use subtitles to display errors (#512)

* use subtitles to display errors

* fix margin calculation

CHANGELOG.md

@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Fix song page links in UI
 - Show song artist in playout detail
 - Include song artist and cover art in channel guide (xmltv)
+- Use subtitles to display errors, which fixes many edge cases of unescaped characters
 
 ### Changed
 - Randomly place song cover art on left or right side of screen

ErsatzTV.Application/Streaming/Queries/GetPlayoutItemProcessByChannelNumberHandler.cs

@@ -193,7 +193,7 @@ namespace ErsatzTV.Application.Streaming.Queries
                         case UnableToLocatePlayoutItem:
                             if (channel.FFmpegProfile.Transcode)
                             {
-                                Process errorProcess = _ffmpegProcessService.ForError(
+                                Process errorProcess = await _ffmpegProcessService.ForError(
                                     ffmpegPath,
                                     channel,
                                     maybeDuration,
@@ -212,7 +212,7 @@ namespace ErsatzTV.Application.Streaming.Queries
                         case PlayoutItemDoesNotExistOnDisk:
                             if (channel.FFmpegProfile.Transcode)
                             {
-                                Process errorProcess = _ffmpegProcessService.ForError(
+                                Process errorProcess = await _ffmpegProcessService.ForError(
                                     ffmpegPath,
                                     channel,
                                     maybeDuration,
@@ -231,7 +231,7 @@ namespace ErsatzTV.Application.Streaming.Queries
                         default:
                             if (channel.FFmpegProfile.Transcode)
                             {
-                                Process errorProcess = _ffmpegProcessService.ForError(
+                                Process errorProcess = await _ffmpegProcessService.ForError(
                                     ffmpegPath,
                                     channel,
                                     maybeDuration,

ErsatzTV.Core/FFmpeg/FFmpegComplexFilterBuilder.cs

@@ -108,31 +108,25 @@ namespace ErsatzTV.Core.FFmpeg
             return this;
         }
 
-        public FFmpegComplexFilterBuilder WithSubtitleFile(
-            MediaVersion videoVersion,
-            Option<string> subtitleFile)
+        public FFmpegComplexFilterBuilder WithSubtitleFile(Option<string> subtitleFile)
         {
             foreach (string file in subtitleFile)
             {
                 string effectiveFile = file;
+                string fontsDir = FileSystemLayout.ResourcesCacheFolder;
                 
-                if (videoVersion is FallbackMediaVersion or CoverArtMediaVersion)
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
                 {
-                    string fontsDir = FileSystemLayout.ResourcesCacheFolder;
+                    fontsDir = fontsDir
+                        .Replace(@"\", @"/\")
+                        .Replace(@":/", @"\\:/");
                     
-                    if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
-                    {
-                        fontsDir = fontsDir
-                            .Replace(@"\", @"/\")
-                            .Replace(@":/", @"\\:/");
-                        
-                        effectiveFile = effectiveFile
-                            .Replace(@"\", @"/\")
-                            .Replace(@":/", @"\\:/");
-                    }
-
-                    _subtitle = $"subtitles={effectiveFile}:fontsdir={fontsDir}";
+                    effectiveFile = effectiveFile
+                        .Replace(@"\", @"/\")
+                        .Replace(@":/", @"\\:/");
                 }
+
+                _subtitle = $"subtitles={effectiveFile}:fontsdir={fontsDir}";
             }
 
             return this;

ErsatzTV.Core/FFmpeg/FFmpegProcessBuilder.cs

@@ -221,14 +221,9 @@ namespace ErsatzTV.Core.FFmpeg
             return this;
         }
 
-        public FFmpegProcessBuilder WithSubtitleFile(
-            MediaVersion videoVersion,
-            Option<string> subtitleFile)
+        public FFmpegProcessBuilder WithSubtitleFile(Option<string> subtitleFile)
         {
-            _complexFilterBuilder = _complexFilterBuilder.WithSubtitleFile(
-                videoVersion,
-                subtitleFile);
-
+            _complexFilterBuilder = _complexFilterBuilder.WithSubtitleFile(subtitleFile);
             return this;
         }
 
@@ -301,24 +296,6 @@ namespace ErsatzTV.Core.FFmpeg
             return this;
         }
 
-        public FFmpegProcessBuilder WithFiltergraph(string graph)
-        {
-            _arguments.Add("-vf");
-            _arguments.Add($"{graph}");
-            return this;
-        }
-
-        public FFmpegProcessBuilder WithFilterComplex(string filter, string finalVideo, string finalAudio)
-        {
-            _arguments.Add("-filter_complex");
-            _arguments.Add($"{filter}");
-            _arguments.Add("-map");
-            _arguments.Add(finalVideo);
-            _arguments.Add("-map");
-            _arguments.Add(finalAudio);
-            return this;
-        }
-
         public FFmpegProcessBuilder WithConcat(string concatPlaylist)
         {
             _isConcat = true;
@@ -372,22 +349,6 @@ namespace ErsatzTV.Core.FFmpeg
             return this;
         }
 
