Added support for surround sound and float audio on Android

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

@@ -1,6 +1,7 @@
 package org.libsdl.app;
 
 import android.media.*;
+import android.os.Build;
 import android.util.Log;
 
 public class SDLAudioManager
@@ -17,41 +18,250 @@ public class SDLAudioManager
 
     // Audio
 
-    /**
-     * This method is called by SDL using JNI.
-     */
-    public static int audioOpen(int sampleRate, boolean is16Bit, boolean isStereo, int desiredFrames) {
-        int channelConfig = isStereo ? AudioFormat.CHANNEL_CONFIGURATION_STEREO : AudioFormat.CHANNEL_CONFIGURATION_MONO;
-        int audioFormat = is16Bit ? AudioFormat.ENCODING_PCM_16BIT : AudioFormat.ENCODING_PCM_8BIT;
-        int frameSize = (isStereo ? 2 : 1) * (is16Bit ? 2 : 1);
+    protected static String getAudioFormatString(int audioFormat) {
+        switch (audioFormat) {
+        case AudioFormat.ENCODING_PCM_8BIT:
+            return "8-bit";
+        case AudioFormat.ENCODING_PCM_16BIT:
+            return "16-bit";
+        case AudioFormat.ENCODING_PCM_FLOAT:
+            return "float";
+        default:
+            return Integer.toString(audioFormat);
+        }
+    }
+
+    protected static int[] open(boolean isCapture, int sampleRate, int audioFormat, int desiredChannels, int desiredFrames) {
+        int channelConfig;
+        int sampleSize;
+        int frameSize;
+
+        Log.v(TAG, "Opening " + (isCapture ? "capture" : "playback") + ", requested " + desiredFrames + " frames of " + desiredChannels + " channel " + getAudioFormatString(audioFormat) + " audio at " + sampleRate + " Hz");
+
+        /* On older devices let's use known good settings */
+        if (Build.VERSION.SDK_INT < 21) {
+            if (desiredChannels > 2) {
+                desiredChannels = 2;
+            }
+            if (sampleRate < 8000) {
+                sampleRate = 8000;
+            } else if (sampleRate > 48000) {
+                sampleRate = 48000;
+            }
+        }
 
-        Log.v(TAG, "SDL audio: wanted " + (isStereo ? "stereo" : "mono") + " " + (is16Bit ? "16-bit" : "8-bit") + " " + (sampleRate / 1000f) + "kHz, " + desiredFrames + " frames buffer");
+        if (audioFormat == AudioFormat.ENCODING_PCM_FLOAT) {
+            int minSDKVersion = (isCapture ? 23 : 21);
+            if (Build.VERSION.SDK_INT < minSDKVersion) {
+                audioFormat = AudioFormat.ENCODING_PCM_16BIT;
+            }
+        }
+        switch (audioFormat)
+        {
+        case AudioFormat.ENCODING_PCM_8BIT:
+            sampleSize = 1;
+            break;
+        case AudioFormat.ENCODING_PCM_16BIT:
+            sampleSize = 2;
+            break;
+        case AudioFormat.ENCODING_PCM_FLOAT:
+            sampleSize = 4;
+            break;
+        default:
+            Log.v(TAG, "Requested format " + audioFormat + ", getting ENCODING_PCM_16BIT");
+            audioFormat = AudioFormat.ENCODING_PCM_16BIT;
+            sampleSize = 2;
+            break;
+        }
+ 
+        if (isCapture) {
+            switch (desiredChannels) {
+            case 1:
+                channelConfig = AudioFormat.CHANNEL_IN_MONO;
+                break;
+            case 2:
+                channelConfig = AudioFormat.CHANNEL_IN_STEREO;
+                break;
+            default:
+                Log.v(TAG, "Requested " + desiredChannels + " channels, getting stereo");
+                desiredChannels = 2;
+                channelConfig = AudioFormat.CHANNEL_IN_STEREO;
+                break;
+            }
+        } else {
+            switch (desiredChannels) {
+            case 1:
+                channelConfig = AudioFormat.CHANNEL_OUT_MONO;
+                break;
+            case 2:
+                channelConfig = AudioFormat.CHANNEL_OUT_STEREO;
+                break;
+            case 3:
+                channelConfig = AudioFormat.CHANNEL_OUT_STEREO | AudioFormat.CHANNEL_OUT_FRONT_CENTER;
+                break;
+            case 4:
+                channelConfig = AudioFormat.CHANNEL_OUT_QUAD;
+                break;
+            case 5:
+                channelConfig = AudioFormat.CHANNEL_OUT_QUAD | AudioFormat.CHANNEL_OUT_FRONT_CENTER;
+                break;
+            case 6:
+                channelConfig = AudioFormat.CHANNEL_OUT_5POINT1;
+                break;
+            case 7:
+                channelConfig = AudioFormat.CHANNEL_OUT_5POINT1 | AudioFormat.CHANNEL_OUT_BACK_CENTER;
+                break;
+            case 8:
+                if (Build.VERSION.SDK_INT >= 23) {
+                    channelConfig = AudioFormat.CHANNEL_OUT_7POINT1_SURROUND;
+                } else {
+                    Log.v(TAG, "Requested " + desiredChannels + " channels, getting 5.1 surround");
+                    desiredChannels = 6;
+                    channelConfig = AudioFormat.CHANNEL_OUT_5POINT1;
+                }
+                break;
+            default:
+                Log.v(TAG, "Requested " + desiredChannels + " channels, getting stereo");
+                desiredChannels = 2;
+                channelConfig = AudioFormat.CHANNEL_OUT_STEREO;
+                break;
+            }
+
+/*
+            Log.v(TAG, "Speaker configuration (and order of channels):");
+
+            if ((channelConfig & 0x00000004) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_FRONT_LEFT");
+            }
+            if ((channelConfig & 0x00000008) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_FRONT_RIGHT");
+            }
+            if ((channelConfig & 0x00000010) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_FRONT_CENTER");
+            }
+            if ((channelConfig & 0x00000020) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_LOW_FREQUENCY");
+            }
+            if ((channelConfig & 0x00000040) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_BACK_LEFT");
+            }
+            if ((channelConfig & 0x00000080) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_BACK_RIGHT");
+            }
+            if ((channelConfig & 0x00000100) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_FRONT_LEFT_OF_CENTER");
+            }
+            if ((channelConfig & 0x00000200) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_FRONT_RIGHT_OF_CENTER");
+            }
+            if ((channelConfig & 0x00000400) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_BACK_CENTER");
+            }
+            if ((channelConfig & 0x00000800) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_SIDE_LEFT");
+            }
+            if ((channelConfig & 0x00001000) != 0) {
+                Log.v(TAG, "   CHANNEL_OUT_SIDE_RIGHT");
+            }
+*/
+        }
+        frameSize = (sampleSize * desiredChannels);
 
