android: implement audio capture support.

android-project/AndroidManifest.xml

@@ -17,6 +17,9 @@
     <!-- Allow writing to external storage -->
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 
+    <!-- if you want to capture audio, uncomment this. -->
+    <!-- <uses-permission android:name="android.permission.RECORD_AUDIO" /> -->
+
     <!-- Create a Java class extending SDLActivity and place it in a
          directory under src matching the package, e.g.
          	src/com/gamemaker/game/MyGame.java

android-project/src/org/libsdl/app/SDLActivity.java

@@ -59,6 +59,7 @@ public class SDLActivity extends Activity {
 
     // Audio
     protected static AudioTrack mAudioTrack;
+    protected static AudioRecord mAudioRecord;
 
     /**
      * This method is called by SDL before loading the native shared libraries.
@@ -106,6 +107,7 @@ public class SDLActivity extends Activity {
         mJoystickHandler = null;
         mSDLThread = null;
         mAudioTrack = null;
+        mAudioRecord = null;
         mExitCalledFromJava = false;
         mBrokenLibraries = false;
         mIsPaused = false;
@@ -544,7 +546,7 @@ public class SDLActivity extends Activity {
     /**
      * This method is called by SDL using JNI.
      */
-    public static int audioInit(int sampleRate, boolean is16Bit, boolean isStereo, int desiredFrames) {
+    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);
@@ -623,13 +625,72 @@ public class SDLActivity extends Activity {
     /**
      * This method is called by SDL using JNI.
      */
-    public static void audioQuit() {
+    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");
+
+        return 0;
+    }
+
+    /** 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);
+    }
+
+    /** 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);
+    }
+
+
+    /** This method is called by SDL using JNI. */
+    public static void audioClose() {
         if (mAudioTrack != null) {
             mAudioTrack.stop();
+            mAudioTrack.release();
             mAudioTrack = null;
         }
     }
 
+    /** This method is called by SDL using JNI. */
+    public static void captureClose() {
+        if (mAudioRecord != null) {
+            mAudioRecord.stop();
+            mAudioRecord.release();
+            mAudioRecord = null;
+        }
+    }
+
+
     // Input
 
     /**

src/audio/android/SDL_androidaudio.c

@@ -24,6 +24,7 @@
 
 /* Output audio to Android */
 
+#include "SDL_assert.h"
 #include "SDL_audio.h"
 #include "../SDL_audio_c.h"
 #include "SDL_androidaudio.h"
@@ -33,23 +34,21 @@
 #include <android/log.h>
 
 static SDL_AudioDevice* audioDevice = NULL;
+static SDL_AudioDevice* captureDevice = NULL;
 
 static int
 AndroidAUD_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
 {
     SDL_AudioFormat test_format;
 
+    SDL_assert((captureDevice == NULL) || !iscapture);
+    SDL_assert((audioDevice == NULL) || iscapture);
+
     if (iscapture) {
-        /* TODO: implement capture */
+        captureDevice = this;
-        return SDL_SetError("Capture not supported on Android");
+    } else {
-    }
-
-    /* !!! FIXME: higher level will prevent this now. Lose this check (and global?). */
-    if (audioDevice != NULL) {
-        return SDL_SetError("Only one audio device at a time please!");
-    }
-
         audioDevice = this;
+    }
 
     this->hidden = (struct SDL_PrivateAudioData *) SDL_calloc(1, (sizeof *this->hidden));
     if (this->hidden == NULL) {
@@ -83,15 +82,16 @@ AndroidAUD_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
         this->spec.freq = 48000;
     }
 
-    /* TODO: pass in/return a (Java) device ID, also whether we're opening for input or output */
+    /* TODO: pass in/return a (Java) device ID */
-    this->spec.samples = Android_JNI_OpenAudioDevice(this->spec.freq, this->spec.format == AUDIO_U8 ? 0 : 1, this->spec.channels, this->spec.samples);
+    this->spec.samples = Android_JNI_OpenAudioDevice(iscapture, this->spec.freq, this->spec.format == AUDIO_U8 ? 0 : 1, this->spec.channels, this->spec.samples);
-    SDL_CalculateAudioSpec(&this->spec);
 
     if (this->spec.samples == 0) {
         /* Init failed? */
         return SDL_SetError("Java-side initialization failed!");
     }
 
+    SDL_CalculateAudioSpec(&this->spec);
+
     return 0;
 }
 
@@ -107,18 +107,33 @@ AndroidAUD_GetDeviceBuf(_THIS)
     return Android_JNI_GetAudioBuffer();
 }
 
