[Feature] Ability to extract files simultaneously

android/src/main/java/com/ryanheise/just_waveform/JustWaveformPlugin.java

@@ -10,6 +10,7 @@
 import android.os.Handler;
 import java.util.List;
 import io.flutter.plugin.common.PluginRegistry.Registrar;
+import java.util.HashMap;
 
 /** JustWaveformPlugin */
 public class JustWaveformPlugin implements FlutterPlugin, MethodCallHandler {
@@ -28,14 +29,21 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull final Result result)
         case "extract":
             String audioInPath = call.argument("audioInPath");
             String waveOutPath = call.argument("waveOutPath");
+            String uuid = call.argument("uuid");
             Integer samplesPerPixel = call.argument("samplesPerPixel");
             Integer pixelsPerSecond = call.argument("pixelsPerSecond");
             WaveformExtractor waveformExtractor = new WaveformExtractor(audioInPath, waveOutPath, samplesPerPixel, pixelsPerSecond);
             waveformExtractor.start(new WaveformExtractor.OnProgressListener() {
                 @Override
                 public void onProgress(int progress) {
-                    invokeMethod("onProgress", progress);
+                    HashMap<String, Object> args = new HashMap();
+                    args.put("progress", progress);
+                    args.put("waveOutFile", waveOutPath);
+                    args.put("uuid", uuid);
+
+                    invokeMethod("onProgress", args);
                 }
+
                 @Override
                 public void onComplete() {
                     handler.post(new Runnable() {
@@ -45,6 +53,7 @@ public void run() {
                         }
                     });
                 }
+
                 @Override
                 public void onError(final String message) {
                     invokeMethod("onError", message);

android/src/main/java/com/ryanheise/just_waveform/WaveformExtractor.java

@@ -228,8 +228,7 @@ void processAudio() {
 
                 frameCount++; // not really frame count anymore
             }
-            onProgressListener.onProgress(100);
-            onProgressListener.onComplete();
+
             System.out.println("End. (" + presentationTime/1000000.0 + "sec) frameCount = " + frameCount + ", totalSampleSize = " + totalSampleSize);
             System.out.println("waitingToDecode:   " + waitingToDecode);
             System.out.println("waitingForDecoded: " + waitingForDecoded);
@@ -257,6 +256,8 @@ void processAudio() {
                 channel.write(scaledByteSamples);
                 System.out.println("Total scaled samples: " + scaledSampleIdx);
             }
+            onProgressListener.onProgress(100);
+            onProgressListener.onComplete();
         }
         catch (Exception e) {
             e.printStackTrace();

darwin/Classes/JustWaveformPlugin.m

@@ -24,6 +24,7 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
     if ([@"extract" isEqualToString:call.method]) {
         NSString *audioInPath = (NSString *)request[@"audioInPath"];
         NSString *waveOutPath = (NSString *)request[@"waveOutPath"];
+        NSString *uuid = (NSString *)request[@"uuid"];
         NSNumber *samplesPerPixelArg = (NSNumber *)request[@"samplesPerPixel"];
         NSNumber *pixelsPerSecondArg = (NSNumber *)request[@"pixelsPerSecond"];
 
@@ -121,7 +122,7 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
             UInt32 scaledSampleIdx = 0;
             int progress = 0;
 
-            while (frameCount > 0) {
+            while (frameCount > 0 && progress < 100) {
                 status = ExtAudioFileRead(audioFileRef, &frameCount, &convertedData);
                 if (status != noErr) {
                     NSLog(@"ExtAudioFileRead error: %i", status);
@@ -154,9 +155,10 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
                                 int newProgress = (int)(100 * scaledSampleIdx / waveLength);
                                 if (newProgress != progress && newProgress <= 100) {
                                     progress = newProgress;
+                                    if (progress >= 100) break;
                                     //NSLog(@"Progress: %d percent", progress);
                                     dispatch_async(dispatch_get_main_queue(), ^{
-                                        [_channel invokeMethod:@"onProgress" arguments:@(progress)];
+                                        [_channel invokeMethod:@"onProgress" arguments:@{@"progress" : @(progress), @"uuid" : uuid, @"waveOutFile" : waveOutPath}];
                                     });
                                 }
                                 //NSLog(@"pixel[%d] %d: %d\t%d", scaledSampleIdx - 2, sampleIdx, minSample, maxSample);
@@ -182,7 +184,9 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
             NSLog(@"Total scaled samples: %d", scaledSampleIdx);
 
