Refactored remaining time estimate.

AaxDecrypter/AaxcDownloadConverter.cs

@@ -168,72 +168,19 @@ namespace AaxDecrypter
             return aaxcProcesser.Succeeded;
         }
 
-        private void AaxcProcesser_ProgressUpdate(object sender, TimeSpan e)
+        private void AaxcProcesser_ProgressUpdate(object sender, AaxcProcessUpdate e)
         {
-            double averageRate = getAverageProcessRate(e);
+            double remainingSecsToProcess = (aaxcTagLib.Properties.Duration - e.ProcessPosition).TotalSeconds;
-            double remainingSecsToProcess = (aaxcTagLib.Properties.Duration - e).TotalSeconds;
+            double estTimeRemaining = remainingSecsToProcess / e.ProcessSpeed;
-            double estTimeRemaining = remainingSecsToProcess / averageRate;
 
             if (double.IsNormal(estTimeRemaining))
                 DecryptTimeRemaining?.Invoke(this, TimeSpan.FromSeconds(estTimeRemaining));           
 
-            double progressPercent = 100 * e.TotalSeconds / aaxcTagLib.Properties.Duration.TotalSeconds;
+            double progressPercent = 100 * e.ProcessPosition.TotalSeconds / aaxcTagLib.Properties.Duration.TotalSeconds;
 
             DecryptProgressUpdate?.Invoke(this, (int)progressPercent);
         }
 
-        /// <summary>
-        /// Calculates the average processing rate based on the last 2 to <see cref="MAX_NUM_AVERAGE"/> samples.
-        /// </summary>
-        /// <param name="lastProcessedPosition">Position in the audio file last processed</param>
-        /// <returns>The average processing rate, in book_duration_seconds / second.</returns>
-        private double getAverageProcessRate(TimeSpan lastProcessedPosition)
-        {
-            streamPositions.Enqueue(new StreamPosition
-            {
-                ProcessPosition = lastProcessedPosition,
-                EventTime = DateTime.Now,
-            });
-
-            if (streamPositions.Count < 2)
-                return double.PositiveInfinity;
-
-            //Calculate the harmonic mean of the last 2 to MAX_NUM_AVERAGE progress updates
-            //Units are Book_Duration_Seconds / second
-
-            var lastPos = streamPositions.Count > MAX_NUM_AVERAGE ?  streamPositions.Dequeue() : null;
-
-            double harmonicDenominator = 0;
-            int harmonicNumerator = 0;
-
-            foreach (var pos in streamPositions)
-            {
-                if (lastPos is null)
-                {
-                    lastPos = pos;
-                    continue;
-                }
-                double dP = (pos.ProcessPosition - lastPos.ProcessPosition).TotalSeconds;
-                double dT = (pos.EventTime - lastPos.EventTime).TotalSeconds;
-
-                harmonicDenominator += dT / dP;
-                harmonicNumerator++;
-                lastPos = pos;
-            }
-
-            double harmonicMean = harmonicNumerator / harmonicDenominator;
-            return harmonicMean;
-        }
-
-        private const int MAX_NUM_AVERAGE = 15;
-        private class StreamPosition
-        {
-            public TimeSpan ProcessPosition { get; set; }
-            public DateTime EventTime { get; set; }
-        }
-
-        private Queue<StreamPosition> streamPositions = new Queue<StreamPosition>();
-
         /// <summary>
         /// Copy all aacx metadata to m4b file, including cover art.
         /// </summary>

AaxDecrypter/FFMpegAaxcProcesser.cs

@@ -7,13 +7,25 @@ using System.Threading.Tasks;
 
 namespace AaxDecrypter
 {
+    class AaxcProcessUpdate
+    {
+        public AaxcProcessUpdate(TimeSpan position, double speed)
+        {
+            ProcessPosition = position;
+            ProcessSpeed = speed;
+            EventTime = DateTime.Now;
+        }
+        public TimeSpan ProcessPosition { get; }
+        public double ProcessSpeed { get; }
+        public DateTime EventTime { get; }
+    }
 
     /// <summary>
     /// Download audible aaxc, decrypt, and remux with chapters.
     /// </summary>
     class FFMpegAaxcProcesser
     {
-        public event EventHandler<TimeSpan> ProgressUpdate;
+        public event EventHandler<AaxcProcessUpdate> ProgressUpdate;
         public string FFMpegPath { get; }
         public DownloadLicense DownloadLicense { get; }
         public bool IsRunning { get; private set; }
@@ -24,7 +36,7 @@ namespace AaxDecrypter
 
         private StringBuilder remuxerError = new StringBuilder();
         private StringBuilder downloaderError = new StringBuilder();
-        private static Regex processedTimeRegex = new Regex("time=(\\d{2}):(\\d{2}):(\\d{2}).\\d{2}", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+        private static Regex processedTimeRegex = new Regex("time=(\\d{2}):(\\d{2}):(\\d{2}).\\d{2}.*speed=\\s{0,1}([0-9]*[.]?[0-9]+)(?:e\\+([0-9]+)){0,1}", RegexOptions.IgnoreCase | RegexOptions.Compiled);
         private Process downloader;
         private Process remuxer;
 
@@ -115,6 +127,7 @@ namespace AaxDecrypter
             if (processedTimeRegex.IsMatch(e.Data))
             {
                 //get timestamp of of last processed audio stream position
+                //and processing speed
                 var match = processedTimeRegex.Match(e.Data);
 
                 int hours = int.Parse(match.Groups[1].Value);
@@ -123,7 +136,11 @@ namespace AaxDecrypter
 
                 var position = new TimeSpan(hours, minutes, seconds);
 
-                ProgressUpdate?.Invoke(sender, position);
+                double speed = double.Parse(match.Groups[4].Value);
+                int exp = match.Groups[5].Success ? int.Parse(match.Groups[5].Value) : 0;
+                speed *= Math.Pow(10, exp);
+
+                ProgressUpdate?.Invoke(this, new AaxcProcessUpdate(position, speed));
             }
 
             if (e.Data.Contains("aac bitstream error"))