+static int
+AndroidAUD_CaptureFromDevice(_THIS, void *buffer, int buflen)
+{
+    return Android_JNI_CaptureAudioBuffer(buffer, buflen);
+}
+
+static void
+AndroidAUD_FlushCapture(_THIS)
+{
+    Android_JNI_FlushCapturedAudio();
+}
+
 static void
 AndroidAUD_CloseDevice(_THIS)
 {
     /* At this point SDL_CloseAudioDevice via close_audio_device took care of terminating the audio thread
        so it's safe to terminate the Java side buffer and AudioTrack
      */
-    Android_JNI_CloseAudioDevice();
+    Android_JNI_CloseAudioDevice(this->iscapture);
-
+    if (this->iscapture) {
-    if (audioDevice == this) {
+        SDL_assert(captureDevice == this);
-        SDL_free(this->hidden);
+        captureDevice = NULL;
+    } else {
+        SDL_assert(audioDevice == this);
         audioDevice = NULL;
     }
+    SDL_free(this->hidden);
 }
 
 static int
@@ -129,9 +144,11 @@ AndroidAUD_Init(SDL_AudioDriverImpl * impl)
     impl->PlayDevice = AndroidAUD_PlayDevice;
     impl->GetDeviceBuf = AndroidAUD_GetDeviceBuf;
     impl->CloseDevice = AndroidAUD_CloseDevice;
+    impl->CaptureFromDevice = AndroidAUD_CaptureFromDevice;
+    impl->FlushCapture = AndroidAUD_FlushCapture;
 
     /* and the capabilities */
-    impl->HasCaptureSupport = 0; /* TODO */
+    impl->HasCaptureSupport = SDL_TRUE;
     impl->OnlyHasDefaultOutputDevice = 1;
     impl->OnlyHasDefaultCaptureDevice = 1;
 
@@ -159,6 +176,19 @@ void AndroidAUD_PauseDevices(void)
             private->resume = SDL_TRUE;
         }
     }
+
+    if(captureDevice != NULL && captureDevice->hidden != NULL) {
+        private = (struct SDL_PrivateAudioData *) captureDevice->hidden;
+        if (SDL_AtomicGet(&captureDevice->paused)) {
+            /* The device is already paused, leave it alone */
+            private->resume = SDL_FALSE;
+        }
+        else {
+            SDL_LockMutex(captureDevice->mixer_lock);
+            SDL_AtomicSet(&captureDevice->paused, 1);
+            private->resume = SDL_TRUE;
+        }
+    }
 }
 
 /* Resume (unblock) all non already paused audio devices by releasing their mixer lock */
@@ -174,6 +204,15 @@ void AndroidAUD_ResumeDevices(void)
             SDL_UnlockMutex(audioDevice->mixer_lock);
         }
     }
+
+    if(captureDevice != NULL && captureDevice->hidden != NULL) {
+        private = (struct SDL_PrivateAudioData *) captureDevice->hidden;
+        if (private->resume) {
+            SDL_AtomicSet(&captureDevice->paused, 0);
+            private->resume = SDL_FALSE;
+            SDL_UnlockMutex(captureDevice->mixer_lock);
+        }
+    }
 }
 
 

src/core/android/SDL_android.c

@@ -71,10 +71,14 @@ static jclass mActivityClass;
 
 /* method signatures */
 static jmethodID midGetNativeSurface;
-static jmethodID midAudioInit;
+static jmethodID midAudioOpen;
 static jmethodID midAudioWriteShortBuffer;
 static jmethodID midAudioWriteByteBuffer;
-static jmethodID midAudioQuit;
+static jmethodID midAudioClose;
+static jmethodID midCaptureOpen;
+static jmethodID midCaptureReadShortBuffer;
+static jmethodID midCaptureReadByteBuffer;
+static jmethodID midCaptureClose;
 static jmethodID midPollInputDevices;
 
