From 54b754ce040d5549d5c58428d2b9c095601e98dc Mon Sep 17 00:00:00 2001 From: Javier Date: Sat, 29 Jan 2022 17:01:28 +0100 Subject: initial import --- pcmalsa.cpp | 230 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 230 insertions(+) create mode 100644 pcmalsa.cpp (limited to 'pcmalsa.cpp') diff --git a/pcmalsa.cpp b/pcmalsa.cpp new file mode 100644 index 0000000..eec9b94 --- /dev/null +++ b/pcmalsa.cpp @@ -0,0 +1,230 @@ +/* + * Copyright (C) 2022 Javier S. Pedro + * + * 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. + */ + +#define LOG_ENABLED 1 +#define LOG_ENABLE_FLOW 1 +#define LOG_GROUP LOG_GROUP_DEV_SB16 + +#include +#include +#include +#include "pcmalsa.h" + +PCMOutAlsa::PCMOutAlsa() : _pcm(NULL) +{ + +} + +PCMOutAlsa::~PCMOutAlsa() +{ +} + +int PCMOutAlsa::open(const char *dev, unsigned int sampleRate, unsigned int channels) +{ + int err; + + err = snd_pcm_open(&_pcm, dev, SND_PCM_STREAM_PLAYBACK, 0); + if (err < 0) { + LogWarn(("ALSA playback open error: %s\n", snd_strerror(err))); + return VERR_AUDIO_STREAM_COULD_NOT_CREATE; + } + + // TODO: Right now, setting a too large period size means we will not let the main + // thread run long enough to actually change notes/voices. Need some actual synchronization. + + int periodSize = 10 /*msec*/; + int bufferSize = 100 /*msec*/; + + err = setParams(sampleRate, channels, bufferSize * 1000 /*usec*/, periodSize * 1000); + if (err < 0) { + snd_pcm_close(_pcm); + _pcm = NULL; + return VERR_AUDIO_STREAM_COULD_NOT_CREATE; + } + + return VINF_SUCCESS; +} + +int PCMOutAlsa::close() +{ + if (_pcm) { + snd_pcm_drain(_pcm); + snd_pcm_close(_pcm); + } + return VINF_SUCCESS; +} + +ssize_t PCMOutAlsa::avail() +{ + snd_pcm_sframes_t frames = snd_pcm_avail(_pcm); + if (frames < 0) { + LogWarn(("ALSA trying to recover from avail error: %s\n", snd_strerror(frames))); + frames = snd_pcm_recover(_pcm, frames, 0); + if (frames == 0) { + frames = snd_pcm_avail(_pcm); + } + } + if (frames < 0) { + LogWarn(("ALSA avail error: %s\n", snd_strerror(frames))); + return VERR_AUDIO_STREAM_NOT_READY; + } + + return frames; +} + +int PCMOutAlsa::wait() +{ + int err = snd_pcm_wait(_pcm, -1); + if (err < 0) { + LogWarn(("ALSA trying to recover from wait error: %s\n", snd_strerror(err))); + err = snd_pcm_recover(_pcm, err, 0); + } + if (err < 0) { + LogWarn(("ALSA wait error: %s\n", snd_strerror(err))); + return VERR_AUDIO_STREAM_NOT_READY; + } + return VINF_SUCCESS; +} + + +ssize_t PCMOutAlsa::write(int16_t *buf, size_t n) +{ + snd_pcm_sframes_t frames = snd_pcm_writei(_pcm, buf, n); + if (frames < 0) { + LogFlow(("ALSA trying to recover from error: %s\n", snd_strerror(frames))); + frames = snd_pcm_recover(_pcm, frames, 0); + } + if (frames < 0) { + LogWarn(("ALSA write error: %s\n", snd_strerror(frames))); + return VERR_AUDIO_STREAM_NOT_READY; + } + return frames; +} + +int PCMOutAlsa::setParams(unsigned int sampleRate, unsigned int channels, unsigned int bufferTime, unsigned int periodTime) +{ + snd_pcm_hw_params_t *hwparams; + snd_pcm_sw_params_t *swparams; + int err; + + snd_pcm_hw_params_alloca(&hwparams); + snd_pcm_sw_params_alloca(&swparams); + + /* choose all parameters */ + err = snd_pcm_hw_params_any(_pcm, hwparams); + if (err < 0) { + LogWarnFunc(("Broken PCM configuration: no configurations available: %s", snd_strerror(err))); + return err; + } + /* set software