[mythtv-users] Stereo sound with PVR-250

Mats Cedergren mats.cedergren at 5d.se
Tue Oct 19 22:17:46 UTC 2004

-----Original Message-----
From: Joseph A. Caputo [mailto:jcaputo1 at comcast.net]
Sent: Mon 10/18/2004 3:52 PM
To: Discussion about mythtv
Subject: Re: [mythtv-users] Stereo sound with PVR-250
Note: please don't top-post.  See below.

On Friday 15 October 2004 17:28, Mats Cedergren wrote:
> From: Joseph A. Caputo [mailto:jcaputo1 at comcast.net]
> > Sent: Fri 10/15/2004 11:01 PM
> > To: Discussion about mythtv
> > Subject: Re: [mythtv-users] Stereo sound with PVR-250
> >
> > On Friday 15 October 2004 15:39, Mats Cedergren wrote:
> > > Is anybody getting stereo sound with there PVR-250 cards under
> > > linux? I only get mono :(
> >
> > What are you recording from?  Tuner or A/V in?  If you're recording
> > from the tuner, then the problem is probably your audio output, not
> > the -250.  If the -250 is really recording mono sound and the source
> > is definitely stereo, then you've got a bad card.
> >
> > More likely, either (1) you've misconfigured your tuner type, (1a) 
> > if you're not using the tuner, does your audio input to the PVR-250
> > have a stereo plug?, or (3) your recordings are just fine, but there
> > is a problem with the way your audio output is configured, which has
> > nothing to do with the PVR-250.  To check (3), try playing a
> > recording on a different machine.
> >
> > -JAC
>> I'm recordning from the Tuner. I have tried the same card in
>> WindowsXP (the same computer, dual boot setup) and there the card
>> works perfectly and I get stereo sound from all channels that
>> transmit in stereo.
>> I have not tried the recordning on another computer yet, will try
>> that tomorrow, but I don't think that it will make any difference.
>> When I play music or other movies (.avi, .mpg, dvd etc) i get stereo
>> sound.

>When you play them with what?  Myth's internal player?  I assume you're 
>playing them with other programs (mplayer, xine, etc).  So all that 
>tells us is that there's nothing wrong with your sound card or driver.

>Now we need to make sure that Myth is properly configured for sound 
>output.  The best way to do this is to take a known good file (like a 
>'good' .avi or .mpg file with stereo sound) and play it using Myth's 
>internal player with the command "mythtv <filename>".  If you get 
>stereo sound here (and I bet you will), then your sound output is 
>configured properly within Myth.

I have tried playing them with both internal mythtv player and with mplayer
and with vlc. None of the players produced stereo from files recorded with
mythtv. However, if I playback an avi file with "mythtv <filename>" I do get

stereo as you guessed.

>> When I play a video captured with "cat /dev/video0 > /tmp/test.mpg"
>> using mplayer "mplayer /tmp/test.mpg" it reports that the file have
>> two channel sound but I can hear that the sound is not in stereo.

>This sounds like there's a problem with your ivtv driver setup, or with 
>your input source.  Since you say you've rebooted the same setup into 
>Windows and heard stereo, I'm guessing that your input source is OK.  
>Therefore I'm guessing there is some problem with your ivtv driver 
>setup.  Try playing with the test_ioctl program to query/change the 
>capture settings for your card (you'll probably need to quit 
>mythbackend to do this).  Specifically, look at the "-A" option, which 
>sets the audio capture mode to Mono, Stereo, Lang2/SAP or Lang1.  I'm 
>afraid this is a bit out of my area of expertise; I suppose it's 
>possible that something is putting your card in Mono capture mode; 
>perhaps your card is being mis-identified by the ivtv driver; in that 
>case, you might need to pass some parameters to the driver via the /
>etc/modules.conf file.  You might want to ask on the ivtv-users list; 
>make sure to have the specific specs of your card handy (i.e., the 
>output of "lspci").

>I to starting to beleave there is something wrong with my ivtv driver.

>Here are some of my test results:

>I tune to a channel that I know does NOT send in stereo:

>[mythtv at localhost mythtv]$ test_ioctl -Z
> current audio mode   : 1
>   (stereo 1, lang1 3, lang2 2, mono 0)
> available subchannels: 0x1
>   (stereo 0x2, lang1 0x8, lang2 0x4, mono 0x1)
>However if I tune to channel that does send in stereo:
>[mythtv at localhost mythtv]$ test_ioctl -Z
> current audio mode   : 1
 >  (stereo 1, lang1 3, lang2 2, mono 0)
> available subchannels: 0x2
>   (stereo 0x2, lang1 0x8, lang2 0x4, mono 0x1)

>This clearly shows that the card/drivers correctly detects when a channel
>does sends in stereo.

>I'm running with 2.6.x kernel, it might have something to do with that? I
>I will try with the ivtv-user lists since it seems that my trouble are
>related to
>the driver and not mythtv.


It think that I found a workaround for my problem. Here is what I did:
I downloaded and installed "ivtv-0.1.10-pre2-ck100z",rebooted the computer
was still getting mono audio. I downloaded new firmware file and extracted
with "ivtvfwextract.pl" (don't know if I have to do anything else, the
files are now locateded in /lib/modules?). Run "ivtvclt -H" to reloade
(don't know if it makes any difference).
After all this I was still getting mono sound. 
I was playing around with ivtvctl's different settings when I all the sudden

found myself listening to stereo sound. Big joy :) 
Rebooted the computer to see if I still was getting stereo sound but no
luck, back
to mono again. I remember that I was playing with "-z" and "-Z" parameter so
I first
run "ivtvctl -z 0" and then "ivtvctl -z 1" and BINGO!! Stereo sound again. 

I think there is a bug/error in the driver that prevents the card from
correctly and my litte trick with "-z" parameter corrects the problem for

/Mats C

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