Problems with webcamd and RTL2832U

[Greg 'groggy' Lehey]

On Friday, 29 April 2016 at  8:43:00 +0200, Hans Petter Selasky wrote:
> On 04/29/16 04:52, Greg 'groggy' Lehey wrote:
>> Certainly I shouldn't be using it, since this is a DVB-T tuner.  This
>> is puzzling: why is MythTV even trying to use it?  I can't find any
>> reference to it in the DVB-T setup, which isn't surprising.  Does
>> webcamd have any connection with DiSEqC?
>
> Diseqc is a set of commands that send special voltage sequences on
> the antenna port, for an external multi-antenna switch.

My understanding is that it only relates to DVB-S.  That's also the
response to the otherwise ignored bug report at
https://code.mythtv.org/trac/ticket/4378 suggests.

> I guess if you use DVB-T, this is not supported by the device. Have
> you connected a Diseqc device with the antenna port?

Not knowingly.  But there are a couple of amplifiers upstream, so I
disconnected the antenna and plugged in the toy antenna that came with
the tuner.  Deleted the entries for the old tuner and tried again.
Once again it created not one, but two entries in the capturecard
table.  It's interesting to note that the only difference between the
two records is the attribute dvb_diseqc_type: one is set to 0, the
other to NULL.  I have already tried removing one record, or setting
both to NULL or 0.  No help.  But it does suggest there's something
broken in Myth.

> Maybe you can check the MythTV code where the error comes from and
> make it ignore the failures?

That's painful.  Here's a snippet of code that I found in Myth years
ago (http://www.lemis.com/grog/diary-sep2004.php#18):

    /* ci must be 0 */
    if(bitoff != 6) {

         (uint8_t)strm[co]= bitten;
         co++;

    }
    goto BAUCHWEH;

   HERZWEH:

In any case, I have another old Myth box (Linux) connected to the same
antenna system, and I don't have problems there.

Greg
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