/**
 *  RetroArch - A frontend for libretro.
 *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 *  Copyright (C) 2011-2017 - Daniel De Matteis
 *
 *  RetroArch 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 3 of the License, or (at your option)
 *  any later version.
 *
 *  RetroArch 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 RetroArch. If not, see <http://www.gnu.org/licenses/>.
 **/

#include <math.h>

#include "audio_driver.h"

#include <string/stdstring.h>
#include <encodings/utf.h>
#include <clamping.h>
#include <memalign.h>
#include <audio/conversion/float_to_s16.h>
#include <audio/conversion/s16_to_float.h>
#ifdef HAVE_AUDIOMIXER
#include <audio/audio_mixer.h>
#include "../tasks/task_audio_mixer.h"
#endif
#ifdef HAVE_DSP_FILTER
#include <audio/dsp_filter.h>
#endif
#include <lists/dir_list.h>

#ifdef HAVE_THREADS
#include "audio_thread_wrapper.h"
#endif

#ifdef HAVE_MENU
#include "../menu/menu_driver.h"
#endif

#ifdef HAVE_NETWORKING
#include "../network/netplay/netplay.h"
#endif

#include "../configuration.h"
#include "../driver.h"
#include "../frontend/frontend_driver.h"
#include "../retroarch.h"
#include "../list_special.h"
#include "../file_path_special.h"
#include "../record/record_driver.h"
#include "../tasks/task_content.h"
#include "../verbosity.h"

#define MENU_SOUND_FORMATS "ogg|mod|xm|s3m|mp3|flac|wav"

 /* Converts decibels to voltage gain. returns voltage gain value. */
#define DB_TO_GAIN(db) (powf(10.0f, (db) / 20.0f))

audio_driver_t audio_null = {
   NULL, /* init */
   NULL, /* write */
   NULL, /* stop */
   NULL, /* start */
   NULL, /* alive */
   NULL, /* set_nonblock_state */
   NULL, /* free */
   NULL, /* use_float */
   "null",
   NULL,
   NULL,
   NULL, /* write_avail */
   NULL
};

audio_driver_t *audio_drivers[] = {
#ifdef HAVE_ALSA
   &audio_alsa,
#if !defined(__QNX__) && !defined(MIYOO) && defined(HAVE_THREADS)
   &audio_alsathread,
#endif
#endif
#ifdef HAVE_TINYALSA
   &audio_tinyalsa,
#endif
#if defined(HAVE_AUDIOIO)
   &audio_audioio,
#endif
#if defined(HAVE_OSS) || defined(HAVE_OSS_BSD)
   &audio_oss,
#endif
#ifdef HAVE_RSOUND
   &audio_rsound,
#endif
#ifdef HAVE_COREAUDIO
   &audio_coreaudio,
#endif
#ifdef HAVE_COREAUDIO3
   &audio_coreaudio3,
#endif
#ifdef HAVE_AL
   &audio_openal,
#endif
#ifdef HAVE_SL
   &audio_opensl,
#endif
#ifdef HAVE_ROAR
   &audio_roar,
#endif
#ifdef HAVE_JACK
   &audio_jack,
#endif
#ifdef HAVE_WASAPI
   &audio_wasapi,
#endif
#ifdef HAVE_XAUDIO
   &audio_xa,
#endif
#ifdef HAVE_DSOUND
   &audio_dsound,
#endif
#if defined(HAVE_SDL) || defined(HAVE_SDL2)
   &audio_sdl,
#endif
#ifdef HAVE_PULSE
   &audio_pulse,
#endif
#if defined(__PSL1GHT__) || defined(__PS3__)
   &audio_ps3,
#endif
#ifdef XENON
   &audio_xenon360,
#endif
#ifdef GEKKO
   &audio_gx,
#endif
#ifdef WIIU
   &audio_ax,
#endif
#ifdef EMSCRIPTEN
   &audio_rwebaudio,
#endif
#if defined(PSP) || defined(VITA) || defined(ORBIS)
  &audio_psp,
#endif
#if defined(PS2)
  &audio_ps2,
#endif
#ifdef _3DS
   &audio_ctr_csnd,
   &audio_ctr_dsp,
#ifdef HAVE_THREADS
   &audio_ctr_dsp_thread,
#endif
#endif
#ifdef SWITCH
   &audio_switch,
   &audio_switch_thread,
#ifdef HAVE_LIBNX
   &audio_switch_libnx_audren,
   &audio_switch_libnx_audren_thread,
#endif
#endif
   &audio_null,
   NULL,
};

static audio_driver_state_t audio_driver_st = {0}; /* double alignment */

/**************************************/

audio_driver_state_t *audio_state_get_ptr(void)
{
   return &audio_driver_st;
}

/**
 * config_get_audio_driver_options:
 *
 * Get an enumerated list of all audio driver names, separated by '|'.
 *
 * Returns: string listing of all audio driver names, separated by '|'.
 **/
const char *config_get_audio_driver_options(void)
{
   return char_list_new_special(STRING_LIST_AUDIO_DRIVERS, NULL);
}

#ifdef HAVE_TRANSLATE
/* TODO/FIXME - Doesn't currently work.  Fix this. */
bool audio_driver_is_ai_service_speech_running(void)
{
#ifdef HAVE_AUDIOMIXER
   enum audio_mixer_state res = audio_driver_mixer_get_stream_state(10);
   bool ret = (res == AUDIO_STREAM_STATE_NONE) || (res == AUDIO_STREAM_STATE_STOPPED);
   if (!ret)
      return true;
#endif
   return false;
}
#endif

static enum resampler_quality audio_driver_get_resampler_quality(
      settings_t *settings)
{
   if (settings)
      return (enum resampler_quality)settings->uints.audio_resampler_quality;
   return RESAMPLER_QUALITY_DONTCARE;
}

static bool audio_driver_free_devices_list(void)
{
   audio_driver_state_t *audio_st = &audio_driver_st;
   if (
            !audio_st->current_audio 
         || !audio_st->current_audio->device_list_free
         || !audio_st->context_audio_data)
      return false;
   audio_st->current_audio->device_list_free(
         audio_st->context_audio_data,
         audio_st->devices_list);
   audio_st->devices_list = NULL;
   return true;
}

#ifdef DEBUG
static void report_audio_buffer_statistics(void)
{
   audio_statistics_t audio_stats;
   audio_stats.samples                   = 0;
   audio_stats.average_buffer_saturation = 0.0f;
   audio_stats.std_deviation_percentage  = 0.0f;
   audio_stats.close_to_underrun         = 0.0f;
   audio_stats.close_to_blocking         = 0.0f;

   if (!audio_compute_buffer_statistics(&audio_stats))
      return;

   RARCH_LOG("[Audio]: Average audio buffer saturation: %.2f %%,"
         " standard deviation (percentage points): %.2f %%.\n"
         "[Audio]: Amount of time spent close to underrun: %.2f %%."
         " Close to blocking: %.2f %%.\n",
         audio_stats.average_buffer_saturation,
         audio_stats.std_deviation_percentage,
         audio_stats.close_to_underrun,
         audio_stats.close_to_blocking);
}
#endif

static void audio_driver_deinit_resampler(void)
{
   audio_driver_state_t *audio_st = &audio_driver_st;
   if (audio_st->resampler && audio_st->resampler_data)
      audio_st->resampler->free(audio_st->resampler_data);
   audio_st->resampler          = NULL;
   audio_st->resampler_data     = NULL;
   audio_st->resampler_ident[0] = '\0';
   audio_st->resampler_quality  = RESAMPLER_QUALITY_DONTCARE;
}


static bool audio_driver_deinit_internal(bool audio_enable)
{
   audio_driver_state_t *audio_st = &audio_driver_st;
   if (     audio_st->current_audio 
         && audio_st->current_audio->free)
   {
      if (audio_st->context_audio_data)
         audio_st->current_audio->free(audio_st->context_audio_data);
      audio_st->context_audio_data = NULL;
   }

   if (audio_st->output_samples_conv_buf)
      memalign_free(audio_st->output_samples_conv_buf);
   audio_st->output_samples_conv_buf     = NULL;

   if (audio_st->input_data)
      memalign_free(audio_st->input_data);

   audio_st->input_data = NULL;
   audio_st->data_ptr   = 0;

