apple: use coreaudio resampling, add coreaudio3 driver to ios/tvos

Author: warmenhoven

audio/audio_driver.c

@@ -99,7 +99,8 @@ audio_driver_t audio_null = {
    NULL,
    NULL,
    NULL, /* write_avail */
-   NULL  /* buffer_size */
+   NULL, /* buffer_size */
+   NULL  /* write_raw */
 };
 
 audio_driver_t *audio_drivers[] = {
@@ -456,6 +457,45 @@ static void audio_driver_flush(audio_driver_state_t *audio_st,
                ? 0.0f
                : audio_st->volume_gain;
 
+   /* Fast path: if driver handles resampling and no DSP/mixer is active,
+    * bypass software resampling entirely. */
+   if (audio_st->current_audio->write_raw
+#ifdef HAVE_DSP_FILTER
+         && !audio_st->dsp
+#endif
+#ifdef HAVE_AUDIOMIXER
+         && audio_st->mixer_streams_playing == 0
+#endif
+      )
+   {
+      size_t frames                  = samples >> 1;
+      double rate_adjust             = 1.0;
+      unsigned input_rate            = (unsigned)audio_st->input;
+
+      /* Rate control for A/V sync */
+      if (audio_st->flags & AUDIO_FLAG_CONTROL)
+      {
+         unsigned write_idx          =
+               audio_st->free_samples_count++ & (AUDIO_BUFFER_FREE_SAMPLES_COUNT - 1);
+         int avail                   = (int)audio_st->current_audio->write_avail(
+               audio_st->context_audio_data);
+         int half_size               = (int)(audio_st->buffer_size / 2);
+         int delta_mid               = avail - half_size;
+         double direction            = (double)delta_mid / half_size;
+
+         audio_st->free_samples_buf[write_idx] = avail;
+         rate_adjust                 = 1.0 + audio_st->rate_control_delta * direction;
+      }
+
+      if (is_slowmotion)
+         rate_adjust                *= slowmotion_ratio;
+
+      /* Note: mute/volume is not applied here - driver must handle or ignore */
+      audio_st->current_audio->write_raw(audio_st->context_audio_data,
+            data, frames, input_rate, rate_adjust);
+      return;
+   }
+
    src_data.data_out                 = NULL;
    src_data.output_frames            = 0;
    /* We'll assign a proper output to the resampler later in this function */
@@ -1121,6 +1161,8 @@ static void audio_mixer_play_stop_cb(
             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;
+            if (audio_driver_st.mixer_streams_playing > 0)
+               audio_driver_st.mixer_streams_playing--;
          }
          break;
       case AUDIO_MIXER_SOUND_STOPPED:
@@ -1143,6 +1185,8 @@ static void audio_mixer_menu_stop_cb(
             unsigned i                              = (unsigned)idx;
             audio_driver_st.mixer_streams[i].state   = AUDIO_STREAM_STATE_STOPPED;
             audio_driver_st.mixer_streams[i].volume  = 0.0f;
+            if (audio_driver_st.mixer_streams_playing > 0)
+               audio_driver_st.mixer_streams_playing--;
          }
          break;
       case AUDIO_MIXER_SOUND_STOPPED:
@@ -1180,6 +1224,8 @@ static void audio_mixer_play_stop_sequential_cb(
             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;
+            if (audio_driver_st.mixer_streams_playing > 0)
+               audio_driver_st.mixer_streams_playing--;
 
             i++;
 
@@ -1330,6 +1376,11 @@ bool audio_driver_mixer_add_stream(audio_mixer_stream_params_t *params)
    audio_driver_st.mixer_streams[free_slot].volume      = params->volume;
    audio_driver_st.mixer_streams[free_slot].stop_cb     = stop_cb;
 
+   if (   params->state == AUDIO_STREAM_STATE_PLAYING
+       || params->state == AUDIO_STREAM_STATE_PLAYING_LOOPED
+       || params->state == AUDIO_STREAM_STATE_PLAYING_SEQUENTIAL)
+      audio_driver_st.mixer_streams_playing++;
+
    return true;
 }
 
@@ -1357,6 +1408,7 @@ static void audio_driver_mixer_play_stream_internal(
                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;
+         audio_driver_st.mixer_streams_playing++;
          break;
       case AUDIO_STREAM_STATE_PLAYING:
       case AUDIO_STREAM_STATE_PLAYING_LOOPED:
@@ -1591,6 +1643,8 @@ void audio_driver_mixer_stop_stream(unsigned i)
                audio_mixer_stop(voice);
             audio_driver_st.mixer_streams[i].state   = AUDIO_STREAM_STATE_STOPPED;
             audio_driver_st.mixer_streams[i].volume  = 1.0f;
+            if (audio_driver_st.mixer_streams_playing > 0)
+               audio_driver_st.mixer_streams_playing--;
          }
          break;
       case AUDIO_STREAM_STATE_STOPPED:

audio/audio_driver.h

@@ -165,6 +165,22 @@ typedef struct audio_driver
    size_t (*write_avail)(void *data);
 
    size_t (*buffer_size)(void *data);
+
+   /**
+    * Optional. Write raw int16 samples with resampling handled by driver.
+    * If non-NULL, audio_driver will call this instead of doing software
+    * resampling. The driver is responsible for resampling from input_rate
+    * to its output rate, applying the rate_adjust factor for A/V sync.
+    *
+    * @param data        Driver context
+    * @param samples     Interleaved int16 stereo samples (LRLRLR...)
+    * @param frames      Number of frames (pairs of samples)
+    * @param input_rate  Source sample rate in Hz
+    * @param rate_adjust Rate adjustment multiplier for A/V sync (1.0 = normal)
+    * @return Number of frames written, or -1 on error
+    */
+   ssize_t (*write_raw)(void *data, const int16_t *samples, size_t frames,
+         unsigned input_rate, double rate_adjust);
 } audio_driver_t;
 
 typedef struct
@@ -247,6 +263,7 @@ typedef struct
    bool mute_enable;
 #ifdef HAVE_AUDIOMIXER
    bool mixer_mute_enable;
+   uint8_t mixer_streams_playing;  /* Count of currently playing mixer streams */
 #endif
 
    /* Sample the flush delta-time when fast forwarding to find the correct ratio. */

audio/drivers/alsa.c

@@ -539,4 +539,5 @@ audio_driver_t audio_alsa = {
    alsa_device_list_free,
    alsa_write_avail,
    alsa_buffer_size,
+   NULL /* write_raw */
 };

audio/drivers/alsa_qsa.c

@@ -377,4 +377,5 @@ audio_driver_t audio_alsa = {
    NULL,
    alsa_qsa_write_avail,
    alsa_qsa_buffer_size,
+   NULL /* write_raw */
 };

audio/drivers/alsathread.c

@@ -673,5 +673,6 @@ audio_driver_t audio_alsathread = {
    alsa_device_list_new, /* Reusing these functions from alsa.c */
    alsa_device_list_free, /* because they don't use the driver context */
    alsa_thread_write_avail,
-   alsa_thread_buffer_size
+   alsa_thread_buffer_size,
+   NULL /* write_raw */
 };

audio/drivers/audioio.c

@@ -205,4 +205,5 @@ audio_driver_t audio_audioio = {
    NULL,
    audioio_write_avail,
    audioio_buffer_size,
+   NULL /* write_raw */
 };

audio/drivers/audioworklet.c

@@ -533,5 +533,6 @@ audio_driver_t audio_audioworklet = {
    NULL,
    NULL,
    audioworklet_write_avail,
-   audioworklet_buffer_size
+   audioworklet_buffer_size,
+   NULL /* write_raw */
 };