[mythtvnz] Pixellation Every ~ 20 minutes

[John McKnight]

On 18/10/12 20:34, mythtvnz-request at lists.linuxnut.co.nz wrote:
> Message: 3
> Date: Thu, 18 Oct 2012 17:18:58 +1300
> From: Curtis Walker<sultanoswing at gmail.com>
> To: MythTV in NZ<mythtvnz at lists.linuxnut.co.nz>
> Subject: Re: [mythtvnz] Pixellation Every ~ 20 minutes
> Message-ID:
> 	<CAPzMZFFzBmgkoNjeP6XJmhb2SZgpifkYMM-Vt_bwpV4fHmTNVg at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> On 18 October 2012 15:50, Paulgir<paulgir at gmail.com>  wrote:
>> >On Thu, 18 Oct 2012 00:06:50 +1300, Steve Hodge<stevehodge at gmail.com>
>> >wrote:
>> >
>> >On Wed, Oct 17, 2012 at 11:17 PM, Curtis Walker<sultanoswing at gmail.com>
>> >wrote:
>>> >>
>>> >>The frontend playback log shows the problem - looks like it's some
>>> >>sort of buffer-related problem after all (although I haven't had
>>> >>LiveTV fail altogether before).
>> >
>> >
>> >The frontend log shows that there is a lack of video packets at that point.
>> >But we already knew that. It doesn't shed any light on the cause. The
>> >buffers it's talking about are playback buffers - they're not relevant.
>> >
>> >Have a look at the options for increasing the verbosity of the backend log.
>> >Also try the kernel logs.
>> >
>> >You said Mediaportal worked ok. So it's not hardware, but you haven't
>> >narrowed down which Linux software is causing the issue. Try to make a
>> >recording outside of MythTV but under Linux using dvbstream or something
>> >similar (I think you could use mplayer as well). That might tell you if the
>> >problem is in MythTV or if the problem is in the kernel drivers.
>> >
>> >You mentioned a fresh install of the very latest Mythbuntu dist. I don't
>> >think you've actually said, but I got the impression that this was a new
>> >problem for you, if so then I would be more inclined to try an older install
>> >(+ matching kernel) than a newer one. If you can narrow down the issue to
>> >the kernel or MythTV then try downgrading just that part.
>> >
>> >Cheers,
>> >Steve
>> >
>> >
>> >Here's a little more info based on my experimentation with this problem.It
>> >may be relevant.after I reduced the signal going into the tuner,TV3 shows 1
>> >or 2 second periods of minor pixellation but it never builds into the 30 to
>> >60 second long event that get progressively worse till something resets and
>> >the picture suddenly comes right.
>> >
>> >-Paul
>> >
>> >
>> >_______________________________________________
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>> >
> Some more tests:
>
> 1) Fresh install of mythbuntu 12.04 (I recorded the Wimbledon Final on
> July 9th without pixellation - so something has happened since that
> time, I think) -pixellation problem occurred.
>
> 2) Back on Arch, I just watched half an hour of TV3 using VLC to open
> the capture device. Pixellation at the 20 minute mark as per mythtv.
> So - it's not something to do with Arch/MythTV (at least not
> directly). A check of system monitor during this period showed CPU
> usage actually fell, presumably as there was less info being presented
> for processing.
>
> So: a lack of frames / info being presented by the card - but only
> under linux (not in Windows or to the TV tuner). Occuring every 20
> minutes or so. Mine wasn't resolved by attenuating the signal (3-20dB
> range) - although I could try again, I suppose to see if I can
> replicate Pauls' findings.
>
> Hopefully the USB DTV-B tuner will arrive tomorrow to test.
>
After fixing some reception issues with a home-made folded dipole, I noticed
a similar problem with pixellation approximately every 20 minutes.

I believe this Pixellation problem may have been due to missing
firmware. Specifically, my system was not loading the firmware for the 
tda10048
devices. It was successfully loading the saa7164, and tda18271 firmware, 
however
the tda10048 firmware file was missing.

I downloaded HVR-12x0-14x0-17x0_1_25_25271_WHQL.zip, and extract.sh from:

http://www.steventoth.net/linux/hvr22xx/

Then extracted the file dvb-fe-tda10048-1.0.fw using extract.sh, and 
copied the
firnmware file to lib/firmware.

Since then I have made four recordings with no pixellation issues 
whatsoever.

The Linuxtv.org wiki describes the tda10048 as a DVB-T demodulator.

I am not completely convinced that the pixellation issue was caused by this
missing firmware file. However results so far are encouraging.

What I don't understand is if this was the cause of the pixellation issue,
how then did the card manage to work while an apparently important component
- the tda10048 - was not actually functioning?

The tda10048 firmware loading failure was in the last block of dmesg 
output, so this
should be easy to spot on your system.


Cheers,
John.