Re: [LAD] JACK and ALSA elucidations

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
To: linux-audio-dev@lists.linuxaudio.org <linux-audio-dev@...>
Date: Wednesday, March 12, 2014 - 11:37 am

This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--d6OiEUptHVV6RbA0ivvwjiVToUO5sQPXb
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: quoted-printable

On 03/12/2014 04:21 AM, Gianfranco Ceccolini wrote:

creveu:
n=92t get it. Is there a relation between the ALSA period with JACK=92s =
period?
d 16 on the BBB
ds for capture)

Hi Gianfranco,

Seems like you're mixing up number of frames (JACK -p option) and number
of periods (JACK -n option). -p128 means 128 frames per period while the
ALSA message normally refers to the -n setting (so 16 equals to -n16 in
your case).

>> =20

double "buffered" model where the total size of the hardware memory area=
used for transfers (what ALSA calls the "hardware buffer") is always twi=
ce the "buffer size".
the total hardware buffer size. This is unusual among audio APIs, except=
that JACK follows the same convention in its ALSA backend. You can speci=
fy the period size (-p) and the number of "periods" that make up the hard=
ware buffer.
per interrupt, is it?
ideal world, those settings mean that the DEVICE will buffer 128 samples =
before issuing an interrupt, and that its total buffer size is 256.
generically to "ALSA will wake the client up whenever at least 128 sample=
s of data (and/or space) are available".
, not the interval ("period") between when the application is woken.
LSA uses 16 periods for capture the sound card will buffer a total of 256=
samples and ALSA will wake the client each 16 frames?

Not sure but I think 128*16=3D2048 frames are buffered in your case.

>=20

?=20

Probably not because the BBB audio cape driver apparently doesn't do -n2
but switches to -n16.

But I could be wrong and I'll risk some spanking ;)

Bye,

Jeremy

--d6OiEUptHVV6RbA0ivvwjiVToUO5sQPXb
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
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=qq1K
-----END PGP SIGNATURE-----

--d6OiEUptHVV6RbA0ivvwjiVToUO5sQPXb--

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
[LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Fri Feb 28, 5:58 pm)
Re: [LAD] JACK and ALSA elucidations, Jeremy Jongepier, (Fri Feb 28, 8:01 pm)
Re: [LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Mon Mar 10, 1:51 pm)
Re: [LAD] JACK and ALSA elucidations, Alex Gagnon, (Mon Mar 10, 2:34 pm)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Mon Mar 10, 2:50 pm)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Mon Mar 10, 2:26 pm)
Re: [LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Wed Mar 12, 2:26 am)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Wed Mar 12, 2:50 am)
Re: [LAD] JACK and ALSA elucidations, Gianfranco Ceccolini, (Wed Mar 12, 3:21 am)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Wed Mar 12, 12:12 pm)
Re: [LAD] JACK and ALSA elucidations, Jeremy Jongepier, (Wed Mar 12, 11:37 am)
Re: [LAD] JACK and ALSA elucidations, Paul Davis, (Fri Feb 28, 6:12 pm)