[mythtv-users] Firewire recording/configuration difficulties

Brent Meyer brent.meyer at gmail.com
Sun Feb 6 21:30:15 UTC 2011


On Sun, Feb 6, 2011 at 12:32 PM, GZ <gzornetzer.lists at gmail.com> wrote:
> On Sun, Feb 6, 2011 at 10:48 AM, Brent Meyer <brent.meyer at gmail.com> wrote:
>
> <snipped>
>
>>
>> I am in Seattle, WA, using Comcast cable. I only attempted to record
>> the OTA channels, all of which I have verified are flagged copy-freely
>> and are unencrypted. My cable box is a Pace RNG110.
>>
>> My backend runs Mythbuntu 10.04.1 (kernel 2.6.32), using the older
>> firewire stack. I have also tested Mythbuntu 10.10 (running kernel
>> 2.6.35 and the newer juju firewire stack) on a different disk on the
>> same machine, with similar results. My firewire card is a cheapo Syba
>> card with a VIA VT6307 chipset.
>>
> <snipped>
>
>>
>> I did the following:
>>
>> $ plugctl -n 1 "oPCR[0].n_p2p_connections=1"
>> $ sudo chmod 666 /dev/raw1394 (on the 10.04 installation only; this
>> doesn't seem to apply to the new stack)
>> $ test-mpeg2 -r 1 > test.mpg (dozens of times, all with the same result)
>
> <snipped>
>
>>
>> I've also tried dozens of combinations of models/transfer rates in the
>> backend setup, all with basically the same results.
>>
>> I'm hoping this is just a case of a cheap firewire card not working
>> properly. Can anybody out there tell where I've gone wrong?
>>
>
> Hi Brent,
> I'm also in Seattle with Comcast (and the RNG-110).
> One question - I couldn't tell from your post if you tested the output of
> test-mpeg2.  Does it have lots of macro-blocks and errors?  Did you try
> playing it in myth as well as other players (VLC or mplayer)?
>
> Although I haven't upgraded my backend to use firewire, I've been testing it
> out with recent Fedora live USB images.  I can comfirm that the output of
> test_mpeg2 is clean on my system.  At the very least, it plays in mplayer
> without nasty blockiness.  I've heard that some people have problems with
> the firewire output from the RNG-110 working in mplayer but not in mythtv.
> IIRC, the RNG-110 in some cases outputs non-standards-compliant streams,
> something out nonexistant PMT tables. you should be able to find it with
> google.  I cannot remember if I've tested for this.  I'll see if I can do
> this tonight.
>
> For your information, I'm using a PCI firewire card with a TI chip (it's an
> old adaptec card), so I would point the finger at your VIA chipset.  Another
> possible problem (that I had) is that older versions of the firewire drivers
> had some problems on 64 bit machines.  Are you running a 32 bit or a 64 bit
> kernel?  I'd highly recommend a live USB image for checking these sorts of
> things.
>
> Good luck - and remember that you're not alone in the Seattle Comcast saga.
> -Greg
>
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>

Hi Greg,

Thanks for the information. I did test the output of test-mpeg2, and
it did have a lot of macroblocks and errors, as you said. The output
was basically the same as, or worse than, the sample video I linked to
in the original message. The results are the same whether played back
in Mythfrontend, VLC, or mplayer.

I'll look into the PMT tables issue (which is mentioned on the
Firewire Cable Boxes wiki page, without much more information).

I'm encouraged to hear that my Firewire card could be the culprit
here. I'll have to pick up some TI- and NEC-chipset-based cards and
see if they do the trick. At least that's an inexpensive fix.

Thanks again,

Brent


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