#ifdef HAVE_REWIND
   if (audio_st->rewind_buf)
      memalign_free(audio_st->rewind_buf);
   audio_st->rewind_buf  = NULL;
   audio_st->rewind_size = 0;
#endif

   if (!audio_enable)
   {
      audio_st->flags   &= ~AUDIO_FLAG_ACTIVE;
      return false;
   }

   audio_driver_deinit_resampler();

   if (audio_st->output_samples_buf)
      memalign_free(audio_st->output_samples_buf);
   audio_st->output_samples_buf = NULL;

#ifdef HAVE_DSP_FILTER
   audio_driver_dsp_filter_free();
#endif
#ifdef DEBUG
   report_audio_buffer_statistics();
#endif

   return true;
}

#ifdef HAVE_AUDIOMIXER
static void audio_driver_mixer_deinit(void)
{
   unsigned i;

   audio_driver_st.flags &= ~AUDIO_FLAG_MIXER_ACTIVE;

   for (i = 0; i < AUDIO_MIXER_MAX_SYSTEM_STREAMS; i++)
   {
      audio_driver_mixer_stop_stream(i);
      audio_driver_mixer_remove_stream(i);
   }

   audio_mixer_done();
}
#endif

bool audio_driver_deinit(void)
{
   settings_t *settings = config_get_ptr();
#ifdef HAVE_AUDIOMIXER
   audio_driver_mixer_deinit();
#endif
   audio_driver_free_devices_list();

   return audio_driver_deinit_internal(
         settings->bools.audio_enable);
}

bool audio_driver_find_driver(
      void *settings_data,
      const char *prefix,
      bool verbosity_enabled)
{
   settings_t *settings    = (settings_t*)settings_data;
   int i                   = (int)driver_find_index(
         "audio_driver",
         settings->arrays.audio_driver);

   if (i >= 0)
      audio_driver_st.current_audio = (const audio_driver_t*)
         audio_drivers[i];
   else
   {
      const audio_driver_t *tmp = NULL;
      if (verbosity_enabled)
      {
         unsigned d;
         RARCH_ERR("Couldn't find any %s named \"%s\"\n", prefix,
               settings->arrays.audio_driver);
         RARCH_LOG_OUTPUT("Available %ss are:\n", prefix);
         for (d = 0; audio_drivers[d]; d++)
         {
            if (audio_drivers[d])
               RARCH_LOG_OUTPUT("\t%s\n", audio_drivers[d]->ident);
         }
         RARCH_WARN("Going to default to first %s...\n", prefix);
      }

      tmp = (const audio_driver_t*)audio_drivers[0];

      if (!tmp)
         return false;
      audio_driver_st.current_audio = tmp;
   }

   return true;
}

/**
 * audio_driver_flush:
 * @data                 : pointer to audio buffer.
 * @right                : amount of samples to write.
 *
 * Writes audio samples to audio driver. Will first
 * perform DSP processing (if enabled) and resampling.
 **/
static void audio_driver_flush(
      audio_driver_state_t *audio_st,
      float slowmotion_ratio,
      bool audio_fastforward_mute,
      const int16_t *data, size_t samples,
      bool is_slowmotion, bool is_fastforward)
{
   struct resampler_data src_data;
   float audio_volume_gain           = (audio_st->mute_enable ||
         (audio_fastforward_mute && is_fastforward))
               ? 0.0f 
               : audio_st->volume_gain;

   src_data.data_out                 = NULL;
   src_data.output_frames            = 0;

   convert_s16_to_float(audio_st->input_data, data, samples,
         audio_volume_gain);

   src_data.data_in                  = audio_st->input_data;
   src_data.input_frames             = samples >> 1;

#ifdef HAVE_DSP_FILTER
   if (audio_st->dsp)
   {
      struct retro_dsp_data dsp_data;

      dsp_data.input                 = NULL;
      dsp_data.input_frames          = 0;
      dsp_data.output                = NULL;
      dsp_data.output_frames         = 0;

      dsp_data.input                 = audio_st->input_data;
      dsp_data.input_frames          = (unsigned)(samples >> 1);

      retro_dsp_filter_process(audio_st->dsp, &dsp_data);

      if (dsp_data.output)
      {
         src_data.data_in            = dsp_data.output;
         src_data.input_frames       = dsp_data.output_frames;
      }
   }
#endif

   src_data.data_out                 = audio_st->output_samples_buf;

   if (audio_st->flags & AUDIO_FLAG_CONTROL)
   {
      /* Readjust the audio input rate. */
      int      half_size             = (int)(audio_st->buffer_size / 2);
         
      int      avail               =
          (int)audio_st->current_audio->write_avail(
               audio_st->context_audio_data);
      int      delta_mid           = avail - half_size;
      double   direction           = (double)delta_mid / half_size;
      double   adjust              = 1.0 +
         audio_st->rate_control_delta * direction;
      unsigned write_idx           =
         audio_st->free_samples_count++ &
         (AUDIO_BUFFER_FREE_SAMPLES_COUNT - 1);

      audio_st->free_samples_buf[write_idx]  = avail;
      audio_st->source_ratio_current         =
         audio_st->source_ratio_original * adjust;

#if 0
      if (verbosity_is_enabled())
      {
         RARCH_LOG_OUTPUT("[Audio]: Audio buffer is %u%% full\n",
               (unsigned)(100 - (avail * 100) /
                  audio_st->buffer_size));
         RARCH_LOG_OUTPUT("[Audio]: New rate: %lf, Orig rate: %lf\n",
               audio_st->source_ratio_current,
               audio_st->source_ratio_original);
      }
#endif
   }

   src_data.ratio           = audio_st->source_ratio_current;

   if (is_slowmotion)
      src_data.ratio       *= slowmotion_ratio;

   if (is_fastforward && config_get_ptr()->bools.audio_fastforward_speedup) {
      const retro_time_t flush_time = cpu_features_get_time_usec();

      if (audio_st->last_flush_time > 0) {
         /* What we should see if the speed was 1.0x, converted to microsecs */
         const double expected_flush_delta =
            (src_data.input_frames / audio_st->input * 1000000);
         /* Exponential moving average of the last AUDIO_FF_EXP_AVG_SAMPLES
            samples. This helps make sure pitches are recognizable by avoiding
            too much variance flush-to-flush.

            It's not needed to avoid crackling (the generated waves are going to
            be continuous either way), but it's important to avoid time
            compression and decompression every single frame, which would make
            sounds irrecognizable.

            https://en.wikipedia.org/wiki/Moving_average#Exponential_moving_average */
         const retro_time_t n = AUDIO_FF_EXP_AVG_SAMPLES;
         audio_st->avg_flush_delta = audio_st->avg_flush_delta * (n - 1) / n +
                                    (flush_time - audio_st->last_flush_time) / n;

         /* How much does the avg_flush_delta deviate from the delta at 1.0x speed? */
         src_data.ratio *=
            MAX(AUDIO_MIN_RATIO,
               MIN(AUDIO_MAX_RATIO,
                  audio_st->avg_flush_delta / expected_flush_delta));
      }

      audio_st->last_flush_time = flush_time;
   }
 
   audio_st->resampler->process(
         audio_st->resampler_data, &src_data);

#ifdef HAVE_AUDIOMIXER
   if (audio_st->flags & AUDIO_FLAG_MIXER_ACTIVE)
   {
      bool override                       = true;
      float mixer_gain                    = 0.0f;
      bool audio_driver_mixer_mute_enable = audio_st->mixer_mute_enable;

      if (!audio_driver_mixer_mute_enable)
      {
         if (audio_st->mixer_volume_gain == 1.0f)
            override                      = false;
         mixer_gain                       = audio_st->mixer_volume_gain;
            
      }
      audio_mixer_mix(audio_st->output_samples_buf,
            src_data.output_frames, mixer_gain, override);
   }
#endif

   {
      const void *output_data = audio_st->output_samples_buf;
      unsigned output_frames  = (unsigned)src_data.output_frames;

      if (audio_st->flags & AUDIO_FLAG_USE_FLOAT)
         output_frames       *= sizeof(float);
      else
      {
         convert_float_to_s16(audio_st->output_samples_conv_buf,
               (const float*)output_data, output_frames * 2);

         output_data          = audio_st->output_samples_conv_buf;
         output_frames       *= sizeof(int16_t);
      }

      audio_st->current_audio->write(audio_st->context_audio_data,
            output_data, output_frames * 2);
   }
}

