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chrisp at tangent

Apr 30, 2005, 12:41 PM

Post #1 of 10 (4633 views)
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ALSA only

Hi all

I am using 0.18 compiled from gentoo's ebuild with USE flags "alsa -oss"
(among others)

I do not have OSS in my kernel at all. I do not have a /dev/dsp device

However, when I try recording, I get these errors in mythbackend.log:

2005-04-30 16:29:29.646 Changing from None to WatchingLiveTV
2005-04-30 16:29:29.764 Using profile 'Live TV' to record
2005-04-30 16:29:29.826 NVR: Error, cannot open DSP '/dev/dsp'
open: No such file or directory
2005-04-30 16:29:29.827 NVR: Could not detect audio blocksize
2005-04-30 16:29:29.844 NVR: Cannot open DSP '/dev/dsp', exiting
open: No such file or directory

How would I configure myth to use alsa for audio input as well as audio
output?
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markknecht at gmail

Apr 30, 2005, 4:22 PM

Post #2 of 10 (4493 views)
Permalink
Re: ALSA only [In reply to]

Chris,
Someone told me something about this a few weeks ago. This is from
memory. Try something like

ALSA:default

or

ALSA:hw0,0

assuming you want to go to your first sound card, etc.

Hope this helps. Don't expect too much as I haven't tried this myslef.

Cheers,
Mark

On 4/30/05, Chris Picton <chrisp [at] tangent> wrote:
> Hi all
>
> I am using 0.18 compiled from gentoo's ebuild with USE flags "alsa -oss"
> (among others)
>
> I do not have OSS in my kernel at all. I do not have a /dev/dsp device
>
> However, when I try recording, I get these errors in mythbackend.log:
>
> 2005-04-30 16:29:29.646 Changing from None to WatchingLiveTV
> 2005-04-30 16:29:29.764 Using profile 'Live TV' to record
> 2005-04-30 16:29:29.826 NVR: Error, cannot open DSP '/dev/dsp'
> open: No such file or directory
> 2005-04-30 16:29:29.827 NVR: Could not detect audio blocksize
> 2005-04-30 16:29:29.844 NVR: Cannot open DSP '/dev/dsp', exiting
> open: No such file or directory
>
> How would I configure myth to use alsa for audio input as well as audio
> output?
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
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knowledgejunkie at gmail

Apr 30, 2005, 11:06 PM

Post #3 of 10 (4495 views)
Permalink
Re: ALSA only [In reply to]

On 5/1/05, Mark Knecht <markknecht [at] gmail> wrote:
> Chris,
> Someone told me something about this a few weeks ago. This is from
> memory. Try something like
>
> ALSA:default

This uses the default ALSA device, which is hw:0,0, unless
specifically overridden in the .asoundrc file by another device.

>
> or
>
> ALSA:hw0,0

I think you need to change that to:

ALSA:hw:0,0

(note the colon between 'hw' and '0,0') This would normally direct
sound to the first device of the first sound card. You can also use:

aplay -l

in order to get a list of hardware playback devices recognised by ALSA, and use:

aplay -L

to get a complete list of all usable ALSA devices (hw, sw, aliases)
for your particular soundcard(s).

As I am still using MythTV 0.16, MythMusic still uses OSS, so I have
installed ALSA with OSS emulation. This is the only time that I use
/dev/dsp or /dev/adsp - everything else is ALSA based and directed out
via the SPDIF.

Nick
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chrisp at tangent

May 2, 2005, 12:26 AM

Post #4 of 10 (4482 views)
Permalink
Re: ALSA only [In reply to]

Nick wrote:

>On 5/1/05, Mark Knecht <markknecht [at] gmail> wrote:
>
>
>>Chris,
>> Someone told me something about this a few weeks ago. This is from
>>memory. Try something like
>>
>>ALSA:default
>>
>>
>ALSA:hw:0,0
>
>(note the colon between 'hw' and '0,0') This would normally direct
>sound to the first device of the first sound card. You can also use:
>
>aplay -l
>
>
Thanks. However I need to use this for recording, not playback. I
already have ALSA:default in my playback device, and can play previously
recorded shows fine. It is the recoring which is not working.

