The best sound over Bluetooth: we tell you what aptX, aptX HD and LDAC are. AptX HD – truly high-quality sound wirelessly
Every mobile phone owner knows why Bluetooth is needed. Not everyone understands why Bluetooth is needed on an audio component that costs a thousand or two euros. Let's try to figure it out.
The main application of Bluetooth is connecting mobile gadgets with each other. The latest innovation is the MFC function, when devices connect automatically when they are close to each other. You just need to touch your mobile phone to the Bluetooth speaker, and it will immediately appear in the menu of your device and will be able to receive a music signal.
If you do not disturb idle journalistic puns on the topic of blue teeth and Scandinavian folklore, then Bluetooth is one of the wireless communication protocols that operates at a frequency of 2.4-2.4835 GHz. We are talking about a section of the radio spectrum specially allocated for the needs of consumer electronics and free from licensing. It is officially called ISM, that is, Industry, Science and Medicine. To ensure reliable transmission of modulated data, the carrier frequency changes 1600 times per second according to a specific algorithm agreed upon between the receiver and transmitter. Thus, many Bluetooth-naps will send their numbers through one or another capillary without the risk of running into each other. Something similar is used for GSM mobile communications. The communication stability of this method is quite good, except that there will always be a slight delay at the receiver.
The first Bluetooth specification was issued in 1998 and has gone through several updates over the past ten years. As everyone understands, audio in this complex occupied only one of the places, and far from the first. The main idea was to combine mobile phones, cameras, computer peripherals, as well as numerous accessories. Subsequently, on this glorious path there was a place for both mega-projects (for example, the AIRcable Bluetooth adapter with a range of up to 30 km) and amusing oddities. Mischievous hackers using an Android tablet have managed to connect via Bluetooth to the menus of famous Japanese toilets, famous for their functional sophistication. With each new iteration, Bluetooth's bandwidth became wider. In version 2.0, the speed exceeded 2 Mbit/s, and in the fourth edition (now living) several operating modes are possible - classic, high-speed with a theoretical limit of 24 Mbit/s and economical, with low consumption.
No matter how wonderful the news about channel width may be, users of wireless headphones and Car Audio systems with Bluetooth are faced with one indisputable fact. Music transmitted via Bluetooth, compared to a cable connection, sounds like it’s coming from a toilet, albeit the same electronic-Japanese one. The distortion and unevenness of the frequency response are growing, horror. As it turns out, the issue here is not so much the bandwidth, but the configuration of the A2DP profile itself, intended for stereo audio data. In normal Bluetooth operation mode, it is impossible to broadcast an audio file intact. Your dead MP3 undergoes additional repackaging with data loss by the Sub Band Codec (SBC), which generally behaves like a real voluntarist. Depending on the communication conditions, he can play it safe and reduce his own already low bitrate, as long as the contact is not interrupted. Command line fans, of course, somehow manage to set the priority of the MPEG codec on their computer using the Bluesoleil manager, but all this entertainment is highly specific. So our Bluetooth would have remained the lot of undemanding users, for whom something booms in the headset, and that’s okay, if not for a new word of three, excuse me, four letters - aptX.
It's funny that work on this audio codec began when there was no Bluetooth, not even GSM. Developers from Queen's University Belfast School in the 80s planned to use aptX for the needs of broadcasting using computer technology. A distinctive feature of the algorithm is the low load on the processor. In fact, this is mainly why the Bluetooth consortium took it under its wing. There was an opportunity to stutter about lossless audio without wires. In particular, transmitting an audio stream with 16-bit/48 kHz parameters will require only 10 million operations per second on the encoder and six on the receiver. Believe me, this is quite divine in today’s times. Theoretically, aptX. supports sampling rates even up to 24 bit/96 kHz. However, in this case, 100% loss is no longer guaranteed, the developer admits that there will be losses in some short sections, but in any case, a frequency range of 20 kHz will be fully guaranteed.
Fortunately, the idea with aptX turned out to be popular; Apple and Samsung, as well as such well-known headphone manufacturers as Sennheiser (models MM400-X and MM500-X), have implemented it in their smartphones. So look for the coveted acronym on Bluetooth-compatible components and let's hope that not a single bit falls off the fur of our favorite track in the wireless space.
Based on materials from Stereo&Video
text by Yaroslav Godyna
AptX HD Bluetooth: what is it and how to get it? July 8th, 2017
The aptX HD protocol is designed to provide Hi-Res audio transmission over Bluetooth. Here you will find everything you need to know about it and how to use it.
One piece of wisdom we've learned along the way is that many people are willing to sacrifice sound quality for convenience. Take wireless headphones, for example. They can rarely compete with good wired ones, but they are much more convenient.
However, some time ago the pendulum swung towards higher quality. The most striking examples of this trend can be considered the revival of vinyl (this is where we are not talking about convenience at all), as well as the growing popularity of Hi-Res audio. So, is there a way to combine usability and sound quality?