#ifdef HAVE_AUDIOMIXER
audio_mixer_stream_t *audio_driver_mixer_get_stream(unsigned i)
{
   if (i > (AUDIO_MIXER_MAX_SYSTEM_STREAMS-1))
      return NULL;
   return &audio_driver_st.mixer_streams[i];
}

const char *audio_driver_mixer_get_stream_name(unsigned i)
{
   if (i > (AUDIO_MIXER_MAX_SYSTEM_STREAMS-1))
      return msg_hash_to_str(MENU_ENUM_LABEL_VALUE_NOT_AVAILABLE);
   if (!string_is_empty(audio_driver_st.mixer_streams[i].name))
      return audio_driver_st.mixer_streams[i].name;
   return msg_hash_to_str(MENU_ENUM_LABEL_VALUE_NOT_AVAILABLE);
}

#endif

bool audio_driver_init_internal(
      void *settings_data,
      bool audio_cb_inited)
{
   unsigned new_rate              = 0;
   float  *samples_buf            = NULL;
   settings_t *settings           = (settings_t*)settings_data;
   size_t max_bufsamples          = AUDIO_CHUNK_SIZE_NONBLOCKING * 2;
   bool audio_enable              = settings->bools.audio_enable;
   bool audio_sync                = settings->bools.audio_sync;
   bool audio_rate_control        = settings->bools.audio_rate_control;
   float slowmotion_ratio         = settings->floats.slowmotion_ratio;
   unsigned setting_audio_latency = settings->uints.audio_latency;
   unsigned runloop_audio_latency = runloop_state_get_ptr()->audio_latency;
   unsigned audio_latency         = (runloop_audio_latency > setting_audio_latency) ?
         runloop_audio_latency : setting_audio_latency;
#ifdef HAVE_REWIND
   int16_t *rewind_buf            = NULL;
#endif
   /* Accomodate rewind since at some point we might have two full buffers. */
   size_t outsamples_max          = AUDIO_CHUNK_SIZE_NONBLOCKING * 2 * AUDIO_MAX_RATIO * slowmotion_ratio;
   int16_t *conv_buf              = (int16_t*)memalign_alloc(64, outsamples_max * sizeof(int16_t));
   float *audio_buf               = (float*)memalign_alloc(64, AUDIO_CHUNK_SIZE_NONBLOCKING * 2 * sizeof(float));
   bool verbosity_enabled         = verbosity_is_enabled();

   convert_s16_to_float_init_simd();
   convert_float_to_s16_init_simd();

   if (!conv_buf || !audio_buf)
      goto error;

   memset(audio_buf, 0, AUDIO_CHUNK_SIZE_NONBLOCKING * 2 * sizeof(float));

   audio_driver_st.input_data              = audio_buf;
   audio_driver_st.output_samples_conv_buf = conv_buf;
   audio_driver_st.chunk_block_size        = AUDIO_CHUNK_SIZE_BLOCKING;
   audio_driver_st.chunk_nonblock_size     = AUDIO_CHUNK_SIZE_NONBLOCKING;
   audio_driver_st.chunk_size              = audio_driver_st.chunk_block_size;

#ifdef HAVE_REWIND
   /* Needs to be able to hold full content of a full max_bufsamples
    * in addition to its own. */
   if (!(rewind_buf = (int16_t*)memalign_alloc(64, max_bufsamples * sizeof(int16_t))))
      goto error;

   audio_driver_st.rewind_buf    = rewind_buf;
   audio_driver_st.rewind_size   = max_bufsamples;
#endif

   if (!audio_enable)
   {
      audio_driver_st.flags     &= ~AUDIO_FLAG_ACTIVE;
      return false;
   }
   else
      audio_driver_st.flags     |= AUDIO_FLAG_ACTIVE;

   if (!(audio_driver_find_driver(settings,
         "audio driver", verbosity_enabled)))
   {
      RARCH_ERR("Failed to initialize audio driver.\n");
      return false;
   }

   if (!audio_driver_st.current_audio || !audio_driver_st.current_audio->init)
   {
      RARCH_ERR("Failed to initialize audio driver. Will continue without audio.\n");
      audio_driver_st.flags &= ~AUDIO_FLAG_ACTIVE;
      return false;
   }

#ifdef HAVE_THREADS
   if (audio_cb_inited)
   {
      RARCH_LOG("[Audio]: Starting threaded audio driver ...\n");
      if (!audio_init_thread(
               &audio_driver_st.current_audio,
               &audio_driver_st.context_audio_data,
               *settings->arrays.audio_device
               ? settings->arrays.audio_device : NULL,
               settings->uints.audio_output_sample_rate, &new_rate,
               audio_latency,
               settings->uints.audio_block_frames,
               audio_driver_st.current_audio))
      {
         RARCH_ERR("Cannot open threaded audio driver ... Exiting ...\n");
         return false;
      }
   }
   else
#endif
   {
      audio_driver_st.context_audio_data =
         audio_driver_st.current_audio->init(*settings->arrays.audio_device ?
               settings->arrays.audio_device : NULL,
               settings->uints.audio_output_sample_rate,
               audio_latency,
               settings->uints.audio_block_frames,
               &new_rate);
   }

   if (new_rate != 0)
      configuration_set_int(settings, settings->uints.audio_output_sample_rate, new_rate);

   if (!audio_driver_st.context_audio_data)
   {
      RARCH_ERR("Failed to initialize audio driver. Will continue without audio.\n");
      audio_driver_st.flags &= ~AUDIO_FLAG_ACTIVE;
   }

   audio_driver_st.flags    &= ~AUDIO_FLAG_USE_FLOAT;
   if (     (audio_driver_st.flags & AUDIO_FLAG_ACTIVE)
         && audio_driver_st.current_audio->use_float(
            audio_driver_st.context_audio_data))
      audio_driver_st.flags |=  AUDIO_FLAG_USE_FLOAT;

   if (     !audio_sync 
         && (audio_driver_st.flags & AUDIO_FLAG_ACTIVE))
   {
      if (     (audio_driver_st.flags & AUDIO_FLAG_ACTIVE)
            && audio_driver_st.context_audio_data)
         audio_driver_st.current_audio->set_nonblock_state(
               audio_driver_st.context_audio_data, true);

      audio_driver_st.chunk_size =
         audio_driver_st.chunk_nonblock_size;
   }

   if (audio_driver_st.input <= 0.0f)
   {
      /* Should never happen. */
      RARCH_WARN("[Audio]: Input rate is invalid (%.3f Hz)."
            " Using output rate (%u Hz).\n",
            audio_driver_st.input, settings->uints.audio_output_sample_rate);

      audio_driver_st.input = settings->uints.audio_output_sample_rate;
   }

   audio_driver_st.source_ratio_original   =
      audio_driver_st.source_ratio_current =
      (double)settings->uints.audio_output_sample_rate / audio_driver_st.input;

   if (!string_is_empty(settings->arrays.audio_resampler))
      strlcpy(audio_driver_st.resampler_ident,
            settings->arrays.audio_resampler,
            sizeof(audio_driver_st.resampler_ident));
   else
      audio_driver_st.resampler_ident[0] = '\0';

   audio_driver_st.resampler_quality =
         audio_driver_get_resampler_quality(settings);

   if (!retro_resampler_realloc(
            &audio_driver_st.resampler_data,
            &audio_driver_st.resampler,
            audio_driver_st.resampler_ident,
            audio_driver_st.resampler_quality,
            audio_driver_st.source_ratio_original))
   {
      RARCH_ERR("Failed to initialize resampler \"%s\".\n",
            audio_driver_st.resampler_ident);
      audio_driver_st.flags &= ~AUDIO_FLAG_ACTIVE;
   }

   audio_driver_st.data_ptr   = 0;

   if (!(samples_buf = (float*)memalign_alloc(64, outsamples_max * sizeof(float))))
      goto error;

   audio_driver_st.output_samples_buf = (float*)samples_buf;
   audio_driver_st.flags             &= ~AUDIO_FLAG_CONTROL;

   if (
            !audio_cb_inited
         && (audio_driver_st.flags & AUDIO_FLAG_ACTIVE)
         && (audio_rate_control)
         )
   {
      /* Audio rate control requires write_avail
       * and buffer_size to be implemented. */
      if (audio_driver_st.current_audio->buffer_size)
      {
         audio_driver_st.buffer_size =
            audio_driver_st.current_audio->buffer_size(
                  audio_driver_st.context_audio_data);
         audio_driver_st.flags |= AUDIO_FLAG_CONTROL;
      }
      else
         RARCH_WARN("[Audio]: Rate control was desired, but driver does not support needed features.\n");
   }

   command_event(CMD_EVENT_DSP_FILTER_INIT, NULL);

   audio_driver_st.free_samples_count = 0;