Under the capture card setup, I only have an option of '(None)' for the
audio device. If I change this, it always reverts to '(None)' when I go
back to the screen, and audio recording does not work.

Any ideas?

Chris
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chrisp at tangent

May 2, 2005, 11:26 AM

Post #5 of 10 (4456 views)
Permalink
Re: ALSA only [In reply to]

On Mon, 2005-05-02 at 16:30 +0100, Nick wrote:

> > >
> > Thanks. However I need to use this for recording, not playback. I
> > already have ALSA:default in my playback device, and can play previously
> > recorded shows fine. It is the recoring which is not working.
> >
> > Under the capture card setup, I only have an option of '(None)' for the
> > audio device. If I change this, it always reverts to '(None)' when I go
> > back to the screen, and audio recording does not work.
> >

> Sorry for misunderstanding - are you using a hardware capture card or
> a v4l framebuffer capture card (is this the NVR entry in your log)? As
> a non-gentoo user, do the compilation options mean that it is
> expecting OSS devices for recording (in which case the OSS compat ALSA
> modules may be useful)? I'll be setting up another machine with a
> couple of WinTV cards (for fun!) in the near future so I may come
> across this problem too if the btaudio drivers do not work with these
> cards.
>
> Nick

NP. It is using a bttv v4l device. btaudio does not work. My full
configure options are:
./configure --prefix=/usr --host=i686-pc-linux-gnu
--mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share
--sysconfdir=/etc --localstatedir=/var/lib --disable-mmx
--disable-altivec --disable-audio-oss --enable-audio-alsa
--disable-audio-arts --disable-audio-jack --enable-lirc
--disable-joystick-menu --disable-xvmc-vld --disable-directfb
--disable-dvb --disable-dvb-eit --dvb-path=/usr/include
--enable-opengl-vsync --enable-vorbis --enable-xvmc --enable-xv
--enable-x11

Note the --disable-audio-oss --enable-audio-alsa. So far it seems to me
that mythbackend will still use the OSS devices /dev/dsp
or /dev/sound/dsp for recording even with --disable-audio-oss.

Is this true?

--
Chris Picton <chrisp [at] tangent>


ijr at case

May 2, 2005, 11:29 AM

Post #6 of 10 (4454 views)
Permalink
Re: ALSA only [In reply to]

On Monday 02 May 2005 02:26 pm, Chris Picton wrote:
> Note the --disable-audio-oss --enable-audio-alsa. So far it seems to me
> that mythbackend will still use the OSS devices /dev/dsp
> or /dev/sound/dsp for recording even with --disable-audio-oss.
>
> Is this true?

Yes. Use ALSA's built in oss emulation.

Isaac
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chrisp at tangent

May 2, 2005, 11:41 AM

Post #7 of 10 (4470 views)
Permalink
Re: ALSA only [In reply to]

On Mon, 2005-05-02 at 14:29 -0400, Isaac Richards wrote:
> On Monday 02 May 2005 02:26 pm, Chris Picton wrote:
> > Note the --disable-audio-oss --enable-audio-alsa. So far it seems to me
> > that mythbackend will still use the OSS devices /dev/dsp
> > or /dev/sound/dsp for recording even with --disable-audio-oss.
> >
> > Is this true?
>
> Yes. Use ALSA's built in oss emulation.

Thanks

I had compiled my kernel without the oss emulation parts, and was trying
to get my machine to work 'pure alsa'.

Anyway, another recompile in the pipeline...