         // Let the user pick a larger buffer if they really want -- but ye
         // gods they probably shouldn't, the minimums are horrifyingly high
         // latency already
-        desiredFrames = Math.max(desiredFrames, (AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat) + frameSize - 1) / frameSize);
+        int minBufferSize;
+        if (isCapture) {
+            minBufferSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
+        } else {
+            minBufferSize = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat);
+        }
+        desiredFrames = Math.max(desiredFrames, (minBufferSize + frameSize - 1) / frameSize);
 
-        if (mAudioTrack == null) {
-            mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate,
-                    channelConfig, audioFormat, desiredFrames * frameSize, AudioTrack.MODE_STREAM);
+        int[] results = new int[4];
 
-            // Instantiating AudioTrack can "succeed" without an exception and the track may still be invalid
-            // Ref: https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/media/java/android/media/AudioTrack.java
-            // Ref: http://developer.android.com/reference/android/media/AudioTrack.html#getState()
+        if (isCapture) {
+            if (mAudioRecord == null) {
+                mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.DEFAULT, sampleRate,
+                        channelConfig, audioFormat, desiredFrames * frameSize);
 
-            if (mAudioTrack.getState() != AudioTrack.STATE_INITIALIZED) {
-                Log.e(TAG, "Failed during initialization of Audio Track");
-                mAudioTrack = null;
-                return -1;
+                // see notes about AudioTrack state in audioOpen(), above. Probably also applies here.
+                if (mAudioRecord.getState() != AudioRecord.STATE_INITIALIZED) {
+                    Log.e(TAG, "Failed during initialization of AudioRecord");
+                    mAudioRecord.release();
+                    mAudioRecord = null;
+                    return null;
+                }
+
+                mAudioRecord.startRecording();
+            }
+
+            results[0] = mAudioRecord.getSampleRate();
+            results[1] = mAudioRecord.getAudioFormat();
+            results[2] = mAudioRecord.getChannelCount();
+            results[3] = desiredFrames;
+
+        } else {
+            if (mAudioTrack == null) {
+                mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate, channelConfig, audioFormat, desiredFrames * frameSize, AudioTrack.MODE_STREAM);
+
+                // Instantiating AudioTrack can "succeed" without an exception and the track may still be invalid
+                // Ref: https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/media/java/android/media/AudioTrack.java
+                // Ref: http://developer.android.com/reference/android/media/AudioTrack.html#getState()
+                if (mAudioTrack.getState() != AudioTrack.STATE_INITIALIZED) {
+                    /* Try again, with safer values */
+
+                    Log.e(TAG, "Failed during initialization of Audio Track");
+                    mAudioTrack.release();
+                    mAudioTrack = null;
+                    return null;
+                }
+
+                mAudioTrack.play();
             }
 
