[mythtv-users] mythtv unable to read /dev/dsp??

Joseph A. Caputo jcaputo1 at comcast.net
Thu Oct 9 13:00:47 EDT 2003


On Thursday 09 October 2003 03:14 pm, jack straw wrote:
> i'm going to try this again, just in case seeing the umpteenth email with 
> (audio sync problem) in the header scared some of you away:
> 
> I'm running a 1.3 duron with 512 mb ram, with a pinnacle PCTV Pro and a 
> Turtle Beach Santa Cruz sound card. I've installed everything clean as per 
> the HOWTO (using RH9 and all the latest bits and pieces)- got the soundcard 
> working (or so i thought) with ALSA (and i rememberd to disable "aRTS"). 
> Everything works fine, EXCEPT for the audio sync issue. In other words,  
> mythtv works fine, the audio works fine- it just isn't synced (ie. there is 
> something wrong with /dev/dsp).
> 
> i followed all of the directions with regard to making sure the capture and 
> volume settings are correctly set (the audio patch cable is in the line-in 
> port, although it doesn't matter, it doesn't work in the mic port either). 
> the problem arises when i mute the line-in and stop getting audio 
> altogether. in MythTV the audio device is set to /dev/dsp.
> 
> when i ls -al /dev/ds* i get:
> 
> crw---------      1 mythtv       14,     3 Jan 30 2003 /dev/dsp         
> (highlighted in yellow)
> crw---------      1 mythtv       14,     3 Jan 30 2003 /dev/dsp1       
> (highlighted in yellow)
> crw---------      1 mythtv       55,     3 Jan 30 2003 /dev/dsp56k   
> (highlighted in yellow)
> 
> there are also adsp0, adsp1. adsp2 and adsp3 listed (looking exactly like 
> the above)
> 
> however, when i "dmesg | grep dsp" as one emailer suggested, i get nothing.
> 
> i know just enough about linux to hurt myself- but i'm pretty good at 
> following directions. any suggestions??

Are you sure that (1) your sound card & driver support full duplex, and (2) 
you've specified the correct audio devices for both record and playback?  The 
recording device is specified in the backend setup program, while the 
playback device is specified under Setup->TV Settings->Playback in the 
frontend.  They must both be correct.

To determine if your problem is playback or recording, try this:  try playing 
something in MythMusic.  If you hear sound, then your Myth audio output is 
fine.  If you don't, then you've got an output problem.  Now, if you got 
sound in the previous step, check the recording.  Set up a scheduled 
recording.  When it's done (NOT before!), try to play it back under 'Watch 
Recordings'.  If there's no sound, then you've got a recording problem.  If 
everything above was fine, then you might have a duplex issue.

-JAC



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