Playback meters active but no sound; OpenSuSE 11.

[XEyedBear]

I have used Audacity for a couple of years under Windows. I am very new to Linux, where I have finally fiddled enough at random to make my installation playback pre-corded Audio CDs and, now, to capture sound at good quality via Audacity. The recording process seems to work exactly as it does under Windows, (with the interesting exception that the waveform graphic is displayed in a much 'jerkier' fashion on this 2.8 GHz CPU than it does with my 2.2 GHz cpu under windows).

The problem I have is that playback produces no sound at my speakers, even though the playback meters are operating as I would expect. Audacity preferences are set appropriately, I think.

My system plays sound events OK.

I can playback an MP3 file produced by Audacity under windows but sound is produced at my speakers only when using the Totem movie player The follwing applications fail to produce any sound:

- Real Player 10 - it crashes almost immediately. Intriguingly, when I right click an MP3 file and choose 'open with' I am given the option of Real Player 10 twice - why is that?

- Banshee: the application does nothing other than presenting a blank window with a title bar

- Audacity - playback meters function, but no sound.

I also notice that when using Totem the sound is severely disrupted , even without any other inter-action with the computer, such as mouse movement. System monitor tells me that the CPU is running at about 96% dedicated to Totem. My less powerful windows computer doesn't take anything like this amount of CPU power to play back an MP3


So, what obscure (to me) system settings have I got wrong in my random fiddling attempts to understand and capture sound under Linux?

[steve]

Make sure that you have ALSA installed - this is usually a lot more efficient than the older OSS sound system.

As in Windows you have the Windows Mixer, in Linux there is the ALSA mixer that allows you to set up all of the inputs and outputs of your sound card.

Unfortunately, most sound card manufacturers do not bother writing drivers for Linux, so the mixer interfaces can often be a bit confusing, though ALSA will support most sound cards very well.

The terminal (console) interface for the ALSA mixer works well (and is graphical, although it runs in a terminal window), and there are various GUI front ends available. I have a SoundBlaster Live card which works well with QAMix (a front end for ALSA mixer).

If you plan to do a lot of audio woek, it may be worth considering a Linux distro that is optimised for audio work such as Ubuntu Studio.

You will find a lot of general information here: http://www.google.com/search?ie=UTF-8&o ... udio+linux

[XEyedBear]

Thanks for the advice. I think I'm going to try your patience - and that of forum browsers by asking a lot of dumb quesiotns here.

1. "Make sure you have ALSA installed". In Open SuSE 11 (OS11) i have used YaST to check what is installed, searching with a filter of ALSA. It does indeed find ALSA as the first of many ALSA-related items. Is this a sufficient proof that ALSA is installed?

I have installed Qamix via YaST. It seems like a 'content-free' application. 3 tabs are presented to me. Clicking any of these presents absolutely no information whatsoever. The only menu option that provides any useful information is File>Open, which tries to open some sort of QAMix GUI description file - but none of those listed appear to apply in any way to an SB card. Mostly they are for the entry level CMI8738 card.

So what exactly does QAMix do? I can find no useful function in it at all.

2. Running the command line 'alsamixer' in a terminal window presents me with a DOS-like screen from the early 80s, showing a single mixer bar, labeled 'Master'; There are no independent controls for the usual things I see in Windows (like Line-Out, Aux-Out, etc) And this single bar appears to apply only to Playback - no control of inputs. So it's not really a mixer at all is it? More like the simple, single volume control under Windows. But VERY crude.

3. This mixer window also shows something called 'PulseAudio' against hardware items 'Chip' and 'Card'. These 2 hardware descriptions don't mean anything to me: I never see this sort of detail under windows against my SB Audigy card. What is 'PulseAudio? I thought I was using ALSA. So does this mean ALSA is not actually installed?

4. If I examine the card hardware details with YaST the Sound Configuration window that is displayed shows 2 line items. But I have only 1 card ( as well as on-board AC'87 sound, which is disabled in BIOS). The first line item has an 'index' (=?) of zero and a Card Model of SB Audigy LS. The is a card model that is unknown to me as well as to Creative Labs. It seems to be one that ALSA has created for itself. In fact I have a Creative SB Live! 24 card. Why can't ALSA correctly identify this very widely used card? Further information in this configuration window says the card has been configured as sound card number 0 with driver snd-ca0106. I do not know what this is. Where is ALSA in this?

The second line item in the configuration is described as a 'not configured Sound Blaster Audigy LS'. Where does the system find this second card with the non-existent model name? I have looked all round the computer and I'm sure there is only 1 sound card installed. All the remaining adapter card slots are empty.


