You might not know it , but when you go out and buy a set ofBluetooth phone , earbuds , or aBluetooth verbaliser , you ’re also inadvertently choose theBluetooth codecthat those devices will use when you connect them to your telephone , computer , or other gimmick . This codec compresses audio sign for effective transmission and then decompresses them for playback .

But not all codecs are produce adequate . Since Bluetooth has limited bandwidth , the choice of codec can be of the essence . That ’s where Qualcomm and its industry - lead “ aptX ” codecs come in . With five different versions of the technology , each offers different levels of carrying into action qualities that can heighten strait , reduce rotational latency , and more .

Confused ? We get it — it can be a heap . Fortunately , you ’ve come to the right berth . We ’re here to aid you infer more about aptX ( pronounced “ ap - tex ” ) so you’re able to make a better - informed decision when grease one’s palms audio product .

What is aptX?

First , a quick primer on why we have Bluetooth codecs in the first spot . Because the wireless piping that Bluetooth creates between equipment is middling narrow when compared to other technical school like Wi - Fi , it ca n’t always accommodatedigital music in its original data formatting . So codecs are employed to squeeze audio until it ’s small enough to go down that pipage .

Ever since 2003 , when the power to stream stereo sound over Bluetooth was set up , sub - band coding ( SBC ) has been the default codec used to do that job . If you own a Bluetooth audio gadget , whether it ’s a phone , a loudspeaker system , or a set of wireless earphone , it supports SBC . Having a default codec is great — it ’s what ensures that all Bluetooth audio devices will work together .

The fuss is that despite the fact that SBC is up to of deliver very proficient sound timbre , many manufacturers hobbled its data rate in the former days of Bluetooth audio as a way of life of insure that dropouts would n’t happen . After all , you might be unforced to put up with less - than - stark sound . But audio that cuts out all the time ? Forget about it . That earned SBC a number of a regretful rap . It also did n’t help that SBC suffer from significant latency .

At this peak , the aptX codec had already been in use in a variety of setting , like filmmaking and broadcast , when the company that possess it realize it had the potential to work as an alternative to SBC . AptX ’s key benefits over SBC are higher - quality audio and lower rotational latency — in other Word , you could require honorable speech sound , and if that auditory sensation was confiscate to video , you could expect better synchronizing between what you saw and what you heard . The aptX retinue of engineering eventually was purchased by Qualcomm in 2015 .

The compatibility problem

The trouble with all alternative codecs ( including aptX , AAC , LDAC , etc . ) is that they require accompaniment on both the beginning ( a phone , computing machine , or other gimmick ) and the sinkhole ( speaker , earpiece , earbuds ) so as to go .

If your phone can do aptX , but your headphones ca n’t , the Bluetooth connection will revert to SBC , or mayhap AAC , if AAC is fend for on both machine . In the Android reality , this is rarely a trouble . AptX has been included in Android almost since the get - go . As long as your audio mathematical product works with aptX , that ’s what the two gadgets will use .

But to this day , Apple , one of the gravid smartphone makers in the world , refuses to admit any non - SBC codec except AAC on its Io and iPadOS equipment .

Are aptX’s benefits real?

Initially , many Cartesian product reviewers were impressed by aptX , and feel that it delivered improved audio timbre over non - aptX - equipped gear . You may still see some reviewers , include folk who write for Digital Trends , complain when wireless phone or earbuds miss aptX.

This is partly because aptX use a different form of lossy compression than SBC or AAC — the SBC alternative favour by Apple —   and some people prefer the way it sounds . But it ’s also something of a holdover from the days when Bluetooth bandwidth was smaller and SBC was often forced to run at lower bit rates , whereas aptX always runs at a set up 352 kilobits per second(Kbps ) .

AptX ’s nondestructive sort of compression was especially beneficial in those early days when most people were listen to digital euphony inMP3 data formatting . SBC and AAC apply psychoacoustic models of contraction , which can make already heavily compressed data file like MP3 strait defective , whereas aptX does a better line of uphold the details in these files .

