[pvrusb2] mythtv and wintv-hvr-1950 - analog/digital scanning

[fivenote]

Mike,

That's probably it. When I set up the DVB in mythtv there's two
options that look like they'll keep the DVB card open...

"Open DVB card on demand" - was unchecked. I'll check that to have
mythtv close the card when not in use.
"Use DVB Card for active EIT scan" - was checked. The help on that
option says it keeps the DVB card constantly in use. I'll uncheck it.

I saw these options mentioned in another post but wasn't sure how they
applied. Your explanation made it clear.

I'll have to wait to try this later tonight when I get home and post a
reply as to the results.

Thanks again... you've gone above-and-beyond explaining parts of v4l
that you probably don't directy support.

-vincent

> Vincent:
>
> Ah, I misread your post.  I thought you were trying to scan for digital
> cable channels.  But you said analog and you had clearly stated
> /dev/video0, the V4L device entry point.  While it's possible that there
> might be problem in the tuner chip's driver, there's another more likely
> possibility:  You can't run the DVB and V4L sides at the same time.  If
> something is holding the DVB side open, the V4L side will be prevented
> from tuning or streaming - it can't run because the hardware resources
> needed are busy servicing the DVB side.
>
> If you're running this completely under MythTV and you've told MythTV
> that the two devices are related to one another (have you?) then this
> collision should not have happened.  If MythTV doesn't know that the two
> sides map to the same hardware then it might erroneously try to operate
> both sides at once.  Alternatively if you might have had something else
> holding the DVB side open when you tried to touch the V4L side (for
> example an instance of the DVB azap utility), then the V4L side won't
> operate.
>
> Knowing that, does this help?
>
>   -Mike

On Sun, Jan 4, 2009 at 10:01 PM, fivenote <fivenote at gmail.com> wrote:
> Thanks Mike.
>
> I think I am telling it QAM mode. In myth TV backend config I choose
> "us-cable" as the "Channel frequency table". I'm doing exactly as I
> did yesterday when it found all the cable channels. Only thing I
> changed was to compile the latest v4l drivers from
> http://linuxtv.org/hg/v4l-dvb. After that the DVB/broadcast channels
> started working and MPEG/cable channels disappeared.
>
> My developer's sense (I'm a web app developer) says the fix for the
> DVB broke the analog side. Please feel free to pass this on to the DVB
> develpoers.
>
> BTW... overall the developers that contribute here are doing a great
> job. I'm excitied to be so close to having this all work.
>
> -vincent
>
> On Sun, Jan 4, 2009 at 9:39 PM, Mike Isely <isely at isely.net> wrote:
>> On Sun, 4 Jan 2009, fivenote wrote:
>>
>>> Mike,
>>>
>>> Thanks so much. Your explanation made sense. I got the latest v4l
>>> driver source from linuxtv.org. It compiled and installed ok. I
>>> noticed it came with a version of pvrusb2 so I used that instead of
>>> the pvrisb2 I had compiled separately before.
>>>
>>> Now I get tons of HD ATSC channels. But I lost my cable channels. I
>>> scanned the input connection for [MPEG : /dev/video0] and get all "no
>>> signal". I had all my expected channels before upgrading the v4l
>>> drivers and now none. I checked the myth and system logs,but nothing
>>> obvious.
>>>
>>> That figures, doesn't it? One day you got cable and no ATSC, the next
>>> day all ATSC and no cable.
>>>
>>> Is the scan and lock for the cable channels likely an issue with the
>>> same tda18271.ko?
>>
>> Cable broadcasts as I understand it are QAM not ATSC.  Probably
>> somewhere you need to tell MythTV it is dealing with a cable signal so
>> that the tuner can drop into QAM mode.
>>
>> At least that's a guess.  I don't get cable here (I *HATE* the cable
>> companies) so I don't know this for a fact.  But it's what I understand
>> about digital cable reception.  The modulation standard is different and
>> the tuner has to know to look for this.  Why is this the case?  I have
>> no idea; seems stupid to me to have different modulation standards for
>> cable versus over-the-air.
>>
>> If you know the tuner (i.e. tda18271.ko) is running in QAM mode then you
>> may have hit a new problem - and if that is the case I know a couple DVB
>> developers who will want to hear about this.
>>
>>  -Mike
>>
>> --
>>
>> Mike Isely
>> isely @ pobox (dot) com
>> PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8
>>
>
>
>
> --
> ~~~~~~~~~~~~~~~~~~~~
> VAO - fivenote at gmail.com
> ~~~~~~~~~~~~~~~~~~~~
>
>
>
> --
> ~~~~~~~~~~~~~~~~~~~~
> VAO - fivenote at gmail.com
> ~~~~~~~~~~~~~~~~~~~~
>



-- 
~~~~~~~~~~~~~~~~~~~~
VAO - fivenote at gmail.com
~~~~~~~~~~~~~~~~~~~~