Streaming Dolby Atmos will finally sound as good as 4K Blu-ray, based on blind test results by audio engineers – but that still won’t entice collectors to ditch physical media

Dolby AC-4 was the preferred codec of many audio professionals
Better than existing Atmos audio without high bandwidth requirements
Peacock is upgrading but other streamers haven’t announced any plans

One of the biggest differences between streaming movies and 4K Blu-rays is sound quality: even the most expensive streaming tiers deliver compressed audio with a marked reduction in dynamic range and clarity compared to disc playback.

But that could change thanks to a new version of Dolby’s sound technology that audio experts apparently can’t distinguish from uncompressed PCM, but which works at streaming bitrates.

The new technology is called Dolby AC-4, and it’s a codec: an encoder/decoder to compress audio. It’s designed to deliver much higher audio quality than current streaming soundtracks, and can do so without requiring a lot of bandwidth.

How Dolby AC-4 Could Make Your Streams Smoother

Most streaming apps use DD+JOC for immersive audio. This is a version of the proven Dolby Digital standard, with the JOC bit standing for “Joint Object Coding”. It allows Dolby Atmos to deliver positional audio without interrupting support for 5.1 channel setups.

Dolby AC-4 is what Dolby calls a next-generation audio codec, and it’s designed to more efficiently deliver sound for listening to headphones and speakers, including information about 3D objects.

As Dolby explains: “The AC-4 coding system uses new aspects of object audio beyond what is already available with Dolby Atmos in other Dolby codecs for features such as dialogue enhancement or commentator substitution. And significantly, it “can deliver equivalent channel-based audio quality at approximately half the bitrate of Dolby Digital Plus.”

It’s impressive, but is it effective?

Immersive Machines’ listening test used three formats: DD+JOC at 768 kbps, uncompressed PCM audio at 13,824 kbps, and AC-4 L4 at 448 kbps. Listeners heard them on a full 7.1.4 channel system, on the same system with specific speakers muted and individual speakers soloed. Each format was given the letter A, B or C and their identity was not revealed until the test was completed.

The test was not based solely on vibrations. Listeners were asked to identify compression artifacts such as gate, swishing, loss of spatial precision, and loss of frequency range. And with all the speakers on – which is how you would listen at home – the AC-4 was in a bind with reference uncompressed PCM audio.

Compression was most noticeable in the AC4 when individual speakers were soloed, but for a full home theater setup, the AC-4 produced sound that matched seemingly losslessly, albeit delivering only 3 percent of the data.

There are a few caveats here, particularly regarding sample size: a test with 16 listeners is not a hard science. But at the same time, 16 audio professionals tasked with critical listening are going to be a lot more picky than you or I probably will be, so that’s still quite an endorsement.

The first TV/movie streaming service providing AC-4 will be Peacock, although the technology will also be used by Amazon Music and TIDAL (but specifically for spatial audio based on binaural headphones). Other streamers could migrate, but so far there have been no further announcements since Peacock’s announcement at CES 2026.

You can read more about Immersive Machines testing here, but while this suggests that streamers could offer 4K Blu-ray-like sound quality in the very near future, it’s worth noting that Dolby AC-4 doesn’t address one of the other reasons people buy Blu-Rays: unlike streaming, purchased Blu-Rays don’t disappear from your library when streaming rights expire or the streamer decides to shrink its catalog.

Better quality has certainly been one of the main reasons people buy 4K Blu-rays, especially if you have a great home theater setup – but collection and ownership are growing as the reason people are investing in Blu-ray again, and AC4 won’t change that.

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