RMS Visualizer

.idea/deploymentTargetSelector.xml

@@ -13,6 +13,9 @@
         </DropdownSelection>
         <DialogSelection />
       </SelectionState>
+      <SelectionState runConfigName="ExampleInstrumentedTest">
+        <option name="selectionMode" value="DROPDOWN" />
+      </SelectionState>
     </selectionStates>
   </component>
 </project>

.idea/misc.xml

@@ -1,4 +1,3 @@
-<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="jbr-21" project-jdk-type="JavaSDK">

app/src/main/java/dev/adriankuta/visualizer/AudioVisualizer.kt

@@ -1,160 +0,0 @@
-package dev.adriankuta.visualizer
-
-import android.media.audiofx.Visualizer
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.State
-import androidx.compose.ui.graphics.Color
-import dev.adriankuta.visualizer.domain.SoundToColorMapper
-import dev.adriankuta.visualizer.domain.SoundToColorMapperFactory
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.Job
-import kotlinx.coroutines.launch
-import timber.log.Timber
-
-/**
- * Interface for audio visualization functionality.
- * Follows Interface Segregation Principle.
- */
-interface AudioVisualizerService {
-    val currentColor: State<Color>
-    val isActive: State<Boolean>
-    
-    fun start()
-    fun stop()
-    fun release()
-}
-
-/**
- * Implementation of AudioVisualizerService using Android's Visualizer API.
- * 
- * Follows Single Responsibility Principle by focusing on audio visualization.
- * Uses Dependency Injection for the sound-to-color mapper.
- */
-class AndroidAudioVisualizer(
-    private val soundToColorMapper: SoundToColorMapper = SoundToColorMapperFactory.createDefault(),
-    private val coroutineScope: CoroutineScope = CoroutineScope(Dispatchers.Main)
-) : AudioVisualizerService {
-    
-    companion object {
-        private const val SAMPLING_RATE = 16000 // Hz
-        private const val CAPTURE_SIZE = 1024 // Window size for audio capture
-    }
-    
-    private var visualizer: Visualizer? = null
-    private var processingJob: Job? = null
-    
-    private val _currentColor = mutableStateOf(Color.Black)
-    override val currentColor: State<Color> = _currentColor
-    
-    private val _isActive = mutableStateOf(false)
-    override val isActive: State<Boolean> = _isActive
-    
-    override fun start() {
-        try {
-            // Initialize visualizer with audio session ID 0 (output mix)
-            visualizer = Visualizer(0).apply {
-                captureSize = CAPTURE_SIZE
-                
-                // Set up waveform data listener
-                setDataCaptureListener(
-                    object : Visualizer.OnDataCaptureListener {
-                        override fun onWaveFormDataCapture(
-                            visualizer: Visualizer?,
-                            waveform: ByteArray?,
-                            samplingRate: Int
-                        ) {
-                            waveform?.let { processWaveform(it) }
-                        }
-                        
-                        override fun onFftDataCapture(
-                            visualizer: Visualizer?,
-                            fft: ByteArray?,
-                            samplingRate: Int
-                        ) {
-                            // Not used in this implementation
-                        }
-                    },
-                    Visualizer.getMaxCaptureRate() / 2, // Capture rate
-                    true, // Waveform
-                    false // FFT
-                )
-                
-                enabled = true
-            }
-            
-            _isActive.value = true
-            Timber.d("AudioVisualizer started successfully")
-            
-        } catch (e: Exception) {
-            Timber.e(e, "Failed to start AudioVisualizer")
-            _isActive.value = false
-        }
-    }
-    
-    override fun stop() {
-        try {
-            visualizer?.enabled = false
-            processingJob?.cancel()
-            _isActive.value = false
-            Timber.d("AudioVisualizer stopped")
-        } catch (e: Exception) {
-            Timber.e(e, "Error stopping AudioVisualizer")
-        }
-    }
-    
-    override fun release() {
-        stop()
-        try {
-            visualizer?.release()
-            visualizer = null
-            soundToColorMapper.reset()
-            Timber.d("AudioVisualizer released")
-        } catch (e: Exception) {
-            Timber.e(e, "Error releasing AudioVisualizer")
-        }
-    }
-    
-    private fun processWaveform(waveform: ByteArray) {
-        processingJob?.cancel()
-        processingJob = coroutineScope.launch(Dispatchers.Default) {
-            try {
-                val color = soundToColorMapper.mapSoundToColor(waveform)
-                
-                // Update UI on main thread
-                launch(Dispatchers.Main) {
-                    _currentColor.value = color
-                }
-            } catch (e: Exception) {
-                Timber.e(e, "Error processing waveform")
-            }
-        }
-    }
-}
-
-/**
- * Factory for creating AudioVisualizerService instances.
- * Follows Factory Pattern and makes testing easier.
- */
-object AudioVisualizerFactory {
-    
-    /**
-     * Creates a default Android audio visualizer.
-     */
-    fun createDefault(coroutineScope: CoroutineScope): AudioVisualizerService {
-        return AndroidAudioVisualizer(
-            soundToColorMapper = SoundToColorMapperFactory.createDefault(),
-            coroutineScope = coroutineScope
-        )
-    }
-    
-    /**
-     * Creates an Android audio visualizer with custom mapper.
-     */
-    fun create(
-        soundToColorMapper: SoundToColorMapper,
-        coroutineScope: CoroutineScope
-    ): AudioVisualizerService {
-        return AndroidAudioVisualizer(soundToColorMapper, coroutineScope)
-    }
-}