             status = ExtAudioFileDispose(audioFileRef);
-
+            dispatch_async(dispatch_get_main_queue(), ^{
+                [_channel invokeMethod:@"onProgress" arguments:@{@"progress" : @(100), @"uuid" : uuid, @"waveOutFile" : waveOutPath}];
+            });
             dispatch_async(dispatch_get_main_queue(), ^{
                 result(nil);
             });

lib/just_waveform.dart

@@ -7,41 +7,49 @@ import 'package:flutter/services.dart';
 /// A utility for extracting a [Waveform] from an audio file suitable for visual
 /// rendering.
 class JustWaveform {
-  static const MethodChannel _channel =
-      MethodChannel('com.ryanheise.just_waveform');
+  static final MethodChannel _channel = MethodChannel('com.ryanheise.just_waveform');
 
   /// Extract a [Waveform] from [audioInFile] and write it to [waveOutFile] at
   /// the specified [zoom] level.
   // XXX: It would be better to return a stream of the actual [Waveform], with
   // progress => wave.data.length / (wave.length*2)
+  static Map<String, StreamController<WaveformProgress>> _map = {};
   static Stream<WaveformProgress> extract({
     required File audioInFile,
     required File waveOutFile,
     WaveformZoom zoom = const WaveformZoom.pixelsPerSecond(100),
   }) {
     final progressController = StreamController<WaveformProgress>.broadcast();
+    final uuid = DateTime.now().microsecondsSinceEpoch.toString();
+    _map[uuid] = progressController;
+
     progressController.add(WaveformProgress._(0.0, null));
     _channel.setMethodCallHandler((MethodCall call) async {
       switch (call.method) {
         case 'onProgress':
-          // ignore: avoid_print
-          print("received onProgress: ${call.arguments}}");
-          int progress = call.arguments;
-          //print("_progressSubject.add($progress)");
+          final args = call.arguments;
+          int progress = args['progress'];
+          String file = args['waveOutFile'];
+          String uuid = args['uuid'];
           Waveform? waveform;
+
           if (progress == 100) {
-            waveform = await parse(waveOutFile);
+            waveform = await parse(File(file));
           }
-          progressController.add(WaveformProgress._(progress / 100, waveform));
+
+          _map[uuid]?.add(WaveformProgress._(progress / 100, waveform));
           if (progress == 100) {
-            progressController.close();
+            _map[uuid]?.close();
+            _map.remove(file);
           }
           break;
       }
     });
+    // print('Started extract $_filename');
     _channel.invokeMethod('extract', {
       'audioInPath': audioInFile.path,
       'waveOutPath': waveOutFile.path,
+      'uuid': uuid,
       'samplesPerPixel': zoom._samplesPerPixel,
       'pixelsPerSecond': zoom._pixelsPerSecond,
     }).catchError(progressController.addError);
@@ -54,9 +62,7 @@ class JustWaveform {
     const headerLength = 20;
     final header = Uint32List.view(bytes, 0, headerLength);
     final flags = header[1];
-    final data = flags == 0
-        ? Int16List.view(bytes, headerLength ~/ 2)
-        : Int8List.view(bytes, headerLength);
+    final data = flags == 0 ? Int16List.view(bytes, headerLength ~/ 2) : Int8List.view(bytes, headerLength);
     return Waveform(
       version: header[0],
       flags: flags,
@@ -123,14 +129,12 @@ class Waveform {
   int getPixelMax(int i) => this[2 * i + 1];
 
   /// The duration of audio, inferred from the length of the waveform data.
-  Duration get duration => Duration(
-      microseconds: 1000 * 1000 * length * samplesPerPixel ~/ sampleRate);
+  Duration get duration => Duration(microseconds: 1000 * 1000 * length * samplesPerPixel ~/ sampleRate);
 
   /// Converts an audio position to a pixel position. The returned position is a
   /// [double] for accuracy, but can be converted `toInt` and used to access the
   /// nearest pixel value via [getPixelMin]/[getPixelMax].
-  double positionToPixel(Duration position) =>
-      position.inMicroseconds * sampleRate / (samplesPerPixel * 1000000);
+  double positionToPixel(Duration position) => position.inMicroseconds * sampleRate / (samplesPerPixel * 1000000);
 }
 
 /// The resolution at which a [Waveform] should be generated.