#ifdef HAVE_AUDIOMIXER
   audio_mixer_init(settings->uints.audio_output_sample_rate);
#endif

   /* Threaded driver is initially stopped. */
   if (
            (audio_driver_st.flags & AUDIO_FLAG_ACTIVE)
         &&  audio_cb_inited
         )
      audio_driver_start(false);

   return true;

error:
   return audio_driver_deinit();
}

void audio_driver_sample(int16_t left, int16_t right)
{
   uint32_t runloop_flags;
   audio_driver_state_t *audio_st  = &audio_driver_st;
   recording_state_t *recording_st = NULL;
   if (audio_st->flags & AUDIO_FLAG_SUSPENDED)
      return;
   audio_st->output_samples_conv_buf[audio_st->data_ptr++] = left;
   audio_st->output_samples_conv_buf[audio_st->data_ptr++] = right;

   if (audio_st->data_ptr < audio_st->chunk_size)
      return;

   runloop_flags                   = runloop_get_flags();
   recording_st                    = recording_state_get_ptr();

   if (  recording_st->data     &&
         recording_st->driver   &&
         recording_st->driver->push_audio)
   {
      struct record_audio_data ffemu_data;

      ffemu_data.data                    = audio_st->output_samples_conv_buf;
      ffemu_data.frames                  = audio_st->data_ptr / 2;

      recording_st->driver->push_audio(recording_st->data, &ffemu_data);
   }

   if (!(    (runloop_flags & RUNLOOP_FLAG_PAUSED)
         || !(audio_st->flags & AUDIO_FLAG_ACTIVE)
         || !(audio_st->output_samples_buf)))
      audio_driver_flush(audio_st,
            config_get_ptr()->floats.slowmotion_ratio,
            config_get_ptr()->bools.audio_fastforward_mute,
            audio_st->output_samples_conv_buf,
            audio_st->data_ptr,
            runloop_flags & RUNLOOP_FLAG_SLOWMOTION,
            runloop_flags & RUNLOOP_FLAG_FASTMOTION);

   audio_st->data_ptr = 0;
}

size_t audio_driver_sample_batch(const int16_t *data, size_t frames)
{
   uint32_t runloop_flags;
   size_t frames_remaining        = frames;
   recording_state_t *record_st   = recording_state_get_ptr();
   audio_driver_state_t *audio_st = &audio_driver_st;

   if ((audio_st->flags & AUDIO_FLAG_SUSPENDED) || (frames < 1))
      return frames;

   runloop_flags                   = runloop_get_flags();

   /* We want to run this loop at least once, so use a
    * do...while (do...while has only a single conditional
    * jump, as opposed to for and while which have a
    * conditional jump and an unconditional jump). Note,
    * however, that this is only relevant for compilers
    * that are poor at optimisation... */
   do
   {
      size_t frames_to_write =
            (frames_remaining > (AUDIO_CHUNK_SIZE_NONBLOCKING >> 1)) ?
                  (AUDIO_CHUNK_SIZE_NONBLOCKING >> 1) : frames_remaining;

      if (    record_st->data
           && record_st->driver
           && record_st->driver->push_audio)
      {
         struct record_audio_data ffemu_data;

         ffemu_data.data   = data;
         ffemu_data.frames = frames_to_write;

         record_st->driver->push_audio(record_st->data, &ffemu_data);
      }

      if (!(    (runloop_flags & RUNLOOP_FLAG_PAUSED)
            || !(audio_st->flags & AUDIO_FLAG_ACTIVE)
            || !(audio_st->output_samples_buf)))
         audio_driver_flush(audio_st,
               config_get_ptr()->floats.slowmotion_ratio,
               config_get_ptr()->bools.audio_fastforward_mute,
               data,
               frames_to_write << 1,
               runloop_flags & RUNLOOP_FLAG_SLOWMOTION,
               runloop_flags & RUNLOOP_FLAG_FASTMOTION);

      frames_remaining -= frames_to_write;
      data             += frames_to_write << 1;
   }
   while (frames_remaining > 0);

   return frames;
}

#ifdef HAVE_REWIND
void audio_driver_sample_rewind(int16_t left, int16_t right)
{
   audio_driver_state_t *audio_st  = &audio_driver_st;
   if (audio_st->rewind_ptr == 0)
      return;

   audio_st->rewind_buf[--audio_st->rewind_ptr] = right;
   audio_st->rewind_buf[--audio_st->rewind_ptr] = left;
}

size_t audio_driver_sample_batch_rewind(
      const int16_t *data, size_t frames)
{
   size_t i;
   audio_driver_state_t *audio_st  = &audio_driver_st;
   size_t              samples     = frames << 1;

   for (i = 0; i < samples; i++)
   {
      if (audio_st->rewind_ptr < 1)
         break;

      audio_st->rewind_buf[--audio_st->rewind_ptr] = data[i];
   }

   return frames;
}
#endif

#ifdef HAVE_DSP_FILTER
void audio_driver_dsp_filter_free(void)
{
   audio_driver_state_t *audio_st  = &audio_driver_st;
   if (audio_st->dsp)
      retro_dsp_filter_free(audio_st->dsp);
   audio_st->dsp = NULL;
}

bool audio_driver_dsp_filter_init(const char *device)
{
   retro_dsp_filter_t *audio_driver_dsp = NULL;
   struct string_list *plugs            = NULL;
#if defined(HAVE_DYLIB) && !defined(HAVE_FILTERS_BUILTIN)
   char ext_name[32];
   char basedir[256];
   ext_name[0]             = '\0';
   fill_pathname_basedir(basedir, device, sizeof(basedir));
   if (!frontend_driver_get_core_extension(ext_name, sizeof(ext_name)))
      return false;
   if (!(plugs = dir_list_new(basedir, ext_name, false, true, false, false)))
      return false;
#endif
   audio_driver_dsp = retro_dsp_filter_new(
         device, plugs, audio_driver_st.input);
   if (!audio_driver_dsp)
      return false;

   audio_driver_st.dsp = audio_driver_dsp;

   return true;
}
#endif

void audio_driver_set_buffer_size(size_t bufsize)
{
   audio_driver_st.buffer_size = bufsize;
}

float audio_driver_monitor_adjust_system_rates(
      double input_sample_rate,
      double input_fps,
      float video_refresh_rate,
      unsigned video_swap_interval,
      float audio_max_timing_skew)
{
   float inp_sample_rate        = input_sample_rate;
   float target_video_sync_rate = video_refresh_rate
         / (float)video_swap_interval;
   float timing_skew            =
      fabs(1.0f - input_fps / target_video_sync_rate);
   if (timing_skew <= audio_max_timing_skew)
      return (inp_sample_rate * target_video_sync_rate / input_fps);
   return inp_sample_rate;
}

#ifdef HAVE_REWIND
void audio_driver_setup_rewind(void)
{
   unsigned i;
   audio_driver_state_t *audio_st  = &audio_driver_st;

   /* Push audio ready to be played. */
   audio_st->rewind_ptr = audio_st->rewind_size;

   for (i = 0; i < audio_st->data_ptr; i += 2)
   {
      if (audio_st->rewind_ptr > 0)
         audio_st->rewind_buf[--audio_st->rewind_ptr] =
            audio_st->output_samples_conv_buf[i + 1];

      if (audio_st->rewind_ptr > 0)
         audio_st->rewind_buf[--audio_st->rewind_ptr] =
            audio_st->output_samples_conv_buf[i + 0];
   }

   audio_st->data_ptr = 0;
}
#endif

bool audio_driver_get_devices_list(void **data)
{
   struct string_list**ptr     = (struct string_list**)data;
   if (!ptr)
      return false;
   *ptr = audio_driver_st.devices_list;
   return true;
}

