fixes #887 - Support ttml subtitle output

3 files changed, 88 insertions, 10 deletions

diff --git a/MediaBrowser.MediaEncoding/MediaBrowser.MediaEncoding.csproj b/MediaBrowser.MediaEncoding/MediaBrowser.MediaEncoding.csproj
index f11c261e2..12a03a876 100644
--- a/MediaBrowser.MediaEncoding/MediaBrowser.MediaEncoding.csproj
+++ b/MediaBrowser.MediaEncoding/MediaBrowser.MediaEncoding.csproj
@@ -66,6 +66,7 @@
     <Compile Include="Subtitles\SsaParser.cs" />
     <Compile Include="Subtitles\SubtitleEncoder.cs" />
     <Compile Include="Subtitles\SubtitleTrackInfo.cs" />
+    <Compile Include="Subtitles\TtmlWriter.cs" />
     <Compile Include="Subtitles\VttWriter.cs" />
   </ItemGroup>
   <ItemGroup>
diff --git a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
index ab9cd546a..82e331dd8 100644
--- a/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
+++ b/MediaBrowser.MediaEncoding/Subtitles/SubtitleEncoder.cs
@@ -48,6 +48,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             string inputFormat,
             string outputFormat,
             long startTimeTicks,
+            long? endTimeTicks,
             CancellationToken cancellationToken)
         {
             var ms = new MemoryStream();
@@ -56,6 +57,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             {
                 // Return the original without any conversions, if possible
                 if (startTimeTicks == 0 && 
+                    !endTimeTicks.HasValue &&
                     string.Equals(inputFormat, outputFormat, StringComparison.OrdinalIgnoreCase))
                 {
                     await stream.CopyToAsync(ms, 81920, cancellationToken).ConfigureAwait(false);
@@ -64,7 +66,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
                 {
                     var trackInfo = await GetTrackInfo(stream, inputFormat, cancellationToken).ConfigureAwait(false);
 
-                    UpdateStartingPosition(trackInfo, startTimeTicks);
+                    FilterEvents(trackInfo, startTimeTicks, endTimeTicks, false);
 
                     var writer = GetWriter(outputFormat);
 
@@ -81,19 +83,30 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             return ms;
         }
 
-        private void UpdateStartingPosition(SubtitleTrackInfo track, long startPositionTicks)
+        private void FilterEvents(SubtitleTrackInfo track, long startPositionTicks, long? endTimeTicks, bool preserveTimestamps)
         {
-            if (startPositionTicks == 0) return;
+            // Drop subs that are earlier than what we're looking for
+            track.TrackEvents = track.TrackEvents
+                .SkipWhile(i => (i.StartPositionTicks - startPositionTicks) < 0 || (i.EndPositionTicks - startPositionTicks) < 0)
+                .ToList();
 
-            foreach (var trackEvent in track.TrackEvents)
+            if (endTimeTicks.HasValue)
             {
-                trackEvent.EndPositionTicks -= startPositionTicks;
-                trackEvent.StartPositionTicks -= startPositionTicks;
+                var endTime = endTimeTicks.Value;
+
+                track.TrackEvents = track.TrackEvents
+                    .TakeWhile(i => i.StartPositionTicks <= endTime)
+                    .ToList();
             }
 
-            track.TrackEvents = track.TrackEvents
-                .SkipWhile(i => i.StartPositionTicks < 0 || i.EndPositionTicks < 0)
-                .ToList();
+            if (!preserveTimestamps)
+            {
+                foreach (var trackEvent in track.TrackEvents)
+                {
+                    trackEvent.EndPositionTicks -= startPositionTicks;
+                    trackEvent.StartPositionTicks -= startPositionTicks;
+                }
+            }
         }
 
         public async Task<Stream> GetSubtitles(string itemId,
@@ -101,6 +114,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             int subtitleStreamIndex,
             string outputFormat,
             long startTimeTicks,
+            long? endTimeTicks,
             CancellationToken cancellationToken)
         {
             var subtitle = await GetSubtitleStream(itemId, mediaSourceId, subtitleStreamIndex, cancellationToken)
@@ -110,7 +124,7 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             {
                 var inputFormat = subtitle.Item2;
 
-                return await ConvertSubtitles(stream, inputFormat, outputFormat, startTimeTicks, cancellationToken).ConfigureAwait(false);
+                return await ConvertSubtitles(stream, inputFormat, outputFormat, startTimeTicks, endTimeTicks, cancellationToken).ConfigureAwait(false);
             }
         }
 
@@ -254,6 +268,10 @@ namespace MediaBrowser.MediaEncoding.Subtitles
             {
                 return new VttWriter();
             }
+            if (string.Equals(format, SubtitleFormat.TTML, StringComparison.OrdinalIgnoreCase))
+            {
+                return new TtmlWriter();
+            }
 
             throw new ArgumentException("Unsupported format: " + format);
         }
diff --git a/MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs b/MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs
new file mode 100644
index 000000000..a937175f0
--- /dev/null
+++ b/MediaBrowser.MediaEncoding/Subtitles/TtmlWriter.cs
@@ -0,0 +1,59 @@
+using System;
+using System.IO;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading;
+
+namespace MediaBrowser.MediaEncoding.Subtitles
+{
+    public class TtmlWriter : ISubtitleWriter
+    {
+        public void Write(SubtitleTrackInfo info, Stream stream, CancellationToken cancellationToken)
+        {
+            // Example: https://github.com/zmalltalker/ttml2vtt/blob/master/data/sample.xml
+            // Parser example: https://github.com/mozilla/popcorn-js/blob/master/parsers/parserTTML/popcorn.parserTTML.js
+
+            using (var writer = new StreamWriter(stream, Encoding.UTF8, 1024, true))
+            {
+                writer.WriteLine("<?xml version=\"1.0\" encoding=\"utf-8\"?>");
+                writer.WriteLine("<tt xmlns=\"http://www.w3.org/ns/ttml\" xmlns:tts=\"http://www.w3.org/2006/04/ttaf1#styling\" lang=\"no\">");
+
+                writer.WriteLine("<head>");
+                writer.WriteLine("<styling>");
+                writer.WriteLine("<style id=\"italic\" tts:fontStyle=\"italic\" />");
+                writer.WriteLine("<style id=\"left\" tts:textAlign=\"left\" />");
+                writer.WriteLine("<style id=\"center\" tts:textAlign=\"center\" />");
+                writer.WriteLine("<style id=\"right\" tts:textAlign=\"right\" />");
+                writer.WriteLine("</styling>");
+                writer.WriteLine("</head>");
+
+                writer.WriteLine("<body>");
+                writer.WriteLine("<div>");
+
+                foreach (var trackEvent in info.TrackEvents)
+                {
+                    var text = trackEvent.Text;
+
+                    text = Regex.Replace(text, @"\\N", "<br/>", RegexOptions.IgnoreCase);
+
+                    writer.WriteLine("<p begin=\"{0}\" dur=\"{1}\">{2}</p>",
+                        trackEvent.StartPositionTicks,
+                        (trackEvent.EndPositionTicks - trackEvent.StartPositionTicks),
+                        text);
+                }
+
+                writer.WriteLine("</div>");
+                writer.WriteLine("</body>");
+                
+                writer.WriteLine("</tt>");
+            }
+        }
+
+        private string FormatTime(long ticks)
+        {
+            var time = TimeSpan.FromTicks(ticks);
+
+            return string.Format(@"{0:hh\:mm\:ss\,fff}", time);
+        }
+    }
+}