Most folks go about their daily lives and never think about Bluetooth codecs. And who can blame them? Why worry about which codec your wireless headphones and/or smartphone are using as long as everything works when you hit play in your favorite streaming music app?
And yet, depending on your gear, your choice of Bluetooth codec could give you better sound quality than you’re currently getting. We’re going to take a look at three of the best options — aptX HD, aptX Adaptive, and LDAC — but before we do, let’s address an important caveat. If you mostly listen to lossy digital music (e.g., all music currently on Spotify) or if you own an iPhone, you can stop right here.
Why? The Bluetooth codecs used by nearly every phone and every set of wireless headphones/earbuds (SBC, AAC, or aptX) are more than capable of transmitting lossy audio without much alteration, and Apple only supports SBC and AAC on its iPhones.
Still with us? OK, let’s dig into it.
Lossless and hi-res audio
Before we start the comparison, it’s worth explaining why these three codecs matter.
As mentioned in the intro, lossy 16-bit music has already been compressed to the point where it can fit into an audio stream that only requires about 328Kbps of bandwidth. This bit rate is easily served by the three standard codecs (SBC, AAC, or aptX). This is the default quality you get from a service like Spotify, but even Apple Music, Amazon Music, and others will perform similar compression unless you change their streaming quality settings.
However, if you listen to lossless CD quality and/or lossless hi-res audio (either from your personal collection or a streaming service), you’re getting pristine quality digital audio. AptX HD, aptX Adaptive, and LDAC are all engineered to preserve much more of that extra detail than standard codecs. In some cases, they can triple the bit rate available for transmitting audio.
For 16-bit audio, this can result in nearly lossless performance. However, all three codecs are also compatible with 24-bit audio sources, which means they can theoretically deliver hi-res audio over Bluetooth, even though it will still involve some loss of information.
Not everyone is convinced that hi-res audio is actually better than CD quality, and not everyone agrees that lossy hi-res is better than lossless CD quality, but these are debates for a different article.
For now, the key takeaway is this: If you want to preserve as much audio quality as possible when using wireless headphones and earbuds, these three codecs are a better choice than SBC, AAC, or aptX.
The players
Qualcomm, which designs chips for mobile phones and other wireless devices, is the driving force behind the aptX family of codecs. There are now several flavors of aptX, including aptX classic, aptX Low Latency (LL), aptX HD, aptX Adaptive, and aptX Lossless, each with their own specifications and hardware requirements.
Sony created LDAC. Initially, it was only available on Sony’s wireless headphones and earbuds, but in recent years, it has sharply increased its licensing of the technology, which means it’s now available on many more products.
But which of these codecs is the best? That depends on a lot of factors, so let’s start at the beginning.
Compatibility and availability
As with any Bluetooth codec, aptX HD, aptX Adaptive, and LDAC need to be supported on both the source device (phone, computer, etc.), as well as the sink device (headphones, earbuds, speakers).
Speaking strictly about smartphones for the moment, Google added AptX HD and LDAC to Android 8.0, letting any Android smartphone manufacturer take advantage of them. If your phone is on Android 8.0 or higher (and as long as your phone’s manufacturer hasn’t intentionally disabled one or both), you should be able to use them with a compatible set of earbuds or headphones.
AptX Adaptive is the newest of the three codecs, and while it also runs on Android devices, it’s not built into the Android operating system. Only Android phones that use Qualcomm’s audio chipsets support aptX Adaptive. You’ll find good support for aptX Adaptive support on Android phones that have been released since about 2020, with two very notable exceptions: No Google Pixel or Samsung Galaxy phones currently support aptX Adaptive.
On the sink side of the equation, any wireless headphones or earbuds that support aptX Adaptive must also use Qualcomm’s chips. From a compatibility and availability point of view, this puts aptX Adaptive at a bit of a disadvantage.
AptX HD has limitations too, but in this case, it’s strictly on the headphones side of the equation. For reasons we’ll get into shortly, aptX HD is primarily used for wireless headphones, not wireless earbuds. There are some exceptions — like the Bowers & Wilkins PI7 — but they’re very rare. If you’re shopping for wireless earbuds, they will most likely offer aptX or aptX Adaptive, but not aptX HD.
LDAC can work on headphones and earbuds, and even though the codec is owned and licensed by Sony, a manufacturer doesn’t need to use Sony’s chips to add LDAC support to their products — it can be implemented using software on a variety of processing platforms.
When we first created this comparison, not many manufacturers had chosen to adopt LDAC. However, as of August 20024, the list includes many popular brands. Other than Sony itself, you’ll find LDAC support on products from 1More, Anker Soundcore, Audeze, Earfun, QCY, Soundpeats, Shure, Audio-Technica, Technics, Tozo, Edifier, Ausounds, Ankbit, Mark Levinson, Dali, and Philips. AptX HD has been used by more than 30 headphone manufacturers, and aptX Adaptive has been used by even more companies when you count both headphones and earbuds.
LDAC’s ability to run on headphones and earbuds without special chipsets, plus its default inclusion on virtually all Android phones, makes it the most widely available of these 24-bit codecs.
Though they’re still rare, we’re beginning to see wireless headphones and earbuds that work with both LDAC and aptX Adaptive, like the Earfun Air Pro 4.
Winner: LDAC
Sound quality part 1: bit depth and sample rate
When it comes to sound quality, most experts would agree that your choice of wireless headphone or earbuds is the most important factor. High-performance headphones will sound better than lower-quality headphones even if the lower-quality ones use a “better” codec.
However, we can still evaluate a codec’s ability to help a set of headphones or earbuds (or even a Bluetooth speaker) sound their best.
