Fix clip downloader sometimes getting stuck when encoding metadata (#926

)

* Actually fix #914

* Kill FFmpeg on error if it hasn't exited yet

* Log instead of throwing

TwitchDownloaderCore/ClipDownloader.cs

@@ -77,7 +77,7 @@ void DownloadProgressHandler(StreamCopyProgress streamProgress)
                 if (!File.Exists(downloadOptions.Filename))
                 {
                     File.Move(tempFile, downloadOptions.Filename);
-                    throw new FileNotFoundException("Unable to serialize metadata (is FFmpeg missing?). The download has been completed without custom metadata.");
+                    _progress.Report(new ProgressReport(ReportType.Log, "Unable to serialize metadata. The download has been completed without custom metadata."));
                 }
 
                 _progress.Report(new ProgressReport(ReportType.SameLineStatus, "Encoding Clip Metadata 100%"));
@@ -149,12 +149,13 @@ private async Task EncodeClipWithMetadata(string inputFile, string destinationFi
         {
             var metadataFile = $"{inputFile}_metadata.txt";
 
+            Process process = null;
             try
             {
                 await FfmpegMetadata.SerializeAsync(metadataFile, clipMetadata.broadcaster.displayName, downloadOptions.Id, clipMetadata.title, clipMetadata.createdAt, clipMetadata.viewCount,
                     videoMomentEdges: new[] { clipChapter }, cancellationToken: cancellationToken);
 
-                var process = new Process
+                process = new Process
                 {
                     StartInfo =
                     {
@@ -169,16 +170,22 @@ await FfmpegMetadata.SerializeAsync(metadataFile, clipMetadata.broadcaster.displ
                 };
 
                 process.Start();
+                process.BeginErrorReadLine();
 
                 // If the process has exited before we call WaitForExitAsync, the thread locks up.
-                // This was probably not intended by the .NET team, but it's an issue regardless.
                 if (process.HasExited)
                     return;
 
                 await process.WaitForExitAsync(cancellationToken);
             }
             finally
             {
+                if (process is { HasExited: false })
+                {
+                    process.Kill();
+                    await Task.Delay(100, cancellationToken);
+                }
+
                 File.Delete(metadataFile);
             }
         }