Non-broadcasting channels

[imilne]

Background to this here (http://forums.nextpvr.com/showthread.php...oadcasting)

Short summary: many channels in the UK "timeshare" their bandwidth with other channels, meaning the channels don't broadcast 24/7. When NPVR tunes into a non-broadcasting channel, it acts like it's frozen, and usually shows either a black screen with no OSD, or a frozen picture from the preview channel, again with no OSD.

I've been sitting on a plugin solution to this for a while - TimeSharer - which lets the user change the tuning information for these channels so that NPVR tunes into an alternative channel that *is* broadcasting during the times that they are normally off air.

I wanted one last discussion about it before releasing it though.

Here's sub's comment from another thread (http://forums.nextpvr.com/showthread.php...dcasting):

Unfortunately the video renderers typically wont update the screen in any way until it is displaying the next frame of video, so when you switch to a channel with no video currently transmitting, the old frame stays on the screen, with no way to make it go black, and no update to the OSD graphics even though the app is telling the renderer to display them.

I guess the main question for sub is: is there really nothing (easy) you can do about it? NPVR seems to manage ok with radio stations (which obviously have no video) but perhaps a different type of graph is built for them?

My plugin works by changing the "local" cache of channel data within NextPVR.exe, so only Live TV is effected; scheduled recordings will still have the correct information in the DB.

To do this, it updates the database with these "fake" values, tells NPVR to reload its settings, then instantly resets the database to the correct values. This does mean the database contains the wrong information for a tiny fraction of a second, which worries me slightly, although technically it wouldn't change the database when a recording was scheduled because the channel must be on-air anyway. I still don't like doing it though. Perhaps there's a way I could override NextPVR.exe's details directly via the API, rather than via the DB?

I've tested it with DVB-T and DVB-S (with merged channels between them too). I have no idea how it would perform with anything else, but maybe that doesn't matter if it's a UK-only problem.

There's some basic documentation on it here (http://www.nextpvr.com/nwiki/pmwiki.php?...TimeSharer) that I wrote yonks ago but never finished. It's actually a very simple problem/concept that I find difficult to explain

Iain

[sub]

Can you try watching one of these offline channels, then right click to see the context menu, then zip and attach the npvr.log?

[imilne]

Can you try watching one of these offline channels, then right click to see the context menu, then zip and attach the npvr.log?

Hopefully this is what you're after.

I used the TV Guide to start Live TV on the "CBBC Channel" which was on-air at the time. I then changed to "BBC Three" which wasn't, but uses the same frequency as CBBC when it is.

Iain

[sub]

Did you right click to view the context menu after changing to when BBC Three? I cant see the item I was looking for in the log.

[imilne]

Yep, I'm pretty sure I did. I even used the context menu to exit NPVR. I'll run through it again in a wee while to be sure though...

[sub]

When you right click, you should see log messages like those below. These are what I want to see for a non-broadcasting channel.

Code:

2011-04-14 06:27:54.034    [INFO][1]    GetCurrentMetadata()
2011-04-14 06:27:54.034    [DEBUG][1]    Current meta data:
<ServiceInformation>
  <Service>
    <ServiceID>1910</ServiceID>
    <PMT_PID>271</PMT_PID>
    <Streams>
      <Stream>
        <PID>517</PID>
        <StreamType>2</StreamType>
      </Stream>
      <Stream>
        <PID>579</PID>
        <StreamType>6</StreamType>
        <teletext_descriptor>
          <page lang="eng" teletext_type="1" teletext_page_number="100"/>
          <page lang="eng" teletext_type="2" teletext_page_number="801"/>
        </teletext_descriptor>
        <stream_identifier_descriptor>
          <component_tag>67</component_tag>
        </stream_identifier_descriptor>
      </Stream>
      <Stream>
        <PID>655</PID>
        <StreamType>4</StreamType>
      </Stream>
      <Stream>
        <PID>1001</PID>
        <StreamType>11</StreamType>
        <stream_identifier_descriptor>
          <component_tag>11</component_tag>
        </stream_identifier_descriptor>
        <data_broadcast_id_descriptor></data_broadcast_id_descriptor>
        <unparsed_descriptor>0x13</unparsed_descriptor>
      </Stream>
    </Streams>
  </Service>
</ServiceInformation>

[imilne]

Nope, it looks like that just doesn't show up when you right-click on a non-broadcasting one. The (empty) entries are there though:

Code:

2011-04-13 08:13:49.569    [INFO][1]    GetCurrentMetadata()
2011-04-13 08:13:50.069    [DEBUG][1]    No service description available
2011-04-13 08:13:50.076    [INFO][1]    GetCurrentMetadata()
2011-04-13 08:13:50.576    [DEBUG][1]    No service description available

I've attached what you *do* get from BBC 3 at the moment (which is on air now, but wasn't during the previous log). It timeshares with CBBC (which is now off) so it might give you what you're after.

You can get PID/SID/etc data for them here (http://www.flysat.com/astra28.php) listed under 10773 H. Perhaps that will help too. This was with DVB-S, but they also timeshare on the same DVB-T multiplex too.

If there's anything else you need, just shout...

Iain

[sub]

When you switch to one of these off air channels, does the live tv buffer file grow, or stay at zero bytes?

Also, could you do a DVB-T scan, and post the npvr.log? I want to see some of the metadata about these non-broadcasting channels. I want to see if I can tell they're present, but not currently broadcasting.

[imilne]

When you switch to one of these off air channels, does the live tv buffer file grow, or stay at zero bytes?

Stays at zero.

Also, could you do a DVB-T scan, and post the npvr.log? I want to see some of the metadata about these non-broadcasting channels. I want to see if I can tell they're present, but not currently broadcasting.

I've just scanned a single multiplex to try to keep it less cluttered for you. The two channels currently off air in that set are "CBBC Channel" and "CBeebies".

NPVR has always found all the offair channels during its scans, unlike GBPVR which would only pick them up when they were active.

Thanks for taking the time to look at this sub. It would be great if it turns out there's something you can do about it, but we can always fall back on my plugin if not.

Oh, and if you skim this list you'll see just how many of these ruddy part-time channels we have.

Iain

[bgowland]

Just some observation on the channels when they're off-air.

According to TSReader, the PCR is set to being on PID 8191 (0x1fff) the Null Packet PID.

Pretty much all other data is there in the PAT, PMT, SDT, NIT etc and the only difference seems to be they don't carry the AV elementary streams.