Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Frank Barknecht]

Hallo,

I have to apologize first for asking a probably totally ignorant
question, but I really have no clue of ALSA-programming :(

But I need/want to get Pd running on my Laptop with a Quattro USB for
the LAD conference next weekend, and this requires, that I somehow
debug what goes wrong in Pd with ALSA.

I keep getting the following error, when starting Pd in ALSA mode with
"hw:0,0" or any other ALSA device (like the ones Patrick set up in his
.asoundrc on alsa-project.org):

ALSA lib pcm_hw:454(snd_pcm_hw_start) SNDRV_PCM_IOCTL_START failed:
Broken pipe

Responsible for ALSA in Pd is the file s_linux.c, that can be seen
at our sourceforge-CVS: 

http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/pure-data/pd/src/s_linux.c?rev=1.1.1.2.2.7&only_with_tag=devel_0_36&content-type=text/vnd.viewcvs-markup

It obviously fails somewhere around:
    
    if (outchans)
    {
	err = snd_pcm_start(alsa_device.outhandle);
	check_error(err, "snd_pcm_start");
    }

Now, what makes this the real problem, is that the same code works on
another machine just fine, all with alsa-0.9rc7 and the same binary
and the same source.

Because of that I somehow doubt (but cannot judge it) that the reason
is a wrong handling of the asound API in Pd's s_linux.c, but something
else, something machine dependent. Also on both machines, ALSA in
general is working fine, I can play music with alsaplayer and all
that.

So now I'm quite clueless with this. Maybe someone here can shed a
light on the question: 
 What are typical reasons for snd_pcm_start failing this way?

Thank you in advance.

Regards,
-- 
 Frank Barknecht                               _ ______footils.org__


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Re: Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Takashi Iwai]

At Mon, 10 Mar 2003 23:33:22 +0100,
Frank Barknecht wrote:
> 
> Hallo,
> 
> I have to apologize first for asking a probably totally ignorant
> question, but I really have no clue of ALSA-programming :(
> 
> But I need/want to get Pd running on my Laptop with a Quattro USB for
> the LAD conference next weekend, and this requires, that I somehow
> debug what goes wrong in Pd with ALSA.
> 
> I keep getting the following error, when starting Pd in ALSA mode with
> "hw:0,0" or any other ALSA device (like the ones Patrick set up in his
> .asoundrc on alsa-project.org):
> 
> ALSA lib pcm_hw:454(snd_pcm_hw_start) SNDRV_PCM_IOCTL_START failed:
> Broken pipe

do you see any kernel message?
if the start fails in the pcm trigger callback, usb-audio driver
should show some error message there.


Takashi


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Re: Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Frank Barknecht]

Hallo,
Takashi Iwai hat gesagt: // Takashi Iwai wrote:

> At Mon, 10 Mar 2003 23:33:22 +0100,
> Frank Barknecht wrote:
> > ALSA lib pcm_hw:454(snd_pcm_hw_start) SNDRV_PCM_IOCTL_START failed:
> > Broken pipe
> 
> do you see any kernel message?
> if the start fails in the pcm trigger callback, usb-audio driver
> should show some error message there.

No, there only are the usual (de-)registering messages regarding
snd-usb-audio. The only difference between my notebook and the laptop
has been the kernel-version. Just 5 minutes ago I downgraded the
notebook's kernel to 2.4.18 and now the error message went away! I'm
currently still getting a lot of clicks, that probrably are caused by
some wrong period settings in my application, but in general it is
fine. For example "jackd -d alsa -d hw:0 -n 2" clicks, but "-n 3" is
smooth.

I was using the Debian kernel 2.4.20 and also the Debian package of
ALSA.  I remember now, that the Debian maintainers send a bunch of
USB-audio related patches. Maybe it's just Debian, that is broken??

Anyway, I can live with 2.4.18 for now, thank you for the help. Now on
to ALSA 1.0 ;)

ciao
-- 
 Frank Barknecht                               _ ______footils.org__


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Re: Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Takashi Iwai]

At Tue, 11 Mar 2003 11:32:09 +0100,
Frank Barknecht wrote:
> 
> Hallo,
> Takashi Iwai hat gesagt: // Takashi Iwai wrote:
> 
> > At Mon, 10 Mar 2003 23:33:22 +0100,
> > Frank Barknecht wrote:
> > > ALSA lib pcm_hw:454(snd_pcm_hw_start) SNDRV_PCM_IOCTL_START failed:
> > > Broken pipe
> > 
> > do you see any kernel message?
> > if the start fails in the pcm trigger callback, usb-audio driver
> > should show some error message there.
> 
> No, there only are the usual (de-)registering messages regarding
> snd-usb-audio. The only difference between my notebook and the laptop
> has been the kernel-version. Just 5 minutes ago I downgraded the
> notebook's kernel to 2.4.18 and now the error message went away! I'm
> currently still getting a lot of clicks, that probrably are caused by
> some wrong period settings in my application, but in general it is
> fine. For example "jackd -d alsa -d hw:0 -n 2" clicks, but "-n 3" is
> smooth.

make sure that you starting the jack with 48kHz and the period size
aligned to 48, such as 48, 96, 192...


Takashi


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Re: Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Frank Barknecht]

Hallo,
Takashi Iwai hat gesagt: // Takashi Iwai wrote:

> make sure that you starting the jack with 48kHz and the period size
> aligned to 48, such as 48, 96, 192...

Sorry, but I do not understand this fully. First, I'd rather like to
run at 44.1 kHz, because that's a bit less computation for the
softsynth I'm using. Will this lead to problems? I can live with a bit
higher latency.

Second: the alsa driver of jack has these options:

alsa PCM driver args: 
    -d alsa-pcm-name (default: default)
    -r sample-rate (default: 48kHz)
    -p frames-per-period (default: 1024)
    -n periods-per-hardware-buffer (default: 2)

I had to run with "-n 3", with "-n 2" jack wouldn't start. 

The period size you mentioned must be "-p frames-per-period", if I'm
right?
So if running with 44.1 kHz, should I use something like "-p 1025"
where  41*25 = 1025?

But this doesn't work with Pd, which expects powers of 2...

ciao
-- 
 Frank Barknecht                               _ ______footils.org__


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Re: Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Paul Davis]

>But this doesn't work with Pd, which expects powers of 2...

i suggest you try to find an "ALSA-native" configuration that Pd and
your quattro *do* work with, then we can map that to JACK.

--p




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Re: Quattro woes or: What does "SNDRV_PCM_IOCTL_START failed" mean?

[Frank Barknecht]

Hallo,
Paul Davis hat gesagt: // Paul Davis wrote:

> >But this doesn't work with Pd, which expects powers of 2...
> 
> i suggest you try to find an "ALSA-native" configuration that Pd and
> your quattro *do* work with, then we can map that to JACK.

Well, jack was a workaround because I couldn't get Pd to work
ALSA-natively in the first place, while the Jack-solution now works.
In fact, I just 0 minutes ago found a working Pd solution as well, by
taking Takashi's tip to run at 48000 Hz at work with Pd. And voila,
now Pd works with the Quattro...

It only required downgrading the kernel and playing (a lot) with all
those parameters, Jack (as I wrote on jack-devel) also had strange
problems on 2.4.20 that went away on 2.4.18, even without Pd involved.

Best Regards,
-- 
 Frank Barknecht                               _ ______footils.org__


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