Program B's start time.



I'm tired and confused. G'night.

Adam

Karoma got there before me (why oh why must boards back up its database :rolleyes:)

Basically if you consider programs in three's:

Program A, B and C

If you check for each block of three that program B's start time is after program A's end time, and program B's end time is before program C's start time, then you cover all angles.

Then all you must do is implement the primary program as program B in all cases, so that the checks run as intended i.e. the variable program in question is checked against the previous and next program in the manner described above.

That should about do it!

How are you running these checks? Is it a programming language in question?

Hagar

Don't forget you have a small cushion when dealing with overlaps. There is a three minute ad-break between programs on the majority of stations so you may be able to force start the second programme by up to three minutes.

Have you considered how to deal with late programme starts/overruns ?

Another condition to be very careful of:
Programme A starts 13:15 and ends at 14:15
Programme B starts 13:30 and ends at 13:45

If you don't phrase your checks carefully that can easily slip through.

I know its obvious but use a 24 clock.

The calendar will also be a problem be careful with programs that span month ends such as start at 23:15 28/02/2004 and finish on 00:30 01/03/2004.

You might want to work on a "day of year" basis ie
31/12/05 becomes day "2005365"
01/01/06 becomes day "2006001"
01/02/06 becomes day "2006032"
Now combine that with a "minutes of day" basis ie
00:30 31/12/05 becomes "20053650030"
00:30 01/01/06 becomes "20060010030"
23:30 01/02/06 becomes "20060321410"

If you do that the comparisons become simple <= >=.

Hope that's some help.

Tenshot

Checking for schedule conflicts is pretty straightforward. Let's assume you have an existing list of scheduled (non-overlapping) programs: A, B, C, D, ..., etc. Now you want to add a new program X to the list, and see if it conflicts.

Program X conflicts with Program A if:

     (StartX >= StartA and StartX < EndA)
  OR
     (EndX > StartA and EndX <= EndA)

Perform similar comparisons for X vs B, X vs C, etc. and you'll end up with a list of schedule conflicts. Most PVRs simply display that list and then let the user decide which program takes precedence. I've never seen one that tried to get fancy by (for example), allowing the last 5 mins of one program to eat into the first five minutes of another.

Don't forget soft-padding: ideally, you'd like to add up to 2 mins before and 3 mins after each recording (if it doesn't cause a scheduling conflict). Many terrestial TV stations don't start and stop exactly on the hour - BBC is especially notorious for this.

Basq

Thanks very much all... very useful input!

Tenshot got it on the button but appreciate everyone's reply.

I think the whole concept of time overlapping just washes over me!

The Sweeper

Eh, something like "Successful scheduling using a PVR has a number of dependencies. The allocated start and finish times for programming on multiple channels must not cause programs to overlap. There must also be a sufficient amount of time between programmes to allow for an advertising break or a voiceover link. Time between programmes must also be short enough to ensure no loss of the viewer's interest". Or some jazz like that?

Let me get this right, you're trying to write up the specifications for how a PVR should work?

muppetkiller

Yes but then you have your Worst Case Senario when for example your schedule doesn't match your content. Ie When pre arranged content is delayed and schedule is not updated to reflect the change.

Eg.. FA Cup final replay go's into injury time. everything else gets delayed on one channel.

Basq

Minesajackdaniels wrote:

Let me get this right, you're trying to write up the specifications for how a PVR should work?

Well yes and no.

I'm actually developing a PVR with a TV Guide from which you can add programs to record (into a scheduler) but if you click two shows which overlap each other, it should notify you.

But i need to know exactly what defines when two shows overlap.

Will post up a couple of screenshots later on to clarify more.

PS - mods - probably could be moved to Programming at this stage.