Add getBufferCapacityInFrames and fix buffer slider logic

Author: madebymozart

samples/powerplay/src/main/cpp/PowerPlayJNI.cpp

@@ -265,6 +265,15 @@ Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_setBufferSize
     return player.setBufferSizeInFrames(bufferSizeInFrames);
 }
 
+/**
+ * Native (JNI) implementation of PowerPlayAudioPlayer.getBufferSizeInFramesNative()
+ */
+JNIEXPORT jint JNICALL
+Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_getBufferCapacityInFramesNative(
+        JNIEnv *env,
+        jobject) {
+    return player.getBufferCapacityInFrames();
+}
 
 #ifdef __cplusplus
 }

samples/powerplay/src/main/cpp/PowerPlayMultiPlayer.cpp

@@ -212,9 +212,6 @@ int32_t PowerPlayMultiPlayer::setBufferSizeInFrames(int32_t requestedFrames) {
         return static_cast<int32_t>(Result::ErrorNull);
     }
 
-    // Determine target size: Use maximum capacity if 0 or less is requested.
-    const int32_t capacity = mAudioStream->getBufferCapacityInFrames();
-
     __android_log_print(ANDROID_LOG_INFO, TAG, "Requesting buffer size: %d frames (Input: %d)",
                         requestedFrames, requestedFrames);
 
@@ -227,10 +224,15 @@ int32_t PowerPlayMultiPlayer::setBufferSizeInFrames(int32_t requestedFrames) {
     }
 
     // Return the actual value granted by the hardware.
-    const int32_t actualFrames = result.value();
-    __android_log_print(ANDROID_LOG_INFO, TAG, "Buffer size set to %d frames (Max Capacity: %d)",
-                        actualFrames, capacity);
-
-    return actualFrames;
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Buffer size set to %d frames.", result.value());
+    return result.value();
 }
 
+int32_t PowerPlayMultiPlayer::getBufferCapacityInFrames() {
+    if (mAudioStream == nullptr) {
+        __android_log_print(ANDROID_LOG_ERROR, TAG, "getBufferCapacityInFrames: Stream is null");
+        return static_cast<int32_t>(Result::ErrorNull);
+    }
+
+    return mAudioStream->getBufferCapacityInFrames();
+}

samples/powerplay/src/main/cpp/PowerPlayMultiPlayer.h

@@ -48,6 +48,8 @@ class PowerPlayMultiPlayer : public iolib::SimpleMultiPlayer {
 
     int32_t setBufferSizeInFrames(int32_t bufferSizeInFrames);
 
+    int32_t getBufferCapacityInFrames();
+
 private:
     class MyPresentationCallback : public oboe::AudioStreamPresentationCallback {
     public:

samples/powerplay/src/main/kotlin/com/google/oboe/samples/powerplay/MainActivity.kt

@@ -341,24 +341,22 @@ class MainActivity : ComponentActivity() {
                         horizontalAlignment = Alignment.CenterHorizontally
                     ) {
                         val requestedFrames = remember { mutableIntStateOf(0) }
-                        val actualSize = remember { mutableIntStateOf(0) }
+                        val actualFrames = remember { mutableIntStateOf(0) }
 
                         Slider(
                             value = sliderPosition,
                             onValueChange = { newValue ->
                                 sliderPosition = newValue
-                                requestedFrames.intValue = (sliderPosition * sampleRate).toInt()
+                                requestedFrames.intValue = sliderPosition.toInt()
                             },
                             onValueChangeFinished = {
-                                requestedFrames.intValue = (sliderPosition * sampleRate).toInt()
-                                actualSize.intValue =
-                                    player.setBufferSizeInFrames(requestedFrames.intValue)
+                                requestedFrames.intValue = sliderPosition.toInt()
+                                actualFrames.value = player.setBufferSizeInFrames(requestedFrames.intValue)
                             },
-                            valueRange = 0f..30f,
+                            valueRange = 0f..player.getBufferCapacityInFrames().toFloat(),
                         )
 
-                        val actualSeconds =
-                            if (sampleRate > 0) actualSize.intValue.toDouble() / sampleRate else 0.0
+                        val actualSeconds = actualFrames.value.toDouble() / sampleRate
                         val formattedSeconds = "%.3f".format(actualSeconds)
 
                         Column(horizontalAlignment = Alignment.CenterHorizontally) {
@@ -368,7 +366,7 @@ class MainActivity : ComponentActivity() {
                                 style = MaterialTheme.typography.bodySmall
                             )
                             Text(
-                                text = "Actual: ${actualSize.intValue} Frames ($formattedSeconds seconds)",
+                                text = "Actual: ${actualFrames.value} Frames ($formattedSeconds seconds)",
                                 color = Color.Black,
                                 style = MaterialTheme.typography.bodySmall
                             )

samples/powerplay/src/main/kotlin/com/google/oboe/samples/powerplay/engine/PowerPlayAudioPlayer.kt

@@ -91,6 +91,8 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
      */
     fun setBufferSizeInFrames(bufferSizeInFrames: Int): Int = setBufferSizeInFramesNative(bufferSizeInFrames)
 
+    fun getBufferCapacityInFrames(): Int = getBufferCapacityInFramesNative()
+
     /**
      * Native functions.
      * Load the library containing the native code including the JNI functions.
@@ -113,6 +115,7 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
     private external fun isMMapEnabledNative(): Boolean
     private external fun isMMapSupportedNative(): Boolean
     private external fun setBufferSizeInFramesNative(bufferSizeInFrames: Int): Int
+    private external fun getBufferCapacityInFramesNative(): Int
 
     /**
      * Companion