-            mAudioTrack.play();
+            results[0] = mAudioTrack.getSampleRate();
+            results[1] = mAudioTrack.getAudioFormat();
+            results[2] = mAudioTrack.getChannelCount();
+            results[3] = desiredFrames;
         }
 
-        Log.v(TAG, "SDL audio: got " + ((mAudioTrack.getChannelCount() >= 2) ? "stereo" : "mono") + " " + ((mAudioTrack.getAudioFormat() == AudioFormat.ENCODING_PCM_16BIT) ? "16-bit" : "8-bit") + " " + (mAudioTrack.getSampleRate() / 1000f) + "kHz, " + desiredFrames + " frames buffer");
+        Log.v(TAG, "Opening " + (isCapture ? "capture" : "playback") + ", got " + results[3] + " frames of " + results[2] + " channel " + getAudioFormatString(results[1]) + " audio at " + results[0] + " Hz");
+
+        return results;
+    }
 
-        return 0;
+    /**
+     * This method is called by SDL using JNI.
+     */
+    public static int[] audioOpen(int sampleRate, int audioFormat, int desiredChannels, int desiredFrames) {
+        return open(false, sampleRate, audioFormat, desiredChannels, desiredFrames);
+    }
+
+    /**
+     * This method is called by SDL using JNI.
+     */
+    public static void audioWriteFloatBuffer(float[] buffer) {
+        if (mAudioTrack == null) {
+            Log.e(TAG, "Attempted to make audio call with uninitialized audio!");
+            return;
+        }
+
+        for (int i = 0; i < buffer.length;) {
+            int result = mAudioTrack.write(buffer, i, buffer.length - i, AudioTrack.WRITE_BLOCKING);
+            if (result > 0) {
+                i += result;
+            } else if (result == 0) {
+                try {
+                    Thread.sleep(1);
+                } catch(InterruptedException e) {
+                    // Nom nom
+                }
+            } else {
+                Log.w(TAG, "SDL audio: error return from write(float)");
+                return;
+            }
+        }
     }
 
     /**
@@ -63,7 +273,7 @@ public class SDLAudioManager
             return;
         }
 
-        for (int i = 0; i < buffer.length; ) {
+        for (int i = 0; i < buffer.length;) {
             int result = mAudioTrack.write(buffer, i, buffer.length - i);
             if (result > 0) {
                 i += result;
@@ -109,53 +319,33 @@ public class SDLAudioManager
     /**
      * This method is called by SDL using JNI.
      */
-    public static int captureOpen(int sampleRate, boolean is16Bit, boolean isStereo, int desiredFrames) {
-        int channelConfig = isStereo ? AudioFormat.CHANNEL_CONFIGURATION_STEREO : AudioFormat.CHANNEL_CONFIGURATION_MONO;
-        int audioFormat = is16Bit ? AudioFormat.ENCODING_PCM_16BIT : AudioFormat.ENCODING_PCM_8BIT;
-        int frameSize = (isStereo ? 2 : 1) * (is16Bit ? 2 : 1);
-
-        Log.v(TAG, "SDL capture: wanted " + (isStereo ? "stereo" : "mono") + " " + (is16Bit ? "16-bit" : "8-bit") + " " + (sampleRate / 1000f) + "kHz, " + desiredFrames + " frames buffer");
-
-        // Let the user pick a larger buffer if they really want -- but ye
-        // gods they probably shouldn't, the minimums are horrifyingly high
-        // latency already
-        desiredFrames = Math.max(desiredFrames, (AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat) + frameSize - 1) / frameSize);
-
-        if (mAudioRecord == null) {
-            mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.DEFAULT, sampleRate,
-                    channelConfig, audioFormat, desiredFrames * frameSize);
-
-            // see notes about AudioTrack state in audioOpen(), above. Probably also applies here.
-            if (mAudioRecord.getState() != AudioRecord.STATE_INITIALIZED) {
-                Log.e(TAG, "Failed during initialization of AudioRecord");
-                mAudioRecord.release();
-                mAudioRecord = null;
-                return -1;
-            }
-
-            mAudioRecord.startRecording();
-        }
-
-        Log.v(TAG, "SDL capture: got " + ((mAudioRecord.getChannelCount() >= 2) ? "stereo" : "mono") + " " + ((mAudioRecord.getAudioFormat() == AudioFormat.ENCODING_PCM_16BIT) ? "16-bit" : "8-bit") + " " + (mAudioRecord.getSampleRate() / 1000f) + "kHz, " + desiredFrames + " frames buffer");
+    public static int[] captureOpen(int sampleRate, int audioFormat, int desiredChannels, int desiredFrames) {
+        return open(true, sampleRate, audioFormat, desiredChannels, desiredFrames);
+    }
 