Chris

--
Chris Picton <chrisp [at] tangent>


knowledgejunkie at gmail

May 2, 2005, 1:07 PM

Post #8 of 10 (4451 views)
Permalink
Re: ALSA only [In reply to]

On 5/2/05, Chris Picton <chrisp [at] tangent> wrote:
> On Mon, 2005-05-02 at 14:29 -0400, Isaac Richards wrote:
> > On Monday 02 May 2005 02:26 pm, Chris Picton wrote:
> > > Note the --disable-audio-oss --enable-audio-alsa. So far it seems to me
> > > that mythbackend will still use the OSS devices /dev/dsp
> > > or /dev/sound/dsp for recording even with --disable-audio-oss.
> > >
> > > Is this true?
> >
> > Yes. Use ALSA's built in oss emulation.

Isaac,

Thanks for the information that OSS emulation is still needed in
certain circumstances - is it for all bttv cards that need to record
audio separately? I only ask as up until now my capture cards - DVB
and PVR-350 - either encode (350) or dump (DVB) audio with the video
and as I'm running 0.16, only mythmusic needs the OSS emulation from
ALSA (AIUI). (As I have a couple WinTV cards in my spares box, I was
going to setup a slave backend with these and maybe another DVB card.)

If I was to install/upgrade to 0.18 and have no bttv cards recording
in the machine, am I able to be completely OSS free? I recall reading
that mythmusic now supports ALSA.

Thanks

>
> Thanks
>
> I had compiled my kernel without the oss emulation parts, and was trying
> to get my machine to work 'pure alsa'.
>
> Anyway, another recompile in the pipeline...
>

Good luck

Nick
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ijr at case

May 2, 2005, 1:11 PM

Post #9 of 10 (4560 views)
Permalink
Re: ALSA only [In reply to]

On Monday 02 May 2005 04:07 pm, Nick wrote:
> Isaac,
>
> Thanks for the information that OSS emulation is still needed in
> certain circumstances - is it for all bttv cards that need to record
> audio separately? I only ask as up until now my capture cards - DVB
> and PVR-350 - either encode (350) or dump (DVB) audio with the video
> and as I'm running 0.16, only mythmusic needs the OSS emulation from
> ALSA (AIUI). (As I have a couple WinTV cards in my spares box, I was
> going to setup a slave backend with these and maybe another DVB card.)
>
> If I was to install/upgrade to 0.18 and have no bttv cards recording
> in the machine, am I able to be completely OSS free? I recall reading
> that mythmusic now supports ALSA.

What's the big deal about keeping alsa's oss emulation turned on? It doesn't
hurt _anything_.

Isaac
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knowledgejunkie at gmail

May 2, 2005, 1:46 PM

Post #10 of 10 (4452 views)
Permalink
Re: ALSA only [In reply to]

On 5/2/05, Isaac Richards <ijr [at] case> wrote:
> On Monday 02 May 2005 04:07 pm, Nick wrote:
> > Isaac,
> >
> > Thanks for the information that OSS emulation is still needed in
> > certain circumstances - is it for all bttv cards that need to record
> > audio separately? I only ask as up until now my capture cards - DVB
> > and PVR-350 - either encode (350) or dump (DVB) audio with the video
> > and as I'm running 0.16, only mythmusic needs the OSS emulation from
> > ALSA (AIUI). (As I have a couple WinTV cards in my spares box, I was
> > going to setup a slave backend with these and maybe another DVB card.)
> >
> > If I was to install/upgrade to 0.18 and have no bttv cards recording
> > in the machine, am I able to be completely OSS free? I recall reading
> > that mythmusic now supports ALSA.
>
> What's the big deal about keeping alsa's oss emulation turned on? It doesn't
> hurt _anything_.

No big deal. I'm just wondering whether it is needed in 0.17+.

For non-uber-linux-geeks like me it's another variable that can (and
has) cause issues when sorting out sound issues (like oss devices not
being created, configuring the oss emu options correctly), so I
figured it'd be one less thing to have to worry about in the future.

On a more general level learning Linux, I also try to understand what
the various modules are doing and what they are needed for. As my PVR
will not have changing hardware, my intention is to remove modules
that are loaded but not required, hence the question about the oss
emulation modules and musing about solely using ALSA.

Nick
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