#ifdef HAVE_AUDIOMIXER
bool audio_driver_mixer_extension_supported(const char *ext)
{
   unsigned i;
   struct string_list str_list;
   union string_list_elem_attr attr;
   bool ret                      = false;

   attr.i = 0;
   if (!string_list_initialize(&str_list))
      return false;

#ifdef HAVE_STB_VORBIS
   string_list_append(&str_list, "ogg", attr);
#endif
#ifdef HAVE_IBXM
   string_list_append(&str_list, "mod", attr);
   string_list_append(&str_list, "s3m", attr);
   string_list_append(&str_list, "xm", attr);
#endif
#ifdef HAVE_DR_FLAC
   string_list_append(&str_list, "flac", attr);
#endif
#ifdef HAVE_DR_MP3
   string_list_append(&str_list, "mp3", attr);
#endif
   string_list_append(&str_list, "wav", attr);

   for (i = 0; i < str_list.size; i++)
   {
      const char *str_ext = str_list.elems[i].data;
      if (string_is_equal_noncase(str_ext, ext))
      {
         ret = true;
         break;
      }
   }

   string_list_deinitialize(&str_list);

   return ret;
}

static int audio_mixer_find_index(
      audio_mixer_sound_t *sound)
{
   unsigned i;

   for (i = 0; i < AUDIO_MIXER_MAX_SYSTEM_STREAMS; i++)
   {
      audio_mixer_sound_t *handle = audio_driver_st.mixer_streams[i].handle;
      if (handle == sound)
         return i;
   }
   return -1;
}

static void audio_mixer_play_stop_cb(
      audio_mixer_sound_t *sound, unsigned reason)
{
   int                     idx = audio_mixer_find_index(sound);

   switch (reason)
   {
      case AUDIO_MIXER_SOUND_FINISHED:
         audio_mixer_destroy(sound);

         if (idx >= 0)
         {
            unsigned i = (unsigned)idx;

            if (!string_is_empty(audio_driver_st.mixer_streams[i].name))
               free(audio_driver_st.mixer_streams[i].name);

            audio_driver_st.mixer_streams[i].name    = NULL;
            audio_driver_st.mixer_streams[i].state   = AUDIO_STREAM_STATE_NONE;
            audio_driver_st.mixer_streams[i].volume  = 0.0f;
            audio_driver_st.mixer_streams[i].buf     = NULL;
            audio_driver_st.mixer_streams[i].stop_cb = NULL;
            audio_driver_st.mixer_streams[i].handle  = NULL;
            audio_driver_st.mixer_streams[i].voice   = NULL;
         }
         break;
      case AUDIO_MIXER_SOUND_STOPPED:
         break;
      case AUDIO_MIXER_SOUND_REPEATED:
         break;
   }
}

static void audio_mixer_menu_stop_cb(
      audio_mixer_sound_t *sound, unsigned reason)
{
   int                     idx = audio_mixer_find_index(sound);

   switch (reason)
   {
      case AUDIO_MIXER_SOUND_FINISHED:
         if (idx >= 0)
         {
            unsigned i                              = (unsigned)idx;
            audio_driver_st.mixer_streams[i].state   = AUDIO_STREAM_STATE_STOPPED;
            audio_driver_st.mixer_streams[i].volume  = 0.0f;
         }
         break;
      case AUDIO_MIXER_SOUND_STOPPED:
      case AUDIO_MIXER_SOUND_REPEATED:
         break;
   }
}

static void audio_mixer_play_stop_sequential_cb(
      audio_mixer_sound_t *sound, unsigned reason)
{
   int                     idx = audio_mixer_find_index(sound);

   switch (reason)
   {
      case AUDIO_MIXER_SOUND_FINISHED:
         audio_mixer_destroy(sound);

         if (idx >= 0)
         {
            unsigned i = (unsigned)idx;

            if (!string_is_empty(audio_driver_st.mixer_streams[i].name))
               free(audio_driver_st.mixer_streams[i].name);

            if (i < AUDIO_MIXER_MAX_STREAMS)
               audio_driver_st.mixer_streams[i].stream_type = AUDIO_STREAM_TYPE_USER;
            else
               audio_driver_st.mixer_streams[i].stream_type = AUDIO_STREAM_TYPE_SYSTEM;

            audio_driver_st.mixer_streams[i].name           = NULL;
            audio_driver_st.mixer_streams[i].state          = AUDIO_STREAM_STATE_NONE;
            audio_driver_st.mixer_streams[i].volume         = 0.0f;
            audio_driver_st.mixer_streams[i].buf            = NULL;
            audio_driver_st.mixer_streams[i].stop_cb        = NULL;
            audio_driver_st.mixer_streams[i].handle         = NULL;
            audio_driver_st.mixer_streams[i].voice          = NULL;

            i++;

            for (; i < AUDIO_MIXER_MAX_SYSTEM_STREAMS; i++)
            {
               if (audio_driver_st.mixer_streams[i].state
                     == AUDIO_STREAM_STATE_STOPPED)
               {
                  audio_driver_mixer_play_stream_sequential(i);
                  break;
               }
            }
         }
         break;
      case AUDIO_MIXER_SOUND_STOPPED:
      case AUDIO_MIXER_SOUND_REPEATED:
         break;
   }
}

static bool audio_driver_mixer_get_free_stream_slot(
      unsigned *id, enum audio_mixer_stream_type type)
{
   unsigned                  i = AUDIO_MIXER_MAX_STREAMS;
   unsigned              count = AUDIO_MIXER_MAX_SYSTEM_STREAMS;

   if (type == AUDIO_STREAM_TYPE_USER)
   {
      i                        = 0;
      count                    = AUDIO_MIXER_MAX_STREAMS;
   }

   for (; i < count; i++)
   {
      if (audio_driver_st.mixer_streams[i].state == AUDIO_STREAM_STATE_NONE)
      {
         *id = i;
         return true;
      }
   }

   return false;
}

bool audio_driver_mixer_add_stream(audio_mixer_stream_params_t *params)
{
   unsigned free_slot            = 0;
   audio_mixer_voice_t *voice    = NULL;
   audio_mixer_sound_t *handle   = NULL;
   audio_mixer_stop_cb_t stop_cb = audio_mixer_play_stop_cb;
   bool looped                   = (params->state == AUDIO_STREAM_STATE_PLAYING_LOOPED);
   void *buf                     = NULL;

   if (params->stream_type == AUDIO_STREAM_TYPE_NONE)
      return false;

   switch (params->slot_selection_type)
   {
      case AUDIO_MIXER_SLOT_SELECTION_MANUAL:
         free_slot = params->slot_selection_idx;

         /* If we are using a manually specified
          * slot, must free any existing stream
          * before assigning the new one */
         audio_driver_mixer_stop_stream(free_slot);
         audio_driver_mixer_remove_stream(free_slot);

         break;
      case AUDIO_MIXER_SLOT_SELECTION_AUTOMATIC:
      default:
         if (!audio_driver_mixer_get_free_stream_slot(
                  &free_slot, params->stream_type))
            return false;
         break;
   }

   if (params->state == AUDIO_STREAM_STATE_NONE)
      return false;

   if (!(buf = malloc(params->bufsize)))
      return false;

   memcpy(buf, params->buf, params->bufsize);

   switch (params->type)
   {
      case AUDIO_MIXER_TYPE_WAV:
         handle = audio_mixer_load_wav(buf, (int32_t)params->bufsize,
               audio_driver_st.resampler_ident,
               audio_driver_st.resampler_quality);
         /* WAV is a special case - input buffer is not
          * free()'d when sound playback is complete (it is
          * converted to a PCM buffer, which is free()'d instead),
          * so have to do it here */
         free(buf);
         buf = NULL;
         break; 
      case AUDIO_MIXER_TYPE_OGG:
         handle = audio_mixer_load_ogg(buf, (int32_t)params->bufsize);
         break;
      case AUDIO_MIXER_TYPE_MOD:
         handle = audio_mixer_load_mod(buf, (int32_t)params->bufsize);
         break;
      case AUDIO_MIXER_TYPE_FLAC:
#ifdef HAVE_DR_FLAC
         handle = audio_mixer_load_flac(buf, (int32_t)params->bufsize);
#endif
         break;
      case AUDIO_MIXER_TYPE_MP3:
#ifdef HAVE_DR_MP3
         handle = audio_mixer_load_mp3(buf, (int32_t)params->bufsize);
#endif
         break;
      case AUDIO_MIXER_TYPE_NONE:
         break;
   }

