[mythtv] Yipee, almost there but audio whine

[Bryce C]

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Update: I've tried a CMI8738 based card and I don't get the same whine I
did.  Now, I get an even higher pitched (worse) whistle when listening
to live tv.  I haven't tried recording yet but I'm not optimistic.

On Thu, 2003-01-02 at 20:41, Chris Liscio wrote:
> Well, I also have a poor quality sound chip (and not just in the
> full-duplex category), but I think that spending the time to get btaudio
> working might pay off.
>=20
> It all depends on your level of patience, I guess.  For me, I have a
> mixture of Alsa (emulating OSS for my snd-via82xx module) and OSS
> (running via btaudio natively).  When you run 'sox -t ossdsp /dev/dsp1
> test.wav' (where /dev/dsp1 is your btaudio device) you should see a
> message that says it's unable to set the sampling rate and it defaults
> to 32000.  That's when you know you're hitting the right device.
>=20
> So to go back to what you said, you don't have to kill alsa.  You just
> have to augment it with the new stuff.  It may be painful but possibly
> worth the learning experience in the end.
>=20
> Hope this helps.  I'm all about making the cheapest configuration work
> best... :)  Oh yeah, it doesn't help that there aren't very many good
> half-height PCI audio cards, either.  ;)
>=20
> Cheers,
> Chris
>=20
> -----Original Message-----
> From: mythtv-dev-admin@snowman.net [mailto:mythtv-dev-admin@snowman.net]
> On Behalf Of Bryce C
> Sent: Thursday, January 02, 2003 10:20 PM
> To: mythtv-dev@snowman.net
> Subject: RE: [mythtv] Yipee, almost there but audio whine
>=20
>=20
> When I WAS TRYING to use btaudio, it created /dev/sound/dsp[1-4] and
> /dev/sound/mixer[1-2] because I have two cards that have separate
> purposes (one only does composite) and and are accessed separately.=20
> dsp[3-4] are the only one's I'm concerned with but I tried a sox on
> dsp[1-2] too and here's what I found. The digital ones said nothing, no
> "Recording at a rate of 8000 of type WAVE" or whatever it was.  It just
> sat their.  Also, yes, ,I am using alsa because oss didn't seem to work
> before and it took a lot of work to get alsa installed so i'm not about
> to try again.  The arecord was used after I reverted to ALSA so yes, it
> was using ALSA's line-in. I think I've found the problem in a poor
> quality implementation of full-duplex capability on my sound chip so i'm
> going to try another one.
>=20
> On Thu, 2003-01-02 at 19:25, Chris Liscio wrote:
> > That is certainly strange.  For me, doing what you've done did not=20
> > yield good results at all.
> >=20
> > I know for one thing that I used sox to do the recording from the oss=20
> > device /dev/dsp1 manually rather than using arecord (to guarantee it=20
> > was using the right input device).  It *is* possible that when you're=20
> > doing arecord >test you are still using the Auxillary input on your=20
> > sound chip.  Someone feel free to correct my highly uninformed=20
> > hypothesis though...
> >=20
> > Also, you must make sure that you are setting mythTV to use the bttv=20
> > device for recording, and the alsa device for playback.
> >=20
> > That's about as much as I can offer right now.  YMMV.
> >=20
> > Cheers,
> > Chris
> >=20
> > -----Original Message-----
> > From: mythtv-dev-admin@snowman.net=20
> > [mailto:mythtv-dev-admin@snowman.net]
> > On Behalf Of Bryce C
> > Sent: Thursday, January 02, 2003 8:30 PM
> > To: mythtv-dev@snowman.net
> > Subject: RE: [mythtv] Yipee, almost there but audio whine
> >=20
> >=20
> > It still doesn't work.  On a considerably more interesting note, I did
>=20
> > an "arecord >test" and then "aplay test" and it was flawless.
> >=20
> > On Thu, 2003-01-02 at 18:10, Bryce C wrote:
> > > I had tried the btaudio driver initially but I could never get it to
> > > work but now that I know my setup DOES work basically, I think I'll=20
> > > try it again.  Just to verify, you're saying that you're using the=20
> > > digital dsp device at 32000 and it works for live and recording?
> > >=20
> > > On Thu, 2003-01-02 at 17:44, Chris Liscio wrote:
> > > > I actually just got my new mainboard which was equipped with a
> > > > VIA8233A SouthBridge and a Realtek ALC101 audio codec chip.
> > > >=20
> > > > When I first started MythTV with this chipset it was
> > > > horrible-sounding. I couldn't figure out what exactly was wrong.
> I=20
> > > > tried xawtv with the Aux line enabled and it sounded just fine.  I
>=20
> > > > am guessing it had to do with the fact that it was just analog in
> to
> >=20
> > > > analog out straight-through.
> > > >=20
> > > > So I used arecord and aplay to verify that recording internally to
> > > > the chipset produced horrid results (crackly, fuzzy audio that=20
> > > > sounded as if it was going through a ring modulation sound effect=20
> > > > processor...).
> > > >=20
> > > > No tweaking at all would change this behavior (other than keeping
> > > > the TV
> > > > *very* quiet) and I was stumped for all of 2 hours.  I remembered
> > that I
> > > > could just use the btaudio module for recording, and keep using my
>=20
> > > > (perfectly fine for PCM) ALC101 for playback.
> > > >=20
> > > > After mucking around and making sure all the OSS stuff worked
> > > > properly (now I have /dev/dsp0, dsp1, and dsp2) and was set up=20
> > > > properly in mythTV (in cvs, you'll have to go into the database
> and=20
> > > > change the input audio device...in older versions this just
> involves
> >=20
> > > > a text file edit).  I also stumbled on the fact that you could=20
> > > > only
> > > > record at a sampling rate of 32000 briefly.
> > > >=20
> > > > Starting mythTV up again (and with my fingers and toes crossed) I
> > > > was pleased to hear everything working correctly.  It now sounds
> as=20
> > > > fantastic as it ever did.
> > > >=20
> > > > Hope this solves your problem.  The ALC101 is a *very* cheap audio
> > > > device and they most likely use crappy ADCs and DACs and mixers=20
> > > > internally to do all the mixing and recording.
> > > >=20
> > > > On another note, the GrooveBox appears to be a go... :)
> > > >=20
> > > > Cheers,
> > > > Chris
> > > >=20
> > > > -----Original Message-----
> > > > From: mythtv-dev-admin@snowman.net
> > > > [mailto:mythtv-dev-admin@snowman.net]
> > > > On Behalf Of Tony Clark
> > > > Sent: Thursday, January 02, 2003 5:15 PM
> > > > To: mythtv-dev@snowman.net
> > > > Subject: Re: [mythtv] Yipee, almost there but audio whine
> > > >=20
> > > >=20
> > > > On Thursday 02 January 2003 22.58, Bryce C wrote:
> > > > > Just the high pitched whine and sometimes the voices are a bit=20
> > > > > "warblely".
> > > >=20
> > > > You may have the AC97 level turned up, I think I got some sort of
> > > > feedback with my SBlive card when I had the AC97 level up.  I
> guess=20
> > > > your using alsa?
> > > >=20
> > > > tony
--=20
Bryce C <Plug@BryceCo.Net>
CoBryce Communications

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