When a codec is used to transmit audio wirelessly, it encodes that audio at a specific resolution (bit depth) and a specific sample rate or frequency (kHz). When those characteristics aren’t an identical match for the bit depth and sample rate of your source music, conversion takes place. In most cases, this conversion is inaudible, but purists insist that any change is undesirable.
AptX HD operates at up to 24 bits, which is the standard for most hi-res audio. However, its sample rate support is limited to 48kHz.
LDAC and aptX Adaptive, on the other hand, can preserve up to 24-bit and 96kHz, without conversion or resampling.
LDAC and aptX Adaptive’s better preservation of original audio is arguably only useful when listening to hi-res audio, but the fact remains that if you’re listening to 24-bit audio and want to preserve as much of that signal as possible, LDAC and aptX Adaptive are preferable to aptX HD.
Winner: Two-way tie between LDAC and aptX Adaptive
Sound quality part 2: bit rate and scalability
The nerds out there are probably yelling at me right now because while resolution and sample frequency might be the be-all and end-all for sound quality when dealing with hi-res audio files, the moment Bluetooth gets involved, you also need to take into account how a codec handles itself under highly variable wireless conditions.
We’re talking about bit rate, or the amount of data a codec uses to send information across a Bluetooth connection. The higher the bit rate, the more information can be sent, and thus (theoretically) the better the sound quality.
Some codecs have fixed bit rates, which means that they can’t react to changes in the quality of a wireless link. AptX HD is a fixed bit rate codec, and it requires a constant speed of 576Kbps when transmitting a 48kHz signal. As long as your connection can handle this speed, aptX HD should be able to deliver its full quality. But if the quality of your connection drops below that speed, which can happen when you’re too far from your phone or there’s a lot of wireless interference, the audio will start to break up. It’s an all-or-nothing proposition.
LDAC and aptX Adaptive are scalable codecs — they can adjust the amount of bandwidth they use in response to your Bluetooth connection. The difference between them is that LDAC steps between three specific speeds — 330Kbps, 660Kbps, and 990Kbps — with no in-between steps, while aptX Adaptive can adjust its speed from 110Kbps to 620Kbps in 10Kbps increments.
Maintaining a Bluetooth connection at LDAC’s top speed of 990Kbps can be tricky in certain environments. Interference from other devices, as well as proximity between your phone and your headphones, can get in the way. If you force your phone to only use the 990Kbps speed (which is possible using the optional Android developer settings), and it can’t be maintained, you’ll get stuttering and dropouts. Allowed to set its own speed, LDAC will typically run at 660Kbps.
AptX Adaptive’s ability to smoothly scale instead of stepping in such large increments, as well as its lower overall speed requirements, means it will be able to connect at its top quality more of the time while presenting a less noticeable transition when it needs to ramp its speed downward. However, there’s no way to force aptX Adaptive to use any specific bit rate — as its name suggests, it’s always adaptive.
Regardless of their minimum, maximum, and incremental bit rates, one thing continues to plague the world of Bluetooth codecs: there’s no way to see your current bit rate.
On paper, LDAC’s 990Kbps bit rate is clearly the best of the three, with almost double the amount of data transmitted per second than aptX HD and almost 50% more than aptX Adaptive. If you can achieve that bit rate (and maintain it), LDAC will be superior.
Winner under ideal conditions: LDAC; winner under variable conditions: aptX Adaptive
Latency
Latency is the time it takes for you to hear a sound after it has been created by your device. For regular music listening, latency doesn’t matter much, but if you’re gaming or watching any kind of video with dialogue, you want that time to be as short as possible. The general consensus within the gaming community is that anything lower than 32 milliseconds is fast enough to be comparable to using a wired headset.
Several factors can affect Bluetooth audio latency, but codecs are an important ingredient. AptX HD has a reported latency of anywhere between 200ms and 300ms. LDAC can exhibit similarly long lag times.
AptX Adaptive, on the other hand, can adjust its performance based on the kind of audio you’re streaming. If it detects that you’re gaming, making a phone call, or doing anything else that might require low latency over high resolution, it can operate as low as 80ms.
That’s enough to earn it a win in the latency category, but it might get even better. Qualcomm says that if you’re using a phone and wireless headphones that have both been certified under its Snapdragon Sound program, latency as low as 40ms — the same performance as its aptX Low Latency codec — could be possible.
Winner: aptX Adaptive
Power consumption
One thing we’ll probably never get enough of when it comes to wireless headphones and earbuds is battery life. No one likes to recharge, so the less frequently we need to do it, the better.
For LDAC, this poses a challenge. Running LDAC on a set of earbuds or headphones can mean a measurable reduction in playtime. On Anker Soundcore’s Liberty 4 earbuds, engaging the LDAC codec drops their playtime from nine hours per charge to just six hours.
The aptX family of codecs has always been more efficient than its rivals, and that goes for both aptX HD and aptX Adaptive. Low power consumption isn’t a key feature of Adaptive, but Qualcomm says it uses less power to deliver the same performance as aptX HD. Manufacturers that incorporate aptX technologies don’t normally cite lower battery life when aptX codecs are used instead of SBC or AAC.
Winner: aptX Adaptive
Conclusion
For Google Pixel, Samsung Galaxy, and any other Android handsets that don’t use Qualcomm chips, it’s an easy answer: LDAC is the best codec of the three.
For phones that are aptX Adaptive capable, it becomes a question of priorities. If you value sound quality above battery life, above latency, and perhaps even above the ability to use your headphones in situations where Bluetooth connections may be dicey, go with LDAC. But for most other scenarios, aptX Adaptive will prove more flexible, with higher consistency.
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