Performing EPG scan on one multiplex only

Martin Underwood

I know that it is possible to scan one single mux for new/changed channels etc.

But it is possible to scan just one mux for updated EPG data? Or is it necessary to start an EPG grab for every mux that TVHeadend knows about? As a result of BBC changes for replacing SD with HD on satellite (Astra 28.2), new channels are being added for each of the regions (London, South East, Yorkshire, etc). It would be useful to trigger an EPG grab for just the muxes that have new channels.

Maybe that's not possible and I need to wait for the crontab-scheduled EPG grab (eg overnight). Google didn't find anything about it - I looked before posting this question.

davep

What EPG source are you using?

On Astra 28.2E the EPG is carried on dedicated multiplexes - 11425H for Freesat and 11778V for Sky - so it isn't necessary to grab EPG from every mux.

Also I believe EPG is stored per channel, not per service. If a service changes mux, and you re-map the channel to the new service, the EPG will still be valid.

Martin Underwood

I'm using three over-the-air grabbers

- EIT: DVB Grabber

- UK: Freesat

- UK: Freeview

I'm not sure whether the first one is necessary, but it was a default when I installed TVH and I've never experimented with disabling it.

I notice that when I trigger an OTA scan (Config | Channel | EPG Grabber, and then either the cron-initiated scan or the manual "Trigger OTA EPG Grabber" button), it goes through every multiplex, not just the dedicated 11425H and/or 11788V.

I take your point about EPG being per channel rather than per service. However what BBC are doing is to remove their BBC One SD services and creating BBC One HD services. And that means that I need to create corresponding HD channels (and delete the old SD ones) so I need to populate the EPGs of those channels.

So is there a way of executing an EPG scan per channel (or per multiplex that contains the channel) without having to trigger an EPG scan of every multiplex which takes ages - over an hour :-(

There are times when schedules are changing frequently and programmes are shifted around, even after being updated overnight (eg when the Queen died), and it would be useful to manually trigger an EPG update per channel. Trying to find a definitive source of what will be shown when at times of overrunning live events can be a problem when listings web sites (Radio Times), apps (Digiguide) and EPG disagree with each other. I would hope that the EPG is the thing that is most likely to be kept up to date with any late-breaking changes.

Normally an overnight scan is perfect: it's only when things are changing rapidly that there needs to be a way of triggering a more selective scan more frequently.

G Kazaroth

The answer is yes you can. BUT... (there is always a but) you will need to write your own grabber. The reason it works is that TVH caches all the data from the xmltv.xml and only updates the new stuff that comes in. So, having a grabber that (for this request) contains one channel of data will only update that channel in the EPG, even if the grabber normally has hundreds of channels. So, due to the way caching happens in TVH, you can programmatically make it send different info each time. Now it is up to you to make this happen... Good luck.

davep

> So is there a way of executing an EPG scan per channel (or per multiplex that contains the channel) without having to trigger an EPG scan of every multiplex which takes ages - over an hour :-(

On 29.2E the individual muxes don't carry EPG for the services they provide, so EPG Scan can be disabled for all except 11425H. To re-scan that mux just play it.

Muxes do however carry 'Now & Next' data for their services. I had a case a while ago where a programme started late; TVH started recording at the original start time but carried on until the new stop time. I'm not sure whether this is default behaviour or whether I've changed something to make that happen...

If you're using the Freeview EPG grabber then presumably you also have a DVB-T tuner? By default the Freeview EPG grabber has higher priority that the Freesat one so most of your EPG will be coming from Freeview anyway. On Freeview each mux transmits EPG for its own channels on a fast loop plus EPG for all other muxes on a slow loop repeating every 7 minutes or so.

(You should also enable the UK: Freesat (EIT) grabber).

Martin Underwood

ann lily wrote:
>

> There are times when schedules are changing frequently and programmes are shifted around, even after being updated overnight (eg when the Queen died), and it would be useful to manually trigger an EPG update per channel. Trying to find a definitive source of what will be shown when at times of overrunning live events can be a problem when listings web sites (Radio Times), apps (Digiguide) and EPG disagree with each other. I would hope that the EPG is the thing that is most likely to be kept up to date with any late-breaking changes.

The problem when the Queen died is that they didn't even adhere to the modified Queen-oriented schedule. I was expecting all "normal" programmes to be replaced, but I missed the beginning of a few of the Queen's biographical programmes on the various channels because they did not start and stop at the times that TVH received in its overnight scan (which I've scheduled for 0200). Once I realised that the EPG was a work of fiction and that they weren't adhering to it, I started adding 1 hour padding on the end of every programme that I'd scheduled to record. I now do a second scan at 1400 each day to catch any changes that are made since 0200.

On a related note, how do you make sure that a schedule recording on a given channel takes precedence over an EPG scan that uses the same tuner? I thought that if the channel/service/tuner had a higher priority than the EPG scan, the schjeduled recording would take prioirty, but I've had a few occasions when a recording has failed because the tuner has already been doing an EPG scan when the timed recording tries to start. If the priorities are correct, should the timed recording take precedence immediately, or should it wait until the end of the EPG scan for the channel that is currently being scanned? And will the EPG scan carry on where it left off when the scheduled recording ends?