   if (!handle)
   {
      free(buf);
      return false;
   }

   switch (params->state)
   {
      case AUDIO_STREAM_STATE_PLAYING_SEQUENTIAL:
         stop_cb = audio_mixer_play_stop_sequential_cb;
         /* fall-through */
      case AUDIO_STREAM_STATE_PLAYING_LOOPED:
      case AUDIO_STREAM_STATE_PLAYING:
         voice = audio_mixer_play(handle, looped, params->volume,
               audio_driver_st.resampler_ident,
               audio_driver_st.resampler_quality, stop_cb);
         break;
      default:
         break;
   }

   audio_driver_st.flags |= AUDIO_FLAG_MIXER_ACTIVE;

   audio_driver_st.mixer_streams[free_slot].name        =
      !string_is_empty(params->basename) ? strdup(params->basename) : NULL;
   audio_driver_st.mixer_streams[free_slot].buf         = buf;
   audio_driver_st.mixer_streams[free_slot].handle      = handle;
   audio_driver_st.mixer_streams[free_slot].voice       = voice;
   audio_driver_st.mixer_streams[free_slot].stream_type = params->stream_type;
   audio_driver_st.mixer_streams[free_slot].type        = params->type;
   audio_driver_st.mixer_streams[free_slot].state       = params->state;
   audio_driver_st.mixer_streams[free_slot].volume      = params->volume;
   audio_driver_st.mixer_streams[free_slot].stop_cb     = stop_cb;

   return true;
}

enum audio_mixer_state audio_driver_mixer_get_stream_state(unsigned i)
{
   if (i >= AUDIO_MIXER_MAX_SYSTEM_STREAMS)
      return AUDIO_STREAM_STATE_NONE;

   return audio_driver_st.mixer_streams[i].state;
}

static void audio_driver_mixer_play_stream_internal(
      unsigned i, unsigned type)
{
   if (i >= AUDIO_MIXER_MAX_SYSTEM_STREAMS)
      return;

   switch (audio_driver_st.mixer_streams[i].state)
   {
      case AUDIO_STREAM_STATE_STOPPED:
         audio_driver_st.mixer_streams[i].voice =
            audio_mixer_play(audio_driver_st.mixer_streams[i].handle,
               (type == AUDIO_STREAM_STATE_PLAYING_LOOPED) ? true : false,
               1.0f, audio_driver_st.resampler_ident,
               audio_driver_st.resampler_quality,
               audio_driver_st.mixer_streams[i].stop_cb);
         audio_driver_st.mixer_streams[i].state = (enum audio_mixer_state)type;
         break;
      case AUDIO_STREAM_STATE_PLAYING:
      case AUDIO_STREAM_STATE_PLAYING_LOOPED:
      case AUDIO_STREAM_STATE_PLAYING_SEQUENTIAL:
      case AUDIO_STREAM_STATE_NONE:
         break;
   }
}

static void audio_driver_load_menu_bgm_callback(retro_task_t *task,
      void *task_data, void *user_data, const char *error)
{
   uint8_t flags = content_get_flags();
   if (!(flags & CONTENT_ST_FLAG_IS_INITED))
      audio_driver_mixer_play_menu_sound_looped(AUDIO_MIXER_SYSTEM_SLOT_BGM);
}

void audio_driver_load_system_sounds(void)
{
   char basename_noext[256];
   char sounds_path[PATH_MAX_LENGTH];
   char sounds_fallback_path[PATH_MAX_LENGTH];
   settings_t *settings                  = config_get_ptr();
   const char *dir_assets                = settings->paths.directory_assets;
   const bool audio_enable_menu          = settings->bools.audio_enable_menu;
   const bool audio_enable_menu_ok       = audio_enable_menu && settings->bools.audio_enable_menu_ok;
   const bool audio_enable_menu_cancel   = audio_enable_menu && settings->bools.audio_enable_menu_cancel;
   const bool audio_enable_menu_notice   = audio_enable_menu && settings->bools.audio_enable_menu_notice;
   const bool audio_enable_menu_bgm      = audio_enable_menu && settings->bools.audio_enable_menu_bgm;
   const bool audio_enable_menu_scroll   = audio_enable_menu && settings->bools.audio_enable_menu_scroll;
   const bool audio_enable_cheevo_unlock = settings->bools.cheevos_unlock_sound_enable;
   const char *path_ok                   = NULL;
   const char *path_cancel               = NULL;
   const char *path_notice               = NULL;
   const char *path_notice_back          = NULL;
   const char *path_bgm                  = NULL;
   const char *path_cheevo_unlock        = NULL;
   const char *path_up                   = NULL;
   const char *path_down                 = NULL;
   struct string_list *list              = NULL;
   struct string_list *list_fallback     = NULL;
   unsigned i                            = 0;

   if (!audio_enable_menu && !audio_enable_cheevo_unlock)
      goto end;

   sounds_path[0] = basename_noext[0] ='\0';

   fill_pathname_join_special(
         sounds_fallback_path,
         dir_assets,
         "sounds",
         sizeof(sounds_fallback_path));

   fill_pathname_application_special(
         sounds_path,
         sizeof(sounds_path),
         APPLICATION_SPECIAL_DIRECTORY_ASSETS_SOUNDS);

   list          = dir_list_new(sounds_path, MENU_SOUND_FORMATS, false, false, false, false);
   list_fallback = dir_list_new(sounds_fallback_path, MENU_SOUND_FORMATS, false, false, false, false);

   if (!list)
   {
      list          = list_fallback;
      list_fallback = NULL;
   }

   if (!list || list->size == 0)
      goto end;

   if (list_fallback && list_fallback->size > 0)
   {
      for (i = 0; i < list_fallback->size; i++)
      {
         if (list->size == 0 || !string_list_find_elem(list, list_fallback->elems[i].data))
         {
            union string_list_elem_attr attr = {0};
            string_list_append(list, list_fallback->elems[i].data, attr);
         }
      }
   }

   for (i = 0; i < list->size; i++)
   {
      const char *path = list->elems[i].data;
      const char *ext  = path_get_extension(path);

      if (audio_driver_mixer_extension_supported(ext))
      {
         basename_noext[0] = '\0';
         fill_pathname_base(basename_noext, path, sizeof(basename_noext));
         path_remove_extension(basename_noext);

         if (string_is_equal_noncase(basename_noext, "ok"))
            path_ok = path;
         else if (string_is_equal_noncase(basename_noext, "cancel"))
            path_cancel = path;
         else if (string_is_equal_noncase(basename_noext, "notice"))
            path_notice = path;
         else if (string_is_equal_noncase(basename_noext, "notice_back"))
            path_notice_back = path;
         else if (string_is_equal_noncase(basename_noext, "bgm"))
            path_bgm = path;
         else if (string_is_equal_noncase(basename_noext, "unlock"))
            path_cheevo_unlock = path;
         else if (string_is_equal_noncase(basename_noext, "up"))
            path_up = path;
         else if (string_is_equal_noncase(basename_noext, "down"))
            path_down = path;
      }
   }

   if (path_ok && audio_enable_menu_ok)
      task_push_audio_mixer_load(path_ok, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_OK);
   if (path_cancel && audio_enable_menu_cancel)
      task_push_audio_mixer_load(path_cancel, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_CANCEL);
   if (audio_enable_menu_notice) {
      if (path_notice)
         task_push_audio_mixer_load(path_notice, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_NOTICE);
      if (path_notice_back)
          task_push_audio_mixer_load(path_notice_back, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_NOTICE_BACK);
   }
   if (path_bgm && audio_enable_menu_bgm)
      task_push_audio_mixer_load(path_bgm, audio_driver_load_menu_bgm_callback, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_BGM);
   if (path_cheevo_unlock && audio_enable_cheevo_unlock)
      task_push_audio_mixer_load(path_cheevo_unlock, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_ACHIEVEMENT_UNLOCK);
   if (audio_enable_menu_scroll) 
   {
      if (path_up)
         task_push_audio_mixer_load(path_up, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_UP);
      if (path_down)
         task_push_audio_mixer_load(path_down, NULL, NULL, true, AUDIO_MIXER_SLOT_SELECTION_MANUAL, AUDIO_MIXER_SYSTEM_SLOT_DOWN);
   }
end:
   if (list)
      string_list_free(list);
   if (list_fallback)
      string_list_free(list_fallback);
}