resampling */ + err = snd_pcm_hw_params_set_rate_resample(_pcm, hwparams, 1); + if (err < 0) { + LogWarnFunc(("Resampling setup failed: %s", snd_strerror(err))); + return err; + } + /* set the selected read/write format */ + err = snd_pcm_hw_params_set_access(_pcm, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); + if (err < 0) { + LogWarnFunc(("Access type not available: %s", snd_strerror(err))); + return err; + } + /* set the sample format */ + err = snd_pcm_hw_params_set_format(_pcm, hwparams, SND_PCM_FORMAT_S16); + if (err < 0) { + LogWarnFunc(("Sample format not available: %s", snd_strerror(err))); + return err; + } + /* set the count of channels */ + err = snd_pcm_hw_params_set_channels(_pcm, hwparams, channels); + if (err < 0) { + LogWarnFunc(("Channels count (%i) not available: %s", channels, snd_strerror(err))); + return err; + } + /* set the stream rate */ + unsigned int rrate = sampleRate; + err = snd_pcm_hw_params_set_rate_near(_pcm, hwparams, &rrate, 0); + if (err < 0) { + LogWarnFunc(("Rate %iHz not available for playback: %s", sampleRate, snd_strerror(err))); + return err; + } + if (rrate != sampleRate) { + LogWarnFunc(("Rate doesn't match (requested %iHz, get %iHz)", sampleRate, rrate)); + return -EINVAL; + } + + /* set the buffer time */ + err = snd_pcm_hw_params_set_buffer_time_near(_pcm, hwparams, &bufferTime, NULL); + if (err < 0) { + LogWarnFunc(("Unable to set buffer time %u for playback: %s\n", bufferTime, snd_strerror(err))); + return err; + } + err = snd_pcm_hw_params_get_buffer_size(hwparams, &_bufferSize); + if (err < 0) { + printf("Unable to get buffer size for playback: %s\n", snd_strerror(err)); + return err; + } + + /* set the period time */ + err = snd_pcm_hw_params_set_period_time_near(_pcm, hwparams, &periodTime, NULL); + if (err < 0) { + printf("Unable to set period time %u for playback: %s\n", periodTime, snd_strerror(err)); + return err; + } + err = snd_pcm_hw_params_get_period_size(hwparams, &_periodSize, NULL); + if (err < 0) { + printf("Unable to get period size for playback: %s\n", snd_strerror(err)); + return err; + } + + /* write the parameters to device */ + err = snd_pcm_hw_params(_pcm, hwparams); + if (err < 0) { + LogWarnFunc(("Unable to set hw params: %s", snd_strerror(err))); + return err; + } + + LogFunc(("Using bufferSize=%lu periodSize=%lu\n", _bufferSize, _periodSize)); + + /* get the current swparams */ + err = snd_pcm_sw_params_current(_pcm, swparams); + if (err < 0) { + LogWarnFunc(("Unable to determine current swparams: %s", snd_strerror(err))); + return err; + } + /* start the transfer when the buffer is almost full: */ + /* (buffer_size / avail_min) * avail_min */ + err = snd_pcm_sw_params_set_start_threshold(_pcm, swparams, (_bufferSize / _periodSize) * _periodSize); + if (err < 0) { + LogWarnFunc(("Unable to set start threshold mode: %s", snd_strerror(err))); + return err; + } + /* allow the transfer when at least period_size samples can be processed */ + err = snd_pcm_sw_params_set_avail_min(_pcm, swparams, _periodSize); + if (err < 0) { + LogWarnFunc(("Unable to set avail min: %s", snd_strerror(err))); + return err; + } + /* write the parameters to the playback device */ + err = snd_pcm_sw_params(_pcm, swparams); + if (err < 0) { + LogWarnFunc(("Unable to set sw params: %s", snd_strerror(err))); + return err; + } + + return 0; +} -- cgit v1.2.3