-        return 0;
+    /** This method is called by SDL using JNI. */
+    public static int captureReadFloatBuffer(float[] buffer, boolean blocking) {
+        return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
     }
 
     /** This method is called by SDL using JNI. */
     public static int captureReadShortBuffer(short[] buffer, boolean blocking) {
-        // !!! FIXME: this is available in API Level 23. Until then, we always block.  :(
-        //return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
-        return mAudioRecord.read(buffer, 0, buffer.length);
+        if (Build.VERSION.SDK_INT < 23) {
+            return mAudioRecord.read(buffer, 0, buffer.length);
+        } else {
+            return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
+        }
     }
 
     /** This method is called by SDL using JNI. */
     public static int captureReadByteBuffer(byte[] buffer, boolean blocking) {
-        // !!! FIXME: this is available in API Level 23. Until then, we always block.  :(
-        //return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
-        return mAudioRecord.read(buffer, 0, buffer.length);
+        if (Build.VERSION.SDK_INT < 23) {
+            return mAudioRecord.read(buffer, 0, buffer.length);
+        } else {
+            return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
+        }
     }
 
-
     /** This method is called by SDL using JNI. */
     public static void audioClose() {
         if (mAudioTrack != null) {

src/audio/SDL_audio.c

@@ -1130,8 +1130,9 @@ prepare_audiospec(const SDL_AudioSpec * orig, SDL_AudioSpec * prepared)
         }
     case 1:                    /* Mono */
     case 2:                    /* Stereo */
-    case 4:                    /* surround */
-    case 6:                    /* surround with center and lfe */
+    case 4:                    /* Quadrophonic */
+    case 6:                    /* 5.1 surround */
+    case 8:                    /* 7.1 surround */
         break;
     default:
         SDL_SetError("Unsupported number of audio channels.");

src/audio/android/SDL_androidaudio.c

@@ -57,7 +57,9 @@ ANDROIDAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
 
     test_format = SDL_FirstAudioFormat(this->spec.format);
     while (test_format != 0) { /* no "UNKNOWN" constant */
-        if ((test_format == AUDIO_U8) || (test_format == AUDIO_S16LSB)) {
+        if ((test_format == AUDIO_U8) ||
+			(test_format == AUDIO_S16) ||
+			(test_format == AUDIO_F32)) {
             this->spec.format = test_format;
             break;
         }
@@ -69,25 +71,8 @@ ANDROIDAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
         return SDL_SetError("No compatible audio format!");
     }
 
-    if (this->spec.channels > 1) {
-        this->spec.channels = 2;
-    } else {
-        this->spec.channels = 1;
-    }
-
-    if (this->spec.freq < 8000) {
-        this->spec.freq = 8000;
-    }
-    if (this->spec.freq > 48000) {
-        this->spec.freq = 48000;
-    }
-
-    /* TODO: pass in/return a (Java) device ID */
-    this->spec.samples = Android_JNI_OpenAudioDevice(iscapture, this->spec.freq, this->spec.format == AUDIO_U8 ? 0 : 1, this->spec.channels, this->spec.samples);
-
-    if (this->spec.samples == 0) {
-        /* Init failed? */
-        return SDL_SetError("Java-side initialization failed!");
+    if (Android_JNI_OpenAudioDevice(iscapture, &this->spec) < 0) {
+        return -1;
     }
 
     SDL_CalculateAudioSpec(&this->spec);

src/core/android/SDL_android.c

@@ -61,6 +61,10 @@
 #define SDL_JAVA_CONTROLLER_INTERFACE(function)         CONCAT1(SDL_JAVA_PREFIX, SDLControllerManager, function)
 #define SDL_JAVA_INTERFACE_INPUT_CONNECTION(function)   CONCAT1(SDL_JAVA_PREFIX, SDLInputConnection, function)
 
+/* Audio encoding definitions */
+#define ENCODING_PCM_8BIT   3
+#define ENCODING_PCM_16BIT  2
+#define ENCODING_PCM_FLOAT  4
 
 /* Java class SDLActivity */
 JNIEXPORT void JNICALL SDL_JAVA_INTERFACE(nativeSetupJNI)(
@@ -248,12 +252,14 @@ static jclass mAudioManagerClass;
 
 /* method signatures */
 static jmethodID midAudioOpen;
-static jmethodID midAudioWriteShortBuffer;
 static jmethodID midAudioWriteByteBuffer;
+static jmethodID midAudioWriteShortBuffer;
+static jmethodID midAudioWriteFloatBuffer;
 static jmethodID midAudioClose;
 static jmethodID midCaptureOpen;
-static jmethodID midCaptureReadShortBuffer;
 static jmethodID midCaptureReadByteBuffer;
+static jmethodID midCaptureReadShortBuffer;
+static jmethodID midCaptureReadFloatBuffer;
 static jmethodID midCaptureClose;
 
