android: Fixed audio device detection.

android-project/app/src/main/java/org/libsdl/app/SDLAudioManager.java

@@ -309,6 +309,16 @@ public class SDLAudioManager {
     public static void registerAudioDeviceCallback() {
         if (Build.VERSION.SDK_INT >= 24 /* Android 7.0 (N) */) {
             AudioManager audioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);
+            // get an initial list now, before hotplug callbacks fire.
+            for (AudioDeviceInfo dev : audioManager.getDevices(AudioManager.GET_DEVICES_OUTPUTS)) {
+                if (dev.getType() == AudioDeviceInfo.TYPE_TELEPHONY) {
+                    continue;  // Device cannot be opened
+                }
+                addAudioDevice(dev.isSink(), dev.getProductName().toString(), dev.getId());
+            }
+            for (AudioDeviceInfo dev : audioManager.getDevices(AudioManager.GET_DEVICES_INPUTS)) {
+                addAudioDevice(dev.isSink(), dev.getProductName().toString(), dev.getId());
+            }
             audioManager.registerAudioDeviceCallback(mAudioDeviceCallback, null);
         }
     }

src/audio/android/SDL_androidaudio.c

@@ -128,6 +128,7 @@ static void ANDROIDAUDIO_CloseDevice(SDL_AudioDevice *device)
 
 static SDL_bool ANDROIDAUDIO_Init(SDL_AudioDriverImpl *impl)
 {
+    // !!! FIXME: if on Android API < 24, DetectDevices and Deinitialize should be NULL and OnlyHasDefaultOutputDevice and OnlyHasDefaultCaptureDevice should be SDL_TRUE, since audio device enum and hotplug appears to require Android 7.0+.
     impl->ThreadInit = Android_AudioThreadInit;
     impl->DetectDevices = Android_StartAudioHotplug;
     impl->Deinitialize = Android_StopAudioHotplug;

src/core/android/SDL_android.c

@@ -1006,10 +1006,14 @@ JNIEXPORT void JNICALL
 SDL_JAVA_AUDIO_INTERFACE(addAudioDevice)(JNIEnv *env, jclass jcls, jboolean is_capture,
                                          jstring name, jint device_id)
 {
-    SDL_assert(SDL_GetCurrentAudioDriver() != NULL);  // should have been started by Android_StartAudioHotplug inside an audio driver.
-    const char *utf8name = (*env)->GetStringUTFChars(env, name, NULL);
-    SDL_AddAudioDevice(is_capture ? SDL_TRUE : SDL_FALSE, SDL_strdup(utf8name), NULL, (void *)((size_t)device_id));
-    (*env)->ReleaseStringUTFChars(env, name, utf8name);
+    if (SDL_GetCurrentAudioDriver() != NULL) {
+        void *handle = (void *)((size_t)device_id);
+        if (!SDL_FindPhysicalAudioDeviceByHandle(handle)) {
+            const char *utf8name = (*env)->GetStringUTFChars(env, name, NULL);
+            SDL_AddAudioDevice(is_capture ? SDL_TRUE : SDL_FALSE, SDL_strdup(utf8name), NULL, handle);
+            (*env)->ReleaseStringUTFChars(env, name, utf8name);
+        }
+    }
 }
 
 JNIEXPORT void JNICALL