Home > Home Theater > Not All High-Def Is Created Equal: Bit Rate Matters!

Not All High-Def Is Created Equal: Bit Rate Matters!

I’m an early adopter, always have been.  I’ve been enjoying high-def TV since 2001.  Back then there wasn’t much high-def to enjoy, Nash Bridges anyone?  But watch it I did.  These days we’re bombarded with High-Def choices from traditional Cable and Satellite offerings and Blu-Ray to online offerings such as You Tube, Hulu (not in Canada, grumble grumble), and many many others.  Recently telephone companies such as Bell Canada have also been entering the high-def TV market with IP TV offerings or VDSL.

All of these services offer high-def that range from 720p to 1080i and 1080p but the one biggest missing piece they don’t provide is bit rate.  What is bit rate you ask?  Bit rate reffers to the number of bits that are conveyed or processed over a given duration of time.  In computer networking terms your bit rate is your upload and download limit, as in 5Mb/second or 100Mb/second.  When you talk about the speed of your DSL line at home you’re talking bitrate.  When it comes to video content bit rate also plays an important role, as it is a sign of picture quality that’s far more important than resolution (720p/1080p/etc).  I’d much rather watch a full bit rate DVD 480p video (9.8MB/sec) than a 1080p video compressed for Internet playback over DSL (1.9Mb/sec).  Why?

Bit rate when it comes to video quality tells you how much information is available in the picture you’re about to watch.  Compression plays a major roll in allowing us to watch video over low speed (DSL) links, even technologies such as Blu-ray use compression because the movie needs to fit on a Blu-Ray disk.  And some compression such as MPEG4 (aka H.264) do a better job (less quality loss and more compression) than others such as MPEG 2.  Blu-ray’s bit rate comes in at 40Mb/second and offers the most stunning picture of any home based High-Def format, but it’s still obviously massively compressed with the uncompressed rate of 1080p 12bit video being 2.5Gb/second.   How do these other “high-def” delivery mechanisms compare to Blu-Ray and uncompressed 12bit video?   Here’s a handy reference list:

Uncompressed 1080p Video:  2.25Gb/sec

Blu-Ray: 40Mb/sec

Over The Air HD: 19.2Mb/sec

Rogers Cable: 10Mb-16Mb (Depends on channel)

Bell ExpressVu: 12Mb/s -15Mb/s

DVD: 9.8Mb/sec

Bell Entertainment (VDSL): Unpublished and no documented anywhere that I can find.

Hulu HD: 2.5Mb/sec

YouTube 1080p: 1.9Mb/sec

* A note about the above bit rates, with the exception of Blu-ray and DVD NONE of these bit rates are published numbers, I had to use my Google Kung-Fu to find these.  If you know any of these to be inaccurate and can point me to official numbers please let me know in the comments.  I was formally told by Bell Canada that they don’t publish bit rates, and that’s what prompted me to make this post.

Now, that you’re starting to understand the difference bit rate plays on the quality of the image you can see that not all Hi Def is created equal.  From where I sit Blu-Ray, being the best we can get at home (Uncompressed High Def isn’t realistic at home) is the benchmark and all other “high def” sources need to compare themselves to Blu-ray, a sort of “Blu-ray scale” where Blu-ray is a 10/10 on the scale and OTA HD would rank a 4.5/10 and You Tube being maybe 2.5/10.

However more important than a scale I’d like to see companies that offer Hi Def content stop talking purely in terms of resolution.  They must start talking in terms of bit rate;  how else is a consumer suppose to make and informed decision and compare the various high def offerings that are available?  Take Rogers for example, they announced to their base a little while back that they were going to start compressing some channels more than others, that directly impacts the quality of the product being delivered to the customer.

So don’t just look at the cost but take into account the picture quality and by extension bit rate, when you’re trying to choose which feeds those great looking high def images to your brand new LCD or Plasma screen.

Categories: Home Theater
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