Default Sample rate for Pulse Audio/Jack etc.

Mike Holstein mikeh789 at
Tue Jan 8 15:22:54 UTC 2013

On Jan 8, 2013 9:40 AM, "Len Ovens" <len at> wrote:
> On Mon, January 7, 2013 11:50 pm, David Henningsson wrote:
> > 2013-01-08 00:45, Len Ovens skrev:
> >> skype where the incoming audio may be at 44.1k but the mic runs at 48k
> >> (only)? This is not uncommon BTW. I have already had to change the
> >> default
> >> on my netbook in pulse so that the built in mic would work.
> >
> > PulseAudio would not switch to something the backend/driver/hardware
> > would not support. In the case of Jack, PA's backend only supports the
> > sample rate that Jack is configured to.
> Assuming device support.... in the case of mixing two streams, which rate
> would be chosen? The rate of the stream to start (say 32k), or the highest
> rate?
> > In the case of your built in mic, this sounds like a bug in the driver
> > (or hardware), if the driver says that it supports 44100 where in fact
> > it does not.
> It is a part of the HDA spec that a device (an HDA controller) may have
> codecs of varying capabilities. I don't know how well ALSA deals with hw:0
> having one input at 44.1/48 and another input at 48 only. I don't know if
> the mic is even a different sub device (hw:0,1 for example), Pulse shows
> the input as selectable line/mic, but the two codecs are not the same. In
> theory a single HDA device should be able to support a phone conversation
> at 32 or 24 k while at the same time streaming 5.1 audio at 48k. Different
> codecs but same HDA controller. This from having read the Intel HDA
> spec... I don't know where the bug should be considered in this case... or
> if it is just something ALSA doesn't support (yet? ever?)
> --
> Len Ovens
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We are also just looking for the "sane" default, not the "best" or "most
optimal"...44.1 is the standard. We have basically 2 types of users..
experienced users who know what settings are best for their hardware, and
will implement those settings easily and ignore the defaults.. there are
also new users or users who don't use jack at all. These users will need to
discover what settings work best for them. There are hardware cases on both
sides of this argument that would work "better" or potentially not at all
depending on if we go 48 or 44.1... the fact is, 44.1 *is* the standard,
and *is* a sane and resonable default setting that is easily changed by the
new or experienced user. Again, it is not our goal to set the "best"
default, nor can it be. We can't set a default setting that will, out of
the box, support everyones needs and hardware configuration. I think we
could just as easily argue that *every* professional studio records at 96
or higher, but we could never assume that setting 96 as default would be
appropriate. I feel this thread has digressed into a "which is better"
agrument, and that is not what this is about. Its about hopefully finding a
setting that we plug into jack, that when *anyone* clicks "start", jack
will start. I think we can all agree that this can never happen. For years,
the out-of-the-box experience has been like this... the new user clicks on
an audio app, they are presented with a jack error that is unclear and
confusing even for experienced users. there are no default Jack settings
that will fix this. Whatever jack settings we go with will break out of the
box functionality with some hardware case.

Can we all agree 44.1 "should" support the largest base of consumer grade
hardware that new users most likely would be using?
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