Developers from Qualcomm are confident of this. Earlier this year, they introduced the aptX HD codec, which allows you to wirelessly stream music in 24-bit Hi-Res audio format. Thus, Bluetooth-enabled devices (such as portable speakers) can theoretically sound much better.
What's good about aptX HD? How to get it and what devices support it? We'll find out now.
What is aptX Bluetooth?
To understand what aptX HD is, you first need to remember the “classic” aptX. It is an audio encoding algorithm created in the 80s and widely used by film producers and radio stations. Today, aptX is closely related to Bluetooth, which is found on many computers, smartphones, AV receivers and other consumer electronic devices.
The main advantage of aptX is its ability to transmit a full-bandwidth music signal in near-CD quality (16 bit/44.1 kHz). This is "close" quality, not true CD quality, as aptX uses compression to reduce latency due to encoding and transmission. Classic aptX uses 4:1 compression and the data transfer rate is 352 kbps.
What is aptX HD?
Now let's move directly to aptX HD. It's essentially aptX, redesigned and improved to deliver higher quality music.
Its development was stimulated by the growing popularity of Hi-Res audio; it supports formats up to 24 bit/48 kHz, the compression ratio remains the same (4:1), and the data transfer rate has increased to 576 kbps.
How the sound quality will be comparable to transmitting a Hi-Res signal via cable remains to be seen; however, Qualcomm proudly waves the "better than CD" flag.
What do you need to evaluate aptX HD?
There's a lot that goes into using aptX HD. First of all, you will need the right equipment. We are talking about the CSR8675 Bluetooth audio system on a chip.
It not only supports full 24-bit audio, but also provides better digital signal processing than its predecessors. Qualcomm promises improved signal-to-noise ratio through encoding and decoding and reduced distortion, especially in the 10-20 kHz range.
The need for a specialized chipset means that to use aptX HD you will have to acquire compatible devices: there are no options for firmware updates. There are no prospects for any “rescaling” of the audio signal.
But you don’t have to worry about backward compatibility: devices with aptX HD will support all headphones and smartphones with “classic” aptX.
What devices support aptX HD?
The LG G5 puts a premium on sound quality with a modular design that includes an external DAC
The aptX HD codec was announced in January 2016. It will be used in Android smartphones and tablets, as well as portable media players.
The first smartphone to support aptX HD was the LG G5 released last year. It was followed by its brothers - G6 and V20.
In addition to them, aptX HD technology is also supported by high-end smartphones - Vertu Constellation Octane and Luna TG-L900S - which can hardly be called widespread.
Among manufacturers of portable music players, Astell & Kern has become the most ardent fan of aptX HD. The new codec is supported by its AK380, AK320, AK300 and AK70 players, as well as the XB10 amplifier/DAC.
Wherever we read anything about Bluetooth, in addition to this name itself, we constantly come across all sorts of incomprehensible numbers and letters. Nowadays, “in fashion” is the designation aptX HD, which has recently replaced the shorter aptX.
It is clear that the prefix HD stands for “ High Definition“, but how High is it, and what does aptX mean? And how is aptX simply different from the new aptX HD?
In general, let's figure it out.
what is aptX?
aptX is a digital technology (also called a Bluetooth codec) that allows you to transmit audio signal quality 16 bit/44.1 kHz at 4:1 compression level and bit rate 352 kbps .
That's it in short. Actually, you can easily find all this in any description of the aptX codec. And it will probably be written that thanks to aptX, your smartphone, laptop, AV receiver can transmit sound via a Bluetooth channel “with quality close to CD.” Which already sounds much more encouraging than boring specification numbers.
In general, aptX technology is capable of providing music sound quality close to CD and, as a rule, it does.
Another thing is that you need to distinguish between “close” and “true” CD quality. And these two “qualities” differ precisely in the level of compression, which aptX, like any other Bluetooth codec, uses to reduce inevitable delays. arising during encoding and transmission of stereo sound. Simply put, aptX always compresses the signal before sending it, and the receiving device (headphones, external speaker, etc.) decompresses this signal during playback. This takes time, otherwise there is no way.
When you listen to music, any delays in the operation of devices do not matter, and you simply do not notice them. Moreover, when transmitting a wireless audio signal, even between your smartphone and headphones, delays can be quite significant. But when you watch a video, any delays appear almost immediately. The actors suddenly stop “putting their lips into words”, the sound of the stream clearly does not match what is happening on the screen, etc. If you watch Netflix or other video streaming services, then this is all familiar to you too.
Therefore, a special version of the codec was developed specifically for transmitting audio to video (and for all other cases when a minimum delay is important) - aptX LL, which means Low Latency, i.e. “short delay”. aptX LL also provides the same “CD-like” sound quality, but reduces the time required to transfer and decompress data to 32 milliseconds. Technically, this is also a lot, but the user’s brain no longer notices such a delay. That’s why aptX LL is used in gaming headphones and headsets, in which minimal latency is even more important than sound quality.
