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You can fairly accurately calculate avg bitrate. Take the file size, and divide by movie playtime length. It's real close because any tags in the file are miniscule compared to the actual media content.
For example, I'm listening to a 3.44 MB song file that shows as 1:47 in length, but ends with the clock showing 1:46 for less than a second. When I right click on the MP3 file in my desktop PC, choose Properties, and look at Size, it shows 3.44 MB (3,616,751 bytes). Now, dividing that by 1:46.5 or 106.5 seconds, I get:
3616751/106.5 = 33960.103... Bps
That's uppercase B, for Bytes. But most often bitrates are stated in units of bps. That's lowercase b for bits. Actually, usual units are in kbps. So, multiply by 8 to convert bytes to bits, and divide by 2^10, which is 1024, to get the k in there. So finally, this gives:
8*(33960.103...) / 1024 = 265.31... kbps
Playing this song on PC, Winamp shows 270 kbps. Playing it in Touch, PocketMusic shows 244 kbps. I use variable bitrate encoding, so players are likely to be less accurate then an actual calculation.
Hope this helps, MrG
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