Argo is a political thriller based on a true story that takes place during the Iranian revolution in 1979. Directed by Ben Affleck, it received seven Oscar nominations and won three, including Best Picture. In this comparison, I will examine the iTunes 720p, iTunes 1080p, Vudu HDX, and Blu-ray versions of this exceptional movie.
Argo earned three sound-related Oscar nominations: best mixing, editing, and score. The Argo Blu-ray utilizes DTS-HD Master Audio with 5.1 channels. iTunes implements Dolby Digital 5.1, while Vudu encodes audio with Dolby Digital Plus 5.1 on dedicated devices running the Vudu app. Vudu on a computer is limited to 2-channel audio, and the sound quality is not comparable to 5.1 audio in any way. No deep bass, no surround sound, no impact.
When comparing sound quality, I used the Vudu app on a PS3, which supports up to 7.1-channel audio. iTunes playback was on a Windows 8 PC, a 2012 DIY build that is capable of uncompressed 7.1-channel output (DTS-HD). Total system power is close to 5000 watts, calibrated to play flat from 16-20,000 Hz at reference levels and beyond.
It was difficult to hear any difference between the Vudu and iTunes versions. I level matched within 1 dB and found nothing to complain about in either mix. It is possible that the deep bass in the Vudu version was deeper by just a hair. It is also possible that I heard a bit more pinpoint rear-channel panning in the iTunes version. If there are differences between Vudu and iTunes when it comes to 5.1 soundtracks, they were extremely subtle. There was no difference in the soundtrack between the two iTunes versions.
Blu-ray audio is another story. DTS-HD MA is essentially a bit-for-bit copy of the studio master. I heard superior dynamics, but the most obvious difference was deeper, tighter bass. The fidelity and discreteness of the surround effects increased, with a greater sense of the space and ambience. Blu-ray dedicates as much bandwidth to audio as Vudu and iTunes do to video—no wonder it sounds better. Both Vudu and iTunes should consider using better and higher-bitrate compression for their audio.
The iTunes and Vudu 1080p versions looked very good. I used my 55" Vizio M3D550KD to view each version. Argo is not a "digital-slick" looking movie—it's a genuine film shot on varied stock including 35mm, 16mm, and 8mm formats. Analog film grain is part of Argo's aesthetic, so that needs to be preserved. You do not want a digital algorithm mistaking the grain for compression artifacts. In this regard, both iTunes versions manage to look better than Vudu HDX, with the iTunes 720p version frequently doing the best job. In some spots, Vudu failed totally, resorting to macroblocking in the shadows. The iTunes 720p copy surprised me with its image quality, often it looked better than the iTunes and Vudu 1080p version. The 1080p streaming versions inadvertently created a more modern looking movie by taking away the film grain that Blu-ray managed to preserve, while the iTunes 720p version fell somewhere in between. Since pictures are worth so many words, I'll let some screen grabs do the talking.
But before I do, I wanted to explain a bit about the screen images. When I did a similar exercise with Skyfall, I used photographs to compare image quality since I had no way of performing a screen capture on a PS3. I used a PS3 to play back the Vudu HDX file because, on a desktop or laptop, Vudu HDX is limited to 2-channel sound.
But in this Argo comparison, I used real screen grabs. The reason for the switch—still photography adds a degree of loss and variability to the comparisons, while screen capture is a 100% pixel-perfect representation of each frame. In order to guarantee the image-quality comparisons are as accurate as possible, it is better to use screen capture, which in turn requires playing the files on a desktop or laptop. My solution: Obtaining screen grabs from the Vudu HDX stream using a PC, then watching the movie using the Vudu app on the PS3 to judge sound quality.
Much of Argo was shot on grainy film, which presents a serious challenge to compression algorithms. Film grain is easily mistaken for noise and also consumes bandwidth in the same way digital noise does. In this frame, Vudu HDX loses the most contrast and detail as a result of compression, all of film grain is treated as noise and eliminated. The iTunes 720p and 1080p versions look nearly identical, preserving more detail and texture than Vudu HD was able to. Unfortunately, iTunes also tends to treat the film grain as noise, just like Vudu. Of the three non Blu-ray formats, iTunes 720p had the fewest problems dealing with film grain.
Here is the same image, brightened in Photoshop by shifting the gamma in order to analyse what's going on in the shadows.
The camera does not move in this shot, giving the iTunes 1080p and Vudu HDX versions time to fill in the details. When compression algorithms can draw from past and future frames, they do much better at preserving details. The Vudu version looks the sharpest, but it is also the least authentic reproduction of the original. Treating the film grain as noise makes the iTunes 1080p and Vudu HDX versions look cleaner than Blu-ray and makes fine details easy to see. The iTunes 720p version has less detail than the 1080p version but preserves some of the original film grain. The Blu-ray version renders the most accurate colors and also properly preserves the film grain.
This scene was shot handheld, likely on 16mm film stock, it is very grainy and blurry on purpose. Vudu HDX and iTunes 1080p try to process the grain, the result is ugly artifacts in the skin tones that look like smooth patches, as if it was airbrushed. Vudu HDX exhibited significant macro blocking in the shadow regions. The iTunes 720p version reduces the film grain but does so in a smooth, natural looking manner. Blu-ray preserves the character of the original film, although it also exhibits some very minor compression artifacts.
In this close-up we see the destructive effects of Vudu's algorithms in full effect, the film grain is wiped out. iTunes 1080p manages to preserve a lot of the details, but there are unnatural-looking smooth patches on the woman's face. The iTunes 720p version loses some fine details but manages to preserve enough of the film grain to look authentic, and it is free of artifacts. Blu-ray renders the scene perfectly preserving all of the film grain, as is appropriate.
This is of the most difficult frame grabs to judge, each version has issues. Vudu HDX looks the most detailed thanks to noise reduction, but the sky picks up some artifacts as a consequence. The iTunes 1080p version does a great job of preserving details and film grain with only a few artifacts, it looks like a modern digital photo. iTunes 720p compression produces the softest looking image, but it is actually more faithful to the original film, as seen in the Blu-ray. The Blu-ray screen grab reveals a lot of grain, in a blind test it might even be singled out as having the worst quality of the bunch.
This frame grab is almost certainly from 8mm film footage. The grain structure is so large, Vudu and iTunes don't even see it as noise. Vudu HDX attempts to re-create the grain as detail and is mostly successful, although there is some macro blocking. Both iTunes versions attempt to smooth the noise to no avail, leaving a patchy mess. I see no real difference between iTunes 720p and 1080p in this scene. Blu-ray reveals the raw nature of 8mm footage, compression algorithms don't know what hit 'em.
In this dark action scene, both the iTunes 1080p and Vudu HDX version convert the out-of-focus background - an effect is known as "bokeh" - into colored blobs. The iTunes 1080p version suffers from the most noise-reduction artifacts while the iTunes 720p remains more faithful to the original, preserving some film grain and introducing no artifacts. When it comes to reproducing actual film, especially gritty grainy film, Blu-ray is superior by a significant margin.
Vudu does well in this scene. The camera and the subject are both static and the film used to shoot the scene has a relatively fine grain structure. The end result is Vudu preserved a lot of fine detail even though it processed all the film grain away. This scene demonstrates the one fundamental weakness of iTunes 720p - the overall sharpness in static scenes is reduced compared to the 1080p version.