These same benefits can still be appreciate today , look on the seed .   If you ’re streaming Spotify using a free account statement , the best potential audio lay only delivers 160 Kbps , which means a lot of compression has already been apply .   And since Spotify flow in the Ogg Vorbis format , which ca n’t be used over Bluetooth , your phone has to decode and then re - encode that stream into SBC , AAC , or ( if your gimmick stand it ) aptX.

On the other hand , if you ’re pop out with lossless , CD - quality strait , you may not hear much of a difference between codecs at all .

Over meter , aptX has evolved from a exclusive codec to an intact family of codecs , each with its own strength , weakness , and compatibility requirement . Latency is a peculiarly thorny challenge for Bluetooth audio because there are so many links in the range of mountains between the metre when a phone is generate by a twist like a phone and when it is in conclusion turned into a speech sound you’re able to hear on your wireless headphones .

AptX Low Latency

Depending on your equipment and their supported codecs , reaction time can range as high as 320 milliseconds . For medicine listening , this does n’t matter at all , but for moving-picture show , YouTube , andespecially play , it ’s too long . AptX Low Latency ( aptX LL ) abbreviate latency dramatically , down to about 38 milliseconds , which makes it possible to react quickly in fast - paced plot . AptX LL is limited to lossy , 16 - moment audio , so it wo n’t be anyone ’s first choice for critical music heed , but it makes wireless earpiece a genuine option to wire phone when a firm connection is needed .

There is a catch , however . Like all other codecs , to get the welfare of aptX LL , it needs to be bear on both closing of the wireless audio connection . Finding earpiece and earbuds that have aptX LL is relatively well-fixed . But there are no smartphones or tablets that offer aptX LL .

It all comes down to how phones utilise their antennas . If we only ever stream local single file from our phones , aptX LL would in all likelihood work just fine . But since the Day of replicate MP3 single file from our computers to our phones are essentially over , it mean antenna need to contend with Bluetooth and Wi - Fi at the same time , piddle reliable implementation of aptX LL very intemperately , or impossible ; it ’s effectively gone from the mobile humanity .

So even though aptX LL headphones are readily usable , the only elbow room to take vantage of their downcast - rotational latency potentiality is to use a dedicated aptX LL transceiver , usually in the form of a USB dongle that can plug into a computer or secret plan cabinet .

AptX HD

SBC , AAC , and aptX are the most - supported Bluetooth codecs around , but all three are typically fix to lossy compression at 16 - bit/44.1kHz , with bit rate that rarely go above 352 kbps . Under most condition , this delivers a close estimation of CD - quality sound recording , assuming you ’re starting with a gamy - tone source for your audio .

Still , it was felt up that greater quality could be achieved if the supported scrap astuteness , sample frequency , and bit pace could be improved , so aptX HD was born . With support for audio at up to 24 - bit/48kHz , and with a boost , fixed datum rate of 576 Kbps , it still expend lossy contraction , but it ’s capable of preserving more item , peculiarly when you ’re rain buckets music that originate off as lossless , 24 - bit audio on your twist . Some the great unwashed even consider aptX HD to be ahi - res audiocodec .

AptX HD ’s encryption improve on aptX ’s sign - to - noise proportion ( SNR ) , as well as full harmonic distortion ( THD+N ) , which are two other region that involve how accurately sound is multiply . AptX HD is also backward compatible with classic aptX - capable headphones and earbuds — it can revert back to classic aptX when these products are detected , without resorting to SBC .

But there are two downside to aptX HD . The first is that it apply a prepare datum rate . If your phone and headphones ca n’t maintain a 576 Kbps connection , the reliableness of the sound recording can sustain .

The 2d is that , due to that higher data point rate requirement , it ca n’t be used on “ honest ” wireless earbuds ( where the earbuds are n’t connected by a cable ) because the earbuds demand some of that bandwidth to communicate with each other . Despite that , some company have tried to make it work — one far-famed example is the Bowers & Wilkins PI7 . Some reviewer have revel the result , but when Digital Trends sample them , we found the Bluetooth connexion to be extremely mentally ill at anything but the shortest distances .