 /* Accelerometer data storage */
@@ -118,21 +122,31 @@ JNIEXPORT void JNICALL SDL_Android_Init(JNIEnv* mEnv, jclass cls)
 
     midGetNativeSurface = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                 "getNativeSurface","()Landroid/view/Surface;");
-    midAudioInit = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+    midAudioOpen = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
-                                "audioInit", "(IZZI)I");
+                                "audioOpen", "(IZZI)I");
     midAudioWriteShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                 "audioWriteShortBuffer", "([S)V");
     midAudioWriteByteBuffer = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                 "audioWriteByteBuffer", "([B)V");
-    midAudioQuit = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+    midAudioClose = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
-                                "audioQuit", "()V");
+                                "audioClose", "()V");
+    midCaptureOpen = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+                                "captureOpen", "(IZZI)I");
+    midCaptureReadShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+                                "captureReadShortBuffer", "([SZ)I");
+    midCaptureReadByteBuffer = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+                                "captureReadByteBuffer", "([BZ)I");
+    midCaptureClose = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
+                                "captureClose", "()V");
     midPollInputDevices = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                 "pollInputDevices", "()V");
 
     bHasNewData = SDL_FALSE;
 
-    if (!midGetNativeSurface || !midAudioInit ||
+    if (!midGetNativeSurface ||
-       !midAudioWriteShortBuffer || !midAudioWriteByteBuffer || !midAudioQuit || !midPollInputDevices) {
+       !midAudioOpen || !midAudioWriteShortBuffer || !midAudioWriteByteBuffer || !midAudioClose || !
+       !midCaptureOpen || !midCaptureReadShortBuffer || !midCaptureReadByteBuffer || !midCaptureClose ||
+       !midPollInputDevices) {
         __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL: Couldn't locate Java callbacks, check that they're named and typed correctly");
     }
     __android_log_print(ANDROID_LOG_INFO, "SDL", "SDL_Android_Init() finished!");
@@ -556,11 +570,14 @@ int Android_JNI_SetupThread(void)
 static jboolean audioBuffer16Bit = JNI_FALSE;
 static jobject audioBuffer = NULL;
 static void* audioBufferPinned = NULL;
+static jboolean captureBuffer16Bit = JNI_FALSE;
+static jobject captureBuffer = NULL;
 
-int Android_JNI_OpenAudioDevice(int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames)
+int Android_JNI_OpenAudioDevice(int iscapture, int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames)
 {
     jboolean audioBufferStereo;
     int audioBufferFrames;
+    jobject jbufobj = NULL;
     jboolean isCopy;
 
     JNIEnv *env = Android_JNI_GetEnv();
@@ -570,15 +587,25 @@ int Android_JNI_OpenAudioDevice(int sampleRate, int is16Bit, int channelCount, i
     }
     Android_JNI_SetupThread();
 
-    __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "SDL audio: opening device");
-    audioBuffer16Bit = is16Bit;
     audioBufferStereo = channelCount > 1;
 
-    if ((*env)->CallStaticIntMethod(env, mActivityClass, midAudioInit, sampleRate, audioBuffer16Bit, audioBufferStereo, desiredBufferFrames) != 0) {
+    if (iscapture) {
+        __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "SDL audio: opening device for capture");
+        captureBuffer16Bit = is16Bit;
+        if ((*env)->CallStaticIntMethod(env, mActivityClass, midCaptureOpen, sampleRate, audioBuffer16Bit, audioBufferStereo, desiredBufferFrames) != 0) {
+            /* Error during audio initialization */
+            __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: error on AudioRecord initialization!");
+            return 0;
+        }
+    } else {
+        __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "SDL audio: opening device for output");
+        audioBuffer16Bit = is16Bit;
+        if ((*env)->CallStaticIntMethod(env, mActivityClass, midAudioOpen, sampleRate, audioBuffer16Bit, audioBufferStereo, desiredBufferFrames) != 0) {
             /* Error during audio initialization */
             __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: error on AudioTrack initialization!");
             return 0;
         }
+    }
 
     /* 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. */
@@ -586,31 +613,43 @@ int Android_JNI_OpenAudioDevice(int sampleRate, int is16Bit, int channelCount, i
     if (is16Bit) {
         jshortArray audioBufferLocal = (*env)->NewShortArray(env, desiredBufferFrames * (audioBufferStereo ? 2 : 1));
         if (audioBufferLocal) {
-            audioBuffer = (*env)->NewGlobalRef(env, audioBufferLocal);
+            jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
             (*env)->DeleteLocalRef(env, audioBufferLocal);
         }
     }
     else {
         jbyteArray audioBufferLocal = (*env)->NewByteArray(env, desiredBufferFrames * (audioBufferStereo ? 2 : 1));
         if (audioBufferLocal) {
-            audioBuffer = (*env)->NewGlobalRef(env, audioBufferLocal);
+            jbufobj = (*env)->NewGlobalRef(env, audioBufferLocal);
             (*env)->DeleteLocalRef(env, audioBufferLocal);
         }
     }
 
