Merge pull request #2332 from google/madebymozart/small-buffer-slider

[Feature] Allow Users to setBufferSizeInFrames when in PCM Offload Mode

Author: madebymozart

samples/powerplay/build.gradle

@@ -46,7 +46,7 @@ android {
         kotlinCompilerExtensionVersion compose_version
     }
 
-    ndkVersion "29.0.13599879 rc2" // Requires NDK r29 for PCM Offload
+    ndkVersion "29.0.14206865" // Requires NDK r29 for PCM Offload
     externalNativeBuild {
         cmake {
             path 'src/main/cpp/CMakeLists.txt'
@@ -76,6 +76,7 @@ dependencies {
     implementation "androidx.compose.material3:material3:1.3.2"
     implementation 'androidx.activity:activity-compose:1.10.1'
     implementation 'androidx.appcompat:appcompat:1.7.1'
+    implementation 'androidx.compose.runtime:runtime-livedata:1.10.0'
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.2.1'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.6.1'

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

@@ -254,7 +254,26 @@ Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_isMMapSupport
     return PowerPlayMultiPlayer::isMMapSupported();
 }
 
+/**
+ * Native (JNI) implementation of PowerPlayAudioPlayer.setBufferSizeInFramesNative()
+ */
+JNIEXPORT jint JNICALL
+Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_setBufferSizeInFramesNative(
+        JNIEnv *env,
+        jobject,
+        jint bufferSizeInFrames) {
+    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

@@ -166,7 +166,6 @@ void PowerPlayMultiPlayer::triggerDown(int32_t index, oboe::PerformanceMode perf
                                     TAG,
                                     "Failed to flush from frame. Error: %s",
                                     convertToText(result.error()));
-                return;
             }
         }
     }
@@ -206,3 +205,34 @@ int32_t PowerPlayMultiPlayer::getCurrentlyPlayingIndex() {
     // No source is currently playing.
     return -1;
 }
+
+int32_t PowerPlayMultiPlayer::setBufferSizeInFrames(int32_t requestedFrames) {
+    if (mAudioStream == nullptr) {
+        __android_log_print(ANDROID_LOG_ERROR, TAG, "setBufferSizeInFrames: Stream is null");
+        return static_cast<int32_t>(Result::ErrorNull);
+    }
+
+    __android_log_print(ANDROID_LOG_INFO, TAG, "Requesting buffer size: %d frames (Input: %d)",
+                        requestedFrames, requestedFrames);
+
+    const auto result = mAudioStream->setBufferSizeInFrames(requestedFrames);
+
+    if (!result) {
+        __android_log_print(ANDROID_LOG_ERROR, TAG, "Failed to set buffer size: %s",
+                            convertToText(result.error()));
+        return static_cast<int32_t>(result.error());
+    }
+
+    // Return the actual value granted by the hardware.
+    __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

@@ -46,6 +46,9 @@ class PowerPlayMultiPlayer : public iolib::SimpleMultiPlayer {
 
     int32_t getCurrentlyPlayingIndex();
 
+    int32_t setBufferSizeInFrames(int32_t bufferSizeInFrames);
+
+    int32_t getBufferCapacityInFrames();
 
 private:
     class MyPresentationCallback : public oboe::AudioStreamPresentationCallback {

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

@@ -60,6 +60,7 @@ import androidx.compose.material3.Checkbox
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.RadioButton
+import androidx.compose.material3.Slider
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -107,14 +108,15 @@ class MainActivity : ComponentActivity() {
     private lateinit var serviceIntent: Intent
     private var isMMapSupported: Boolean = false
     private var isOffloadSupported: Boolean = false
+    private var sampleRate: Int = 48000;
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setUpPowerPlayAudioPlayer()
 
         val format = AudioFormat.Builder()
             .setEncoding(AudioFormat.ENCODING_PCM_FLOAT)
-            .setSampleRate(48000)
+            .setSampleRate(sampleRate)
             .setChannelMask(AudioFormat.CHANNEL_OUT_STEREO)
             .build()
 
