🐛 Fix extractor requires audio player to be initialised

Author: Ujas-Majithiya

android/src/main/kotlin/com/simform/audio_waveforms/AudioPlayer.kt

@@ -24,36 +24,6 @@ class AudioPlayer(
     private var isPlayerPrepared: Boolean = false
     private var finishMode = FinishMode.Stop
     private var key = playerKey
-    private var waveformExtractor: WaveformExtractor? = null
-    private var noOfSamples = 100
-
-    fun extractWaveform(
-        result: MethodChannel.Result,
-        path: String?,
-        noOfSamples: Int?,
-    ) {
-        if (path != null) {
-            this.noOfSamples = noOfSamples ?: 100
-            waveformExtractor = WaveformExtractor(
-                path = path,
-                expectedPoints = this.noOfSamples,
-                key = key,
-                methodChannel = methodChannel,
-                context = appContext,
-                result = result,
-                extractorCallBack = object : ExtractorCallBack {
-                    override fun onProgress(value: Float) {
-                        if (value == 1.0F) {
-                            result.success(waveformExtractor?.sampleData)
-                        }
-                    }
-                }
-            )
-            waveformExtractor?.startDecode()
-            waveformExtractor?.stop()
-
-        }
-    }
 
     fun preparePlayer(
         result: MethodChannel.Result,

android/src/main/kotlin/com/simform/audio_waveforms/AudioWaveformsPlugin.kt

@@ -33,9 +33,8 @@ class AudioWaveformsPlugin : FlutterPlugin, MethodCallHandler, ActivityAware {
     private var sampleRate: Int = 44100
     private var bitRate: Int? = null
     private lateinit var applicationContext: Context
-
-    //Todo: bitrate
     private var audioPlayers = mutableMapOf<String, AudioPlayer?>()
+    private var extractors = mutableMapOf<String, WaveformExtractor?>()
 
     override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
         channel = MethodChannel(flutterPluginBinding.binaryMessenger, Constants.methodChannelName)
@@ -144,7 +143,12 @@ class AudioWaveformsPlugin : FlutterPlugin, MethodCallHandler, ActivityAware {
                 val path = call.argument(Constants.path) as String?
                 val noOfSample = call.argument(Constants.noOfSamples) as Int?
                 if (key != null) {
-                    audioPlayers[key]?.extractWaveform(result, path, noOfSample)
+                    createOrUpdateExtractor(
+                        playerKey = key,
+                        result = result,
+                        path = path,
+                        noOfSamples = noOfSample ?: 100,
+                    )
                 } else {
                     result.error(Constants.LOG_TAG, "Player key can't be null", "")
                 }
@@ -217,6 +221,36 @@ class AudioWaveformsPlugin : FlutterPlugin, MethodCallHandler, ActivityAware {
         return
     }
 
+    private fun createOrUpdateExtractor(
+        playerKey: String,
+        noOfSamples: Int,
+        path: String?,
+        result: Result,
+    ) {
+        if (path == null) {
+            result.error(Constants.LOG_TAG, "Path cant be null", "")
+            return
+        }
+        extractors[playerKey] = WaveformExtractor(
+            context = applicationContext,
+            methodChannel = channel,
+            expectedPoints = noOfSamples,
+            key = playerKey,
+            path = path,
+            result = result,
+            extractorCallBack = object : ExtractorCallBack {
+                override fun onProgress(value: Float) {
+                    if (value == 1.0F) {
+                        result.success(extractors[playerKey]?.sampleData)
+                    }
+                }
+
+            }
+        )
+        extractors[playerKey]?.startDecode()
+        extractors[playerKey]?.stop()
+    }
+
     override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
         channel.setMethodCallHandler(null)
     }
@@ -236,6 +270,8 @@ class AudioWaveformsPlugin : FlutterPlugin, MethodCallHandler, ActivityAware {
     override fun onDetachedFromActivity() {
         recorder?.release()
         recorder = null
+        audioPlayers.clear()
+        extractors.clear()
         activity = null
     }
 }

android/src/main/kotlin/com/simform/audio_waveforms/WaveformExtractor.kt

@@ -7,8 +7,6 @@ import android.media.MediaExtractor
 import android.media.MediaFormat
 import android.net.Uri
 import android.os.Build
-import android.os.Handler
-import android.os.Looper
 import io.flutter.plugin.common.MethodChannel
 import java.nio.ByteBuffer
 import java.util.concurrent.CountDownLatch
@@ -23,8 +21,7 @@ class WaveformExtractor(
     private val result: MethodChannel.Result,
     private val extractorCallBack: ExtractorCallBack,
     private val context: Context,
-    ) {
-    private val handler = Handler(Looper.getMainLooper())
+) {
     private var decoder: MediaCodec? = null
     private var extractor: MediaExtractor? = null
     private var duration = 0L
@@ -45,7 +42,7 @@ class WaveformExtractor(
         val mediaExtractor = MediaExtractor()
         this.extractor = mediaExtractor
         val uri = Uri.parse(path)
-        mediaExtractor.setDataSource(context,uri,null)
+        mediaExtractor.setDataSource(context, uri, null)
         val trackCount = mediaExtractor.trackCount
         repeat(trackCount) {
             val format = mediaExtractor.getTrackFormat(it)
@@ -169,6 +166,13 @@ class WaveformExtractor(
         if (sampleCount == perSamplePoints) {
             currentProgress++
             progress = currentProgress / expectedPoints
+
+            // Discard redundant values and release resources
+            if (progress > 1.0F) {
+                stop()
+                return
+            }
+
             val rms = sqrt(sampleSum / perSamplePoints)
             sampleData.add(rms.toFloat())
             extractorCallBack.onProgress(progress)

