[mythtv-users] Re: SAA7134 (Flyvideo 3000) not alwayscapturingaudio

Christian Hack christianh at pdd.edmi.com.au
Wed Jul 16 12:52:17 EDT 2003


> -----Original Message-----
> From: mythtv-users-bounces at snowman.net 
> [mailto:mythtv-users-bounces at snowman.net] On Behalf Of Christian Hack
> Sent: Tuesday, 15 July 2003 7:27 PM
> To: 'Discussion about mythtv'
> Subject: RE: [mythtv-users] Re: SAA7134 (Flyvideo 3000) not 
> alwayscapturingaudio
> 
> 
> > -----Original Message-----
> > From: mythtv-users-bounces at snowman.net 
> > [mailto:mythtv-users-bounces at snowman.net] On Behalf Of Rob Nielsen
> > Sent: Tuesday, 15 July 2003 6:57 PM
> > 
> > CH wrote:
> >  >Anyone else had similar problems? I don't think it's the 
> > driver since 
> >  >if I use aplay /dev/dsp1 (the device created by the SAA7134 
> > driver) it
> >  >always works. It only seems to happen with Myth capturing 
> the audio.
> > 
> > Hi.  I've just setup a system with 2 Flyvideo 3000 cards 
> > (sound through 
> > PCI bus) and am experiencing exactly the same thing.  It is 
> > definately 
> > on the recording side and looks like either a problem with 
> > the driver or 
> > the way MythTV tunes the channels as plugging speakers 
> > directly into the 
> > capture card produces no sound when it happens.
> > 

I believe this is probably a driver issue. After pluggin speakers into
the audio output of the tuner card, I have verified that the tuner is
not outputting any sound. This is watching LiveTV. However when I drop
back to the menu with the escape key, I can then hear the sound. It's as
if something in the driver is not being toggle when it should and vice
versa. i.e. some kind of mute is being toggle rather than set. Points
toward the driver some more I believe.

> 
> Well at least it is reproducable. I haven't tried plugging speakers
> directly into the tuner card when there is no audio, but I 
> will tonight.
> If as you report, no sound is coming from the card, then it basically
> has to be a driver issue rather than a MythTV issue. Myth 
> simply sets a
> channel though V4L interface as I understand and then records from
> /dev/videox and /dev/dspx.
> 
> > Other things I've found is that after a reboot, both tuners almost 
> > always have no sound initially and I need to go to Watch TV, 
> > ESC, Watch 
> > TV... a few times to get them going but then after that you get the 
> > occasional recording with no sound.
> 
> I am seeing this exact behaviour too.
> 

After a bit a mucking around last night, it seems a reboot makes it
happen more for the initial few goes. Some sort of initialization thing?

> > As a workaround for this, if the cause can't be found, how 
> > hard would it 
> > be to sample the sound for a small period of time after a 
> > channel change 
> > and if there is no sound detected, then try retuning?
> 
> I'd rather fix it in the driver if possible than go hacking myth code.
> 
> I am back on the video4linux list and once I get a good description I
> will see what Gerd thinks. I'm unable to find any technical 
> doco on the
> SAA7134 (registers etc) so he's possibly the only one who can help.
> 



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