Vote 2020 graphic
Everything you need to know about and expect during
the most important election of our lifetimes

Comcast Compressing HDTV Signals to Fit Three Shows into Two Shows' Bandwidth

Illustration for article titled Comcast Compressing HDTV Signals to Fit Three Shows into Two Shows Bandwidth

Comcast has begun compressing HDTV shows in order to deliver more HD channels to you while using the same amount of bandwidth. They didn't use to do this before, but now, when compared to Verizon FiOS, the channels are grainy and blocky and full of artifacts—a result of shoving three channels into a space where only two previously occupied. A guy at AVSForum measured how the new bitrate stacks up against Verizon.

Advertisement
Illustration for article titled Comcast Compressing HDTV Signals to Fit Three Shows into Two Shows Bandwidth

DVice has a side-by-side of the FiOS vs. Comcast comparison as well, and things look pretty damn ugly.

Advertisement

The forum poster says that the compression isn't too horrible with still images, but gets really bad when stuff moves around.

The greatest differences are seen with movement. With slow movement on Comcast, the first thing you notice is added noise and a softer image, as fine detail is filtered from the picture signal. The greater the rate of movement, the more detail you lose and the more noise you see. With intense movement, you see more blocking and skipped frames. In VideoRedo, I noticed that a number of frames in the FiOS signal simply did not exist in the Comcast signal during motion intensive scenes. This may be responsible for the stutter and excessive motion blur seen with some video sequences on Comcast.

To Comcast's credit, I saw little to no difference on movie channels such as HBO, Cinemax, and Starz. I did see some blurring and reduced detail during fast movement on Starz, but the recordings from Cinemax and HBO were virtually identical, even on action movies such as 300 and Gladiator. When there was blocking on the Comcast feed of Cinemax, that blocking was also on the FiOS feed.

[AVSforum via DVice]

Share This Story

Get our newsletter

DISCUSSION

Whether you agree with more government interference or not, it does seem as though a company should not be able to call highly compressed HD video as high definition. When you compare over the air HD & Blu-ray level quality to what these compressed examples are like, there really is no comparison. Heck, I would rather watch a DVD of a movie than the 'HD download' version of it that the various folks put out, because in my experience the quality is much better.

That said, I do think this stuff is so confusing to the average person that there is not much that can be done. We will have everything labeled as 'HD', and people will not know whether it is 'good HD', 'bad HD' or 'ugly HD' until they use it.