Why Discs Remain the King of Quality

Top Product: Sony UBP-X700 4K Blu-Ray Player | $198 | Amazon

For most people, watching a movie on a disc is as antiquated as listening to music on a cassette tape. But unlike the tape decks of yore, which were undeniably worse than their successors, streaming is actually a step down from its “old” media counterpart. If you care about picture and audio quality, you should really buy your favorite movies on disc.

It may seem like a hassle to pop in a disc before you start watching (I have to get UP out of my seat?) but provided you have a decent 4K Blu-ray player—or a capable game console—your efforts will be worthwhile. The level of difference you see will depend on your eye, the streaming service you use, and the gear in your living room—both your TV and speakers. Sometimes it’s subtle and you have to look closely to spot the downgrades. But other times, the difference is rather stark, particularly in scenes where streaming’s heavier compression just can’t handle the level of detail required by the scene. Remember, it’s not just about the number of pixels—just because the disc is 4K and your stream is 4K doesn’t mean they’ll be identical. The bitrate, or the amount of data being pushed through in a given moment, matters just as much, if not more, than the resolution.

Bitrate is especially important in fast-paced action scenes, with a lot of things going on in the frame. Take, for example, Spider-Man: Into the Spider-Verse—a movie that uses remarkably complex animation, which in turn requires a lot of data—to replicate. In the first collider scene, which introduces the Kingpin, the animated effects are distinct on 4K Blu-ray: the comic book dot shading in the background, the fluid movement of Spider-Gwen, and the abstract splotches and lines coming from the collider explosion. But watch that same scene on Google Play Movies, where bitrate caps at around 15Mbps (less than 1/3rd the bitrate of the Spider-Verse disc), and the collider explosion is noticeably blurrier, littered with compression artifacts required to fit each frame into the service’s limited streaming capacity (not to mention the occasional stutter). The Apple TV version of the film handles these scenes better thanks to a much higher bitrate, though some small differences are still apparent—you can see how your streaming service of choice matters a lot, too.

But even with Apple TV’s superior bitrate, streaming can’t quite hold up to Blu-ray. Scenes with rain, snow, confetti, and other similar effects are, again, super dependent on the bitrate available to them. The opening scene of Aquaman, for example, takes place during a raucous thunderstorm in the middle of the night, with lightning flashing and water droplets rushing through the frame. On 4K Blu-ray, this scene looks as fantastic as any other in this movie, with sharp detail on the character’s face, and a clear distinction between the raindrops as he runs down the stairs to the ocean. iTunes’ version of the movie, while undoubtedly superior to other streaming offerings, is still noticeably lower quality than the 4K Blu-ray during this scene, with softer details in the face and a more blurry, pixelated look to the rain falling down from the sky. There’s so much going on in the frame that the compression algorithm has to sacrifice something to keep the data flowing through your series of tubes. Aquaman has a few scenes like this, and I wouldn’t watch it on anything other than a 4K disc.

That scene is also dark, which has been the enemy of compression as long as we’ve been using it to deliver media. Dark scenes tend to exhibit more banding and blocking artifacts when compressed, which makes the differences between streaming and disc much more apparent than many well-lit scenes. This has gotten better in recent years thanks to better compression algorithms, though. Remember watching Game of Thrones on HBO Go? It’s a lot better on HBO Max, and even better on disc now that the 4K Blu-rays are out.

But dark level compression is still apparent here and there, despite its improvements. Tron: Legacy—one of my favorite movies that still hasn’t gotten a 4K release—is a good example of streaming compression in the dark, since most of the movie takes place in the black cloudy atmosphere of The Grid. Even in the opening titles, the Amazon Prime stream showcased more banding and blocking in the dark skies, which look much cleaner on the 1080p Blu-ray disc. In the scene where Sam talks to Gem on the street, his cloak has less detail, with a mass of blocky black shadow instead of the smoother, grain-accented shading you see on the disc. (Film grain is also something you lose in streaming compression.) Dark performance has improved drastically over the years, and if you have a TV with local dimming, it can help hide those flaws further—but they’re there, and they bug me every time.

Sometimes, it’s less about “difficult scenes” and just about a loss of overall detail. Lord of the Rings, despite some issues with de-noising, was one of the movies that truly sold me on 4K resolution, offering more fine detail than the 1080p Blu-ray—especially in those close-up face shots Peter Jackson seems to love so much. But if you look at some of those shots in the streaming copy, you will notice small differences. Take Gandalf’s little pep talk on morality when Frodo spots Gollum in the mines: on the 4K disc, Gandalf’s skin and beard looks shockingly detailed, with each wiry hair standing out from those next to it. In the 4K stream from iTunes, this shot still looks great, but side-by-side you’ll notice just a tad more fuzziness, as his hair and beard lose a bit of detail compared to the 4K disc. These are the kinds of things that extra bitrate gives you, and while it’s subtle, it’s the difference between a great picture and the best possible picture (especially if you’re watching on a large TV).

And I haven’t even brought up practical concerns, like stuttering, bandwidth issues, or other quirks that can plague streaming movies. Or the fact that so many offer standard HD versions of the films even though 4K versions exist (get it together, Netflix). Nor have I delved into audio, where Blu-ray discs have the benefit of uncompressed DTS-HD Master Audio and Dolby TrueHD vs the typical Dolby Digital and Dolby Digital Plus sources you’ll see in streaming movies. There’s a lot more debate on whether you can actually tell the difference between these audio formats—especially since services like Netflix have improved their bitrates—but I swear I still hear subtle differences in the fullness of low frequency effects of movies like Mad Max: Fury Road. If there is an audible difference, it’s certainly not nearly as night and day as it once was when streaming was giving us peanuts, but if you’re the kind of person who wants the best audio possible, you know where to find it (especially if you want Dolby Atmos, which not all streaming services offer—looking at you, Hulu).

So all in all? I’m pretty impressed with how far streaming has come. I’d never go so far as to say you should avoid it, or that the quality is garbage. We stream plenty of TV in my house, whether it’s due to platform exclusives (have you watched Ted Lasso yet?) or certain comedy shows where quality just isn’t a concern (I’ll watch Happy Endings over and over again, in whatever quality it’s available in). But when picture and audio quality actually matters, do yourself a favor: buy the disc. Streaming is good, but the top-end experience of physical media still can’t be beat.