app/src/main/java/dev/adriankuta/visualizer/data/AudioVisualizer.kt

@@ -3,7 +3,6 @@ package dev.adriankuta.visualizer.data
 import kotlinx.coroutines.flow.Flow
 
 interface AudioVisualizer: AudioVisualizerController {
-    fun waveform(): Flow<WaveformFrame>
 
-    fun fft(): Flow<FftFrame>
+    fun visualizerFlow(): Flow<VisualizerFrame>
 }

app/src/main/java/dev/adriankuta/visualizer/data/AudioVisualizerImpl.kt

@@ -1,11 +1,12 @@
 package dev.adriankuta.visualizer.data
 
 import android.media.audiofx.Visualizer
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.conflate
-import kotlinx.coroutines.flow.filterIsInstance
+import kotlinx.coroutines.flow.flowOn
 import javax.inject.Inject
 
 class AudioVisualizerImpl @Inject constructor(
@@ -13,22 +14,14 @@ class AudioVisualizerImpl @Inject constructor(
 ) : AudioVisualizer {
 
     override fun start() {
-        visualizer.enabled = true
+       // visualizer.enabled = true
     }
 
     override fun stop() {
         visualizer.enabled = false
     }
 
-    override fun waveform(): Flow<WaveformFrame> =
+    override fun visualizerFlow(): Flow<VisualizerFrame> = callbackFlow {
-        visualizerFlow()
-            .filterIsInstance(WaveformFrame::class)
-
-    override fun fft(): Flow<FftFrame> =
-        visualizerFlow()
-            .filterIsInstance(FftFrame::class)
-
-    private fun visualizerFlow(): Flow<VisualizerFrame> = callbackFlow {
         val listener = object : Visualizer.OnDataCaptureListener {
             override fun onFftDataCapture(
                 visualizer: Visualizer?,
@@ -47,13 +40,15 @@ class AudioVisualizerImpl @Inject constructor(
             }
         }
 
-        visualizer.setDataCaptureListener(
+        val result = visualizer.setDataCaptureListener(
             listener,
             Visualizer.getMaxCaptureRate(),
             true,
             true
         )
 
+        visualizer.enabled = true
+
         awaitClose {
             runCatching {
                 visualizer.enabled = false
@@ -63,13 +58,17 @@ class AudioVisualizerImpl @Inject constructor(
         }
     }
         .conflate()
+        .flowOn(Dispatchers.Default)
+}
+
+sealed interface VisualizerFrame {
+    val data: ByteArray
 }
 
-sealed interface VisualizerFrame
 data class WaveformFrame(
-    val data: ByteArray,
+    override val data: ByteArray,
 ) : VisualizerFrame
 
 data class FftFrame(
-    val data: ByteArray,
+    override val data: ByteArray,
 ) : VisualizerFrame

app/src/main/java/dev/adriankuta/visualizer/data/RmsValueProvider.kt

@@ -0,0 +1,26 @@
+package dev.adriankuta.visualizer.data
+
+import kotlinx.coroutines.channels.BufferOverflow
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.SharedFlow
+import javax.inject.Inject
+import javax.inject.Singleton
+
+@Singleton
+class RmsValueProvider @Inject constructor() {
+
+    private val currentRms =
+        MutableSharedFlow<RmsValue>(1, 1, onBufferOverflow = BufferOverflow.DROP_OLDEST)
+
+    fun emit(value: RmsValue) {
+        currentRms.tryEmit(value)
+    }
+
+    fun observe(): SharedFlow<RmsValue> = currentRms
+}
+
+data class RmsValue(
+    val current: Double,
+    val max: Double,
+    val min: Double = 0.0
+)

app/src/main/java/dev/adriankuta/visualizer/di/VisualizerModule.kt

@@ -9,6 +9,8 @@ import dagger.hilt.components.SingletonComponent
 import dev.adriankuta.visualizer.data.AudioVisualizer
 import dev.adriankuta.visualizer.data.AudioVisualizerController
 import dev.adriankuta.visualizer.data.AudioVisualizerImpl
+import dev.adriankuta.visualizer.domain.processors.HSLSoundToColorMapper
+import dev.adriankuta.visualizer.domain.processors.VisualizerProcessor
 import javax.inject.Singleton
 