So, how do I go about ensuring that my SB Live! 24 card is correctly recognised, correctly configured, has the correct drivers and has full support for both recording and playback? - Things that I expect to work out of the box on main-stream hardware like this. After that I can start to ask why I can't get any playback from Audacity, and why the systems seems to be suing 100% CPU to do recording (which it doesn't do under Windows)

Any further advice will be most welcome. I've been reading widely about sound under Linux and have learned really only 1 thing: I don't understand any of the information I have read and it is time for me to stop fooling myself that I do.

[kozikowski]

I have to ask. First names "Gladly T.?"

Koz

[XEyedBear]

I have to ask. First names "Gladly T.?"

Koz

No, Matthew Hope! (Sadly missed along with his close friends Ed and Evan)

[steve]

Running the command line 'alsamixer' in a terminal window presents me with a DOS-like screen from the early 80s, showing a single mixer bar, labeled 'Master'; There are no independent controls for the usual things I see in Windows (like Line-Out, Aux-Out, etc) And this single bar appears to apply only to Playback - no control of inputs. So it's not really a mixer at all is it? More like the simple, single volume control under Windows. But VERY crude.

There should be more sliders than this (so then it would be a mixer), so it seems that there is some problem with the sound card driver.

AlsaMixer is a command line program - so yes it looks like a DOS application.

QAMix is a graphical front end for AlsaMixer. It uses an XML file to configure the user interface to suit several different soundcards. If everything was working correctly you would probably have loads of sliders in AlsaMixer, including sliders for inputs and outputs that are supported by the sound chip, even if they are not implemented on your physical sound card.
Additional profiles are available for various sound cards and usually provide a "simple", and an "advanced" GUI that just show the features that are relevant for your hardware. Because AlsaMixer is not showing sliders (except for the master), QAMix is not showing them either (it is just a graphical front end for AlsaMixer).

So, how do I go about ensuring that my SB Live! 24 card is correctly recognised, correctly configured, has the correct drivers and has full support for both recording and playback? - Things that I expect to work out of the box on main-stream hardware like this

You've been a bit unlucky, usually it does work "out-of-the-box", but until hardware manufacturers start including Linux support with their hardware we are going to get these sort of problems from time to time.

The sound system in Linux is quite complex (as I'm sure it also is for Windows). In Windows you generally only see the front end of it (the Windows Mixer) if it is working, or nothing (except for a yellow question mark in the device manager) if it is not working. In Linux you can see every part of the system, which makes it very versatile and open for developers, but unless it works "out-of-the-box" it can be rather confusing. We need to investigate why AlsaMixer is not showing your sound card correctly.

The sound support soundcore module needs to be enabled in the kernel - this should happen by default, but we can check to see if it is by opening a Terminal window and typing:

Code: Select all

modinfo soundcore

This should return some information about the "Core Sound Module". On my system it shows this:

Code: Select all

~$ modinfo soundcore
filename:       /lib/modules/2.6.24-19-generic/kernel/sound/soundcore.ko
alias:          char-major-14-*
license:        GPL
author:         Alan Cox
description:    Core sound module
srcversion:     548AA54AF08207316C104F8
depends:        
vermagic:       2.6.24-19-generic SMP mod_unload 586 

In fact I have a Creative SB Live! 24 card. Why can't ALSA correctly identify this very widely used card?

Is this an external USB sound card?

[XEyedBear]

Thanks for the lengthy reply - I find these most helpful, rather than the very abbreviated technical responses, which assume I understand much more than in reality I do.

Firstly, I suspect that the problem with the command line ALSAMIXER not showing any mixer bars )other than Master) is that I provided no parameters with the command. This, in turn, is because I cannot understand the command syntax, even after reading the man page. (Just to dispel any suspicion that I am terminally stupid, I should add that I have been fiddling around in the world of computing since 1959 and did play some part on the creation of the PC part of the industry.)

For example, I cannot understand the format and content of the 'mixer device' parameter which qualifies the '-D' option of the Alsamixer command. The word 'device' appears only one more time in the man pages, under the 'general control' heading. The implication is that this data should be the alphanumeric name of a mixer 'histogram' that would be displayed by Alsamixer. Is this correct?

