One of the biggest joys of owning a home theater is watching a great action movie like Skyfall, the latest James Bond film. Typically, I prefer to watch high-budget movies on Blu-ray—after all, when I watch a blockbuster, I want the sound and image quality to be as good as possible. Last week, iTunes made Skyfall available for purchase one week earlier than the Blu-ray release. Because it is the middle of winter, I decided to succumb to the urge for instant gratification; I bought the movie and watched it instead of waiting.
What I saw truly surprised me. From the very first moment to the very last credit, I scrutinized Skyfall for any significant flaws in the image quality. To my surprise, iTunes managed to get through the whole film without any obvious signs of compression. I have an aversion to banding, macroblocking, smearing pixelation, and tearing, and I saw no egregious artifacts. Impressed, I decided to see how Vudu compares. The Vudu HDX version became available Friday Feb. 9, still four days ahead of the Blu-ray release, so I bought the Vudu version and began my comparison.
Conventional wisdom holds that Vudu offers the best streaming quality. Vudu promotes their TruHD encoding process, claiming an ability to preserve film grain while avoiding pixilation artifacts. In the past, I have found this to be true, at least in relative terms. Shadow regions tend to be much smoother looking in Vudu streams as opposed to iTunes downloads. Vudu also boasts support for Dolby Digital Plus 7.1 surround sound on some devices, beating iTunes' Dolby Digital 5.1 support. But since encoding algorithms are improving all the time, the service with the best quality could potentially change over time, or even from movie to movie.
For the Skyfall comparison, I utilized the iTunes desktop application on a PC running Windows 8. I dismissed using Vudu through a browser, because it only offers 2-channel sound and the quality was clearly unacceptable. I tried out Vudu on a Roku as well as through my 55" Vizio TV's built-in app. Unacceptable artifacts abounded, but at least the Dolby surround worked. I found the best implementation of Vudu on my PS3, with 7.1 surround and much smoother gradients than the other Vudu streams. Bravo to the PS3.
Skyfall is a very impressive movie, a special-effects extravaganza with a complex and challenging color palette. Quite a few scenes in the movie present a serious challenge to compression algorithms, with fast action and overlapping layers, action filmed in the dark with monochrome palettes ranging from all blue to orange. If there are any flaws in the encoding process, they would show up in these shadows as banding, pixelation, and random noise.
The iTunes version of Skyfall somehow managed to play through without a single distracting artifact calling attention to itself. Vudu was also excellent 95 percent of the time, but when it came to difficult scenes, Vudu struggled more frequently. What makes the new iTunes version look so natural?
The answer seems to be in the grain. iTunes appears to preserve film grain at all costs, even if it means losing some details, like high-contrast lines. Vudu tends to smooth out areas that lack significant texture. As soon as you smooth out a dark tone and compress it, you end up with blocky artifacts, and that is what I kept seeing in the Vudu version. The PS3 kept the blocking to a minimum, but it was still visible. The flip side to Vudu's approach is that it sometimes manages to preserve sharp lines that iTunes obscures.iTunes preserves shadow gradient integrity but sacrifices details to do so
After studying the three formats (iTunes, Vudu HDX, and Blu-ray), I found the Blu-ray remains the highest quality source—no surprise there. Pixel peeping is the fine art of scrutinizing individual pixels while ignoring the image as a whole. I photographed freeze-frames from the movie with a professional camera and scrutinized the results in Photoshop. I would not expect the average viewer to do the same, after all nobody watches a big-screen TV from 2 feet away. Proper pixel peeping can reveal exactly how much more information is preserved thanks to higher bit rates and better compression.
At a normal viewing distance, however, the missing detail in the iTunes version is not readily apparent. The movie plays through without any hint that it is a highly compressed download. The largest difference I noticed was not even visual—it was the sound. The iTunes version suffers a little bit for using 5.1 Dolby Digital encoding, while Vudu's 7.1 surround was more dynamic and enveloping, coming rather close to the Blu-ray's shattering explosiveness. For some home-theater addicts, that could be a deciding factor, but I did not think it was a big deal.
My conclusion? If you are going to stream or download, Skyfall is better on iTunes than Vudu. Enjoy the show.Update:
A thank you AVS members who brought this to my attention. iTunes 720p files can look better than their 1080p equivalents. I had to see for myself and the results are surprising but undeniable. When it comes to fidelity iTunes 720p has the best overall image quality, especially during difficult to render scenes. Here are two examples.
In light of this observation, future comparisons will also include examples of the iTunes 720p version as well as 1080p.
The following images illustrate the differences in compression quality0:34 - Fade in from black, stationary shot
iTunes achieves a nice fade-in with smooth gradients and a bit of extra grain
Blu-ray achieves proper color and smooth gradients
Vudu renders color more accurately but struggles with the gradients10:11 - Fight on top of train, daylight high action with complex movement
iTunes loses the most detail in this rather complex scene
Blu-ray manages an artifact-free render
Vudu preserves a great deal of detail, is closer to Blu-ray than iTunes39:02 - At the museum. A well lit stationary shot
iTunes may have the best color rendition for this shot, with great detail
Blu-ray adds a bit of contrast to this easy-to-render scene
Vudu pushes the saturation of the skin tones a bit but is equally good56:39 - Casino scene. Dark with deep reds and yellows and some motion
iTunes has a hard time with color and details but keeps the deep shadows fairly clean
Blu-ray stumbles for once with loss of shadow details, still the best rendition
Vudu renders accurate shadow color and more detail vs. iTunes but has more artifacts1:48:38 - Bond walking with M. Natural indoor light with moderate motion
iTunes loses the crease in the jacket and the cloth texture but preserves the gradients
Blu-ray does its job, preserving texture and gradients
Vudu smears the details while creating significant artifacts, renders only part of the crease1:59:12 - Skyfall battle. All blue palette, very dark with explosive action
iTunes cannot render details, renders acceptably smooth shadow gradients
Blu-ray shows why it's still the top dog when it comes to image quality
Vudu gives up on this scene. Detail is totally lost, blocking artifacts take their placeIn response to several comments, here are a few screen captures from my PC
The differences are not as obvious compared to my 'pixel peeping' camera
The Vudu screen capture comes from the web app
I do not have a way to screen capture Blu-ray
The two approaches to shadow detail are still on display here
You will need to view the image full-size to make a proper comparison
Detail levels are similar but the iTunes version looks more natural
The Blu-ray version (not seen) has finer textures, more detail
Vudu on the PC has somewhat inaccurate colorI'll wrap up with this shot, which is where Vudu had the hardest time
This is a full screen capture. If anything it is even more revealing than the photos
Click into the picture to open the gallery, check out the original 1920x1080 image
I brightened the image in a totally non-destructive manner with Photoshop
On a large screen Vudu's rendition of this scene was unacceptable
iTunes lost significant amounts of detail, but the dark fast action helped hide most of the loss