-    if (audioBuffer == NULL) {
+    if (jbufobj == NULL) {
         __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: could not allocate an audio buffer!");
         return 0;
     }
 
+    if (iscapture) {
+        captureBuffer = jbufobj;
+    } else {
+        audioBuffer = jbufobj;
+    }
+
     isCopy = JNI_FALSE;
-    if (audioBuffer16Bit) {
+
+    if (is16Bit) {
+        if (!iscapture) {
             audioBufferPinned = (*env)->GetShortArrayElements(env, (jshortArray)audioBuffer, &isCopy);
+        }
         audioBufferFrames = (*env)->GetArrayLength(env, (jshortArray)audioBuffer);
     } else {
+        if (!iscapture) {
             audioBufferPinned = (*env)->GetByteArrayElements(env, (jbyteArray)audioBuffer, &isCopy);
+        }
         audioBufferFrames = (*env)->GetArrayLength(env, (jbyteArray)audioBuffer);
     }
+
     if (audioBufferStereo) {
         audioBufferFrames /= 2;
     }
@@ -638,18 +677,75 @@ void Android_JNI_WriteAudioBuffer(void)
     /* JNI_COMMIT means the changes are committed to the VM but the buffer remains pinned */
 }
 
-void Android_JNI_CloseAudioDevice(void)
+int Android_JNI_CaptureAudioBuffer(void *buffer, int buflen)
+{
+    JNIEnv *env = Android_JNI_GetEnv();
+    jboolean isCopy = JNI_FALSE;
+    jint br;
+
+    if (captureBuffer16Bit) {
+        SDL_assert((*env)->GetArrayLength(env, (jshortArray)captureBuffer) == (buflen / 2));
+        br = (*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_TRUE);
+        if (br > 0) {
+            jshort *ptr = (*env)->GetShortArrayElements(env, (jshortArray)captureBuffer, &isCopy);
+            br *= 2;
+            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, mActivityClass, 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);
+        }
+    }
+
+    return (int) 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 */ }
+    }
+    #else
+    if (captureBuffer16Bit) {
+        const jint len = (*env)->GetArrayLength(env, (jshortArray)captureBuffer);
+        (*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadShortBuffer, (jshortArray)captureBuffer, JNI_FALSE);
+    } else {
+        const jint len = (*env)->GetArrayLength(env, (jbyteArray)captureBuffer);
+        (*env)->CallStaticIntMethod(env, mActivityClass, midCaptureReadByteBuffer, (jbyteArray)captureBuffer, JNI_FALSE);
+    }
+    #endif
+}
+
+void Android_JNI_CloseAudioDevice(const int iscapture)
 {
     JNIEnv *env = Android_JNI_GetEnv();
 
-    (*env)->CallStaticVoidMethod(env, mActivityClass, midAudioQuit);
+    if (iscapture) {
-
+        (*env)->CallStaticVoidMethod(env, mActivityClass, midCaptureClose);
+        if (captureBuffer) {
+            (*env)->DeleteGlobalRef(env, captureBuffer);
+            captureBuffer = NULL;
+        }
+    } else {
+        (*env)->CallStaticVoidMethod(env, mActivityClass, midAudioClose);
         if (audioBuffer) {
             (*env)->DeleteGlobalRef(env, audioBuffer);
             audioBuffer = NULL;
             audioBufferPinned = NULL;
         }
     }
+}
 
 /* Test for an exception and call SDL_SetError with its detail if one occurs */
 /* If the parameter silent is truthy then SDL_SetError() will not be called. */

src/core/android/SDL_android.h

@@ -40,10 +40,12 @@ extern void Android_JNI_HideTextInput(void);
 extern ANativeWindow* Android_JNI_GetNativeWindow(void);
 
 /* Audio support */
-extern int Android_JNI_OpenAudioDevice(int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames);
+extern int Android_JNI_OpenAudioDevice(int iscapture, int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames);
 extern void* Android_JNI_GetAudioBuffer(void);
 extern void Android_JNI_WriteAudioBuffer(void);
-extern void Android_JNI_CloseAudioDevice(void);
+extern int Android_JNI_CaptureAudioBuffer(void *buffer, int buflen);
+extern void Android_JNI_FlushCapturedAudio(void);
+extern void Android_JNI_CloseAudioDevice(const int iscapture);
 
 #include "SDL_rwops.h"