 /* controller manager */
@@ -397,24 +403,28 @@ JNIEXPORT void JNICALL SDL_JAVA_AUDIO_INTERFACE(nativeSetupJNI)(JNIEnv* mEnv, jc
     mAudioManagerClass = (jclass)((*mEnv)->NewGlobalRef(mEnv, cls));
 
     midAudioOpen = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
-                                "audioOpen", "(IZZI)I");
-    midAudioWriteShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
-                                "audioWriteShortBuffer", "([S)V");
+                                "audioOpen", "(IIII)[I");
     midAudioWriteByteBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
                                 "audioWriteByteBuffer", "([B)V");
+    midAudioWriteShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
+                                "audioWriteShortBuffer", "([S)V");
+    midAudioWriteFloatBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
+                                "audioWriteFloatBuffer", "([F)V");
     midAudioClose = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
                                 "audioClose", "()V");
     midCaptureOpen = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
-                                "captureOpen", "(IZZI)I");
-    midCaptureReadShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
-                                "captureReadShortBuffer", "([SZ)I");
+                                "captureOpen", "(IIII)[I");
     midCaptureReadByteBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
                                 "captureReadByteBuffer", "([BZ)I");
+    midCaptureReadShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
+                                "captureReadShortBuffer", "([SZ)I");
+    midCaptureReadFloatBuffer = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
+                                "captureReadFloatBuffer", "([FZ)I");
     midCaptureClose = (*mEnv)->GetStaticMethodID(mEnv, mAudioManagerClass,
                                 "captureClose", "()V");
 
-    if (!midAudioOpen || !midAudioWriteShortBuffer || !midAudioWriteByteBuffer || !midAudioClose ||
-       !midCaptureOpen || !midCaptureReadShortBuffer || !midCaptureReadByteBuffer || !midCaptureClose) {
+    if (!midAudioOpen || !midAudioWriteByteBuffer || !midAudioWriteShortBuffer || !midAudioWriteFloatBuffer || !midAudioClose ||
+       !midCaptureOpen || !midCaptureReadByteBuffer || !midCaptureReadShortBuffer || !midCaptureReadFloatBuffer || !midCaptureClose) {
         __android_log_print(ANDROID_LOG_WARN, "SDL", "Missing some Java callbacks, do you have the latest version of SDLAudioManager.java?");
     }
 
@@ -1043,17 +1053,19 @@ int Android_JNI_SetupThread(void)
 /*
  * Audio support
  */
-static jboolean audioBuffer16Bit = JNI_FALSE;
+static int audioBufferFormat = 0;
 static jobject audioBuffer = NULL;
 static void* audioBufferPinned = NULL;
-static jboolean captureBuffer16Bit = JNI_FALSE;
+static int captureBufferFormat = 0;
 static jobject captureBuffer = NULL;
 
-int Android_JNI_OpenAudioDevice(int iscapture, int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames)
+int Android_JNI_OpenAudioDevice(int iscapture, SDL_AudioSpec *spec)
 {
-    jboolean isStereo;
+    int audioformat;
     int numBufferFrames;
     jobject jbufobj = NULL;
+    jobject result;
+    int *resultElements;
     jboolean isCopy;
 
     JNIEnv *env = Android_JNI_GetEnv();
@@ -1063,78 +1075,123 @@ int Android_JNI_OpenAudioDevice(int iscapture, int sampleRate, int is16Bit, int
     }
     Android_JNI_SetupThread();
 
-    isStereo = channelCount > 1;
+    switch (spec->format) {
+    case AUDIO_U8:
+        audioformat = ENCODING_PCM_8BIT;
+        break;
+    case AUDIO_S16:
+        audioformat = ENCODING_PCM_16BIT;
+        break;
+    case AUDIO_F32:
+        audioformat = ENCODING_PCM_FLOAT;
+        break;
+    default:
+        return SDL_SetError("Unsupported audio format: 0x%x", spec->format);
+    }
 
     if (iscapture) {
         __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "SDL audio: opening device for capture");
-        captureBuffer16Bit = is16Bit;
-        if ((*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureOpen, sampleRate, is16Bit, isStereo, desiredBufferFrames) != 0) {
-            /* Error during audio initialization */
-            __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: error on AudioRecord initialization!");
-            return 0;
-        }
+        result = (*env)->CallStaticObjectMethod(env, mAudioManagerClass, midCaptureOpen, spec->freq, audioformat, spec->channels, spec->samples);
     } else {
         __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "SDL audio: opening device for output");
-        audioBuffer16Bit = is16Bit;
-        if ((*env)->CallStaticIntMethod(env, mAudioManagerClass, midAudioOpen, sampleRate, is16Bit, isStereo, desiredBufferFrames) != 0) {
-            /* Error during audio initialization */
-            __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: error on AudioTrack initialization!");
-            return 0;
-        }
+        result = (*env)->CallStaticObjectMethod(env, mAudioManagerClass, midAudioOpen, spec->freq, audioformat, spec->channels, spec->samples);
+    }
+    if (result == NULL) {
+        /* Error during audio initialization, error printed from Java */
+        return SDL_SetError("Java-side initialization failed");
     }
 
