Non-broadcasting channels

[imilne]

This might only be a problem for UK users, with our silly half-and-half shared frequency channels, such as BBC Three/CBeebies and BBC Four/CBBC.

In GBPVR, if you tried to view BBC Three during the day, it would actually show CBeebies (with the OSD/EPG showing the details for BBC Three). Not ideal, but more than easy enough to live with.

NPVR is much cleverer now though, and knows not to do this. However, you get a slightly worse problem because if you change to a channel when it's not broadcasting then nothing happens. If you were channel flicking, you're left with either a frozen picture from the previous channel or a black screen. If you jumped to it from the Guide, then you just get the black screen. In both cases, no OSD appears to tell you what channel you're on.

It's particularly bad if you have a couple of these channels back to back. For example, my channels go:

- Channel 4
- Five
- BBC Three
- BBC Four
- Dave

As you go from Five to BBC Three, NPVR acts like it's hung, because the picture freezes, and no OSD appears to let you know you're on a new channel. If you're lucky, you can then channel-up to BBC Four (even though there's nothing to let you know it worked). Normal service only resumes once Dave is reached. In very rare occasions, NPVR *will* actually hang and needs to be restarted.

I'm not really sure what the solution should be. At the very least, I think the OSD needs to appear to let you know you've changed channel. Beyond that, perhaps a way for us to tell NPVR when these channels are active, so it could display a custom banner (eg "channel not broadcasting") when you switch to it.

(The only time I've noticed a visual indication of what's going on is when using Windowed mode, and you'll see, for example, BBC Three appear in the title bar.)

I've attached a log file that shows loading NPVR, going to the Guide, selecting BBC Three, then channel flicking to BBC Four, and then Dave.

Sorry for the long post, but I wanted to try and explain it properly

Iain

[sub]

Unfortunately OSD graphics can only be shown when the video window is displaying video frames. In this case, NPVR is actually asking it to show OSD graphics, with the channel name etc but you're just not seeing them because it's not displaying video frames. This is a limitation of the EVR and VMR renderers.

[johnsonx42]

Perhaps just have it just keep changing channels until it finds an available channel?

[imilne]

Bummer.

Crazy idea time. The channels switch over at set times every day. Could a plugin, running in the background, change the tuning information in the database so that an attempt to watch BBC Three during the day would mean CBBC gets tuned in instead, therefore allowing video/audio to play and the correct OSD/EPG to display. Come 7pm (changeover time), the plugin updates the tuning information so that BBC Three now has its correct details. Pretty much faking the way GBPVR works.

There'd be a few complications to work through, but does the basic idea sound feasible?

(In fact, maybe it wouldn't even have to be a BBC Three/CBBC swap; just so long as it picks something valid to tune into during the period the actual channel is off air)

Iain

[imilne]

No thoughts on my crazy idea sub?

I had a quick play with changing the database on the fly while NPVR was running, but it looks like it caches the channel data? If it was exited, and restarted, then it would pick up my changes. I wonder how it links with the recording service in terms of what it does, ie, does it only read the tuning information when it's time to start recording, or does it have it cached too?

Perhaps a simple API call we could make, to ask NPVR to reload its tuning data?

Would capturing a minute or so of data from one of these timesharing multiplexes give you a better idea of what is or isn't possible?

Iain

[sub]

No thoughts on my crazy idea sub?

No, not really.

I had a quick play with changing the database on the fly while NPVR was running, but it looks like it caches the channel data? If it was exited, and restarted, then it would pick up my changes. I wonder how it links with the recording service in terms of what it does, ie, does it only read the tuning information when it's time to start recording, or does it have it cached too?

Perhaps a simple API call we could make, to ask NPVR to reload its tuning data?

If you call EventBus.GetInstance().Notify("RELOAD_SETTINGS"), then it should reload it's channel information.

[BrainStormer]

Hmm What about a 1 min mpeg file which contains the "Channel Off Air" Message that would be played in the event the channel is not broadcasting?

[imilne]

Hmm What about a 1 min mpeg file which contains the "Channel Off Air" Message that would be played in the event the channel is not broadcasting?

It would be good, but I'm not sure if it's practical.

- NPVR has to realise the channel isn't broadcasting. If it could, then maybe johnsonx42's suggestion is all that's needed, ie, it just keeps changing channel until it finds a live one again.
- It would have to break out of Live TV to play the file, then go back into Live TV again. That might take longer than you'd want to wait.

No, not really.

:p

If you call EventBus.GetInstance().Notify("RELOAD_SETTINGS"), then it should reload it's channel information.

Nice. And the results are encouraging too.

I knocked out a quick plugin that calls this every 30s, and NPVR seems happy enough to reload its settings without affecting whatever else is going on (certainly not watching Live TV anyway). So I can watch a blank BBC Three, change to something else, fudge the values in the database (by hand for now), wait for the reload, then go back to BBC Three and see picture/audio. All without leaving Live TV.

Maybe what I need to do is have the plugin - upon first activation - decide what time of day it is and update the database entries so that every offair channel contains the data for one that is actually broadcasting. Then tell NPVR to reload its data, and then instantly reset the database to its correct values. That way, if you exit (or NPVR crashes ) the database will always be correct. It should also mean that nothing really interferes with the recording service.

Is this of interest to other users? If so, I'll try to write it properly. If not, it'll be a quick n dirty hack for my own needs.

Iain

[markbb1]

This might only be a problem for UK users, with our silly half-and-half shared frequency channels, such as BBC Three/CBeebies and BBC Four/CBBC.

In GBPVR, if you tried to view BBC Three during the day, it would actually show CBeebies (with the OSD/EPG showing the details for BBC Three). Not ideal, but more than easy enough to live with.

NPVR is much cleverer now though, and knows not to do this. However, you get a slightly worse problem because if you change to a channel when it's not broadcasting then nothing happens. If you were channel flicking, you're left with either a frozen picture from the previous channel or a black screen. If you jumped to it from the Guide, then you just get the black screen. In both cases, no OSD appears to tell you what channel you're on.

It's particularly bad if you have a couple of these channels back to back. For example, my channels go:

- Channel 4
- Five
- BBC Three
- BBC Four
- Dave

As you go from Five to BBC Three, NPVR acts like it's hung, because the picture freezes, and no OSD appears to let you know you're on a new channel. If you're lucky, you can then channel-up to BBC Four (even though there's nothing to let you know it worked). Normal service only resumes once Dave is reached. In very rare occasions, NPVR *will* actually hang and needs to be restarted.

I'm not really sure what the solution should be. At the very least, I think the OSD needs to appear to let you know you've changed channel. Beyond that, perhaps a way for us to tell NPVR when these channels are active, so it could display a custom banner (eg "channel not broadcasting") when you switch to it.

(The only time I've noticed a visual indication of what's going on is when using Windowed mode, and you'll see, for example, BBC Three appear in the title bar.)

I've attached a log file that shows loading NPVR, going to the Guide, selecting BBC Three, then channel flicking to BBC Four, and then Dave.

Sorry for the long post, but I wanted to try and explain it properly

Iain

If you are using XMLTV to get your listings data, use a tool to change the channel ID of CBeebies to BBC Three in your xmltv file before it is imported into NPVR (and the same for all channels that share airtime/frequency). That way the listings for the channel(s) will be continuous and your problems will vanish.
If only the time is shared between channels, and not the frequency, this won't work (so ignore this post).

[sub]

No thoughts on my crazy idea sub?

This main risk is that'll you'll have a recording start prior to the channel coming on, ie starting the pre-padding a few minutes before the channel starts, and it'll get the wrong details passed to that recording.