virtualx-engine/drivers/alsa/audio_driver_alsa.cpp

/*************************************************************************/
/*  audio_driver_alsa.cpp                                                */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
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/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
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/* The above copyright notice and this permission notice shall be        */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
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/*************************************************************************/
#include "audio_driver_alsa.h"

#ifdef ALSA_ENABLED

#include "global_config.h"

#include <errno.h>

Error AudioDriverALSA::init() {

	active=false;
	thread_exited=false;
	exit_thread=false;
	pcm_open = false;
	samples_in = NULL;
	samples_out = NULL;

	mix_rate = GLOBAL_DEF("audio/mix_rate",44100);
	speaker_mode = SPEAKER_MODE_STEREO;
	channels = 2;


	int                  status;
	snd_pcm_hw_params_t *hwparams;
	snd_pcm_sw_params_t *swparams;

#define CHECK_FAIL(m_cond)\
	if (m_cond) {\
		fprintf(stderr,"ALSA ERR: %s\n",snd_strerror(status));\
		snd_pcm_close(pcm_handle);\
		ERR_FAIL_COND_V(m_cond,ERR_CANT_OPEN);\
	}

	//todo, add
	//6 chans - "plug:surround51"
	//4 chans - "plug:surround40";

	status = snd_pcm_open(&pcm_handle, "default", SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);

	ERR_FAIL_COND_V( status<0, ERR_CANT_OPEN );

	snd_pcm_hw_params_alloca(&hwparams);

	status = snd_pcm_hw_params_any(pcm_handle, hwparams);
	CHECK_FAIL( status<0 );

	status = snd_pcm_hw_params_set_access(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED);
	CHECK_FAIL( status<0 );

	//not interested in anything else
	status = snd_pcm_hw_params_set_format(pcm_handle, hwparams, SND_PCM_FORMAT_S16_LE);
	CHECK_FAIL( status<0 );

	//todo: support 4 and 6
	status = snd_pcm_hw_params_set_channels(pcm_handle, hwparams, 2);
	CHECK_FAIL( status<0 );

	status = snd_pcm_hw_params_set_rate_near(pcm_handle, hwparams, &mix_rate, NULL);
	CHECK_FAIL( status<0 );

	int latency = GLOBAL_DEF("audio/output_latency",25);
	buffer_size = nearest_power_of_2( latency * mix_rate / 1000 );

	// set buffer size from project settings
	status = snd_pcm_hw_params_set_buffer_size_near(pcm_handle, hwparams, &buffer_size);
	CHECK_FAIL( status<0 );

	// make period size 1/8 
	period_size = buffer_size >> 3;
	status = snd_pcm_hw_params_set_period_size_near(pcm_handle, hwparams, &period_size, NULL);
	CHECK_FAIL( status<0 );

	unsigned int periods=2;
	status = snd_pcm_hw_params_set_periods_near(pcm_handle, hwparams, &periods, NULL);
	CHECK_FAIL( status<0 );

	status = snd_pcm_hw_params(pcm_handle,hwparams);
	CHECK_FAIL( status<0 );

	//snd_pcm_hw_params_free(&hwparams);


	snd_pcm_sw_params_alloca(&swparams);

	status = snd_pcm_sw_params_current(pcm_handle, swparams);
	CHECK_FAIL( status<0 );

	status = snd_pcm_sw_params_set_avail_min(pcm_handle, swparams, period_size);
	CHECK_FAIL( status<0 );

	status = snd_pcm_sw_params_set_start_threshold(pcm_handle, swparams, 1);
	CHECK_FAIL( status<0 );

	status = snd_pcm_sw_params(pcm_handle, swparams);
	CHECK_FAIL( status<0 );

	samples_in = memnew_arr(int32_t, period_size*channels);
	samples_out = memnew_arr(int16_t, period_size*channels);

	snd_pcm_nonblock(pcm_handle, 0);

	mutex=Mutex::create();
	thread = Thread::create(AudioDriverALSA::thread_func, this);

	return OK;
};

void AudioDriverALSA::thread_func(void* p_udata) {

	AudioDriverALSA* ad = (AudioDriverALSA*)p_udata;

	while (!ad->exit_thread) {
		if (!ad->active) {
			for (unsigned int i=0; i < ad->period_size*ad->channels; i++) {
				ad->samples_out[i] = 0;
			};
		} else {
			ad->lock();

			ad->audio_server_process(ad->period_size, ad->samples_in);

			ad->unlock();

			for(unsigned int i=0;i<ad->period_size*ad->channels;i++) {
				ad->samples_out[i]=ad->samples_in[i]>>16;
			}
		};


		int todo = ad->period_size;
		int total = 0;

		while (todo) {
			if (ad->exit_thread)
				break;
			uint8_t* src = (uint8_t*)ad->samples_out;
			int wrote = snd_pcm_writei(ad->pcm_handle, (void*)(src + (total*ad->channels)), todo);

			if (wrote < 0) {
				if (ad->exit_thread)
					break;

				if ( wrote == -EAGAIN ) {
					//can't write yet (though this is blocking..)
					usleep(1000); 
					continue;
				}
				wrote = snd_pcm_recover(ad->pcm_handle, wrote, 0);
				if ( wrote < 0 ) {
					//absolute fail
					fprintf(stderr, "ALSA failed and can't recover: %s\n", snd_strerror(wrote));
					ad->active=false;
					ad->exit_thread=true;
					break;
				}
				continue;
			};

			total += wrote;
			todo -= wrote;
		};
	};

	ad->thread_exited=true;

};

void AudioDriverALSA::start() {

	active = true;
};

int AudioDriverALSA::get_mix_rate() const {

	return mix_rate;
};

AudioDriver::SpeakerMode AudioDriverALSA::get_speaker_mode() const {

	return speaker_mode;
};

void AudioDriverALSA::lock() {

	if (!thread || !mutex)
		return;
	mutex->lock();
};

void AudioDriverALSA::unlock() {

	if (!thread || !mutex)
		return;
	mutex->unlock();
};

void AudioDriverALSA::finish() {

	if (!thread)
		return;

	exit_thread = true;
	Thread::wait_to_finish(thread);

	if (pcm_open)
		snd_pcm_close(pcm_handle);

	if (samples_in) {
		memdelete_arr(samples_in);
		memdelete_arr(samples_out);
	};

	memdelete(thread);
	if (mutex)
		memdelete(mutex);
	thread = NULL;
};

AudioDriverALSA::AudioDriverALSA() {

	mutex = NULL;
	thread=NULL;
	pcm_handle=NULL;
};

AudioDriverALSA::~AudioDriverALSA() {

};

#endif