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Prepare to allow using ALSA backend with nperiods > 3

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This will still need an update for Alsa_pcmi::set_hwpar() capture
channel (which is fixed at 2, unless FRAG_NEAR is used).
This commit is contained in:
Robin Gareus 2020-04-28 03:28:34 +02:00
parent 13ed8da2bc
commit d3d120fa28
Signed by: rgareus
GPG Key ID: A090BCE02CF57F04
3 changed files with 30 additions and 17 deletions
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1
libs/ardouralsautil/ardouralsautil/deviceinfo.h
View File

@ -24,6 +24,7 @@ namespace ARDOUR {
struct ALSADeviceInfo {
unsigned int max_channels;
unsigned int min_rate, max_rate;
unsigned int min_nper, min_nper;
unsigned long min_size, max_size;
bool valid;
};

19
libs/ardouralsautil/deviceparams.cc
View File

@ -34,7 +34,6 @@ ARDOUR::get_alsa_device_parameters (const char* device_name, const bool play, AL
unsigned long min_psiz, max_psiz;
unsigned long min_bufz, max_bufz;
unsigned int min_nper, max_nper;
err = snd_pcm_open (&pcm, device_name,
play ? SND_PCM_STREAM_PLAYBACK : SND_PCM_STREAM_CAPTURE,
@ -91,12 +90,12 @@ ARDOUR::get_alsa_device_parameters (const char* device_name, const bool play, AL
goto error_out;
}
err = snd_pcm_hw_params_get_periods_min (hw_params, &min_nper, 0);
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, &max_nper, 0);
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;
@ -117,19 +116,13 @@ ARDOUR::get_alsa_device_parameters (const char* device_name, const bool play, AL
fprintf (stdout, " max_psiz : %lu\n", nfo->max_size);
fprintf (stdout, " min_bufz : %lu\n", min_bufz);
fprintf (stdout, " max_bufz : %lu\n", max_bufz);
fprintf (stdout, " min_nper : %d\n", min_nper);
fprintf (stdout, " max_nper : %d\n", max_nper);
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);
}
/* AlsaAudioBackend supports n-periods 2, 3 */
if (min_nper > 2 || max_nper < 3) {
errmsg = "Unsupported period count";
return 1;
}
nfo->min_size = std::max (min_psiz, min_bufz / 3);
nfo->max_size = std::min (max_psiz, max_bufz / 2);
nfo->min_size = std::max (min_psiz, min_bufz / nfo->max_nper);
nfo->max_size = std::min (max_psiz, max_bufz / nfo->min_nper);
nfo->valid = true;
return 0;

27
libs/backends/alsa/alsa_audiobackend.cc
View File

@ -270,8 +270,27 @@ std::vector<uint32_t>
AlsaAudioBackend::available_period_sizes (const std::string& driver) const
{
std::vector<uint32_t> ps;
ps.push_back (2);
ps.push_back (3);
ALSADeviceInfo *nfo = NULL;
if (device == get_standard_device_name(DeviceNone)) {
return ps;
}
if (device == _output_audio_device && _output_audio_device_info.valid) {
nfo = &_output_audio_device_info;
} else {
ps.push_back (2);
return ps;
}
if (nfo->min_nper == 2) {
ps.push_back (2);
if (nfo->max_nper >= 3) {
ps.push_back (3);
}
} else {
ps.push_back (nfo->min_nper);
}
return ps;
}
@ -370,7 +389,7 @@ AlsaAudioBackend::set_sample_rate (float sr)
int
AlsaAudioBackend::set_peridod_size (uint32_t n)
{
if (n == 0 || n > 3) {
if (n == 0) {
return -1;
}
if (_run) {
@ -830,7 +849,7 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
(duplex & 1) ? alsa_device.c_str() : NULL,
/* ctrl name */ 0,
_samplerate, _samples_per_period,
_periods_per_cycle, /* _periods_per_cycle */ 2,
_periods_per_cycle, /* capture p/c */ 2,
/* debug */ 0);
AudioBackend::ErrorCode error_code = NoError;