Audio Format .opus

My CellPhone can Record Audio and in the Audio Options Menu I Pick 44k for the Bit Rate.

Now I Record some Audio and then I Copy it to my Win7. 64 Bit DeskTop.

I then open it in MediaInfo and the Readout Says
Format : OGG
File size : 29.4 KiB
Duration : 5s 297ms
Overall bit rate : 45.5 Kbps
Writing application : Mozilla2.5

The Overall bit rate should Say 44k why does it Say 45.5kbps?

 

This is what the Full Readout Says

Format : OGG
File size : 29.4 KiB
Duration : 5s 297ms
Overall bit rate : 45.5 Kbps
Writing application : Mozilla2.5
Audio
ID : 291262527 (0x115C503F)
Format : Opus
Duration : 5s 297ms
Channel(s) : 1 channel
Channel positions : Front: C
Sampling rate : 48.0 KHz
Compression mode : Lossy
Writing library : libopus unknown-fixed

And if I Pick 8.k from my Record Options and Open it in MediaInfo thios is the Readout.
Format : OGG
File size : 6.46 KiB
Duration : 6s 627ms
Overall bit rate : 7 982 bps
Writing application : Mozilla2.5
General
Format : OGG
File size : 6.46 KiB
Duration : 6s 627ms
Overall bit rate : 7 982 bps
Writing application : Mozilla2.5
Audio
ID : 672535720 (0x281614A8)
Format : Opus
Duration : 6s 627ms
Channel(s) : 1 channel
Channel positions : Front: C
Sampling rate : 48.0 KHz
Compression mode : Lossy
Writing library : libopus unknown-fixed