 @Module
@@ -25,6 +27,11 @@ abstract class VisualizerModule {
         audioVisualizerImpl: AudioVisualizerImpl
     ): AudioVisualizerController
 
+    @Binds
+    abstract fun bindProcessor(
+        fftToColor: HSLSoundToColorMapper
+    ): VisualizerProcessor
+
     companion object {
         @Provides
         @Singleton
@@ -33,5 +40,11 @@ abstract class VisualizerModule {
                 captureSize = 1024
             }
         }
+
+        /*@Provides
+        @Singleton
+        fun provideProcessor(): VisualizerProcessor {
+            return HSLSoundToColorMapper()
+        }*/
     }
 }

app/src/main/java/dev/adriankuta/visualizer/domain/ObserveVisualizerColorUseCase.kt

@@ -2,22 +2,28 @@ package dev.adriankuta.visualizer.domain
 
 import androidx.compose.ui.graphics.Color
 import dev.adriankuta.visualizer.data.AudioVisualizer
+import dev.adriankuta.visualizer.data.FftFrame
+import dev.adriankuta.visualizer.data.VisualizerFrame
 import dev.adriankuta.visualizer.data.WaveformFrame
+import dev.adriankuta.visualizer.domain.processors.VisualizerProcessor
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.filterIsInstance
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onStart
 import javax.inject.Inject
 
 class ObserveVisualizerColorUseCase @Inject constructor(
-    private val audioVisualizer: AudioVisualizer
+    private val audioVisualizer: AudioVisualizer,
+    private val processor: VisualizerProcessor,
 ) {
 
-    private val colorMapper = HSLSoundToColorMapper()
-
     operator fun invoke(): Flow<Color> =
-        audioVisualizer.waveform()
+        audioVisualizer.visualizerFlow()
-            .map { processColor(it) }
+            .process(processor)
-
+            .onStart { emit(Color.Black) }
-    private fun processColor(waveformFrame: WaveformFrame): Color {
-        return colorMapper.mapSoundToColor(waveformFrame.data)
-    }
 }
+
+fun Flow<VisualizerFrame>.process(processor: VisualizerProcessor) =
+    this.filterIsInstance(WaveformFrame::class)
+        .map(processor::invoke)
+

app/src/main/java/dev/adriankuta/visualizer/domain/SoundToColorMapper.kt

@@ -1,97 +0,0 @@
-package dev.adriankuta.visualizer.domain
-
-import androidx.compose.ui.graphics.Color
-import dev.adriankuta.visualizer.HSL
-import dev.adriankuta.visualizer.MovingAverage
-import dev.adriankuta.visualizer.calculateRms
-
-/**
- * Interface for mapping sound data to colors.
- * Follows the Interface Segregation Principle by defining a focused contract.
- */
-interface SoundToColorMapper {
-    /**
-     * Maps audio waveform data to a color.
-     * 
-     * @param waveform Audio waveform data as byte array
-     * @return Compose Color representing the mapped sound
-     */
-    fun mapSoundToColor(waveform: ByteArray): Color
-    
-    /**
-     * Resets the internal state of the mapper.
-     */
-    fun reset()
-}
-
-/**
- * Default implementation of SoundToColorMapper that uses HSL color space
- * and moving average for smooth color transitions.
- * 
- * Follows Single Responsibility Principle by focusing on sound-to-color mapping.
- * Follows Dependency Inversion Principle by depending on abstractions.
- */
-class HSLSoundToColorMapper(
-    private val baseHue: Float = 0f, // Blue hue as default
-    private val saturation: Float = 1f,
-    private val movingAverageWindowSize: Int = 1
-) : SoundToColorMapper {
-    
-    private val movingAverage = MovingAverage(movingAverageWindowSize)
-    private var rmsMax = 0.0
-    
-    override fun mapSoundToColor(waveform: ByteArray): Color {
-        // Calculate RMS value for current frame
-        val currentRms = calculateRms(waveform)
-        
-        // Update maximum RMS value for normalization
-        if (currentRms > rmsMax) {
-            rmsMax = currentRms
-        }
-        
-        // Calculate energy ratio (0-1)
-        val energyRatio = if (rmsMax > 0) currentRms / rmsMax else 0.0
-        
-        // Apply moving average for smooth transitions
-        val adjustedLightness = movingAverage.process(energyRatio)
-        
-        // Create HSL color and convert to Compose Color
-        val hslColor = HSL(
-            hue = baseHue,
-            saturation = saturation,
-            lightness = adjustedLightness.toFloat().coerceIn(0f, 1f)
-        )
-        
-        return hslColor.toComposeColor()
-    }
-    
-    override fun reset() {
-        movingAverage.reset()
-        rmsMax = 0.0
-    }
-}
-
-/**
- * Factory for creating SoundToColorMapper instances.
- * Follows the Factory Pattern and Open/Closed Principle.
- */
-object SoundToColorMapperFactory {
-    
-    /**
-     * Creates a default HSL-based sound to color mapper.
-     */
-    fun createDefault(): SoundToColorMapper = HSLSoundToColorMapper()
-    
-    /**
-     * Creates an HSL-based sound to color mapper with custom parameters.
-     * 
-     * @param baseHue The base hue for the color (0-360)
-     * @param saturation The saturation level (0-1)
-     * @param movingAverageWindowSize Window size for moving average smoothing
-     */
-    fun createHSLMapper(
-        baseHue: Float = 240f,
-        saturation: Float = 1f,
-        movingAverageWindowSize: Int = 7
-    ): SoundToColorMapper = HSLSoundToColorMapper(baseHue, saturation, movingAverageWindowSize)
-}

