Understanding Video Bit Rates and Why They Matter


When it comes to video cameras, most people focus on one thing; the word HD.  But HD is actually a video dimension, not an indication of video quality.  With video cameras, there are multiple factors that determine the actual quality of the video.  And one of the biggest ones is the video bit rate at which a camera records.

Bit rates are defined by mega bits per second (mbps).  And in a nutshell, the higher the bit rate of a video, the higher the video quality.  For example, most video you watch on the web has a bit rate of around 800 kbps (less than 1 mbps).  Video on DVD has a bit rate between 4-8 mbps, or roughly 4-8 times higher quality than web video.  And video on Blu-Ray has a bit rate of around 25 mbps, or roughly 25 times the quality of web video.

Which brings us back to video cameras, the bit rates they record at and why it matters.

When most people pick up a pocket or Flip-style camera, they are enamored that it “shoots in HD”.  Remember, HD is a recording dimension, not an absolute indication of quality.  And besides having cheap lenses and electronics, these cameras also record at a low bit rate…typically around 10 mbps.  If you’ve been paying attention, you might say “well gee, that’s still above DVD quality”.  And it is, but when putting that video on the web it has to be compressed down to around 800 kbps.  And when you compress something, you lose quality.  The higher quality you start with before compression, means the more quality you’ll retain after compression.

Which leads us to the more expensive cameras.  Most consumer-level cameras (and increasingly some pro-level cameras) shoot in the AVCHD format.  This format has a maximum bit rate of 24 mbps, or roughly 2 times the quality of Flip-style cameras.  Does that mean when compressing this footage down for the web that you’ll retain twice the quality over Flip-style cameras?  Well, quality is a subjective thing.  Whether your video looks twice as good is open for discussion.  But it will look better.  In some cases, far better.

And then you have pro-level cameras, which record video at bit rates from 35 mbps all the way up to 100 mbps.  These are broadcast quality cameras with hefty price tags.  And to be sure, you’re getting a whole lot more in terms of quality than just the high recording bit rates.  But if you were to take one of these cameras…with their advanced electronics and expensive glass…and record a video with them at Flip-style bit rates (10 mbps), the video would look bad.  Not Flip-style bad, but significantly worse than if the footage was recorded at a higher bit rate.

Which is why bit rate matters.  The higher the bit rate you record at, the better your footage will look in the end.  It’s not the only thing that will determine the quality of your video…far from it.  But it is a critical, and often overlooked, piece of the puzzle.


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