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livetrax/libs/ardouralsautil/deviceparams.cc
Robin Gareus 3a6a9cfa6c
Tweak ALSA nperiod setting, fallback to nearest
This is mainly for RME RayDAT that has a fixed buffersize of 16k:

  dev_name : hw:HDSPMxc2f6c5,0
  channels : 36
  min_rate : 32000
  max_rate : 192000
  min_bufz : 16384
  max_bufz : 16384
  min_nper : 4
  max_nper : 512

However nperiod configuration determines the effective latency
regardless.

This is similar to https://github.com/jackaudio/jack1/blob/master/drivers/alsa/alsa_driver.c#L476-L486
2020-04-29 23:56:24 +02:00

136 lines
4.0 KiB
C++

/*
* Copyright (C) 2015-2019 Robin Gareus <robin@gareus.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <alsa/asoundlib.h>
#include "pbd/convert.h"
#include "ardouralsautil/deviceinfo.h"
using namespace std;
int
ARDOUR::get_alsa_device_parameters (const char* device_name, const bool play, ALSADeviceInfo *nfo)
{
snd_pcm_t *pcm;
snd_pcm_hw_params_t *hw_params;
std::string errmsg;
int err;
nfo->valid = false;
unsigned long min_psiz, max_psiz;
unsigned long min_bufz, max_bufz;
err = snd_pcm_open (&pcm, device_name,
play ? SND_PCM_STREAM_PLAYBACK : SND_PCM_STREAM_CAPTURE,
SND_PCM_NONBLOCK);
if (err < 0) {
fprintf (stderr, "ALSA: Cannot open device '%s': %s\n", device_name, snd_strerror (err));
return 1;
}
snd_pcm_hw_params_alloca (&hw_params);
err = snd_pcm_hw_params_any (pcm, hw_params);
if (err < 0) {
errmsg = "Cannot get hardware parameters";
goto error_out;
}
err = snd_pcm_hw_params_get_channels_max (hw_params, &nfo->max_channels);
if (err < 0) {
errmsg = "Cannot get maximum channels count";
goto error_out;
}
err = snd_pcm_hw_params_get_rate_min (hw_params, &nfo->min_rate, NULL);
if (err < 0) {
errmsg = "Cannot get minimum rate";
goto error_out;
}
err = snd_pcm_hw_params_get_rate_max (hw_params, &nfo->max_rate, NULL);
if (err < 0) {
errmsg = "Cannot get maximum rate";
goto error_out;
}
err = snd_pcm_hw_params_get_period_size_min (hw_params, &min_psiz, 0);
if (err < 0) {
errmsg = "Cannot get minimum period size";
goto error_out;
}
err = snd_pcm_hw_params_get_period_size_max (hw_params, &max_psiz, 0);
if (err < 0) {
errmsg = "Cannot get maximum period size";
goto error_out;
}
err = snd_pcm_hw_params_get_buffer_size_min (hw_params, &min_bufz);
if (err < 0) {
errmsg = "Cannot get minimum buffer size";
goto error_out;
}
err = snd_pcm_hw_params_get_buffer_size_max (hw_params, &max_bufz);
if (err < 0) {
errmsg = "Cannot get maximum buffer size";
goto error_out;
}
err = snd_pcm_hw_params_get_periods_min (hw_params, &nfo->min_nper, 0);
if (err < 0) {
errmsg = "Cannot get minimum period count";
goto error_out;
}
err = snd_pcm_hw_params_get_periods_max (hw_params, &nfo->max_nper, 0);
if (err < 0) {
errmsg = "Cannot get maximum period count";
goto error_out;
}
snd_pcm_close (pcm);
nfo->min_size = std::max (min_psiz, min_bufz / nfo->max_nper);
nfo->max_size = std::min (max_psiz, max_bufz / nfo->min_nper);
/* see also libs/backends/alsa/zita-alsa-pcmi.cc
* If any debug parameter is set, print device info.
*/
if (getenv ("ZITA_ALSA_PCMI_DEBUG")) {
fprintf (stdout, "ALSA: *%s* device-info\n", play ? "playback" : "capture");
fprintf (stdout, " dev_name : %s\n", device_name);
fprintf (stdout, " channels : %u\n", nfo->max_channels);
fprintf (stdout, " min_rate : %u\n", nfo->min_rate);
fprintf (stdout, " max_rate : %u\n", nfo->max_rate);
fprintf (stdout, " min_psiz : %lu\n", min_psiz);
fprintf (stdout, " max_psiz : %lu\n", max_psiz);
fprintf (stdout, " min_bufz : %lu\n", min_bufz);
fprintf (stdout, " max_bufz : %lu\n", max_bufz);
fprintf (stdout, " min_nper : %d\n", nfo->min_nper);
fprintf (stdout, " max_nper : %d\n", nfo->max_nper);
fprintf (stdout, " possible : %lu .. %lu\n", nfo->min_size, nfo->max_size);
}
nfo->valid = true;
return 0;
error_out:
fprintf (stderr, "ALSA: %s: %s\n", errmsg.c_str(), snd_strerror (err));
snd_pcm_close (pcm);
return 1;
}