app/src/main/java/dev/adriankuta/visualizer/domain/processors/BrightnessMapper.kt

@@ -0,0 +1,142 @@
+package dev.adriankuta.visualizer.domain.processors
+
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.colorspace.ColorSpaces
+import dev.adriankuta.visualizer.data.FftFrame
+import dev.adriankuta.visualizer.data.VisualizerFrame
+import dev.adriankuta.visualizer.data.WaveformFrame
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import javax.inject.Inject
+import kotlin.math.ln
+import kotlin.math.max
+import kotlin.math.sqrt
+import kotlin.reflect.KClass
+
+/**
+ * Shared utilities for brightness mapping.
+ */
+class BrightnessMapper(
+    private val hue: Float = 210f,            // blue-ish
+    private val saturation: Float = 0.9f,     // vivid color
+    private val gain: Float = 8f,             // log mapping strength (higher -> more sensitive)
+    private val attack: Float = 0.35f,        // 0..1, higher = faster rise
+    private val release: Float = 0.08f,       // 0..1, lower = slower fall
+    private val peakDecay: Float = 0.995f     // 0..1, how fast auto-gain reference decays
+) {
+    private var smoothed = 0f
+    private var peak = 0.1f
+
+    /**
+     * @param rawEnergy input in [0, +inf) (e.g., RMS or avg magnitude)
+     * @return Color with brightness (V) in [0,1]
+     */
+    fun toColor(rawEnergy: Float): Color {
+        // 1) Log loudness mapping: map [0, +inf) → [0, 1]
+        // normalizedLog = ln(1 + gain * x) / ln(1 + gain)
+        val loud = if (rawEnergy <= 0f) 0f
+        else (ln(1f + gain * rawEnergy) / ln(1f + gain))
+
+        // 2) Peak/auto-gain tracking
+        peak = max(loud, peak * peakDecay)
+        val norm = if (peak > 1e-6f) loud / peak else loud
+        val clamped = norm.coerceIn(0f, 1f)
+
+        // 3) Attack/Release smoothing
+        val a = if (clamped > smoothed) attack else release
+        smoothed = smoothed + a * (clamped - smoothed)
+
+        // 4) HSV → Color (fixed hue & saturation; dynamic value)
+        return Color.hsv(
+            hue = hue.coerceIn(0f, 360f),
+            saturation = saturation.coerceIn(0f, 1f),
+            value = smoothed.coerceIn(0f, 1f),
+            colorSpace = ColorSpaces.Srgb
+        )
+    }
+}
+
+/**
+ * Visualizer waveform → brightness.
+ * Visualizer's waveform bytes are unsigned 8-bit: 0..255 with 128 ≈ 0.
+ */
+class WaveformToColorProcessor @Inject constructor(
+) : VisualizerProcessor {
+    private val brightness: BrightnessMapper = BrightnessMapper(
+        hue = 210f,
+        saturation = 0.9f,
+        gain = 8f,
+        attack = 0.35f,
+        release = 0.08f,
+        peakDecay = 0.995f
+    )
+
+    override suspend fun invoke(frame: VisualizerFrame): Color = withContext(Dispatchers.Default) {
+        val bytes = frame.data
+        if (bytes.isEmpty()) {
+            return@withContext Color.Black
+        }
+
+        // Convert to [-1, 1] floats, compute RMS.
+        var sumSq = 0.0
+        val inv = 1f / 128f
+        for (b in bytes) {
+            // unsigned -> center at 128 -> normalize
+            val s = ((b.toInt() and 0xFF) - 128) * inv
+            sumSq += (s * s)
+        }
+        val rms = sqrt(sumSq / bytes.size).toFloat() // 0..~1
+
+        brightness.toColor(rms)
+    }
+}
+
+/**
+ * Visualizer FFT → brightness.
+ * Visualizer's FFT bytes are 8-bit signed fixed-point: interleaved (re, im).
+ * We compute mean magnitude over bins. You can bias ranges by adding weights.
+ */
+class FftToColorProcessor @Inject constructor(
+) : VisualizerProcessor {
+    private val brightness: BrightnessMapper = BrightnessMapper(
+        hue = 210f,
+        saturation = 0.9f,
+        gain = 10f,
+        attack = 0.30f,
+        release = 0.10f,
+        peakDecay = 0.996f
+    )
+    private val binWeighting: ((binIndex: Int, totalBins: Int) -> Float)? = null
+
+    override suspend fun invoke(frame: VisualizerFrame): Color = withContext(Dispatchers.Default) {
+        val bytes = frame.data
+        if (bytes.size < 2) {
+            return@withContext Color.Black
+        }
+
+        // Each bin: (re, im) as signed bytes. Skip DC/nyquist if you like; here we include all valid pairs.
+        val pairCount = bytes.size / 2
+        var sumMag = 0.0
+        var weightSum = 0.0
+
+        var bin = 0
+        var i = 0
+        while (i + 1 < bytes.size) {
+            val re = bytes[i].toInt().toByte().toInt() // ensure sign
+            val im = bytes[i + 1].toInt().toByte().toInt()
+            val mag = sqrt((re * re + im * im).toDouble()) // magnitude in byte units
+            val w = binWeighting?.invoke(bin, pairCount)?.coerceAtLeast(0f)?.toDouble() ?: 1.0
+            sumMag += mag * w
+            weightSum += w
+            bin += 1
+            i += 2
+        }
+
+        // Average magnitude → normalize to something close to [0,1].
+        // 8-bit range ≈ [-128,127], so typical magnitude can be up to ~181; average is far lower.
+        val avgMag = if (weightSum > 0.0) sumMag / weightSum else 0.0
+        val norm = (avgMag / 128.0).toFloat().coerceAtLeast(0f) // rough normalization
+
+        brightness.toColor(norm)
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/domain/processors/FftToColor.kt

