20 Feb
2016
20 Feb
'16
12:57 p.m.
On 02/20/2016 10:47 AM, Robin Gareus wrote:
On 02/20/2016 03:46 AM, Markus Seeber wrote:
I am unsure. It seems as if this behaviour is really broken but I am not
that familiar about which assumptions ALSA permits here.
@Adrian what do you think? You have been working on these drivers.
On 02/19/2016 11:46 PM, Robin Gareus wrote:
[...]
That is correct, the AIO, same as the RayDAT has a fixed buffer of 16K.
This means that regardless of the requested number of periods and frame
size, it will always report a buffer size of 16K and a number of periods
equal to buffersize divided by framesize.
Thanks for confirmation.
Usually I use 48KHz p256 n2:
[rocketmouse@archlinux ~]$ jackd -dalsa -dhw:0 -r48000 -p256 -n2
jackdmp 1.9.10
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2014 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
no message buffer overruns
no message buffer overruns
no message buffer overruns
JACK server starting in realtime mode with priority 10
self-connect-mode is "Don't restrict self connect requests"
audio_reservation_init
Acquire audio card Audio0
creating alsa driver ... hw:0|hw:0|256|2|48000|0|0|nomon|swmeter|-|32bit
configuring for 48000Hz, period = 256 frames (5.3 ms), buffer = 2 periods
ALSA: final selected sample format for capture: 32bit integer little-endian
ALSA: use 64 periods for capture
ALSA: final selected sample format for playback: 32bit integer little-endian
ALSA: use 64 periods for playback
and 64.
I dimly recall seeing some message on LAU fly by about some RME devices
requiring 16K buffers.
If you have such a kernel/card, Ardour/ALSA won't currently support it
directly, sorry.
Never the less, if requested 2
periods with framesize of 64 samples, the card will still work correctly
and have a latency that corresponds to 2 frames of 64 samples.
What is the case for exposing those this to userland?
I ask for two, I get behavior of two, but when checking the parameters
the value is 16. That sounds like a bug to me.
Did anyone flag this up at ALSA-dev, or report a bug?
As said before, there are applications that make
(most likely too many)
assumptions about these numbers and therefor break with these cards.
Ardour is not as forgiving as JACK. if a call to a snd_pcm_hw_params_*
fails or if the requested value does not match the one reported by the
card, it constitutes hard failure.
best,
robin