[Portaudio] PA not playing on Linux with ALSA

Matthias Geier matthias.geier at gmail.com
Sun Jan 13 10:48:53 EST 2019


On Sun, Jan 13, 2019 at 1:23 PM Diemo Schwarz wrote:
>
> Hi Matthias,
>
> I tried to stop and even kill pulseaudio and am still getting no timing
> information.

I don't know how to properly stop PulseAudio. When you kill it, it
normally restarts immediately. Probably a wooden stake helps?

You should be able to completely uninstall it, though, as long as you
don't need any other packages that depend on it.

> I'm not quite sure how to force PA to use a "real" device (iterating through
> Pa_GetDeviceInfo and checking the name?),

Yes, that was what I meant.

I normally use my little Python wrapper
(https://python-sounddevice.readthedocs.io/) to show a list of devices
and find the right device number:

    python3 -m sounddevice

> but it looks like ALSA is used,

Yes, ALSA is used, but via some kind of a PulseAudio/ALSA compatibility layer.

And it turns out that this doesn't work well for ALSA's "virtual"
devices, but it seems to work fine for the "real" devices (named
"hw:X,Y").

BTW, "virtual" and "real" are not the official terms ...

cheers,
Matthias

> since
> pa_devs reports this as default:
>
> --------------------------------------- device #10
> [ Default Input, Default Output ]
> Name                        = default
> Host API                    = ALSA
> Max inputs = 128, Max outputs = 128
> Default low input latency   =   0.0213
> Default low output latency  =   0.0213
> Default high input latency  =   0.0213
> Default high output latency =   0.0213
> Default sample rate         = 48000.00
>
> Best...
>                                                                 ...Diemo
>
> On 13/01/19 11:07, Matthias Geier wrote:
> > Hi Diemo, sqweek and others.
> >
> > On Sat, Jan 12, 2019 at 12:33 AM sqweek E. wrote:
> >>
> >> Hi Diemo,
> >>
> >> I remember seeing this before, and I think it was ultimately due to the pulseaudio <-> alsa bridge not providing timing information, rather than something portaudio was doing/not doing. I remember resolving the issue by having my application detect when the stream time was not progressing and fall back to a different time source (can't remember if I used system clock or a calculation based on the number of processed frames).
> >
> > I've also experienced the lack of timing when using PulseAudio.
> >
> > However, this only happened when using the default device (called
> > "default"), which is some kind of "virtual" device.
> > When I'm using a "real" device (e.g. "hw:0,0"), the timing information works!
> >
> > cheers,
> > Matthias
> >
> >> If you search this list you'll also find a pulseaudio backend implentation for portaudio, courtesy of Tuukka Pasenen. Unfortunately it is yet to be merged into the main branch, and I also don't remember if the stream timing info has been implemented yet.
> >>
> >> ... I shouldn't send emails from my phone where it's difficult to check the history xD
> >>
> >> -sqweek
> >>
> >>> On 12 Jan 2019, at 03:44, Diemo Schwarz <Diemo.Schwarz at ircam.fr> wrote:
> >>>
> >>>
> >>> Hello again,
> >>>
> >>> thanks to your hints, I do get sound on RPi (and Mac). The next step is to run this program on an Intel Linux box, where I'm back with time being stuck:
> >>>
> >>> You see how the stream callback's currentTime is stuck at 0, and the outputBufferDacTime cycles through 6 buffers before resetting to 0.
> >>> I tried lower and higher latencies with same result.
> >>>
> >>> audio_callback: curtime 0  outtime 0  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0232  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0464  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0697  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0929  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.116  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0232  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0464  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0697  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.0929  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0.116  latency 0.557279  n 1024 flags 0
> >>> audio_callback: curtime 0  outtime 0  latency 0.557279  n 1024 flags 0
> >>>
> >>> Could this all be due to some mismatch with ALSA libs? The box has a pristine Debian installation [1], with ALSA already installed (aplay, etc. work), but I don't have root access, so I had to compile libasound 1.1.8 (from 7.1.2019!) from source, to get PA to compile with ALSA support (setenv LDFLAGS and CFLAGS before configure).
> >>> There's also pulseaudio installed, which I don't know if it can interfere with PA, and these ALSA errors remain:
> >>>
> >>> ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
> >>> ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
> >>> ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
> >>> ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