@@ -171,6 +173,8 @@ class MainActivity : ComponentActivity() {
         val isPlaying = remember {
             mutableStateOf(false)
         }
+        var sliderPosition by remember { mutableFloatStateOf(0f) }
+
 
         LaunchedEffect(pagerState) {
             snapshotFlow { pagerState.currentPage }
@@ -240,13 +244,6 @@ class MainActivity : ComponentActivity() {
                     }
                 }
                 Spacer(modifier = Modifier.height(54.dp))
-                Column(
-                    modifier = Modifier
-                        .fillMaxWidth()
-                        .padding(horizontal = 32.dp),
-                ) {
-                }
-                Spacer(modifier = Modifier.height(8.dp))
                 Text(
                     "Performance Modes"
                 )
@@ -335,6 +332,47 @@ class MainActivity : ComponentActivity() {
                         modifier = Modifier.padding(start = 8.dp)
                     )
                 }
+                if (offload.intValue == 3) {
+                    Column(
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .padding(horizontal = 32.dp)
+                            .padding(top = 8.dp),
+                        horizontalAlignment = Alignment.CenterHorizontally
+                    ) {
+                        val requestedFrames = remember { mutableIntStateOf(0) }
+                        val actualFrames = remember { mutableIntStateOf(0) }
+
+                        Slider(
+                            value = sliderPosition,
+                            onValueChange = { newValue ->
+                                sliderPosition = newValue
+                                requestedFrames.intValue = sliderPosition.toInt()
+                            },
+                            onValueChangeFinished = {
+                                requestedFrames.intValue = sliderPosition.toInt()
+                                actualFrames.value = player.setBufferSizeInFrames(requestedFrames.intValue)
+                            },
+                            valueRange = 0f..player.getBufferCapacityInFrames().toFloat(),
+                        )
+
+                        val actualSeconds = actualFrames.value.toDouble() / sampleRate
+                        val formattedSeconds = "%.3f".format(actualSeconds)
+
+                        Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                            Text(
+                                text = "Requested: ${requestedFrames.intValue} Frames (BufferSize)",
+                                color = Color.Black,
+                                style = MaterialTheme.typography.bodySmall
+                            )
+                            Text(
+                                text = "Actual: ${actualFrames.value} Frames ($formattedSeconds seconds)",
+                                color = Color.Black,
+                                style = MaterialTheme.typography.bodySmall
+                            )
+                        }
+                    }
+                }
                 Spacer(modifier = Modifier.height(24.dp))
                 Row(
                     horizontalArrangement = Arrangement.SpaceEvenly,

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

@@ -62,7 +62,6 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
         assetFD.close()
     }
 
-
     /**
      * Sets whether the audio stream should use MMap audio.
      * @param enabled True to enable MMap, false to disable.
@@ -81,6 +80,19 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
      */
     fun isMMapSupported(): Boolean = isMMapSupportedNative()
 
+    /**
+     * Sets the buffer size in frames for the audio stream.
+     *
+     * Lower buffer sizes provide lower latency but increase the risk of audio glitches (underruns).
+     * This can only be set if the user is in PCM Offload mode.
+     *
+     * @param bufferSizeInFrames The requested buffer size in frames.
+     * @return The actual buffer size set by the native audio engine.
+     */
+    fun setBufferSizeInFrames(bufferSizeInFrames: Int): Int = setBufferSizeInFramesNative(bufferSizeInFrames)
+
+    fun getBufferCapacityInFrames(): Int = getBufferCapacityInFramesNative()
+
     /**
      * Native functions.
      * Load the library containing the native code including the JNI functions.
@@ -102,6 +114,8 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
     private external fun setMMapEnabledNative(enabled: Boolean): Boolean
     private external fun isMMapEnabledNative(): Boolean
     private external fun isMMapSupportedNative(): Boolean
+    private external fun setBufferSizeInFramesNative(bufferSizeInFrames: Int): Int
+    private external fun getBufferCapacityInFramesNative(): Int
 
     /**
      * Companion