+    if ((*env)->GetArrayLength(env, (jintArray)result) != 4) {
+        return SDL_SetError("Unexpected results from Java, expected 4, got %d", (*env)->GetArrayLength(env, (jintArray)result));
+    }
+    isCopy = JNI_FALSE;
+    resultElements = (*env)->GetIntArrayElements(env, (jintArray)result, &isCopy);
+    spec->freq = resultElements[0];
+    audioformat = resultElements[1];
+    switch (audioformat) {
+    case ENCODING_PCM_8BIT:
+        spec->format = AUDIO_U8;
+        break;
+    case ENCODING_PCM_16BIT:
+        spec->format = AUDIO_S16;
+        break;
+    case ENCODING_PCM_FLOAT:
+        spec->format = AUDIO_F32;
+        break;
+    default:
+        return SDL_SetError("Unexpected audio format from Java: %d\n", audioformat);
+    }
+    spec->channels = resultElements[2];
+    spec->samples = resultElements[3];
+    (*env)->ReleaseIntArrayElements(env, (jintArray)result, resultElements, JNI_ABORT);
+    (*env)->DeleteLocalRef(env, result);
+
     /* Allocating the audio buffer from the Java side and passing it as the return value for audioInit no longer works on
      * Android >= 4.2 due to a "stale global reference" error. So now we allocate this buffer directly from this side. */
-
-    if (is16Bit) {
-        jshortArray audioBufferLocal = (*env)->NewShortArray(env, desiredBufferFrames * (isStereo ? 2 : 1));
-        if (audioBufferLocal) {
-            jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
-            (*env)->DeleteLocalRef(env, audioBufferLocal);
+    switch (audioformat) {
+    case ENCODING_PCM_8BIT:
+        {
+            jbyteArray audioBufferLocal = (*env)->NewByteArray(env, spec->samples * spec->channels);
+            if (audioBufferLocal) {
+                jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
+                (*env)->DeleteLocalRef(env, audioBufferLocal);
+            }
         }
-    }
-    else {
-        jbyteArray audioBufferLocal = (*env)->NewByteArray(env, desiredBufferFrames * (isStereo ? 2 : 1));
-        if (audioBufferLocal) {
-            jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
-            (*env)->DeleteLocalRef(env, audioBufferLocal);
+        break;
+    case ENCODING_PCM_16BIT:
+        {
+            jshortArray audioBufferLocal = (*env)->NewShortArray(env, spec->samples * spec->channels);
+            if (audioBufferLocal) {
+                jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
+                (*env)->DeleteLocalRef(env, audioBufferLocal);
+            }
         }
+        break;
+    case ENCODING_PCM_FLOAT:
+        {
+            jfloatArray audioBufferLocal = (*env)->NewFloatArray(env, spec->samples * spec->channels);
+            if (audioBufferLocal) {
+                jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
+                (*env)->DeleteLocalRef(env, audioBufferLocal);
+            }
+        }
+        break;
+    default:
+        return SDL_SetError("Unexpected audio format from Java: %d\n", audioformat);
     }
 
     if (jbufobj == NULL) {
-        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: could not allocate an audio buffer!");
-        return 0;
+        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: could not allocate an audio buffer");
+        return SDL_OutOfMemory();
     }
 
     if (iscapture) {
+        captureBufferFormat = audioformat;
         captureBuffer = jbufobj;
     } else {
+        audioBufferFormat = audioformat;
         audioBuffer = jbufobj;
     }
+    numBufferFrames = (*env)->GetArrayLength(env, (jarray)jbufobj);
 
-    isCopy = JNI_FALSE;
+    if (!iscapture) {
+        isCopy = JNI_FALSE;
 