@@ -0,0 +1,58 @@
+package dev.adriankuta.visualizer.domain.processors
+
+import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.data.FftFrame
+import dev.adriankuta.visualizer.data.VisualizerFrame
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import javax.inject.Inject
+import kotlin.math.sqrt
+import kotlin.reflect.KClass
+
+class FftToColor @Inject constructor() : VisualizerProcessor {
+
+    override suspend fun invoke(frame: VisualizerFrame): Color = withContext(Dispatchers.Default) {
+        // --- Extract raw FFT bytes from your frame ---
+        // Adjust the property name if your FftFrame differs (e.g., `frame.data`, `frame.bytes`, etc.)
+        val fft: ByteArray = frame.data
+
+        if (fft.isEmpty()) return@withContext Color.Black
+
+        // Visualizer FFT format: interleaved [re0, im0, re1, im1, ...]
+        // Skip DC (bin 0: re0, im0) as it often behaves like noise/offset.
+        var sumMagnitude = 0.0
+        var bins = 0
+
+        var i = 2 // start from bin 1 (skip DC)
+        while (i + 1 < fft.size) {
+            val re = fft[i].toInt()
+            val im = fft[i + 1].toInt()
+            val mag = sqrt((re * re + im * im).toDouble())
+            sumMagnitude += mag
+            bins++
+            i += 2
+        }
+
+        val avgMagnitude = if (bins > 0) sumMagnitude / bins else 0.0
+
+        // Normalize ~[0..1]. Each component is in [-128..127], so magnitude upper bound ~181.
+        // 128 is a practical normalization for stable visuals; then clamp.
+        val normalized = (avgMagnitude / 128.0).coerceIn(0.0, 1.0)
+
+        // Perceptual easing to avoid flicker and give more dynamic range at lower levels.
+        val eased = sqrt(normalized).toFloat()
+
+        // Simple noise gate so tiny ambient levels don’t glow.
+        val value = if (eased < NOISE_FLOOR) 0f else eased
+
+        // Single, stable color – only brightness changes with the music.
+        Color.hsv(BASE_HUE, BASE_SATURATION, value)
+    }
+
+    private companion object {
+        // Tune these to your taste (degrees 0..360, 0..1).
+        const val BASE_HUE = 0f          // cool blue
+        const val BASE_SATURATION = 0.85f  // vivid
+        const val NOISE_FLOOR = 0.05f      // ignore very low energy
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/domain/processors/SoundToColorMapper.kt

