[vdr] VDR and Hybrid DVB Cards ( was "HVR 4000 drivers broken - adapter0/frontend1 busy" in linux-media list )

L. Hanisch dvb at flensrocker.de
Wed Nov 16 19:16:30 CET 2011

Am 15.11.2011 23:29, schrieb Hawes, Mark:
>>   http://projects.vdr-developer.org/projects/plg-dynamite
>>   https://github.com/flensrocker/vdr-plugin-dynamite
> I had a look at the readme. The approach of making all devices hot
> pluggable is an interesting one and provides for a flexible solution.
> How important it is to get plugins to adapt to the approach is still
> unclear to me. Presumably if they are in the plugin list prior to the
> dynamite plugin they will be 'immune' as they will declare their own
> devices to the pool first.

  This is right. But just like the cDvbDeviceProbe there's a cDynamicDeviceProbe class which plugins can use to add 
hotplugging features to their devices. pvrinput is an example for this.

> While the approach has its merits I believe that it is probably overkill
> in this case. I believe that VDR should be able to cater for hybrid
> cards natively alongside existing cards with more conventional adapter
> layouts and any patch should ultimately have that as its goal.

  What I tried to communicate is, that I have some work done which is part of the problem: closing the handles and the 
right places. I will try to reuse some of the code to extend the cDvbDevice for multiple frontends.
  Difficult to explain, please let me do some code first. ;-)

  I will post it on the list when I have something to show.

> As I see it there are two possible approaches: try to bolt on support
> for hybrid cards as exception cases to the current code, or redesign the
> handling of the devices from the ground up to also cater for the more
> exotic adapter layouts. There could be a third 'hybrid' solution which
> sits somewhere between the two.

  I think there are cards which have a digital and an analog tuner. But they are only interesting if they support 
hardware encoding of the analog material like the Hauppauge PVRx50 cards. I don't think it would be needed to support 
such cards (iow the analog part of those cards). But one should keep this at the back of one's head.

> The comment above from Steffen seems to make some sense ' if the device
> nodes are created within one adapter an application needs to assume that
> the devices cannot be used concurrently and needs to close one "device
> node group" before opening the other one'. As I understand it this would
> mean that VDR should register all front ends on initialisation and then
> only try to open them when required. If another frontend is found to be
> open on the same device hierarchy a decision is then made to see if it
> can be closed, e.g. no recordings on it etc. If it can't then the
> attempt to switch channel fails with 'Channel not available". I may be
> simplifying things a bite here but that is as I see it. Happy to be
> corrected.

  Yes, that's the way I want to try to go.


> Mark.
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