When I watch live LV with XawTV (unmuting the Line-in output) sound is good. But when I run mythtv I hear a high-pitched whine along with the audio. (although audio is in sync)

I have muted all unused outputs, as well as adjusted the volumes of inputs and outputs. Nothing helps. If I select /dev/adsp instead of /dev/dsp the sound is a little louder, but so is the noise.

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

I've been fighting with this all day with no luck.

The sound itself is good. I can unmute the Line-in and watch XawTV great. When I watch TV in PVR mode, I get the noise. The distortion is not from the cable, and not from the capture card. The noise somehow is getting recorded bad, I think. Even though that same line sounds fine straight though.

I've tried all the sample rates in myth-setup (32000, 44100, 48000) but got absolutely no difference in the audio quality.


Can someone at least point me in the right direction?

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

I hate to tell you, but some sound hardware just does not like operating in full duplex. I had a sound card long time ago when I first started with myth that just wouldn't work had the same kind of problems you are describing. I replaced it with a sblive and everything was great. the sb has since been replaced with onboard sound from newer motherboards, but there are some sound chipsets that just won't work.

_________________
Have a question search the forum and have a look at the KnoppMythWiki.

Xsecrets

Thanks again for your help.

I happened to have an old SBlive gold laying around. I disabled the onboard audio and reinstalled Knoppmyth from scratch again. My SBlive detected just fine and XawTV plays TV and sound well.

But no matter what I do, I cannot get it to work in PVR mode. I mute the line in, select it for capture and crank up the capture volume.

No sound at all now.


EDIT: Mythtv-setup allows for different sound devices for capture. How do I find out which device I need to select? /dev/dsp dev/dsp0, dev/dsp1, dev/dsp2, dev/adsp0, etc. Whats the difference?
Is /dev/dsp the same thing as /dev/dsp0? What am I missing here?

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

Yet another clean install of KnoppMyth R5A16.

This time with better luck. The CPU gods have finally smiled upon me.

This is what I did differently:
Disabled ACPI and all power management in BIOS before KnoppMyth install
Enabled Via onboard Audio along with my SB live


Now I can use one card for record and one for play. Neither card will work on its own full-duplex. But I can use either card for record or play, as long as its not the same card doing both.

Not sure why. Still not sure what the difference is between /dev/dsp and /dev/dsp0, or /dev/adsp for that matter. But right now I have /dev/dsp0 for in and /dev/dsp1 for out. Anyone help with that?

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

Arrrrgh! now it doesn't work anymore.

I can get it to record through the CMI, and playback through the SBlive, but I get that whine again. It won't work the other way around at all.

Something is fishy here. Sometimes running alsaconf makes a difference. Usually I try to adjust the volume through PuTTY on another computer while mythTV is runnning.

I think MythTV is using OSS (because I see no ALSA settings in the myth setup). So am I screwing things up with the ALSA mixer? The nebulous myth documentation doesn't help very much.

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

mythtv on knoppmyth is compiled with alsa support, if you want to make sure you are using alsa you can try ALSA:default in place of /dev/dsp. you'll have to type it in.

_________________
Have a question search the forum and have a look at the KnoppMythWiki.

Xsecrets

Thanks for being patient with me Xsecrets.

ALSA:default works but only for my first "card", the onboard via sound. (which gives me that high-pitched whine again) My SBLive is my other card (HW1, I think) I've been trying to figure out how it all is supposed to work from these pages:

http://alsa.opensrc.org/index.php?page=DmixPlugin
http://www.alsa-project.org/alsa-doc/do ... le=Generic
http://alsa.opensrc.org/index.php?page=.asoundrc

But they all assume I'm a linux whiz, which I'm not. I'm not a stranger to unix. I'v programmed in C, in college on unix, I use Mysql and write PHP on linux. But I've never used linux for multimedia, only as a server.

I keep seeing commands like

But they don't make sense.... am I supposed to add this code to the end of the file using VI? Am I supposed to replace it?

I've tried all sorts of combinations to no avail. When I try the command:
I get
I can get a file to play ok by typing


At this point I feel like I'm banging rocks together. What do I do now?

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

well never tried to use two cards, but I can explain that first block of code to you



the first line is the important one. cat is a command it works like type if you familiar with that command in windows. basically it prints the contents of a file to the screen. (among many other things) the second part of the screen is what file it is going to display. In this case the ~ means home for instance on knoppmyth if you are logged in as mythtv ~ = /home/mythtv so if you ran that command it would print the contents of /home/mythtv/.asoundrc the . in front of asoundrc means it's hidden. what comes below it would just be the contents of the file, so the person is just telling you here is what my asoundrc looks like.