-        public FFmpegProcessBuilder WithErrorText(IDisplaySize desiredResolution, string text)
-        {
-            string fontPath = Path.Combine(FileSystemLayout.ResourcesCacheFolder, "Roboto-Regular.ttf");
-            var fontFile = $"fontfile={fontPath}";
-            const string FONT_COLOR = "fontcolor=white";
-            const string X = "x=(w-text_w)/2";
-            const string Y = "y=(h-text_h)/3*2";
-
-            string fontSize = text.Length > 80 ? "fontsize=30" : text.Length > 60 ? "fontsize=40" : "fontsize=60";
-
-            return WithFilterComplex(
-                $"[0:0]scale={desiredResolution.Width}:{desiredResolution.Height},drawtext={fontFile}:{fontSize}:{FONT_COLOR}:{X}:{Y}:text='{text}'[v]",
-                "[v]",
-                "1:a");
-        }
-
         public FFmpegProcessBuilder WithDuration(TimeSpan duration)
         {
             _arguments.Add("-t");

ErsatzTV.Core/FFmpeg/FFmpegProcessService.cs

@@ -167,7 +167,7 @@ namespace ErsatzTV.Core.FFmpeg
             }
         }
 
-        public Process ForError(
+        public async Task<Process> ForError(
             string ffmpegPath,
             Channel channel,
             Option<TimeSpan> duration,
@@ -179,6 +179,22 @@ namespace ErsatzTV.Core.FFmpeg
 
             IDisplaySize desiredResolution = channel.FFmpegProfile.Resolution;
 
+            var fontSize = (int)Math.Round(channel.FFmpegProfile.Resolution.Height / 20.0);
+            var margin = (int)Math.Round(channel.FFmpegProfile.Resolution.Height * 0.05);
+            
+            string subtitleFile = await new SubtitleBuilder(_tempFilePool)
+                .WithResolution(desiredResolution)
+                .WithFontName("Roboto")
+                .WithFontSize(fontSize)
+                .WithAlignment(2)
+                .WithMarginV(margin)
+                .WithPrimaryColor("&HFFFFFF")
+                .WithFormattedContent(errorMessage.Replace(Environment.NewLine, "\\N"))
+                .BuildFile();
+
+            var videoStream = new MediaStream { Index = 0 };
+            var audioStream = new MediaStream { Index = 0 };
+
             FFmpegProcessBuilder builder = new FFmpegProcessBuilder(ffmpegPath, false, _logger)
                 .WithThreads(1)
                 .WithQuiet()
@@ -187,12 +203,18 @@ namespace ErsatzTV.Core.FFmpeg
                 .WithLoopedImage(Path.Combine(FileSystemLayout.ResourcesCacheFolder, "background.png"))
                 .WithLibavfilter()
                 .WithInput("anullsrc")
-                .WithErrorText(desiredResolution, errorMessage)
+                .WithSubtitleFile(subtitleFile)
+                .WithFilterComplex(
+                    videoStream,
+                    audioStream,
+                    Path.Combine(FileSystemLayout.ResourcesCacheFolder, "background.png"),
+                    "fake-audio-path",
+                    playbackSettings.VideoCodec)
                 .WithPixfmt("yuv420p")
                 .WithPlaybackArgs(playbackSettings)
                 .WithMetadata(channel, None);
 
-            duration.IfSome(d => builder = builder.WithDuration(d));
+            await duration.IfSomeAsync(d => builder = builder.WithDuration(d));
 
             switch (channel.StreamingMode)
             {
@@ -292,7 +314,7 @@ namespace ErsatzTV.Core.FFmpeg
                     .WithFormatFlags(playbackSettings.FormatFlags)
                     .WithSongInput(videoPath, videoStream.Codec, videoStream.PixelFormat, boxBlur, randomColor)
                     .WithWatermark(watermarkOptions, channel.FFmpegProfile.Resolution)
-                    .WithSubtitleFile(videoVersion, subtitleFile);
+                    .WithSubtitleFile(subtitleFile);
 
                 foreach (IDisplaySize scaledSize in scalePlaybackSettings.ScaledSize)
                 {

ErsatzTV.Core/Interfaces/FFmpeg/IFFmpegProcessService.cs

@@ -29,7 +29,7 @@ namespace ErsatzTV.Core.Interfaces.FFmpeg
             TimeSpan inPoint,
             TimeSpan outPoint);
 
-        Process ForError(
+        Task<Process> ForError(
             string ffmpegPath,
             Channel channel,
             Option<TimeSpan> duration,