> >>>
> >>> Forgive me if this is an off-PA question (it's been more than 15 years since I last meddled with Linux audio), but any help would be appreciated.
> >>>
> >>> Best...
> >>>                                 ...Diemo
> >>>
> >>> [1] Linux 4.9.0-8-amd64 #1 SMP Debian 4.9.130-2 (2018-10-27) x86_64 GNU/Linux
> >>>
> >>> I also now realise that this response didn't go to the list:
> >>>
> >>>> On 19/12/18 12:34, Diemo Schwarz wrote:
> >>>> Hi Phil,
> >>>> thanks for the hint, that info pointed me into the right direction to augment the requested output latency, and now I get sound!
> >>>> Should I worry about all these
> >>>> ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.front
> >>>> messages?
> >>>> Cheers...
> >>>>                                  ...Diemo
> >>>>> On 19/12/18 05:58, Phil Burk wrote:
> >>>>> Hello Diemo,
> >>>>>
> >>>>> PA on RPi specific info is here: https://app.assembla.com/wiki/show/portaudio/Platforms_RaspberryPi
> >>>>>
> >>>>>   > the audio callback is called only once.
> >>>>>
> >>>>> What value are you returning from your callback? If you do not return paContinue then it will stop.
> >>>>>
> >>>>> http://portaudio.com/docs/v19-doxydocs/portaudio_8h.html#a8a60fb2a5ec9cbade3f54a9c978e2710
> >>>>>
> >>>>> Are you using the built-in PWM output? That is very low quality.
> >>>>> If you want good quality then you may need an audio board. I had good luck with the HifiBerry DAC+.
> >>>>> https://www.hifiberry.com/products/dacplus/
> >>>>>
> >>>>> See also: http://portaudio.com/docs/v19-doxydocs/compile_linux.html
> >>>>>
> >>>>> Phil Burk
> >>>>>
> >>>>>
> >>>>>
> >>>>> On Tue, Dec 18, 2018 at 10:28 AM Diemo Schwarz <Diemo.Schwarz at ircam.fr <mailto:Diemo.Schwarz at ircam.fr>> wrote:
> >>>>>
> >>>>>
> >>>>>      Hi, this is probably more a question of configuring ALSA correctly on a
> >>>>>      Raspberry (3) with Raspbian (stretch), but I'm humbly asking for where to look.
> >>>>>
> >>>>>      So I have a program that plays fine on Mac, but on Raspberry, it doesn't, since
> >>>>>      the audio callback is called only once.
> >>>>>      Some of the PA test programs have the same behaviour (paex_sine), some do work
> >>>>>      (paex_pink), some work with lots of glitches (patest_sine_time, patest_sine8,
> >>>>>      patest_sine_srate).
> >>>>>
> >>>>>      It might have something to do with sr (see output of patest_sine_srate below).
> >>>>>      If that rings a bell with someone please let me know, thank you!...
> >>>>>                                                                       ...Diemo
> >>>>>
> >>>>>
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.front
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround21
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround21
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround40
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround41
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround50
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround51
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.surround71
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.iec958
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.iec958
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.iec958
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.hdmi
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.hdmi
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
> >>>>>      ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition
> >>>>>      'defaults.bluealsa.device'
> >>>>>      ALSA lib conf.c:4528:(_snd_config_evaluate) function snd_func_refer returned
> >>>>>      error: No such file or directory
> >>>>>      ALSA lib conf.c:4996:(snd_config_expand) Args evaluate error: No such file or
> >>>>>      directory
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM bluealsa
> >>>>>      ALSA lib confmisc.c:1281:(snd_func_refer) Unable to find definition
> >>>>>      'defaults.bluealsa.device'
> >>>>>      ALSA lib conf.c:4528:(_snd_config_evaluate) function snd_func_refer returned
> >>>>>      error: No such file or directory
> >>>>>      ALSA lib conf.c:4996:(snd_config_expand) Args evaluate error: No such file or
> >>>>>      directory
> >>>>>      ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM bluealsa
> >>>>>      PortAudio Test: output sine wave. SR = 44100, BufSize = 64
> >>>>>      Hardware SR changing not being tested on this platform.
> >>>>>      Play for 5 seconds.
> >>>>>      PortAudio Test: output sine wave. SR = 48000, BufSize = 64
> >>>>>      Hardware SR changing not being tested on this platform.
> >>>>>      Play for 5 seconds.
> Diemo Schwarz, PhD -- http://diemo.concatenative.net
> Sound–Music–Movement Interaction Team -- http://ismm.ircam.fr
> IRCAM - Centre Pompidou -- 1, place Igor-Stravinsky, 75004 Paris, France
> Phone +33-1-4478-4879 -- Fax +33-1-4478-1540


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