-    if (is16Bit) {
-        if (iscapture) {
-            numBufferFrames = (*env)->GetArrayLength(env, (jshortArray)captureBuffer);
-        } else {
-            audioBufferPinned = (*env)->GetShortArrayElements(env, (jshortArray)audioBuffer, &isCopy);
-            numBufferFrames = (*env)->GetArrayLength(env, (jshortArray)audioBuffer);
-        }
-    } else {
-        if (iscapture) {
-            numBufferFrames = (*env)->GetArrayLength(env, (jbyteArray)captureBuffer);
-        } else {
+        switch (audioformat) {
+        case ENCODING_PCM_8BIT:
             audioBufferPinned = (*env)->GetByteArrayElements(env, (jbyteArray)audioBuffer, &isCopy);
-            numBufferFrames = (*env)->GetArrayLength(env, (jbyteArray)audioBuffer);
+            break;
+        case ENCODING_PCM_16BIT:
+            audioBufferPinned = (*env)->GetShortArrayElements(env, (jshortArray)audioBuffer, &isCopy);
+            break;
+        case ENCODING_PCM_FLOAT:
+            audioBufferPinned = (*env)->GetFloatArrayElements(env, (jfloatArray)audioBuffer, &isCopy);
+            break;
+        default:
+            return SDL_SetError("Unexpected audio format from Java: %d\n", audioformat);
         }
     }
-
-    if (isStereo) {
-        numBufferFrames /= 2;
-    }
-
-    return numBufferFrames;
+    return 0;
 }
 
 int Android_JNI_GetDisplayDPI(float *ddpi, float *xdpi, float *ydpi)
@@ -1178,12 +1235,22 @@ void Android_JNI_WriteAudioBuffer(void)
 {
     JNIEnv *mAudioEnv = Android_JNI_GetEnv();
 
-    if (audioBuffer16Bit) {
-        (*mAudioEnv)->ReleaseShortArrayElements(mAudioEnv, (jshortArray)audioBuffer, (jshort *)audioBufferPinned, JNI_COMMIT);
-        (*mAudioEnv)->CallStaticVoidMethod(mAudioEnv, mAudioManagerClass, midAudioWriteShortBuffer, (jshortArray)audioBuffer);
-    } else {
+    switch (audioBufferFormat) {
+    case ENCODING_PCM_8BIT:
         (*mAudioEnv)->ReleaseByteArrayElements(mAudioEnv, (jbyteArray)audioBuffer, (jbyte *)audioBufferPinned, JNI_COMMIT);
         (*mAudioEnv)->CallStaticVoidMethod(mAudioEnv, mAudioManagerClass, midAudioWriteByteBuffer, (jbyteArray)audioBuffer);
+        break;
+    case ENCODING_PCM_16BIT:
+        (*mAudioEnv)->ReleaseShortArrayElements(mAudioEnv, (jshortArray)audioBuffer, (jshort *)audioBufferPinned, JNI_COMMIT);
+        (*mAudioEnv)->CallStaticVoidMethod(mAudioEnv, mAudioManagerClass, midAudioWriteShortBuffer, (jshortArray)audioBuffer);
+        break;
+    case ENCODING_PCM_FLOAT:
+        (*mAudioEnv)->ReleaseFloatArrayElements(mAudioEnv, (jfloatArray)audioBuffer, (jfloat *)audioBufferPinned, JNI_COMMIT);
+        (*mAudioEnv)->CallStaticVoidMethod(mAudioEnv, mAudioManagerClass, midAudioWriteFloatBuffer, (jfloatArray)audioBuffer);
+        break;
+    default:
+        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: unhandled audio buffer format");
+        break;
     }
 
     /* JNI_COMMIT means the changes are committed to the VM but the buffer remains pinned */
@@ -1195,44 +1262,84 @@ int Android_JNI_CaptureAudioBuffer(void *buffer, int buflen)
     jboolean isCopy = JNI_FALSE;
     jint br;
 