@@ -0,0 +1,59 @@
+package dev.adriankuta.visualizer.domain.processors
+
+import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.HSL
+import dev.adriankuta.visualizer.MovingAverage
+import dev.adriankuta.visualizer.calculateRms
+import dev.adriankuta.visualizer.data.RmsValue
+import dev.adriankuta.visualizer.data.RmsValueProvider
+import dev.adriankuta.visualizer.data.VisualizerFrame
+import timber.log.Timber
+import javax.inject.Inject
+
+/**
+ * Default implementation of SoundToColorMapper that uses HSL color space
+ * and moving average for smooth color transitions.
+ *
+ * Follows Single Responsibility Principle by focusing on sound-to-color mapping.
+ * Follows Dependency Inversion Principle by depending on abstractions.
+ */
+class HSLSoundToColorMapper @Inject constructor(
+    private val rmsValueProvider: RmsValueProvider
+) : VisualizerProcessor {
+    private val baseHue: Float = 0f // Blue hue as default
+    private val saturation: Float = 1f
+    private val movingAverageWindowSize: Int = 2
+
+    private val movingAverage = MovingAverage(movingAverageWindowSize)
+    private var rmsMax = 0.0
+
+    override suspend fun invoke(frame: VisualizerFrame): Color {
+        val waveform = frame.data
+        // Calculate RMS value for current frame
+        val currentRms = calculateRms(waveform)
+
+        rmsMax -= 0.01
+        // Update maximum RMS value for normalization
+        if (currentRms > rmsMax) {
+            rmsMax = currentRms
+        }
+        rmsValueProvider.emit(RmsValue(currentRms, rmsMax))
+
+        Timber.d("Max RMS: %s, current %s", rmsMax, currentRms)
+
+        // Calculate energy ratio (0-1)
+        val energyRatio = if (rmsMax > 0) currentRms / rmsMax else 0.0
+
+        // Apply moving average for smooth transitions
+        val adjustedLightness = movingAverage.process(energyRatio)
+
+        // Create HSL color and convert to Compose Color
+        val hslColor = HSL(
+            hue = baseHue,
+            saturation = saturation,
+            lightness = adjustedLightness.toFloat().coerceIn(0f, 1f)
+        )
+
+        return hslColor.toComposeColor()
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/domain/processors/VisualizerProcessor.kt

@@ -0,0 +1,10 @@
+package dev.adriankuta.visualizer.domain.processors
+
+import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.data.VisualizerFrame
+import kotlin.reflect.KClass
+
+interface  VisualizerProcessor {
+
+    suspend operator fun invoke(frame: VisualizerFrame): Color
+}

app/src/main/java/dev/adriankuta/visualizer/ui/components/KeepScreenOn.kt

@@ -0,0 +1,20 @@
+package dev.adriankuta.visualizer.ui.components
+
+import android.view.WindowManager
+import androidx.activity.compose.LocalActivity
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+
+@Composable
+fun KeepScreenOn() {
+    val activity = LocalActivity.current
+
+    DisposableEffect(Unit) {
+        activity?.window?.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+
+        onDispose {
+            // Clear the flag when the composable is disposed
+            activity?.window?.clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
+        }
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/view/VisualizerScreen.kt

@@ -4,14 +4,40 @@ import android.Manifest
 import android.content.pm.PackageManager
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.animation.animateColorAsState
+import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.core.tween
 import androidx.compose.foundation.background
-import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.material3.*
+import androidx.compose.material3.AlertDialog
-import androidx.compose.runtime.*
+import androidx.compose.material3.Button
+import androidx.compose.material3.Card
+import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
+import androidx.compose.ui.draw.drawBehind
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.font.FontWeight
@@ -24,35 +50,21 @@ import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
 import androidx.lifecycle.compose.LocalLifecycleOwner
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
-import dev.adriankuta.visualizer.AudioVisualizerFactory
+import dev.adriankuta.visualizer.data.RmsValue
-import dev.adriankuta.visualizer.AudioVisualizerService
+import dev.adriankuta.visualizer.ui.components.KeepScreenOn
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.SupervisorJob
 import timber.log.Timber
 
 
-@Composable
-fun VisualizerScreen(
-    viewModel: VisualizerScreenViewModel = hiltViewModel()
-) {
-
-    val uiState by viewModel.uiState.collectAsStateWithLifecycle()
-
-}
 @Composable
 fun VisualizerScreen(
     modifier: Modifier = Modifier,
-    audioVisualizer: AudioVisualizerService = remember {
+    viewModel: VisualizerScreenViewModel = hiltViewModel()
-        AudioVisualizerFactory.createDefault(
-            CoroutineScope(Dispatchers.Main + SupervisorJob())
-        )
-    }
 ) {
     val context = LocalContext.current
     val lifecycleOwner = LocalLifecycleOwner.current
-    val currentColor by audioVisualizer.currentColor
+    val uiState by viewModel.uiState.collectAsStateWithLifecycle()
-    val isActive by audioVisualizer.isActive
+
+    KeepScreenOn()
 