ios/Classes/AudioPlayer.swift

@@ -11,38 +11,13 @@ class AudioPlayer: NSObject, AVAudioPlayerDelegate {
     var plugin: SwiftAudioWaveformsPlugin
     var playerKey: String
     var flutterChannel: FlutterMethodChannel
-    private var waveformExtractor: WaveformExtractor?
+
     init(plugin: SwiftAudioWaveformsPlugin, playerKey: String, channel: FlutterMethodChannel) {
         self.plugin = plugin
         self.playerKey = playerKey
         flutterChannel = channel
     }
 
-    func extractWaveformData(path: String?, result: @escaping FlutterResult, noOfSamples: Int?) {
-        if(!(path ?? "").isEmpty) {
-            do {
-                let audioUrl = URL.init(string: path!)
-                if(audioUrl == nil){
-                    result(FlutterError(code: Constants.audioWaveforms, message: "Failed to initialise Url from provided audio file", details: "If path contains `file://` try removing it"))
-                    return
-                }
-                waveformExtractor = try WaveformExtractor(url: audioUrl!, flutterResult: result, channel: flutterChannel)
-                if(waveformExtractor != nil) {
-                    let data = waveformExtractor!.extractWaveform(samplesPerPixel: noOfSamples, playerKey: playerKey)
-                    waveformExtractor!.cancel()
-                    if(waveformExtractor!.progress == 1.0) {
-                        let waveformData = waveformExtractor!.getChannelMean(data: data!)
-                        result(waveformData)
-                    }
-                }
-            } catch {
-                result(FlutterError(code: Constants.audioWaveforms, message: "Failed to decode audio file", details: nil))
-            }
-        } else {
-            result(FlutterError(code: Constants.audioWaveforms, message: "Audio file path can't be empty or null", details: nil))
-        }
-    }
-    
     func preparePlayer(path: String?, volume: Double?, result: @escaping FlutterResult) {
         if(!(path ?? "").isEmpty) {
             let audioUrl = URL.init(string: path!)

ios/Classes/SwiftAudioWaveformsPlugin.swift

@@ -5,13 +5,18 @@ public class SwiftAudioWaveformsPlugin: NSObject, FlutterPlugin {
 
     final var audioRecorder = AudioRecorder()
     var audioPlayers = [String: AudioPlayer]()
+    var extractors = [String: WaveformExtractor]()
     var flutterChannel: FlutterMethodChannel
 
     init(registrar: FlutterPluginRegistrar, flutterChannel: FlutterMethodChannel) {
         self.flutterChannel = flutterChannel
         super.init()
     }
 
+    deinit {
+        audioPlayers.removeAll()
+        extractors.removeAll()
+    }
     public static func register(with registrar: FlutterPluginRegistrar) {
         let channel = FlutterMethodChannel(name: Constants.methodChannelName, binaryMessenger: registrar.messenger())
         let instance = SwiftAudioWaveformsPlugin(registrar: registrar, flutterChannel: channel)
@@ -113,8 +118,8 @@ public class SwiftAudioWaveformsPlugin: NSObject, FlutterPlugin {
             let key = args?[Constants.playerKey] as? String
             let path = args?[Constants.path] as? String
             let noOfSamples = args?[Constants.noOfSamples] as? Int
-            if(key != nil){
-                audioPlayers[key!]?.extractWaveformData(path: path, result: result,noOfSamples: noOfSamples)
+            if(key != nil) {
+                createOrUpdateExtractor(playerKey: key!, result: result, path: path, noOfSamples: noOfSamples)
             } else {
                 result(FlutterError(code: Constants.audioWaveforms, message: "Can not get waveform data", details: "Player key is null"))
             }
@@ -130,4 +135,28 @@ public class SwiftAudioWaveformsPlugin: NSObject, FlutterPlugin {
             audioPlayers[playerKey] = newPlayer
         }
     }
+    
+    func createOrUpdateExtractor(playerKey: String, result: @escaping FlutterResult,path: String?, noOfSamples: Int?) {
+        if(!(path ?? "").isEmpty) {
+            do {
+                let audioUrl = URL.init(string: path!)
+                if(audioUrl == nil){
+                    result(FlutterError(code: Constants.audioWaveforms, message: "Failed to initialise Url from provided audio file", details: "If path contains `file://` try removing it"))
+                    return
+                }
+                var newExtractor = try WaveformExtractor(url: audioUrl!, flutterResult: result, channel: flutterChannel)
+                extractors[playerKey] = newExtractor
+                let data = newExtractor.extractWaveform(samplesPerPixel: noOfSamples, playerKey: playerKey)
+                newExtractor.cancel()
+                if(newExtractor.progress == 1.0) {
+                    let waveformData = newExtractor.getChannelMean(data: data!)
+                    result(waveformData)
+                }
+            } catch {
+                result(FlutterError(code: Constants.audioWaveforms, message: "Failed to decode audio file", details: nil))
+            }
+        } else {
+            result(FlutterError(code: Constants.audioWaveforms, message: "Audio file path can't be empty or null", details: nil))
+        }
+    }
 }