-    if (captureBuffer16Bit) {
-        SDL_assert((*env)->GetArrayLength(env, (jshortArray)captureBuffer) == (buflen / 2));
+    switch (captureBufferFormat) {
+    case ENCODING_PCM_8BIT:
+        SDL_assert((*env)->GetArrayLength(env, (jshortArray)captureBuffer) == buflen);
+        br = (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadByteBuffer, (jbyteArray)captureBuffer, JNI_TRUE);
+        if (br > 0) {
+            jbyte *ptr = (*env)->GetByteArrayElements(env, (jbyteArray)captureBuffer, &isCopy);
+            SDL_memcpy(buffer, ptr, br);
+            (*env)->ReleaseByteArrayElements(env, (jbyteArray)captureBuffer, (jbyte *)ptr, JNI_ABORT);
+        }
+        break;
+    case ENCODING_PCM_16BIT:
+        SDL_assert((*env)->GetArrayLength(env, (jshortArray)captureBuffer) == (buflen / sizeof(Sint16)));
         br = (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_TRUE);
         if (br > 0) {
             jshort *ptr = (*env)->GetShortArrayElements(env, (jshortArray)captureBuffer, &isCopy);
-            br *= 2;
+            br *= sizeof(Sint16);
             SDL_memcpy(buffer, ptr, br);
             (*env)->ReleaseShortArrayElements(env, (jshortArray)captureBuffer, (jshort *)ptr, JNI_ABORT);
         }
-    } else {
-        SDL_assert((*env)->GetArrayLength(env, (jshortArray)captureBuffer) == buflen);
-        br = (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadByteBuffer, (jbyteArray)captureBuffer, JNI_TRUE);
+        break;
+    case ENCODING_PCM_FLOAT:
+        SDL_assert((*env)->GetArrayLength(env, (jfloatArray)captureBuffer) == (buflen / sizeof(float)));
+        br = (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadFloatBuffer, (jfloatArray)captureBuffer, JNI_TRUE);
         if (br > 0) {
-            jbyte *ptr = (*env)->GetByteArrayElements(env, (jbyteArray)captureBuffer, &isCopy);
+            jfloat *ptr = (*env)->GetFloatArrayElements(env, (jfloatArray)captureBuffer, &isCopy);
+            br *= sizeof(float);
             SDL_memcpy(buffer, ptr, br);
-            (*env)->ReleaseByteArrayElements(env, (jbyteArray)captureBuffer, (jbyte *)ptr, JNI_ABORT);
+            (*env)->ReleaseFloatArrayElements(env, (jfloatArray)captureBuffer, (jfloat *)ptr, JNI_ABORT);
         }
+        break;
+    default:
+        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: unhandled capture buffer format");
+        break;
     }
-
-    return (int) br;
+    return br;
 }
 
 void Android_JNI_FlushCapturedAudio(void)
 {
     JNIEnv *env = Android_JNI_GetEnv();
 #if 0  /* !!! FIXME: this needs API 23, or it'll do blocking reads and never end. */
-    if (captureBuffer16Bit) {
-        const jint len = (*env)->GetArrayLength(env, (jshortArray)captureBuffer);
-        while ((*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_FALSE) == len) { /* spin */ }
-    } else {
-        const jint len = (*env)->GetArrayLength(env, (jbyteArray)captureBuffer);
-        while ((*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadByteBuffer, (jbyteArray)captureBuffer, JNI_FALSE) == len) { /* spin */ }
+    switch (captureBufferFormat) {
+    case ENCODING_PCM_8BIT:
+        {
+            const jint len = (*env)->GetArrayLength(env, (jbyteArray)captureBuffer);
+            while ((*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadByteBuffer, (jbyteArray)captureBuffer, JNI_FALSE) == len) { /* spin */ }
+        }
+        break;
+    case ENCODING_PCM_16BIT:
+        {
+            const jint len = (*env)->GetArrayLength(env, (jshortArray)captureBuffer);
+            while ((*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_FALSE) == len) { /* spin */ }
+        }
+        break;
+    case ENCODING_PCM_FLOAT:
+        {
+            const jint len = (*env)->GetArrayLength(env, (jfloatArray)captureBuffer);
+            while ((*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadFloatBuffer, (jfloatArray)captureBuffer, JNI_FALSE) == len) { /* spin */ }
+        }
+        break;
+    default:
+        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: flushing unhandled capture buffer format");
+        break;
     }
 #else
-    if (captureBuffer16Bit) {
-        (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_FALSE);
-    } else {
+    switch (captureBufferFormat) {
+    case ENCODING_PCM_8BIT:
         (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadByteBuffer, (jbyteArray)captureBuffer, JNI_FALSE);
+        break;
+    case ENCODING_PCM_16BIT:
+        (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_FALSE);
+        break;
+    case ENCODING_PCM_FLOAT:
+        (*env)->CallStaticIntMethod(env, mAudioManagerClass, midCaptureReadFloatBuffer, (jfloatArray)captureBuffer, JNI_FALSE);
+        break;
+    default:
+        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: flushing unhandled capture buffer format");
+        break;
     }
 #endif
 }

src/core/android/SDL_android.h

@@ -31,6 +31,7 @@ extern "C" {
 #include <EGL/eglplatform.h>
 #include <android/native_window_jni.h>
 
+#include "SDL_audio.h"
 #include "SDL_rect.h"
 
 /* Interface from the SDL library into the Android Java activity */
@@ -47,7 +48,7 @@ extern ANativeWindow* Android_JNI_GetNativeWindow(void);
 extern int Android_JNI_GetDisplayDPI(float *ddpi, float *xdpi, float *ydpi);
 
 /* Audio support */
-extern int Android_JNI_OpenAudioDevice(int iscapture, int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames);
+extern int Android_JNI_OpenAudioDevice(int iscapture, SDL_AudioSpec *spec);
 extern void* Android_JNI_GetAudioBuffer(void);
 extern void Android_JNI_WriteAudioBuffer(void);
 extern int Android_JNI_CaptureAudioBuffer(void *buffer, int buflen);