I have to xvids that I would like to convert and burn on 1 DVD. They are both AC3 5.1 (384kbps) encoded. I am using the bitcalc to calculate what bitrate to encode the files in order to fit on 1 DVD. I used the advanced button and was wondering if anyone knew if AC3 5.1 was 1 track or is each channel considered a track? My thinking was that if you had the sound in 5.1 and in dolby prologic that would be 2 tracks or as in on in english and one in spanish. Since it is just english 5.1 I was using 1 track for that setting to calculate the bitrate. Am I correct in this understanding?