increase smart cut bitrate by 20%

see discussion in #126

src/smartcut.js

@@ -46,6 +46,10 @@ export async function getSmartCutParams({ path, videoDuration, desiredCutFrom, s
     videoBitrate = stats.size / videoDuration;
   }
 
+  // to account for inaccuracies and quality loss
+  // see discussion https://github.com/mifi/lossless-cut/issues/126#issuecomment-1602266688
+  videoBitrate = Math.floor(videoBitrate * 1.2);
+
   const { codec_name: videoCodec } = videoStream;
   if (videoCodec == null) throw new Error('Unable to determine codec for smart cut');