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What is LDAC / LHDC? The audio codecs explained

Discover the tech that promises headphone heaven

Sony Music Entertainment artist Khalid wearing the Sony WH-1000XM5 headphones in silver
Sony Music Entertainment artist Khalid wearing the Sony WH-1000XM5 headphones in silver

If you’ve been reading about some of the best headphones such as Sony’s marvellous WF-1000XM5s or similarly high-end alternatives, you may have spotted one or two acronyms that might not be very familiar: LDAC and LHDC. They’re both audio technologies that are designed to make your headphones sound more heavenly, but what are they – and should you be seeking them out? Let’s discover what LDAC and LHDC are and why they matter.

What does LDAC stand for, and where does it come from?

Nobody seems to know what LDAC stands for, but the most likely explanation is Lossless Digital Audio Codec. But its creator Sony has never confirmed or denied that, so it’s all a bit of a mystery. It could be Let’s Dance to Abba Classics, Large Dogs Are Cool or Larry’s Dad’s A –whatever it actually stands for, what matters is that Sony created LDAC to deliver high-resolution audio streaming over Bluetooth connections, and it’s one of only two standards certified as Hi-Res Audio by the Japan Audio Society. The other is LHDC.

As you’d expect from a standard developed by Sony, you’ll find LDAC support in Sony Xperia smartphones, in Sony hi-res audio players, in Sony home entertainment kit and in Sony headphones and earbuds. Many other firms support LDAC too, but if you want LDAC on an iPhone you’re out of luck. Apple devices don’t currently support LDAC and aren’t likely to.

Sony has published a list of LDAC-compatible products here.

Illustration of the LDAC Bluetooth pathway. Credit: Sony

What does LHDC stand for?

LHDC stands for Low Latency High Definition Audio Codec. It was created by a company called Savitech as an alternative to the likes of LDAC and aptX-HD. You’ll find it in some Android audio apps; the first phone to support it was the Huawei Mate 10.

What’s a codec?

Codec is a portmanteau of “encoder/decoder” or “compressor/decompressor” and it’s usually used to describe a technology that makes file sizes smaller and easier to transmit without sacrificing too much, or in some cases any, of the originals’ quality.

Codecs have been with us for decades because we’ve always wanted to transmit more data than our existing technology allowed. And in the case of LDAC and LHDC, because we wanted to transmit better quality audio than Bluetooth was designed to deliver.

With a normal Bluetooth connection, audio is transferred at roughly 300 kilobits per second. That’s a lot of data, but it’s not all the data (or all the data Bluetooth is now capable of shifting; more of that in a moment).

A CD quality recording is 1,411 kilobits per second, so if it’s streaming at 300kbps then clearly you’re not getting to hear the whole thing.

And these days CD quality is seen as rather old hat in serious audio circles: high-res audio with even higher sampling rates and higher bit rates is where it’s at. Normal Bluetooth codecs can’t cope with that at all.

Illustration of Bluetooth codec compression. Credit: Sony

Where do LDAC and LHDC come in?

LDAC and LHDC are designed to deliver better audio quality through more efficient compression. While every important audio codec can squeeze audio files down in size, LDAC and LHDC can do it much more efficiently – so they can deliver better quality streaming over the same connections. In the case of Sony’s LDAC, it can take the 1,411 kilobits of a CD quality recording down to 990kbps without losing any of the audio information. With Bluetooth 4 onwards delivering data rates of 1,024 kilobits per second or more, that means LDAC can deliver CD quality or better over Bluetooth.

Or at least, it does if two other things are true. First of all, both your phone and your headphones need to have a version of Bluetooth that delivers the necessary data rates. And secondly, both your phone and your headphones need to work with the LDAC codec. If your phone supports LDAC but your headphones don’t, or vice versa, then LDAC won’t be available.

That very much depends on what you want to listen to and what you’ll be listening to it on. If you’ll be sitting on the sofa streaming delicate music from a really high quality source such as Super Audio CD, Tidal Hi-Fi, Qobuz or your own collection of hi-res audio files to an equally high quality set of headphones then yes, it’s absolutely worth having; it’s a bit like the difference between 4K on a basic TV and 4K on a really good, big OLED TV.

If on the other hand you’re streaming Spotify on the subway, then the answer’s a definite no: Spotify doesn’t stream at high enough audio quality for LDAC or LHDC to be necessary and even with noise cancelling, you’re not really going to benefit from higher res audio in such a noisy environment.

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