_________________
Have a question search the forum and have a look at the KnoppMythWiki.

Xsecrets

Thanks again.

I''m going to install knoppmyth again because I've made so many changes trying to get sound to work. I've made it as far as getting my cheap-o Kworld card working great and I've learned a helluva lot of linux in the past few days.

Tell me if this is a good idea or not:

I use PuTTY on my windows box to login as root and use alsamixer to change the volumes while watching mythTV on the linux box. This is a lot faster than doing it all on the linux box since I never have to stop the tv. But, if myth uses OSS by default, does using the alsamixer mess anything up? What mixer should I use with oss?

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

the only mixer I've ever used even with /dev/dsp is alsamixer. Once you get the controls set there really should be no need to go messing with them much, and honestly the settings should be dead simple. plug the kworld to line in and make sure line in is muted and set as capture device. (these should be the default settings by the way) then make sure main and pcm are turned up a bit are all you should have to do. plus if you simply use /dev/dsp instead of ALSA:whatever then you can use the internal myth controls to control the volume. which could be another thing to check that they are not turned all the way down, because they will override what you set in alsamixer.

_________________
Have a question search the forum and have a look at the KnoppMythWiki.

Xsecrets

I've figured out that --although alsa-config allows you to configure only one card at a time-- it will effect your ability to use both cards at once. Using alsa-config to config my SBLive would set it to HW0, and disable the onboard audio previously set to that address. Several module-updates and reboots later, I've managed to figure out how to get them to input and output sound independantaly (full-duplex) and with eachother (via 82xx in, SBLive out).


Each of these configurations produces the same result: static and distortion in the output of PVR video. XawTV receives clear TV channels and excellent audio (straighthru) I can also rip CDs and play the ogg files with excellent fidelity. Either soundcard, same results.

The inputs seem okay, the outputs seem okay. The playback seems okay... There seems to be something wrong with the way myth is encoding the audio signal. Tested different sample rates (in mythtv-setup) with same results.

Running out of ideas. I don't know what else to do from here.

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

I had similiar problems getting sound to work with my onboard SIS soundcard. I put in a CM chipset pci sound card and had poor results again (Tinny sound on video/live tv) I found many posts on google stating that my onboad sis and the pci CM chipset cards did not work right with linux using the line in like we are.

I tried a 3rd sound card, an ancient Ensoniq pci soundcard from a pile of old hardware I have as extras and got the sound to work very wll with the exact Kworld card you have.

My suggestion, try one more sound pci sound card that is not a CM chipset. Your SB live card should of worked, but you never know.

_________________
SIS K7S5A mb R4V5
Amd 2000 + cpu Atheros chipset wireless NIC
GF4 ti4200 Video onboard ALSA sound card
768 meg sdram partial install on Nuv2disc
120 g maxtor HD
PVR 250 Video Capture card

Thank's for the tip, sanger440!

• Replaced SBLive with "Ensoniq AudioPCI" (SigmaTtel STAC 9708/11)
• Disabled onboard sound thru BIOS.
• Ran alsaconf
• rebooted
• reconfiged myth for a single audio device
  
• Ran mythtv...

This ensoniq card card runs audio in full-duplex 100% better than the other cards ever could in half-duplex. It works! My SBLive Gold (expensive, for the time, with lots of extra ins and outs) is outshined by $20 card thats nearly as old.

Thank you both for all the help in this.

The audio sounds just a little "tinny" but prolly has something to do with either the bit-depth or the compression algorithm. Anyone know how I can change either?

_________________
AthlonXP 2000+
Via KM400 (PC Chips M851G)
512MB pc3200 DDR
Nvidia Ti4400 w/s-video out
Kworld VS-TV878RF
Ensoniq AudioPCI [Working in full-duplex)
KnoppMyth R5A16

-Via onboard sound (CMI9761) [distorted]
-SB Live! Gold [distorted]

I believe you said you are using a v4l card (too lazy to look back and see) if so then both the compression algoritm and the bitrate can be set in mythtv-setup under the card configuration.

thinking more about it those settings may be under recording profiles, and I can't look right now, but they are in one of those two places.

_________________
Have a question search the forum and have a look at the KnoppMythWiki.

Xsecrets