[vdr] DVB (usb) device hotswapping?

Georg Acher acher at in.tum.de
Sun Apr 4 17:22:27 CEST 2010


On Sun, Apr 04, 2010 at 10:54:02AM +0200, Udo Richter wrote:
 
> How did you solve the case that a device disappears while being used? If
> this happens for a recording, then VDR would terminate with a VDSB, or?
> Do you silently switch the device to another resource?

As long as the device is used by vdr with a successful Provides() at the
beginning, it cannot disappear, even if the "real" device behind it is gone.
However, the vdr-device will get a no-lock after 10s and femon sees no
longer a type and description after one minute. That also triggers the VDSB
message, but recording goes on if the resource re-appears, as the vdr-device
is not shutdown.

Since the tuner behind it is already virtualized, it will be immediately
attached again to the "dangling" dvbdevice if something matching appears,
e.g. when the network gets reconnected. This is due to the fact that the
tuning parameters are included in the MLDv2-messages the mcli-plugin will
resend every few seconds for an open device. The streaming starts again when
an appropriate server gets these messages.

In principle it is possible to switch to another resource, but the current
firmware supports no distributed sources (=satellite positions) over
different NetCeivers, they need to be exclusive. We have already a
peer-to-peer-like firmware that supports distributed resources and would
allow redundant NetCeivers, but it still needs some CPU optimizations for
the slow CPU on the NetCeiver...

However, internally in one NetCeiver an expensive resource (like a rotor or a
S2-tuner that were used because no other tuners were free at that time) is
automatically switched back to a cheaper resource if possible. This is
almost invisible from the outside...

-- 
         Georg Acher, acher at in.tum.de         
         http://www.lrr.in.tum.de/~acher
         "Oh no, not again !" The bowl of petunias          



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