View Bitrate

I need to figure out the bitrate of some pre-existing quicktime files, and I can't figure out how to do that. Any advice?
Open the files in a QT Player. Then open the "Inspector" window and check "Data Rate:" entry. The is the total average bit rate for all tracks in the file. If you have QT Pro, you can open the properties window and check the bit rate by track. As to how to calculating the data/bit rate:

Total Average Bit Rate = Total Data / Total Time.

Any tips on how to do this programmatically? (via the SDK?)

This may warrant its own topic or may fit here: Viewing data rate in QT does not match up with file size and duration in 1 h.264 file I have:

6.2 mb/54 s = 940 kbits/s

QT shows it as 460.9 kbit/s which is what its target was when I encoded using Episode.

I would say the 1st is correct. But then what about what QT says?

Thoughts?

6.2 mb/54 s = 940 kbits/s
Actually, I get

(6.2MBs x 8b) / 54sec = 0.9185 Mbps or 918.5 Kbps

However, you don't say is the 6.2 MBs is the data size or the file size which includes file headers + data + unfilled data block and may include space allocated for data which was deleted/trimmed from the file but not removed by re-compressing the data. Also is 1 K here defined as 1000 (10^3) or 1024 (2^10)?

QT shows it as 460.9 kbit/s which is what its target was when I encoded using Episode.
Is the data rate indicated/target setting referenced the "Total" data rate or just the video target rate/track?

6.2 MB is file size

k is referred to as 1024

QT data rate is total

So, what QT reports as Data rate is to be taken as the correct average data rate for the file, correct?

So, what QT reports as Data rate is to be taken as the correct average data rate for the file, correct?
No data rate should be considered "accurate." All data rates are calculated whether by QT or the Finder and are the quotient of either the "file size" (sum of allocated VTOC data storage blocks times their size) or the "data size" (sum of allocated data storage within the movie file container) and the file duration. I don't know why your files seem so disproportionate. Mine are much closer to the readings. For instance the same file in...

Finder info:
(File) Size: 12 MB (12,585,277 bytes)
Duration: 01:00.00
Total bit Rate: 1665 Kbps

Cross checking I get
(1.665 Mbps / 8 bits/byte) x 60.00 = 12 MBs (or 12,487,500 bytes)
and
(12,585,277 bytes /60 sec) x 8 bits/byte = 1.678 Mbps or 1678 Kbps

QT Inspector:
Data Size: 11.92 MBs
Duration: 00:59.99
Data Rate: 1665.92 Kbps

Cross checking I get
(((1665.92 Kbps / 8 bits/byte) x 59.99 sec = 12,492 KBs) / 1.024 KBs Dec/Bin = 12,200 KBs) / 1024 KB Dec/ MB Bin = 11.91 MBs
and
(((11.92 MBs x 1.024 MBs Dec/Bin = 12.206 MBs) x 1024 KB Dec/MB Bin = 12,500 KBs) / 59.99 sec = 208.35 KBps) x 8 bits/byte = 1667 Kbps

Having no experience with your work flow and not knowing if your file has been manipulated in any way which changed the amount of "active" data within the file without changing the "physical" file size, it is difficult to speculate further. BTW, if you want more specific data rate readings, you can always trim your file to a short segment, save the result to a new file, and evaluate the data rate for that specific segment. Depending on the encoding mode (Single-pass/multi-pass) these figures can change drastically. And, as the duration of your segments approach zero, you get a better picture of the instantaneous data rates, their fluctuations, and total excursions.