[linux-dvb] Re: No sound on some channels (sometimes)

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Martin Holst wrote:
> 
> Hi
> 
> although I believe that this bug is well known by the dvb-developer, I'll
> describe it another time:
> 
> Many people noticed, that the sound on some channel gets lost and only a
> restart of the dvb driver solves that problem. In my case I'm pretty sure, that
> this problem doesn't exist within dvb-driver from 20.09.2003. But some other
> people on the vdr-ML said, that they have this problem with drivers before
> that date. Affected channels are: RTL, ARD.
> 
> Oliver Endriss wrote on the vdr-ML:
> * I often have missing sound on ARD (pid 102), but sometimes other
> * pids are affected (101, 104). 101 is used by picture on ARD, 104
> * by sound on RTL...
> *
> * This is a known and pretty old bug. I had some off-list discussion
> * with the driver developers in April 2003 about this issue. It was
> * mentioned on the ML several times, too.
> 
> As discussed on the vdr-ML this problem occurs on a DVB-s 1.3 and 1.6 as
> well as with a Nexus. I've tried recent dvb-driver and dvb-kernel with the same
> result.
> 
> Has anyone of the driver-gurus an idea, where we can start to get rid of
> this problem?

I wouldn't call myself a "driver guru", but here's an observation I made:

The Sat.1/Pro7 transponder uses the PIDs 97...107 for their PMT data.
Maybe, when switching from a channel on that transponder to, say, RTL
the PID 104, for instance, is still in use by the PMT section filter
and thus can't be used for audio at that time.

VDR does stop all section filtering before switching channels, so I
would assume that from VDR's point of view the PIDs should all be available
as necessary. Maybe there is a race condition in the driver that causes
the already freed PIDs to still be "in use"?

Klaus


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