[mythtv-users] Strange Audio Behavior - Static in One Speaker

[Dave Bixler]

Tom Burt wrote:
> On Sunday 22 January 2006 17:13, Dave Bixler wrote:
>   
>> I've been searching the lists for the last few days trying to find out
>> what I may have done wrong to cause the behavior that I'm experiencing
>> with no luck so I finally decided to ask for help here.
>>
>> Everything is working very well and my system is stable.  I can watch TV
>> using the TV Viewer in Redhat FC4 and if I un-mute the line in, audio is
>> flawless.  Sound/music also plays flawlessly.
>>
>> So, I have the patch cable from the Hauppauge WinTV Go Plus to the line
>> in of my Diamond Monster Sound audio card.  When I run MythTV and select
>> Watch TV, it fires up fine.  However, only the right speaker has audio.
>> The left speaker starts having a tiny amount of static.  This static
>> then starts getting louder about every second preceded by a small "pop"
>> sound.  Each time, it's as if the volume of the static is doubled until
>> it becomes so loud it just distorts horribly.  If I use kmix and slide
>> the balance all the way to the right speaker, I still hear the audio
>> from the TV card fine.  If I slide it all the way to the left, it's pure
>> static.  Does anyone have ANY suggestions whatsoever?  I'm including
>> potential hardware info at the end of this message and if I've forgotten
>> anything, or can include additional information, please let me know.
>> I'm dying to have this working, it's such a sweet application!
>>
>> Thanks in advance for any insight!
>>     
>
> I think I have a very similar problem to yours except that I have TV audio on 
> the left hand side. I'm still testing my problem and trying to find a 
> solution. My findings so far:
> - if I unmute line in, audio is perfect with tvtime
> - if I mute line in, I get sound from the left speaker in myth. However, sound 
> from the right speaker is not simply static, it is recording form the mic! 
> Yes, that's what is happening: left input is line-in, right input is from the 
> mic at the same time! Please check if this is your case, too. I have two mic 
> plugs, one in the front, one on the rear side of the machine, so if you 
> happen to have a similar PC, you might need to also select the correct mic in 
> kmix to check this.
> - I can reproduce the "pop" sound getting louder, can't remember which setting 
> influences this in kmix, but by playing around with controls I could easily 
> get rid of this problem. I cannot check this right now, as a longer recording 
> is in progress on my box.
> - the problem does not seem to be related to myth however: if I eg. record 
> sound from line in with krecord, the same thing happens: the left side is 
> recording from the line input, the right side from the mic.
>
> I suspect the problem is that the sound driver is incompatible with the mixer 
> circuit in the integrated sound card. My motherboard is an ASUS A7N8X-X 
> (nforce2 chipset). Recording works perfectly under Windows, at least.
>
> I have no idea where to go next, already tried google, without success. But 
> I'm not an expert in Linux...
>
> Tom
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>   
Thanks for the feedback.  I tried what you suggested, but the mic does 
not seem to be on the other channel.  Granted, this card has several 
inputs on the board itself, so it's completely possible that one of 
those are being used.  I tried changing the settings from mic1 to mic2 
in kmix but it didn't seem to matter.  I do think that what you've said 
about our problems possibly being the same is correct.

Another thing that I tried was enabling the microphone as record.  I 
fired up MythTV and then spoke into the mic.  What came out of the left 
channel was my voice, but then the right channel (again) started to 
degrade.  However, what I noticed was that my voice was echoed into that 
channel as well as the static, like a feedback loop.

--Dave
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