You ’ll still see plenty of wireless headphones that pop the question aptX HD — even models that debut in 2022 — but the engineering has been supercede by Qualcomm ’s novel aptX variant , aptX Adaptive .

aptX Adaptive

Bluetooth wireless connections are ill-famed for their up - and - down nature . If you populate in the countryside and hold your speech sound in your hand , less than a foot from your headphones , with your Wi - Fi and cellular functions turned off , you ’re probably getting a really good connection at close to the maximum information rate that Bluetooth can support because you ’ve heavily thin out potential sources of interference .

But for most of us , this is the elision , not the rule . Changing distances between devices and hindrance from a huge miscellany of other wireless frequencies can dramatically pretend the quality of Bluetooth links , making any codec that operates at a rigid data rate ( like aptX and aptX HD ) susceptible to wretched execution .

A scalable codec that can set its datum rate in real - time can help solve the interference job . If you ’ve ever watched Netflix and notice how theimage quality sometimes goes from penetrating to a bit pixelated , then back to sharp again , you ’re see Netflix ’s scaling at study as it responds to changes in your internet connexion speeding .

AptX Adaptive supersedes aptX and aptX HD ( yet is still back compatible with both ) and has the ability to ramp its data point pace from 110 Kbps to 620 Kbps as link conditions change .

By nonremittal , aptX Adaptive uses the same 24 - bit/48kHz resolution of aptX HD , but it can also go higher , up to 24/96 , giving it the same maximum solution as Sony ’s LDAC codec . It ’s also a more effective codec , according to the ship’s company , which enunciate it can attain the same quality as aptX HD at just 420 Kbps , as liken to HD ’s fixed 576 Kbps . But straight to its name , it ’s not just a 24 - bit codec . Adaptive can also operate in 16 - bit/44.1kHz mode when required .

The codec ’s adaptive nature goes beyond bit depths and sampling frequencies . It can also respond to the kind of audio activity you ’re engaged in . When it notice that you ’re gaming , it can automatically move to a low - latency modality , which , under optimal conditions , can match the performance of aptX LL . If it find that you ’re on a call , it can adjust its setting so that you and your phoner are both let in high spirits - calibre audio ( aptX Voice ) .

If this sounds like a good - casing scenario , it is , but as is often the caseful , there are several caveats .

Unlike aptX and aptX HD , which can be enabled using software on the author side of the equation ( which likely explain why they ’re include with the Android operating organisation regardless of which phone you buy ) , aptX Adaptive take the utilization of Qualcomm ’s chips on both the source and sinkhole devices .

you could no longer bribe an Android phone and don it support aptX Adaptive . Google ’s Pixel telephone set are a right instance . Even the newestPixel 8 seriesdoesn’t   have aptX Adaptive built - in .

Qualcomm has also given manufacturers grand discretion over which aptX Adaptive characteristic they can enable . For example , the power to do hi - Ra audio at 24/96 was added to aptX Adaptive in 2020 , and the manufacturer must turn over it on . The same thing go for low - reaction time and eminent - quality vocalisation call . Some company will make up one’s mind not to do that . Unfortunately , the only elbow room to bang if your devices will render a specific feature is if they are listed in the specifications for both products .

For instance , both theSennheiser Momentum True Wireless 3earbuds and theMaster & Dynamic MW75headphones support aptX Adaptive , but the MW75 is currently restrict to 24/48 , while theSennheisers will go up to 24/96 — but again , only if the rootage gadget also stick out it .

On the huge majority of sound , you’re able to not see the data rate your two gadget are using , micturate it difficult to have intercourse if you ’re get the best potential audio quality or how changing your length or locations is affect that link .

AptX Lossless

So far , all of these Qualcomm codecs practice lossy densification , which removes some of the original selective information in an audio file . In an ideal world , codecs would operate losslessly — compress the file size without affecting audible bits .