void audio_driver_mixer_play_stream(unsigned i)
{
   audio_driver_st.mixer_streams[i].stop_cb = audio_mixer_play_stop_cb;
   audio_driver_mixer_play_stream_internal(i, AUDIO_STREAM_STATE_PLAYING);
}

void audio_driver_mixer_play_menu_sound_looped(unsigned i)
{
   audio_driver_st.mixer_streams[i].stop_cb = audio_mixer_menu_stop_cb;
   audio_driver_mixer_play_stream_internal(i, AUDIO_STREAM_STATE_PLAYING_LOOPED);
}

void audio_driver_mixer_play_menu_sound(unsigned i)
{
   audio_driver_st.mixer_streams[i].stop_cb = audio_mixer_menu_stop_cb;
   audio_driver_mixer_stop_stream(i);
   audio_driver_mixer_play_stream_internal(i, AUDIO_STREAM_STATE_PLAYING);
}

void audio_driver_mixer_play_scroll_sound(bool direction_up) 
{
   settings_t *settings          = config_get_ptr();
   bool        audio_enable_menu = settings->bools.audio_enable_menu;
   bool audio_enable_menu_scroll = settings->bools.audio_enable_menu_scroll;
   if (audio_enable_menu && audio_enable_menu_scroll)
      audio_driver_mixer_play_menu_sound(direction_up ? AUDIO_MIXER_SYSTEM_SLOT_UP : AUDIO_MIXER_SYSTEM_SLOT_DOWN);  
}

void audio_driver_mixer_play_stream_looped(unsigned i)
{
   audio_driver_st.mixer_streams[i].stop_cb = audio_mixer_play_stop_cb;
   audio_driver_mixer_play_stream_internal(i, AUDIO_STREAM_STATE_PLAYING_LOOPED);
}

void audio_driver_mixer_play_stream_sequential(unsigned i)
{
   audio_driver_st.mixer_streams[i].stop_cb = audio_mixer_play_stop_sequential_cb;
   audio_driver_mixer_play_stream_internal(i, AUDIO_STREAM_STATE_PLAYING_SEQUENTIAL);
}

float audio_driver_mixer_get_stream_volume(unsigned i)
{
   if (i >= AUDIO_MIXER_MAX_SYSTEM_STREAMS)
      return 0.0f;

   return audio_driver_st.mixer_streams[i].volume;
}

void audio_driver_mixer_set_stream_volume(unsigned i, float vol)
{
   audio_mixer_voice_t *voice             = NULL;

   if (i >= AUDIO_MIXER_MAX_SYSTEM_STREAMS)
      return;

   audio_driver_st.mixer_streams[i].volume = vol;

   voice                                  =
      audio_driver_st.mixer_streams[i].voice;

   if (voice)
      audio_mixer_voice_set_volume(voice, DB_TO_GAIN(vol));
}

void audio_driver_mixer_stop_stream(unsigned i)
{
   if (i >= AUDIO_MIXER_MAX_SYSTEM_STREAMS)
      return;

   switch (audio_driver_st.mixer_streams[i].state)
   {
      case AUDIO_STREAM_STATE_PLAYING:
      case AUDIO_STREAM_STATE_PLAYING_LOOPED:
      case AUDIO_STREAM_STATE_PLAYING_SEQUENTIAL:
         {
            audio_mixer_voice_t *voice     = audio_driver_st.mixer_streams[i].voice;

            if (voice)
               audio_mixer_stop(voice);
            audio_driver_st.mixer_streams[i].state   = AUDIO_STREAM_STATE_STOPPED;
            audio_driver_st.mixer_streams[i].volume  = 1.0f;
         }
         break;
      case AUDIO_STREAM_STATE_STOPPED:
      case AUDIO_STREAM_STATE_NONE:
         break;
   }
}

void audio_driver_mixer_remove_stream(unsigned i)
{
   if (i >= AUDIO_MIXER_MAX_SYSTEM_STREAMS)
      return;

   switch (audio_driver_st.mixer_streams[i].state)
   {
      case AUDIO_STREAM_STATE_PLAYING:
      case AUDIO_STREAM_STATE_PLAYING_LOOPED:
      case AUDIO_STREAM_STATE_PLAYING_SEQUENTIAL:
         audio_driver_mixer_stop_stream(i);
         /* fall-through */
      case AUDIO_STREAM_STATE_STOPPED:
         {
            audio_mixer_sound_t *handle = audio_driver_st.mixer_streams[i].handle;
            if (handle)
               audio_mixer_destroy(handle);

            if (!string_is_empty(audio_driver_st.mixer_streams[i].name))
               free(audio_driver_st.mixer_streams[i].name);

            audio_driver_st.mixer_streams[i].state   = AUDIO_STREAM_STATE_NONE;
            audio_driver_st.mixer_streams[i].stop_cb = NULL;
            audio_driver_st.mixer_streams[i].volume  = 0.0f;
            audio_driver_st.mixer_streams[i].handle  = NULL;
            audio_driver_st.mixer_streams[i].voice   = NULL;
            audio_driver_st.mixer_streams[i].name    = NULL;
         }
         break;
      case AUDIO_STREAM_STATE_NONE:
         break;
   }

}

bool audio_driver_mixer_toggle_mute(void)
{
   audio_driver_st.mixer_mute_enable  =
      !audio_driver_st.mixer_mute_enable;
   return true;
}
#endif

bool audio_driver_enable_callback(void)
{
   if (!audio_driver_st.callback.callback)
      return false;
   if (audio_driver_st.callback.set_state)
      audio_driver_st.callback.set_state(true);
   return true;
}

bool audio_driver_disable_callback(void)
{
   if (!audio_driver_st.callback.callback)
      return false;

   if (audio_driver_st.callback.set_state)
      audio_driver_st.callback.set_state(false);
   return true;
}

bool audio_driver_callback(void)
{
   settings_t *settings        = config_get_ptr();
   uint32_t runloop_flags      = runloop_get_flags();
   bool runloop_paused         = runloop_flags & RUNLOOP_FLAG_PAUSED;
#ifdef HAVE_MENU
#ifdef HAVE_NETWORKING
   bool core_paused            = runloop_paused ||
      (    settings->bools.menu_pause_libretro 
       && (menu_state_get_ptr()->flags & MENU_ST_FLAG_ALIVE)
       &&  netplay_driver_ctl(RARCH_NETPLAY_CTL_ALLOW_PAUSE, NULL));
#else
   bool core_paused            = runloop_paused ||
     (settings->bools.menu_pause_libretro 
      && (menu_state_get_ptr()->flags & MENU_ST_FLAG_ALIVE));
#endif
#else
   bool core_paused            = runloop_paused;
#endif

   if (!audio_driver_st.callback.callback)
      return false;

   if (!core_paused && audio_driver_st.callback.callback)
      audio_driver_st.callback.callback();

   return true;
}

bool audio_driver_has_callback(void)
{
   return audio_driver_st.callback.callback != NULL;
}

static INLINE bool audio_driver_alive(void)
{
   audio_driver_state_t *audio_st = &audio_driver_st;
   if (     audio_st->current_audio
         && audio_st->current_audio->alive
         && audio_st->context_audio_data)
      return audio_st->current_audio->alive(audio_st->context_audio_data);
   return false;
}

bool audio_driver_start(bool is_shutdown)
{
   audio_driver_state_t *audio_st = &audio_driver_st;
   if (
            !audio_st->current_audio 
         || !audio_st->current_audio->start
         || !audio_st->context_audio_data)
      goto error;
   if (!audio_st->current_audio->start(
            audio_st->context_audio_data, is_shutdown))
      goto error;

   return true;

error:
   RARCH_ERR("%s\n",
         msg_hash_to_str(MSG_FAILED_TO_START_AUDIO_DRIVER));
   audio_driver_st.flags &= ~AUDIO_FLAG_ACTIVE;
   return false;
}

bool audio_driver_stop(void)
{
   if (     !audio_driver_st.current_audio
         || !audio_driver_st.current_audio->stop
         || !audio_driver_st.context_audio_data
         || !audio_driver_alive()
      )
      return false;
   return audio_driver_st.current_audio->stop(
         audio_driver_st.context_audio_data);
}

