Are 4K Blu-ray discs better quality than streaming?

You can't deny the convenience of video streaming, but what about the quality?

While the best video streaming services support 4K and HDR, can they match the picture quality of physical media? Or are you better off reaching for a 4K Blu-ray every time?

Let's dive into the detail.

Bitrate

The big one. 4K Blu-rays come in a range of capacities, each with different bitrates: 50GB has either 72Mbps or 92Mbps, while the 66GB and 100GB capacities have 92Mbps, 123Mbps or 144Mbps.

The bitrate refers to the number of 'bits' of data that are transmitted in a unit of time, in this case how many megabits are transferred per second. The higher the bitrate, the more data can be transferred per second, and hence the higher the picture quality.

Most streaming services (such as Netflix and Prime Video) have around 15-25Mbps. Apple TV has 40Mbps, while Sony Pictures Core tops the list with up to 80Mbps. But that's still a fair way behind what's possible with 4K Blu-ray.

Hence a 4K Blu-ray will usually give you a far more detailed picture.

In order to achieve the best picture quality on streaming, you'll also need an internet connection capable of delivering the requisite speed (Netflix recommends a 25Mbps connection per device to watch in 4K, while a 115Mbps connection will give you the best experience with Sony Pictures Core).

Even if you have a sufficiently speedy connection, it will still be impacted by other internet activity – if someone else starts gaming in another room, for example, the streaming viewer will suffer.

For the best experience, you'll need an uninterrupted connection – hence the 25Mbps connection 'per device' that Netflix recommends.

Compression

Streaming loses out here, too.

Because the information is being delivered over the internet rather than from a locally running disc, it has to be compressed to ensure consistently smooth playback.

Streamers have to prioritise smooth running over picture quality, as otherwise the movie would keep stopping (or 'buffering') in order for sufficient information to arrive to render the picture in the requisite detail.

For example, the AV1 codec is now used in 30 per cent of all Netflix streaming, making it the service's second most-used codec. While AV1 might be more efficient than rival codecs, it still compromises the picture to prioritise smooth playback.

Compression is also variable, with the service sending more information for more dynamic scenes, like action, and less information for static scenes. This can result in an uneven look, with occasional blocky 'artefacts' especially during dark scenes.

4K Blu-rays do use compression but to a much lesser extent than streaming, allowing for the higher bitrates and richer 10-bit colours with virtually no banding.

HDR

Again, HDR is significantly better on a 4K Blu-ray disc than on streaming, thanks to the disc's higher bit depth and less compression.

With HDR able to reach its full potential, you'll get a greater difference between the light and dark parts of the picture, meaning brighter highlights, blacker blacks, and more detail visible both within these extremes and across the image as a whole.

Lossless audio

While most streaming services support advanced audio formats, such as Dolby Atmos, a 4K Blu-ray will still sound far better.

That's because streaming services compress the audio in order to make it a smaller file to transmit, losing detail in the process. Whereas a physical disc's greater capacity allows for lossless audio, meaning more detail, greater expression and a more immersive and cinematic experience.

A streaming service's sound quality may vary depending on your internet connection too, making it less consistent throughout the duration of a film.

Other advantages of discs

4K Blu-rays have other advantages besides the superior picture and sound quality. Each disc is a one-off cost, whereas streaming's monthly fee means you're paying each month.

Once you've bought a 4K Blu-ray, it's yours to keep. Whereas streaming rights are constantly changing, meaning each service's library can vary month to month – annoying when something on your watchlist goes walkies to a rival service.

Conclusion

There's no question that 4K Blu-rays can offer better picture and sound quality than movie streaming services.

But you can't deny the convenience of streaming – no physical discs to store, instant delivery, thousands of titles all at your fingertips... It also works out much cheaper if you watch a lot of films (and shows), and there's a growing library of titles that are exclusive to streaming.

The technology is also improving. As internet speeds get higher, the need to compress audio and video diminishes. Sony Pictures Core shows a glimmer of what's possible, with quality comparable to some 4K Blu-ray discs (though you do need a Sony TV to get the best streaming quality).

So while 4K Blu-ray should be the choice for those serious about prioritising picture and sound quality, streaming is undeniably convenient for everyday viewing. And as the tech improves, it may not be long before streaming equals or even surpasses the quality of a physical disc.

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