Along with Apple’s refreshed Apple TV capable of 1080p video output, iTunes movies also got a bump up to 1080p with the introduction of iTunes 10.6. While there were some concerns over increased file sizes, iTunes users for the most part seem to be quite pleased with the quality of iTunes movies encoded in 1080p compared to the 720p they were stuck with before. On that note, Ars Technica decided to find out exactly how the 1080p movies compare to the same content on a Blu-ray. Here is what it found:
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I used the movie 30 Days of Night for the test. According to the Internet Movie Database, this 2007 movie was filmed in the common Super 35 (film) format and then transferred to a 2k digital intermediate, in other words, it was edited in the digital domain. The iTunes download clocks in at a handsome 3.62GB (where 1GB = 2^30 bytes). It contains a stereo AAC track as well as a Dolby Digital 5.1 track. The video resolution is 1920×798. The BRD is a dual layer BD 50 and has a Dolby Digital 5.1 as well as a DTS-HD track, a number of special features and 30 seconds worth of unskippable copyright warnings.
The images above are photos taken of a Dell U2312HM monitor (1,920-by-1,080) that was used to test both copies. Ars explained screenshots were not possible due to DRM restrictions. iTunes content was played from a MacBook Air. The Blu-ray content played from a Panasonic DMP-BD65 Blu-ray player connected through HDMI-to-DVI. Images from iTunes are always on the left or top, and those from Blu-ray are to the right and bottom. As you can see from the images, iTunes content encoded in 1080p holds up pretty well to Blu-ray quality—especially given the much smaller file size. In the image of truck and telephone poles, the report noted iTunes removes “both detail and noise” to hit the compressed file size target, which is something Blu-ray does not have to worry about. Ars explained there are a few areas where Blu-ray noticeably outshines the iTunes encode:
iTunes has been able to keep up with Blu-ray for the most part. But early in the movie, there is a fade from black to dark clouds. Dark gradients are often a problem area with image compression. So it’s no surprise that iTunes stumbles at this point, and shows significant banding. Blu-ray, on the other hand, has no problems… Pay attention to the detail on the bright parts of the nose and the forehead. The BRD retains detail while the iTunes version blows them out.