#ifdef HAVE_REWIND
void audio_driver_frame_is_reverse(void)
{
   audio_driver_state_t *audio_st  = &audio_driver_st;
   recording_state_t *recording_st = recording_state_get_ptr();
   uint32_t runloop_flags          = runloop_get_flags();

   /* We just rewound. Flush rewind audio buffer. */
   if (  recording_st->data   &&
         recording_st->driver &&
         recording_st->driver->push_audio)
   {
      struct record_audio_data ffemu_data;

      ffemu_data.data              = audio_st->rewind_buf +
         audio_st->rewind_ptr;
      ffemu_data.frames            = (audio_st->rewind_size -
            audio_st->rewind_ptr) / 2;

      recording_st->driver->push_audio(
            recording_st->data,
            &ffemu_data);
   }

   if (!(
             (runloop_flags & RUNLOOP_FLAG_PAUSED)
         || !(audio_st->flags & AUDIO_FLAG_ACTIVE)
         || !(audio_st->output_samples_buf)))
      if (!(audio_st->flags & AUDIO_FLAG_SUSPENDED))
      {
         settings_t *settings = config_get_ptr();
         audio_driver_flush(audio_st,
               settings->floats.slowmotion_ratio,
               settings->bools.audio_fastforward_mute,
               audio_st->rewind_buf  +
               audio_st->rewind_ptr,
               audio_st->rewind_size -
               audio_st->rewind_ptr,
               runloop_flags & RUNLOOP_FLAG_SLOWMOTION,
               runloop_flags & RUNLOOP_FLAG_FASTMOTION);
      }
}
#endif

void audio_set_float(enum audio_action action, float val)
{
   switch (action)
   {
      case AUDIO_ACTION_VOLUME_GAIN:
         audio_driver_st.volume_gain        = DB_TO_GAIN(val);
         break;
      case AUDIO_ACTION_MIXER_VOLUME_GAIN:
#ifdef HAVE_AUDIOMIXER
         audio_driver_st.mixer_volume_gain  = DB_TO_GAIN(val);
#endif
         break;
      case AUDIO_ACTION_RATE_CONTROL_DELTA:
         audio_driver_st.rate_control_delta = val;
         break;
      case AUDIO_ACTION_NONE:
      default:
         break;
   }
}

float *audio_get_float_ptr(enum audio_action action)
{
   switch (action)
   {
      case AUDIO_ACTION_RATE_CONTROL_DELTA:
         return &audio_driver_st.rate_control_delta;
      case AUDIO_ACTION_NONE:
      default:
         break;
   }

   return NULL;
}

bool *audio_get_bool_ptr(enum audio_action action)
{
   switch (action)
   {
      case AUDIO_ACTION_MIXER_MUTE_ENABLE:
#ifdef HAVE_AUDIOMIXER
         return &audio_driver_st.mixer_mute_enable;
#else
         break;
#endif
      case AUDIO_ACTION_MUTE_ENABLE:
         return &audio_driver_st.mute_enable;
      case AUDIO_ACTION_NONE:
      default:
         break;
   }

   return NULL;
}

bool audio_compute_buffer_statistics(audio_statistics_t *stats)
{
   unsigned i, low_water_size, high_water_size, avg, stddev;
   uint64_t accum                 = 0;
   uint64_t accum_var             = 0;
   unsigned low_water_count       = 0;
   unsigned high_water_count      = 0;
   audio_driver_state_t *audio_st = &audio_driver_st;
   unsigned samples               = MIN(
         (unsigned)audio_st->free_samples_count,
         AUDIO_BUFFER_FREE_SAMPLES_COUNT);

   if (samples < 3)
      return false;

   stats->samples                = (unsigned)
      audio_st->free_samples_count;

#ifdef WARPUP
   /* uint64 to double not implemented, fair chance
    * signed int64 to double doesn't exist either */
   /* https://forums.libretro.com/t/unsupported-platform-help/13903/ */
   (void)stddev;
#elif defined(_MSC_VER) && _MSC_VER <= 1200
   /* FIXME: error C2520: conversion from unsigned __int64
    * to double not implemented, use signed __int64 */
   (void)stddev;
#else
   for (i = 1; i < samples; i++)
      accum += audio_st->free_samples_buf[i];

   avg = (unsigned)accum / (samples - 1);

   for (i = 1; i < samples; i++)
   {
      int diff     = avg - audio_st->free_samples_buf[i];
      accum_var   += diff * diff;
   }

   stddev                                = (unsigned)
      sqrt((double)accum_var / (samples - 2));

   stats->average_buffer_saturation      = (1.0f - (float)avg
         / audio_st->buffer_size) * 100.0;
   stats->std_deviation_percentage       = ((float)stddev
         / audio_st->buffer_size)  * 100.0;
#endif

   low_water_size  = (unsigned)(audio_st->buffer_size * 3 / 4);
   high_water_size = (unsigned)(audio_st->buffer_size     / 4);

   for (i = 1; i < samples; i++)
   {
      if (audio_st->free_samples_buf[i] >= low_water_size)
         low_water_count++;
      else if (audio_st->free_samples_buf[i] <= high_water_size)
         high_water_count++;
   }

   stats->close_to_underrun      = (100.0f * low_water_count)  / (samples - 1);
   stats->close_to_blocking      = (100.0f * high_water_count) / (samples - 1);

   return true;
}

#ifdef HAVE_MENU
void audio_driver_menu_sample(void)
{
   static int16_t samples_buf[1024]       = {0};
   settings_t *settings                   = config_get_ptr();
   video_driver_state_t *video_st         = video_state_get_ptr();
   uint32_t runloop_flags                 = runloop_get_flags();
   recording_state_t *recording_st        = recording_state_get_ptr();
   struct retro_system_av_info *av_info   = &video_st->av_info;
   const struct retro_system_timing *info =
      (const struct retro_system_timing*)&av_info->timing;
   unsigned sample_count                  = (info->sample_rate / info->fps) * 2;
   audio_driver_state_t *audio_st         = &audio_driver_st;
   bool check_flush                       = !(
             (runloop_flags & RUNLOOP_FLAG_PAUSED)
         || !(audio_st->flags & AUDIO_FLAG_ACTIVE)
         || !audio_st->output_samples_buf);
   if ((audio_st->flags & AUDIO_FLAG_SUSPENDED))
      check_flush                         = false;

   while (sample_count > 1024)
   {
      if (  recording_st->data   &&
            recording_st->driver &&
            recording_st->driver->push_audio)
      {
         struct record_audio_data ffemu_data;

         ffemu_data.data                    = samples_buf;
         ffemu_data.frames                  = 1024 / 2;

         recording_st->driver->push_audio(
               recording_st->data, &ffemu_data);
      }
      if (check_flush)
         audio_driver_flush(audio_st,
               settings->floats.slowmotion_ratio,
               settings->bools.audio_fastforward_mute,
               samples_buf,
               1024,
               runloop_flags & RUNLOOP_FLAG_SLOWMOTION,
               runloop_flags & RUNLOOP_FLAG_FASTMOTION);
      sample_count -= 1024;
   }
   if (  recording_st->data   &&
         recording_st->driver &&
         recording_st->driver->push_audio)
   {
      struct record_audio_data ffemu_data;

      ffemu_data.data                    = samples_buf;
      ffemu_data.frames                  = sample_count / 2;

      recording_st->driver->push_audio(
            recording_st->data, &ffemu_data);
   }
   if (check_flush)
      audio_driver_flush(audio_st,
            settings->floats.slowmotion_ratio,
            settings->bools.audio_fastforward_mute,
            samples_buf,
            sample_count,
            runloop_flags & RUNLOOP_FLAG_SLOWMOTION,
            runloop_flags & RUNLOOP_FLAG_FASTMOTION);
}
#endif
