ffprobe duration parsing

- on large recordings (e.g. radio transmissions), ffprobe might return number of hours which is too large for TimeSpan.Parse (exception: The TimeSpan string '149:07:50.911750' could not be parsed because at least one of the numeric components is out of range or contains too many digits.)
- use regex groups to extract components (hours/minutes/seconds/millis) then parse/create new timespan from that
- NOTICE: this will discard microseconds provided by ffprobe, not sure if this is significant
- ffprobe has inconsitencies with how it represents millisecond component. Sometimes it may return just `82` for 820 milliseconds, so padding with 0s is required on the left. Likewise, sometimes it might return microseconds past milliseconds (first 3 significant figures); this is currently discarded
- Added InternalsVisibleTo to help with unit testing *just* the duration parsing function


Former-commit-id: 35ca34c0b0

FFMpegCore.Test/FFProbeTests.cs

@@ -24,6 +24,22 @@ public async Task Audio_FromStream_Duration()
             Assert.IsTrue(fileAnalysis.Duration == streamAnalysis.Duration);
         }
 
+        [TestMethod]
+        public void MediaAnalysis_ParseDuration()
+        {
+            var durationHHMMSS = new FFProbeStream { Duration = "05:12:59.177" };
+            var longDuration = new FFProbeStream { Duration = "149:07:50.911750" };
+            var shortDuration = new FFProbeStream { Duration = "00:00:00.83" };
+
+            var testdurationHHMMSS = MediaAnalysis.ParseDuration(durationHHMMSS);
+            var testlongDuration = MediaAnalysis.ParseDuration(longDuration);
+            var testshortDuration = MediaAnalysis.ParseDuration(shortDuration);
+
+            Assert.IsTrue(testdurationHHMMSS.Days == 0 && testdurationHHMMSS.Hours == 5 && testdurationHHMMSS.Minutes == 12 && testdurationHHMMSS.Seconds == 59 && testdurationHHMMSS.Milliseconds == 177);
+            Assert.IsTrue(testlongDuration.Days == 6 && testlongDuration.Hours == 5 && testlongDuration.Minutes == 7 && testlongDuration.Seconds == 50 && testlongDuration.Milliseconds == 911);
+            Assert.IsTrue(testdurationHHMMSS.Days == 0 && testshortDuration.Hours == 0 && testshortDuration.Minutes == 0 && testshortDuration.Seconds == 0 && testshortDuration.Milliseconds == 830);
+        }
+
         [TestMethod]
         public void Probe_Success()
         {

FFMpegCore/Assembly.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("FFMpegCore.Test")]

FFMpegCore/FFProbe/MediaAnalysis.cs

@@ -7,7 +7,7 @@ namespace FFMpegCore
 {
     internal class MediaAnalysis : IMediaAnalysis
     {
-        private static readonly Regex DurationRegex = new Regex("^(\\d{1,2}:\\d{1,2}:\\d{1,2}(.\\d{1,7})?)", RegexOptions.Compiled);
+        private static readonly Regex DurationRegex = new Regex(@"^(\d+):(\d{1,2}):(\d{1,2})\.(\d{1,3})", RegexOptions.Compiled);
 
         internal MediaAnalysis(string path, FFProbeAnalysis analysis)
         {
@@ -23,7 +23,7 @@ private MediaFormat ParseFormat(Format analysisFormat)
         {
             return new MediaFormat
             {
-                Duration = TimeSpan.Parse(analysisFormat.Duration ?? "0"),
+                Duration = ParseDuration(analysisFormat.Duration),
                 FormatName = analysisFormat.FormatName,
                 FormatLongName = analysisFormat.FormatLongName,
                 StreamCount = analysisFormat.NbStreams,
@@ -74,17 +74,41 @@ private VideoStream ParseVideoStream(FFProbeStream stream)
             };
         }
 
-        private static TimeSpan ParseDuration(FFProbeStream ffProbeStream)
+        internal static TimeSpan ParseDuration(string duration)
         {
-            return !string.IsNullOrEmpty(ffProbeStream.Duration)
-                ? TimeSpan.Parse(ffProbeStream.Duration)
-                : TimeSpan.Parse(TrimTimeSpan(ffProbeStream.GetDuration()) ?? "0");
+            if (!string.IsNullOrEmpty(duration))
+            {
+                var match = DurationRegex.Match(duration);
+                if (match.Success)
+                {
+                    // ffmpeg may provide < 3-digit number of milliseconds (omitting trailing zeros), which won't simply parse correctly
+                    // e.g. 00:12:02.11 -> 12 minutes 2 seconds and 110 milliseconds
+                    var millisecondsPart = match.Groups[4].Value;
+                    if (millisecondsPart.Length < 3)
+                    {
+                        millisecondsPart = millisecondsPart.PadRight(3, '0');
                     }
 
-        private static string? TrimTimeSpan(string? durationTag)
+                    var hours = int.Parse(match.Groups[1].Value);
+                    var minutes = int.Parse(match.Groups[2].Value);
+                    var seconds = int.Parse(match.Groups[3].Value);
+                    var milliseconds = int.Parse(millisecondsPart);
+                    return new TimeSpan(0, hours, minutes, seconds, milliseconds);
+                }
+                else
                 {
-            var durationMatch = DurationRegex.Match(durationTag ?? "");
-            return durationMatch.Success ? durationMatch.Groups[1].Value : null;
+                    return TimeSpan.Zero;
+                }
+            }
+            else
+            {
+                return TimeSpan.Zero;
+            }
+        }
+
+        internal static TimeSpan ParseDuration(FFProbeStream ffProbeStream)
+        {
+            return ParseDuration(ffProbeStream.Duration);
         }
 
         private AudioStream ParseAudioStream(FFProbeStream stream)