anchor.diff:  
       return output;
     }
  +
     Future<List<int>> generateFfmpegThumbnail(String originalFile) async {
       _log.fine("generateFfmpegThumbnail start");
       final Directory tempFolder =
           await Directory.systemTemp.createTemp("dartlery_ffempeg_output");
       final String tempfile = path.join(tempFolder.path, "thumbnail.png");
       try {
  -      final ProcessResult result = await Process.run("ffmpeg",
  -          <String>['-i', originalFile, '-vf', "thumbnail", '-frames:v', '1', tempfile]);
  +      final ProcessResult result = await Process.run("ffmpeg", <String>[
  +        '-i',
  +        originalFile,
  +        '-vf',
  +        "thumbnail",
  +        '-frames:v',
  +        '1',
  +        tempfile
  +      ]);
         if (result.exitCode != 0) {
           throw new Exception(
               "Error while generating video thumbnail: ${result.stderr
  
positive.code:       }
        _log.fine("_createAndSaveThumbnail end");
      }
  
  
      return thumbnailFile;
    }
  
negative.code:         originalImage = decodeImage(item.fileData);
          _log.fine("image decoded");
        }
        if (mime == MimeTypes.jpeg || mime == MimeTypes.tiff) {
          try {
            _log.fine("Reading exif data");
            final Map<String, IfdTag> data =
                await readExifFromFile(new File(originalFile));
            for (String key in data.keys) {
              item.metadata[key] = data[key].toString();
            }
            _log.fine("Done reading exif data", item.metadata);
          } catch (e, st) {
            _log.warning("Error while fetching exif data", e, st);
            item.errors.add("Error while fetching exif data: ${e.toString()}");
          }
        }
      } else if (MimeTypes.videoTypes.contains(mime) || mime == MimeTypes.swf) {
        try {
          _log.fine("Is video mime type");
          item.video = true;
          originalImage = decodePng(await generateFfmpegThumbnail(originalFile));
          await getFfprobeData(item, originalFile);
        } catch (e, st) {
          if (mime == MimeTypes.swf) {
            _log.warning("Error while genereting thumbnail of swf", e, st);
            item.errors
                .add("Error while genereting thumbnail of swf: ${e.toString()}");
          } else {
            rethrow;
          }
  