www.makemkv.com

I found this odd, and I'm wondering if anyone here could provide some insight:

I ripped a Blu-Ray, resulting in a file with the following attributes:

Size: 25.6GB
Data rate: 36,370
Audio Bitrate: 640
Total Bitrate: 37,054

I've always assumed that the total bit rate is (more or less) the total of the data rate and the audio bitrate. But while I was updating my digital collection, I inadvertently re-ripped the exact same disc. HOWEVER....the second time, the attributes looked like this:

Size: 30.6GB
Data rate: 36,370
Audio Bitrate: 640
Total Bitrate: 44,287

I didn't change any settings between runs, so I'm wondering why the increase in file size and Total Bitrate?
Also, if the Data rate and Audio Bitrate didn't change, where is the extra file size coming from?

Thanks in advance for your input!

Are you sure both files have the same tracks in them? One might have additional audio tracks in it.