However, I have tried a few hundred different combination of keyboard characters (like Line, Mic, Line In, Aux, IEC958) variously separated from the '-D' option by nothing, space(s), single quotes, double quotes, the '<' and '>' characters shown in the prototype command, in upper case and lower case, with and without embedded blanks - and so on. After a couple of hours of trying I draw 2 conclusions:

1. The man pages don't give me sufficient help.
2. It seems that these commands are designed to separate those who cannot guess the correct content for the command, from those who can. Presumably this is some sort of test of suitability for the user to use Linux?

Be that as it may, I still do not understand why the Alsamixer shows my 'Card' and 'chip' as PulseAudio. I don't think I want to use PulseAudio, do I?

The card is a very common, widely used,consumer-quality, standard PCI interface card from Creative Labs. It is a Sound Blaster Live! 24 bit 7.1 card. Having been released in the 90's, it predates the Audigy range from Creative Labs. - that's how I know it is not an Audigy. I also knw that Creative Labs never released a product with the name 'Audigy LS'. I think this card must exist only in the minds of the ALSA development team. But surely, I am not the first person to have tried to use ALSA with this card. I'm years behind the rest of the world in this. Surely ALSA must be able, somehow, to correctly identity and support this card?

The output from the modinfo command is very revealing:

[email protected]:~> modinfo soundcore
bash: modinfo: command not found

From this I conclude that the little I thought I knew is even less than I think!

[XEyedBear]

Further info:

It sounded to me that the command 'modinfo' couldn't possibly NOT exist, so in a flash of inspiration I tried the command with root privileges. Now I get some useful output:

filename: /lib/modules/2.6.25.5-1.1-pae/kernel/sound/soundcore.ko
alias: char-major-14-*
license: GPL
author: Alan Cox
description: Core sound module
srcversion: 548AA54AF08207316C104F8
depends:
supported: yes
vermagic: 2.6.25.5-1.1-pae SMP mod_unload 586


I assume this proves that the correct ALSA sound modules are correctly loaded?

I have also tried the command 'alsamixer -c 0' (a typo for another attempt to get the -D option to work), and found, miraculously,, a totally different picture. This tells me that the command is vulnerable in the extreme to the parameters - suerly is should default to '-c 0' if NO parameters are supplied?

I also notice that the 'Card' label is now described as 'CA0106' and there is no information for 'chip'. What happened to PulseAudio?

Now I see a number of histograms, depending on whether I display 'Playback', 'Capture' or 'ALL. But I'm not at all sure what to do with the info I have no idea what IEC958 is, aside from a Wikipedia article which suggests it is to do with SPDIF I/O - and I'm not using this. I've muted these 'devices' and set the playback volumes to something significant.

When I try Audacity with these changed settings I see a tremendous difference in the way Audacity now performs: previously I could record but not hear any playback, even though the playback meters were operating. Now, I cannot record, so there is obviously no response from the playback meters.

1 step forward. One giant leap backwards.

Surprisingly, I am able to play Audio CDs. An application called Sound Juicer starts when I mount an audio CD, but I cannot find this application with YaST.

None of the YaST hardware tests are successful.

This is confusing in the extreme.

[steve]

For example, I cannot understand the format and content of the 'mixer device' parameter which qualifies the '-D' option of the Alsamixer command.

the -D option is for selecting the audio device by its identification ame, for example:

Code: Select all

alsamixer -D hw:0

Where hw:0 is the first audio hardware device. This option does not select specific inputs, but selects the complete device (sound card).
The -c option does the same thing, but by device number (starting at 0).

I also notice that the 'Card' label is now described as 'CA0106' and there is no information for 'chip'. What happened to PulseAudio?

PulseAudio is not the sound chip, it is a software layer that lies between the audio application (Audacity) and the audio hardware. Audacity uses PulseAudio because it provides a cross platform method of accessing the audio hardware.

Creative Labs have a peculiar way of naming their sound cards. Just because two Creative sound cards have the same "series" name does not mean that they use the same chip, in fact there is little relationship between the hardware and the name, and the names sometimes change from one country to another.

The "Sound Blaster Live 24bit", "Audigy LS" and the "Sound Blaster Live 7.1" are all CA0106 sound cards in various guises.

Can you post screenshots to show AlsaMixer when you use the command

Code: Select all

alsamixer -c 0

[XEyedBear]

Sorry, it took me a while to figure out how to do this. Hopefully 3 screen shots should follow:

Playback screenshot:

Playback mixer settings

Playback.png (29.79 KiB) Viewed 6576 times

Capture Screen shot:

Capture mixer settings

Capture.png (29.87 KiB) Viewed 6581 times

All Screenshot:

ALL mixer settings

All.png (34.29 KiB) Viewed 6579 times