[MPlayer-users] Problem with sound volume in mplayer + alsa usb-audio

[Piotr Krukowiecki]

On Mon, Oct 29, 2007 at 06:00:19PM +0300, Vladimir Mosgalin wrote:
> Hi Piotr Krukowiecki!
> 
>  On 2007.10.28 at 22:21:59 +0100, Piotr Krukowiecki wrote next:
> 
> > hardware volume control is a bit inconvenient. Video playback halts for half
> 
> This shouldn't happen, maybe it's alsa problem.

I'll write to them later this week if nothing new happens.


> Well it's not like softvol is bad, or reduces quality. Keeping hardware

ok
[...]

> > I'm using mplayer 1.0rc2 with alsa 1.0.15. My sound card is a built-in cm6501
> > chipset handled by snd_usb_audio driver.
> 
> Sorry, I don't quite get this. You say that your card is built-in, but
> uses usb audio driver?

Yes, it's one of the small wonders of this world :)


> Can you show
> cat /proc/asound/cards
> and
> /sbin/lsmod |grep snd
> results?

piotr at piotr:~$ cat /proc/asound/cards
 0 [default        ]: USB-Audio - PnP Audio Device        
                      PnP Audio Device         at usb-0000:00:02.0-7, full speed
piotr at piotr:~$ lsmod | grep snd
snd_usb_audio          77472  0 
snd_pcm                71812  1 snd_usb_audio
snd_timer              21124  1 snd_pcm
snd_page_alloc         10184  1 snd_pcm
snd_usb_lib            15872  1 snd_usb_audio
snd_rawmidi            23008  1 snd_usb_lib
snd_seq_device          8140  1 snd_rawmidi
snd_hwdep               9028  1 snd_usb_audio
snd                    50084  7 snd_usb_audio,snd_pcm,snd_timer,snd_usb_lib,snd_rawmidi,snd_seq_device,snd_hwdep
soundcore               7648  1 snd
usbcore               130696  6 snd_usb_audio,snd_usb_lib,usbhid,ehci_hcd,ohci_hcd


> You sure you are not using any so-called "usb speakers" or "usb
> headphones", which actually don't utilize your internal sound card?

Not sure what are usb speakers/headphones (I suppose they are connected 
to usb and sound is rerouted to them somehow), but I'm using normal old-school 
headphones (and want to switch to cordless headphones btw ;))
 
 
> > I can hear voices even if I set volume level to 0% in alsamixer, so maybe this 
> > is alsa's fault.
> 
> Depends on what do you mean. When you use stereo output, tweaking Master
> and/or PCM level in mixer should change volume and mute sound completely
> when set to 0%. In some situations, tweaking PCM level won't change
> volume, because it's about something else than hardware output plug
> that you use (for example, card can have two analog outputs, line out
> and amplified out, and PCM / PCM2 mixers that correspond to each of
> them).

I'm completly new to all this alsa/pcm/mixers etc so I don't really understand
what you are asking about. What I meant was that I was starting 'alsamixer' and 
changing all settings ("CD", "Mic", speakers) to 0. After that for Speaker,1 
(the one that controls front panel audio connector) I have:

piotr at piotr:~$ amixer get Speaker,1
Simple mixer control 'Speaker',1
  Capabilities: pvolume pswitch pswitch-joined
  Playback channels: Front Left - Front Right - Rear Left - Rear Right - Front Center - Woofer - Side Left - Side Right
  Limits: Playback 0 - 197
  Mono:
  Front Left: Playback 0 [0%] [-36.93dB] [on]
  Front Right: Playback 0 [0%] [-36.93dB] [on]
  Rear Left: Playback 0 [0%] [-36.93dB] [on]
  Rear Right: Playback 0 [0%] [-36.93dB] [on]
  Front Center: Playback 0 [0%] [-36.93dB] [on]
  Woofer: Playback 0 [0%] [-36.93dB] [on]
  Side Left: Playback 196 [99%] [-1.65dB] [on]
  Side Right: Playback 196 [99%] [-1.65dB] [on]

What I now notice and what is interesting:

1. There is only 1 microphone and 1 headphone port in front chasis panel, 
but there are more "possibilities" for Speaker,1

2. Side Left and Side Right are not 0%, I though that maybe they are the
reason why I still can heard sound, but I can set them all to 0 with
'amixer Speaker,1 0' and nothing changes, so it not their fault.


> Also note that a lot of USB devices don't support mixer anyway. However,
> if your volume level actually changes when you change mixer settings,
> but you still hear sound at 0%, it means that something is wrong.

It does change.
 

> Also all of this doesn't apply to 5.1/6.1/7.1 multichannel playback, in
> which case you can get some really strange results, like the mixer you
> are used to not working at all or changing only a few channels, while
> leaving the rest of them the same.

Don't know what to say...


-- 
Piotrek
irc: #debian.pl
Mors Drosophilis melanogastribus!