     // Permission state management
     var hasAudioPermission by remember {
@@ -73,7 +85,7 @@ fun VisualizerScreen(
         hasAudioPermission = isGranted
         if (isGranted) {
             Timber.d("Audio permission granted, starting visualizer")
-            audioVisualizer.start()
+            viewModel.start()
         } else {
             Timber.w("Audio permission denied")
             showPermissionRationale = true
@@ -84,8 +96,9 @@ fun VisualizerScreen(
     fun startVisualizerWithPermissionCheck() {
         when {
             hasAudioPermission -> {
-                audioVisualizer.start()
+                viewModel.start()
             }
+
             else -> {
                 Timber.d("Requesting audio permission")
                 permissionLauncher.launch(Manifest.permission.RECORD_AUDIO)
@@ -98,7 +111,7 @@ fun VisualizerScreen(
         val observer = LifecycleEventObserver { _, event ->
             when (event) {
                 Lifecycle.Event.ON_START -> startVisualizerWithPermissionCheck()
-                Lifecycle.Event.ON_STOP -> audioVisualizer.stop()
+                Lifecycle.Event.ON_STOP -> viewModel.stop()
                 else -> {}
             }
         }
@@ -107,7 +120,7 @@ fun VisualizerScreen(
 
         onDispose {
             lifecycleOwner.lifecycle.removeObserver(observer)
-            audioVisualizer.release()
+            viewModel.stop()
         }
     }
 
@@ -127,19 +140,15 @@ fun VisualizerScreen(
             modifier = Modifier.padding(bottom = 32.dp)
         )
 
-        // Color display area
+        // Color display and RMS progress bar area
-        Box(
+        Row(
-            modifier = Modifier
+            horizontalArrangement = Arrangement.spacedBy(16.dp),
-                .size(300.dp)
+            verticalAlignment = Alignment.CenterVertically
-                .clip(RoundedCornerShape(16.dp))
-                .background(currentColor)
-                .padding(16.dp),
-            contentAlignment = Alignment.Center
         ) {
-            // Show color information
+            ColorDisplay(uiState)
-            ColorInfoCard(
+            RmsProgressBar(
-                color = currentColor,
+                rmsValue = uiState.rmsValue,
-                isActive = isActive
+                modifier = Modifier
             )
         }
 
@@ -147,7 +156,7 @@ fun VisualizerScreen(
 
         // Status indicator
         StatusIndicator(
-            isActive = isActive,
+            isActive = uiState.isActive,
             hasPermission = hasAudioPermission
         )
 
@@ -157,7 +166,7 @@ fun VisualizerScreen(
         Text(
             text = when {
                 !hasAudioPermission -> "Audio permission is required to visualize sound"
-                isActive -> "Play some music or make sounds to see the colors change!"
+                uiState.isActive -> "Play some music or make sounds to see the colors change!"
                 else -> "Starting audio visualizer..."
             },
             fontSize = 16.sp,
@@ -211,13 +220,35 @@ fun VisualizerScreen(
     }
 }
 
+@Composable
+private fun ColorDisplay(uiState: VisualizerScreenUiState) {
+    val animatedColor by animateColorAsState(
+        uiState.color,
+        animationSpec = tween(50),
+    )
+    Box(
+        modifier = Modifier
+            .size(300.dp)
+            .clip(RoundedCornerShape(16.dp))
+            .drawBehind {
+                drawRect(animatedColor)
+            }
+            .padding(16.dp),
+        contentAlignment = Alignment.Center
+    ) {
+        // Show color information
+        ColorInfoCard(
+            color = uiState.color,
+        )
+    }
+}
+
 /**
  * Card displaying color information.
  */
 @Composable
 private fun ColorInfoCard(
     color: Color,
-    isActive: Boolean,
     modifier: Modifier = Modifier
 ) {
     Card(
@@ -298,3 +329,101 @@ private fun StatusIndicator(
         )
     }
 }
+
+/**
+ * Vertical progress bar showing RMS values.
+ */
+@Composable
+private fun RmsProgressBar(
+    rmsValue: RmsValue?,
+    modifier: Modifier = Modifier
+) {
+    Card(
+        modifier = modifier,
+        colors = CardDefaults.cardColors(
+            containerColor = MaterialTheme.colorScheme.surface
+        ),
+        elevation = CardDefaults.cardElevation(defaultElevation = 4.dp)
+    ) {
+        Column(
+            modifier = Modifier.padding(16.dp),
+            horizontalAlignment = Alignment.CenterHorizontally
+        ) {
+            Text(
+                text = "RMS Level",
+                fontSize = 14.sp,
+                fontWeight = FontWeight.Medium,
+                color = MaterialTheme.colorScheme.onSurface
+            )
+
+            Spacer(modifier = Modifier.height(8.dp))
+
+            if (rmsValue != null) {
+                val animatedProgress by animateFloatAsState(
+                    targetValue = if (rmsValue.max > 0) {
+                        (rmsValue.current / rmsValue.max).coerceIn(0.0, 1.0).toFloat()
+                    } else {
+                        0f
+                    },
+                    animationSpec = tween(50)
+                )
+                val animatedColor by animateColorAsState(
+                    when {
+                        animatedProgress > 0.8f -> Color.Red
+                        animatedProgress > 0.6f -> Color.Yellow
+                        else -> Color.Green
+                    },
+                    animationSpec = tween(50)
+                )
+
+                // Vertical progress bar
+                Box(
+                    modifier = Modifier
+                        .width(40.dp)
+                        .height(200.dp)
+                        .clip(RoundedCornerShape(20.dp))
+                        .background(MaterialTheme.colorScheme.surfaceVariant)
+                ) {
+                    Box(
+                        modifier = Modifier
+                            .fillMaxSize()
+                            .clip(RoundedCornerShape(20.dp))
+                            .drawBehind {
+                                val fillHeight = size.height * animatedProgress
+                                drawRect(
+                                    color = animatedColor,
+                                    topLeft = Offset(0f, size.height - fillHeight),
+                                    size = Size(size.width, fillHeight)
+                                )
+                            }
+                    )
+                }
+
+                Spacer(modifier = Modifier.height(8.dp))
+
+                // Show current value
+                Text(
+                    text = String.format("%.3f", rmsValue.current),
+                    fontSize = 12.sp,
+                    color = MaterialTheme.colorScheme.onSurface.copy(alpha = 0.7f)
+                )
+            } else {
+                // Placeholder when no RMS data
+                Box(
+                    modifier = Modifier
+                        .width(40.dp)
+                        .height(200.dp)
+                        .clip(RoundedCornerShape(20.dp))
+                        .background(MaterialTheme.colorScheme.surfaceVariant),
+                    contentAlignment = Alignment.Center
+                ) {
+                    Text(
+                        text = "No Data",
+                        fontSize = 10.sp,
+                        color = MaterialTheme.colorScheme.onSurface.copy(alpha = 0.5f)
+                    )
+                }
+            }
+        }
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/view/VisualizerScreenUiState.kt

