GNG News Guy
03-25-2008, 12:46 PM
http://i.dslr.net/urls/60/2660.gif (http://www.dslreports.com/shownews/Comcast-HD-Image-Quality-Vs-FiOS-92969)
An interesting thread over in the AVSForums (http://www.avsforum.com/avs-vb/showthread.php?t=1008271) discusses how Comcast is sacrificing HD image quality as it faces competitive pressure on the HD front from both DirecTV and Verizon. Verizon obviously has ample capacity thanks to their FTTH network, and DirecTV decided to dump broadband and focus their satellite capacity on MPEG-4 HD back in 2004. Comcast on the other hand, waiting for DOCSIS 3.0, has started cramming three HD channels into each 38.8Mbps QAM, reducing image quality:For the most part, fine detail remains very good on static (non-moving) images with Comcast's added compression, but you do see reduced contrast, with more dithering artifacts (banding) between colors and objects. It looks a bit like Comcast is taking a 24-bit image and reducing it to 18-20 bit. This tends to reduce the 'pop' effect in some images. The difference in 'pop' was quite noticeable on Food HD, despite the relatively small bitrate reduction. 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.
So much for that survey last year (http://www.comcast.com/About/PressRelease/PressReleaseDetail.ashx?PRID=665) that claimed Comcast HD image superiority. Comcast plans to have 20% of their network wired for DOCSIS 3.0 by year's end, with broader deployment coming next year -- so this could all be a moot point in short order. Technologies like switched digital video will also free up capacity for additional broadband and HD bandwidth. Still, reduced image quality and a low HD channel count is truly annoying HD fans.
read comment(s) (http://www.dslreports.com/shownews/Comcast-HD-Image-Quality-Vs-FiOS-92969)
An interesting thread over in the AVSForums (http://www.avsforum.com/avs-vb/showthread.php?t=1008271) discusses how Comcast is sacrificing HD image quality as it faces competitive pressure on the HD front from both DirecTV and Verizon. Verizon obviously has ample capacity thanks to their FTTH network, and DirecTV decided to dump broadband and focus their satellite capacity on MPEG-4 HD back in 2004. Comcast on the other hand, waiting for DOCSIS 3.0, has started cramming three HD channels into each 38.8Mbps QAM, reducing image quality:For the most part, fine detail remains very good on static (non-moving) images with Comcast's added compression, but you do see reduced contrast, with more dithering artifacts (banding) between colors and objects. It looks a bit like Comcast is taking a 24-bit image and reducing it to 18-20 bit. This tends to reduce the 'pop' effect in some images. The difference in 'pop' was quite noticeable on Food HD, despite the relatively small bitrate reduction. 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.
So much for that survey last year (http://www.comcast.com/About/PressRelease/PressReleaseDetail.ashx?PRID=665) that claimed Comcast HD image superiority. Comcast plans to have 20% of their network wired for DOCSIS 3.0 by year's end, with broader deployment coming next year -- so this could all be a moot point in short order. Technologies like switched digital video will also free up capacity for additional broadband and HD bandwidth. Still, reduced image quality and a low HD channel count is truly annoying HD fans.
read comment(s) (http://www.dslreports.com/shownews/Comcast-HD-Image-Quality-Vs-FiOS-92969)