Fix progress bar, remove temp file on ffmpeg error (#66)

* Delete the video file on ffmpeg error

* rework chunk calculation (with more tests it turns out it was not good for all durations)

Co-authored-by: kylon <kylonux@gmail.com>

src/Utils.ts

@@ -137,5 +137,5 @@ export function ffmpegTimemarkToChunk(timemark: string) {
     const mins = parseInt(timeVals[1]);
     const secs = parseInt(timeVals[2]);
 
-    return hrs * 1000 + mins * 100 + secs;
+    return (hrs * 60) + mins + (secs / 60);
 }