@@ -1,7 +1,10 @@
 package dev.adriankuta.visualizer.view
 
 import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.data.RmsValue
 
 data class VisualizerScreenUiState(
-    val color: Color
+    val color: Color,
+    val isActive: Boolean = false,
+    val rmsValue: RmsValue? = null
 )

app/src/main/java/dev/adriankuta/visualizer/view/VisualizerScreenViewModel.kt

@@ -1,23 +1,59 @@
+@file:OptIn(FlowPreview::class)
+
 package dev.adriankuta.visualizer.view
 
 import androidx.compose.ui.graphics.Color
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
+import dev.adriankuta.visualizer.data.AudioVisualizerController
+import dev.adriankuta.visualizer.data.RmsValueProvider
 import dev.adriankuta.visualizer.domain.ObserveVisualizerColorUseCase
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.sample
 import kotlinx.coroutines.flow.stateIn
 import javax.inject.Inject
+import kotlin.time.Duration.Companion.milliseconds
 
 @HiltViewModel
 class VisualizerScreenViewModel @Inject constructor(
-    private val observeVisualizerColorUseCase: ObserveVisualizerColorUseCase
+    observeVisualizerColorUseCase: ObserveVisualizerColorUseCase,
+    private val audioVisualizerController: AudioVisualizerController,
+    private val rmsValueProvider: RmsValueProvider
 ) : ViewModel() {
 
-    val uiState = observeVisualizerColorUseCase()
+    private val _isActive = MutableStateFlow(false)
-        .stateIn(
+
+    val uiState = combine(
+        observeVisualizerColorUseCase().sample(50.milliseconds),
+        _isActive,
+        rmsValueProvider.observe().sample(50.milliseconds)
+    ) { color, isActive, rmsValue ->
+        VisualizerScreenUiState(
+            color = color,
+            isActive = isActive,
+            rmsValue = rmsValue
+        )
+    }.stateIn(
         scope = viewModelScope,
         started = SharingStarted.WhileSubscribed(5_000),
-            initialValue = Color.Black
+        initialValue = VisualizerScreenUiState(
+            color = Color.Black,
+            isActive = false,
+            rmsValue = null
         )
+    )
+
+    fun start() {
+        audioVisualizerController.start()
+        _isActive.value = true
+    }
+
+    fun stop() {
+        audioVisualizerController.stop()
+        _isActive.value = false
+    }
 }

app/src/test/java/dev/adriankuta/visualizer/ExampleUnitTest.kt

@@ -1,17 +0,0 @@
-package dev.adriankuta.visualizer
-
-import org.junit.Test
-
-import org.junit.Assert.*
-
-/**
- * Example local unit test, which will execute on the development machine (host).
- *
- * See [testing documentation](http://d.android.com/tools/testing).
- */
-class ExampleUnitTest {
-    @Test
-    fun addition_isCorrect() {
-        assertEquals(4, 2 + 2)
-    }
-}