Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: What is the difference between PCM and Front in kmix?

  1. #1
    Join Date
    Jun 2008
    Location
    Kln, Deutschland
    Posts
    1,054

    Arrow What is the difference between PCM and Front in kmix?

    I have no idea what PCM is, can someone please explain?

    I have 2 sliders in kmix, one PCM, the other is called "Front".

    I mapped my laptop volume controls to the "Front" one, and it seems to work (although NO on screen feedback!), but was wondering if I should map them to "PCM" instead.

    Thanks

  2. #2
    Uwe Buckesfeld NNTP User

    Default Re: What is the difference between PCM and Front in kmix?

    * wehrmacht,

    different channels: PCM (pulse code modulation) cares about the internal signal, means you are changing the volume "before" it leaves the soundcard. "Front" and others are the output channels.
    I wonder why your output is named "Front": That's normally the output jack where you put in your head set. Do you see "Master"?
    Anyway, it doesn't really matter which one you use, as long as you don't record things.

    Uwe

  3. #3
    Join Date
    Jun 2008
    Location
    Bowling Green, KY
    Posts
    157

    Default Re: What is the difference between PCM and Front in kmix?

    I have a Dell Inspiron 1501 with only a Front and PCM option in KMix, on first boot PCM was what was set as the main channel. All that I did was right click the KMix icon in the system tray, click select master channel, and set it to front.

    After doing that, I set the volume keys to the corresponding shortcuts, and everything worked great. Of course, it seems to forget these shortcuts on reboot...

    Anyway, I've always preffered front as the master channel. I usually don't keep PCM at full volume though, as I find the sound quality can be better that way.
    lysdestic@suseforums:~>make install --not-war

  4. #4
    Join Date
    Mar 2008
    Location
    Phuket, Thailand
    Posts
    26,595
    Blog Entries
    38

    Default Re: What is the difference between PCM and Front in kmix?

    Quote Originally Posted by Lysdestic View Post
    I have a Dell Inspiron 1501 with only a Front and PCM option in KMix, on first boot PCM was what was set as the main channel.
    Lysdestic those are rather limited options, ... it has my curiousity perked. ... Would you mind running the following from an xterm/terminal/konsole (as a regular user) with your PC on the internet (copy and paste it into the xterm/terminal/konsole). It will automatically download and run an audio diagnostic script, creating a URL with a summary of your PC's audio configuration. And then paste that URL here?
    Code:
    wget -O alsa-info.sh http://www.alsa-project.org/alsa-info.sh && bash alsa-info.sh

  5. #5
    Join Date
    Jun 2008
    Location
    Bowling Green, KY
    Posts
    157

    Default Re: What is the difference between PCM and Front in kmix?

    I would hate to feel as if I am hijacking a thread, but as it is on topic I will happily post the URL for you.

    Here it is.
    lysdestic@suseforums:~>make install --not-war

  6. #6
    Join Date
    Mar 2008
    Location
    Phuket, Thailand
    Posts
    26,595
    Blog Entries
    38

    Default Re: What is the difference between PCM and Front in kmix?

    Quote Originally Posted by Lysdestic View Post
    I would hate to feel as if I am hijacking a thread, but as it is on topic I will happily post the URL for you.Here it is.
    Thanks, ... I'm surprised you don't have more options in your kmix. Looking at the script I do see it limited to:
    # Simple mixer control 'Master',0
    # Simple mixer control 'PCM',0
    # Simple mixer control 'Capture',0
    # Simple mixer control 'Capture Mux',0
    # Simple mixer control 'Digital',0
    # Simple mixer control 'Input Source',0

    ... and I note the laptop has an HDA ATI SB and your audio hardware codec is recognized as a "Conexant ID 2bfa" but the "2bfa" is not decoded. It makes me think alsa driver support is still lacking a bit for this laptop.

  7. #7
    Join Date
    Jun 2008
    Location
    Bowling Green, KY
    Posts
    157

    Default Re: What is the difference between PCM and Front in kmix?

    Yeah, I knew of the other channels, it just appeared as if they were all capture type channels.

    As nice as it would be to have full use of the card, it isn't that important. It makes noise, and laptop sounds are never amazing anyway. Who knows, maybe a future alsa updare will remedy the situation.
    lysdestic@suseforums:~>make install --not-war

  8. #8
    Join Date
    Jun 2008
    Location
    Kln, Deutschland
    Posts
    1,054

    Default Re: What is the difference between PCM and Front in kmix?

    Ooops!

    I ran your script out of curiosity and it uploaded stuff to pastebin!

    Sorry if I messed anything up oldcpu :S.

    Thanks for the clarification.

    I also lose my key assignments on reboot! Not a very good situation with laptop keys in this release .

    I think I'm going to hit bugzilla because it seems silly to not have something we had in previous releases.

    Oh yes, here is the pastebin URL if it is of interest to anyone: general pastebin - kev - post number 1056255

  9. #9
    Join Date
    Jun 2008
    Location
    Bowling Green, KY
    Posts
    157

    Default Re: What is the difference between PCM and Front in kmix?

    I found from another thread that if you use keytouch you will have better luck. It works better, and keeps the settings after reboot. Solves my issues with the reboot.
    lysdestic@suseforums:~>make install --not-war

  10. #10
    Join Date
    Mar 2008
    Location
    Phuket, Thailand
    Posts
    26,595
    Blog Entries
    38

    Default Re: What is the difference between PCM and Front in kmix?

    Quote Originally Posted by wehrmacht View Post
    Oh yes, here is the pastebin URL if it is of interest to anyone: general pastebin - kev - post number 1056255
    Thanks, I was looking at that. It notes you have an option in your /etc/modprobe.d/sound file of: model=laptop and that you have a CX20549. The 20549 used to be called the 5045 and 5047. When I look at the model options for the 5045 I see this (which does not have a "laptop" option):
    Code:
    948		Conexant 5045
    949		  laptop-hpsense    Laptop with HP sense (old model laptop)
    950		  laptop-micsense   Laptop with Mic sense (old model fujitsu)
    951		  laptop-hpmicsense Laptop with HP and Mic senses
    952		  benq		Benq R55E
    953		  test		for testing/debugging purpose, almost all controls
    954				can be adjusted.  Appearing only when compiled with
    955				$CONFIG_SND_DEBUG=y
    but the 5047 has these options (which include model=laptop):
    Code:
    957		Conexant 5047
    958		  laptop	Basic Laptop config 
    959		  laptop-hp	Laptop config for some HP models (subdevice 30A5)
    960		  laptop-eapd	Laptop config with EAPD support
    961		  test		for testing/debugging purpose, almost all controls
    962				can be adjusted.  Appearing only when compiled with
    963				$CONFIG_SND_DEBUG=y
    Linux Kernel Documentation :: sound : alsa : ALSA-Configuration.txt

    If you are curious, you could in your /etc/modprobe.d/sound file, try changing "laptop" to "laptop-hpsense" and restart your alsa (from an xterm/konsole with root permissions) via "rcalsasound restart" and then check out your mixer. If that doesn't improve your options, then instead try "laptop-micsense" (with same "rcalsasound restart" .... ) and also laptop-hpmicsense, laptop-hp, laptop-eapd.

    And of course, you can simply leave it (or put it back to) model=laptop

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •