[mythtv-users] Re: PVR-350: audio without patch cable (Andrew Dodd)

Andrew Dodd atd7 at cornell.edu
Wed Mar 10 15:31:55 EST 2004


Quoting Andreas Weder <aweder at mac.com>:

> Andrew,
> 
> > > I wonder how many of you are using a PVR-350 with mythTV without
> > > an audio patch cable, but in a setting, which makes the PVR-350
> > > take audio over the PCI bus.
> > > 
> > > Did you have to apply any special settings in modules.conf?
> > Almost everyone?
> > 
> > Unless your 350 is horrendously misconfigured, the audio will be 
> > in the recorded
> > MPEG program stream.
> > 
> > No need for a patch cable with any ivtv board.  Patch cables are 
> > only for "dumb"
> > capture chipsets like the Bt8x8 and cx88 - And even then some 
> > 878s and probably
> > the cx88s can pass audio over the PCI bus too.
> 
> that's what I thought.
> 
> In fact, I do get audio after a fresh installation ivtv and
> mythTV, but loose it after a couple of reboots.
> 
> Any idea how a 350 could be horrendously misconfigured to cause
> such behaviour?
> 
> I've checked msp3400.o (I'm loading a good version), alsamixer
> settings, test_ioctl settings (input/output indices, mute/unmute).
> 
> One thing coming to my mind right now: could the SMP kernel on 
> my hyperthreading P4 be the culprit? 
> 
> As far as I know there are issues with SMP and only newer
> (2.6.x) versions of the kernel properly support hyperthreading
> CPUs.
> 
> I'm running FC1, mythTV 0.14, ivtv 0.1.19 with a HT P4 2.4 GHz
> CPU, and am installing all software using ATrpms binary pkgs.
Check the FAQ on the ivtv site (http://itvt.sf.net/) - One of the entries
regards a problem with the sound standard autodetection functionality of the MSP
chip.  (In short, it sucks and some people have to force the setting - In fact,
it's a good idea to force this setting even if it works 95% of the time, as that
5% of the time where your recordings don't have audio REALLY SUCKS.)  Even if
the PVR-350 had the alternative of a patch cable for recording, it wouldn't help
in this situation - the audio enters the MSP and never comes out.

For example, my modules.conf line has

options msp3400 once=1 simple=1 standard=0x20

for North American NTSC.  The ivtv FAQ has a table of other standards.




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