The file is completely read from start to end. Only this enables Plex to determine the real ‘peak’ bitrate of the file.
Then several bitrate values are calculated for different player buffer sízes. Depending on the player type which later does the playback the appropriate bitrate number is picked and used for the decision, whether to transcode or not.
Take a look at the XML info of the item.
If the deep analysis has been performed, there will be one or several requiredBandwidths="27166,26312,24247,22347,21003,19838,15765,14563"
entries in there, one for the whole file and sometimes one for each of the video, audio and subtitle streams.
The first number is the required bandwidth for the worst case, if your Plex client has only a tiny network buffer.
The various numbers are the required bitrate for 5/10/25/50/75/100/250/500MB network buffer sizes.
Deep analysis is either performed when a new item is added or during maintenance hours by the Plex Butler.
You can export this info with Plex2CSV. Just make sure to use the latest version of the plugin and set a detail level of at least ‘5’ (for movies) in its preferences.
