(Android) Set buffer count to 4 instead of 8 for Jelly Bean and

higher - test experimental lower latency for fast OpenSL mixer

android/native/jni/android_general.h

@@ -34,9 +34,10 @@ struct droid
    unsigned width;
    unsigned height;
    struct saved_state state;
-   int version;
 };
 
 extern struct droid g_android;
 
+extern int android_get_sdk_version(void);
+
 #endif

android/native/jni/main.c

@@ -65,6 +65,11 @@ static void print_cur_config(struct android_app* android_app)
          AConfiguration_getUiModeNight(android_app->config));
 }
 
+int android_get_sdk_version(void)
+{
+   return AConfiguration_getSdkVersion(g_android.app->config);
+}
+
 static void android_get_char_argv(char *argv, size_t sizeof_argv, const char *arg_name)
 {
    JNIEnv *env;
@@ -283,15 +288,11 @@ static void* android_app_entry(void* param)
 
    char rom_path[512];
    char libretro_path[512];
-   char android_version[16];
 
    // Get arguments */
    android_get_char_argv(rom_path, sizeof(rom_path), "ROM");
    android_get_char_argv(libretro_path, sizeof(libretro_path), "LIBRETRO");
-   android_get_char_argv(android_version, sizeof(android_version), "ANDROIDVER");
-   g_android.version = atoi(android_version);
 
-   RARCH_LOG("Android version: %d\n", g_android.version);
    RARCH_LOG("Checking arguments passed...\n");
    RARCH_LOG("ROM Filename: [%s].\n", rom_path);
    RARCH_LOG("Libretro path: [%s].\n", libretro_path);

android/phoenix/src/com/retroarch/phoenix.java

@@ -91,7 +91,6 @@ public class phoenix extends Activity
     				   myIntent = new Intent(this, NativeActivity.class);
     				   myIntent.putExtra("ROM", data.getStringExtra("PATH"));
     				   myIntent.putExtra("LIBRETRO", libretro_path);
-    				   myIntent.putExtra("ANDROIDVER", Integer.toString(android.os.Build.VERSION.SDK_INT));
     				   startActivity(myIntent);
     			   }
     			   else

audio/opensl.c

@@ -36,7 +36,6 @@
 
 // TODO: Are these sane?
 #define BUFFER_SIZE 4096
-#define NUM_BUFFERS 8
 
 typedef struct sl
 {
@@ -53,6 +52,7 @@ typedef struct sl
    slock_t *lock;
    scond_t *cond;
    bool nonblock;
+   unsigned buf_count;
 } sl_t;
 
 static void opensl_callback(SLAndroidSimpleBufferQueueItf bq, void *ctx)
@@ -132,6 +132,17 @@ static void *sl_init(const char *device, unsigned rate, unsigned latency)
    GOTO_IF_FAIL(SLEngineItf_CreateOutputMix(sl->engine, &sl->output_mix, 0, NULL, NULL));
    GOTO_IF_FAIL(SLObjectItf_Realize(sl->output_mix, SL_BOOLEAN_FALSE));
 
+   int api_level = android_get_sdk_version();
+   if(api_level > 15)
+   {
+      RARCH_LOG("API level 16 and higher has a fast OpenSL mixer - adjust settings for lower audio latency...\n");
+      sl->buf_count = 4;
+   }
+   else
+      sl->buf_count = 8;
+
+   RARCH_LOG("[SLES] : Android API level [%d] detected, setting audio latency (buffer size: [%d])..\n", api_level, sl->buf_count * BUFFER_SIZE);
+
    fmt_pcm.formatType    = SL_DATAFORMAT_PCM;
    fmt_pcm.numChannels   = 2;
    fmt_pcm.samplesPerSec = rate * 1000; // Samplerate is in milli-Hz.
@@ -144,7 +155,7 @@ static void *sl_init(const char *device, unsigned rate, unsigned latency)
    audio_src.pFormat  = &fmt_pcm;
 
    loc_bufq.locatorType = SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE;
-   loc_bufq.numBuffers  = NUM_BUFFERS;
+   loc_bufq.numBuffers  = sl->buf_count;
 
    loc_outmix.locatorType = SL_DATALOCATOR_OUTPUTMIX;
    loc_outmix.outputMix   = sl->output_mix;
@@ -161,7 +172,7 @@ static void *sl_init(const char *device, unsigned rate, unsigned latency)
 
    sl->cond = scond_new();
    sl->lock = slock_new();
-   sl->fifo = fifo_new(BUFFER_SIZE * NUM_BUFFERS);
+   sl->fifo = fifo_new(BUFFER_SIZE * sl->buf_count);
 
    (*buffer_queue)->RegisterCallback(buffer_queue, opensl_callback, sl);
    (*buffer_queue)->Enqueue(buffer_queue, sl->buffer, BUFFER_SIZE);
@@ -248,7 +259,8 @@ static size_t sl_write_avail(void *data)
 
 static size_t sl_buffer_size(void *data)
 {
-   return BUFFER_SIZE * NUM_BUFFERS;
+   sl_t *sl = (sl_t*)data;
+   return BUFFER_SIZE * sl->buf_count;
 }
 
 const audio_driver_t audio_opensl = {

driver_funcs.h

@@ -74,7 +74,7 @@ static inline bool input_key_pressed_func(int key)
 #define audio_free_func()                       sl_free(driver.audio_data)
 #define audio_use_float_func()                  driver.audio->use_float(driver.audio_data)
 #define audio_write_avail_func()                sl_write_avail(driver.audio_data)
-#define audio_buffer_size_func()                (BUFFER_SIZE * NUM_BUFFERS)
+#define audio_buffer_size_func()                (BUFFER_SIZE * ((sl_t*)driver.audio_data)->buf_count)
 
 #else