As the name indicate , aptX Lossless forebode a bit - for - bit utter pitch of CD caliber at 16 - bit/44.1kHz — a sort of Holy Grail for wireless phone — something that has traditionally been unacceptable because of the inherent limitations of Bluetooth bandwidth .

Qualcomm claims to have overcome this limitation by combining aptX Adaptive ’s power to engage at 16 - bit/44.1kHz and Qualcomm ’s Bluetooth gamey - Speed linkup , which can deliver the 1 Mbps snatch rate call for to do lossless audio .

The company says it has seen aptX Lossless oeuvre even at distance of 15 foot or more in congested wireless environment . But since inter-group communication quality can be knockout to predict , aptX Lossless will descale accord to existent - time shape , going all the path down to 140 Kbps if needed . That wo n’t be anywhere confining to bit - sodding lossless sound , but you wo n’t get disconnected .

At the top of the data rate scale , users can decide if they want the codec to deliver 16/44.1 lossless audio or aptX Adaptive ’s 24/96 lossy sound .

Getting aptX Lossless to work correctly requires many technology to operate in lockstep with one another , so Qualcomm only make up aptX Lossless available on devices that have passed its Snapdragon Sound certification program .

How do you know if you’re getting aptX’s speed benefits?

You would intend that the expensive pair of earphone and/or your phone would come with all the tools you need to track and affirm whether you ’re getting all the benefits of this innovative tech . Alas , it is not so . As we point out in item in our splendid explainer onwireless audio ’s absent speedometerproblem , users have to bank on the speech sound or headphone makers let in an app or some other mean value of showing you the intelligent quality you ’re in reality getting .

Some streaming music apps , likeAmazon Music , do show some of this entropy , and there are outside devices such as DACs that indicate things like the codec you ’re using , but for the most part , pass with flying colors down the performance of your whole audio - quality trail is unfortunately not easy .

Snapdragon Sound

AptX Adaptive ushered in a newfangled storey of codec capabilities , but as we detailed above , many of those capabilities are at the free will of manufacturers . That create a job : How do you know what you ’re actually have when you buy a product that publicise itself as supporting aptX Adaptive ?

To help call this , Qualcomm createdSnapdragon Sound . Contrary to what it sounds like , Snapdragon Sound is n’t a young technology or codec . Instead , it ’s a certification , one that guarantees that the following aptX Adaptive lineament will work when two Snapdragon Sound devices are used together :

Technically speaking , there ’s no hole-and-corner sauce here . Any manufacturing business that usesQualcomm ’s S3 or S5 chipscan deliver all of these features if they pick out . But you ’ll only see the Snapdragon Sound label on a product if it supports them allandif the equipment maker has relegate their product to Qualcomm to undergo its verification tests .

The spirit behind the Snapdragon Sound program is to let emptor take a breather a sigh of relief , screw that as long as they see the label on their wireless audio machine and their headphone , everything will “ just cultivate . ” However , the list of feature that Qualcomm includes in its Snapdragon Sound label will not remain static , even though the brand will expect the same .

For instance , you ’ll notice that the tilt of features above does not include aptX Lossless . That ’s because the initial definition of Snapdragon Sound was explicate before Qualcomm was ready to release aptX Lossless . As of 2022 , losslessisincluded in Snapdragon Sound , and that ’s where the note value of a single label starts to waver .

If your Snapdragon Sound wireless earbuds were one of the early mannikin , like theOddict Twig Pro , they credibly do n’t bear aptX Lossless , and ca n’t be update to back up it , even if you ’re using them with a Snapdragon Sound earphone that does back up lossless .

It does n’t stop there . Snapdragon Sound ’s features will likely change each year . Among its unexampled tools ishead - trail spacial audio , which is slowly arriving on new supported devices . Bluetooth LE Audiocompatibility , lower latency for gaming , and financial support for in - game back - channel voice are also newer gain . Snapdragon Sound is also increasing aptX Lossless ’ try out rates from 44.1 to 48kHz .

Buyers will need to do their homework once again . Snapdragon Sound certificate from Qualcomm indicates that features and performance have been tested and license . However , it may not reliably signal which specific lineament you could habituate .