New Sennheiser MOMENTUM Free mobile headset with aptX Low Latency codec support
Now we can summarize: Bluetooth headphones, headsets, external speakers and other devices sound better with aptX, plus aptX also works more efficiently than most other Bluetooth codecs, so aptX support is provided in almost every device that sends and/or receives audio via Bluetooth. channel.
What is aptX HD?
aptX HD is the same aptX Bluetooth codec, but improved and which allows you to transfer audio signal in 24-bit/48 kHz quality at a compression level of 4:1 and a bit rate of 576 kbps.
Yes, numbers again. But there are still not many of them and, as we see, they are a little different. It is not difficult to see that aptX HD is capable of transmitting higher quality sound and at a much higher speed (lower latency). And files in 24-bit/48 kHz format are already real HD sound, which is so appreciated by owners of expensive wired headphones, and in which there is very little background noise and even the smallest nuances of sound are clearly audible.
It is worth noting that some “music” smartphone models (for example, LG V series) can also transmit such sound, but only in wired mode, i.e. via a 3.5 mm mini-jack for headphones, and 24-bit/48 kHz quality is actually the limit for them.
However, there is a difference between wired 24bit/48kHz and wireless (ie Bluetooth) 24bit/48kHz. And it consists of signal compression. The new aptX HD differs from regular aptX in a more efficient compression algorithm (in descriptions it is also called “soft”), but not flawless.
In the sense that any compression always adds extra noise and hiss to the signal. And you hear it, although you don’t always understand what it is and where it comes from. By the way, rock guitarists often use signal compression intentionally to give the guitar sound additional “roughness” and “fuzzyness.”
For the aptX HD codec, a special “soft” one was developed, specifically in order to minimize any “roughness” and “fuzziness”, but even aptX HD is not yet able to completely remove excess noise resulting from signal compression from the audio stream.
Secondly, as we have already noted, if Apt X transmits data at a speed of 352 kbps, then aptX HD audio transmission speed is increased to 576 kbps. And taking into account the fact that the more kilo-, mega-, etc. bits per second are transmitted, the better, then the higher speed is what allows aptX HD to use a “softer” compression algorithm.
Total : it turns out that in comparison with just aptX, the new aptX HD in wireless mode can transmit higher quality sound with lower delays and more gentle compression, and thus, as it were, brings us closer to the sound quality that is only achievable with wired transmission audio signal.
aptX HD support
... - of course, it is still in short supply. Since aptX HD is also a development from Qualcomm (like regular aptX along with all its variations), this codec is supported only by Qualcomm hardware and/or software solutions. And at this point in time it is still only the CSR8675 audio processor with Bluetooth 5 and active noise reduction via Bluetooth and Qualcomm TrueWireless Stereo audio transmission technology. But they also provide backward compatibility, that is, aptX support.
The first smartphone to implement aptX HD support was the G5 from LG, with the release of which the South Korean company actually launched and led the process of promoting the new codec in the consumer-class mobile device market. The LG V20, the LG G6 and the LG V30 also work with aptX HD. Following LG, other brands have actively begun to implement aptX HD. In particular, Sony (Xperia XZ1 and XZ1 compact smartphones), OnePlus (OnePlus 3, 3T and 5 smartphones), as well as Sharp, Luna, as well as a number of Chinese Android smartphone manufacturers.
LG G6 and wireless Audio-Technica with AptX HD codec support
On the other hand, that is, from the playback devices side, you can find aptX HD in headphones from Sony, Audio-Technica, LG and other less famous brands. The number of such devices will grow as manufacturers release new models. And they will release them, because aptX HD, as we have already found out, really improves sound quality. But to what extent, the user has to determine this on his own in each individual case.
Are you unhappy with the sound from your Bluetooth headphones? Perhaps the whole point is that your Android uses a “bad” SBC audio codec instead of the advanced LDAC, aptX, aptX HD, AAC?
More and more manufacturers are abandoning the 3.5 mm audio jack in favor of transmitting sound via Bluetooth, but such innovations are not always so useful! It's all about the codecs... and Android doesn't use the best one by default!
A little about Bluetooth audio codecs
SBC (Subband Coding) - this lossy codec is currently used in most cases of audio transmission over wireless headphones. The main problem with SBC is that the codec distorts the sound very much, more than MP3, so it is clearly not suitable for listening to high-quality audio material.
A.A.C.(Advanced Audio Coding) is also a lossy audio codec, but the sound quality is much higher than SBC.
aptX And aptX HD is an audio codec developed by Qualcomm, so it can be found almost only on devices with a Snapdragon processor. The aptX and aptX HD codec, unlike SBC and AAC, has virtually no loss, audio is compensated and transmitted via Bluetooth.
LDAC- a recently developed audio codec by Sony, which should displace the established SBC codec. This audio codec performs low-loss compression. Since Android 8.0 Oreo, it has become part of the system, so LDAC will soon become standard for transmitting audio over wireless headphones and speakers.
If the headphones only support the SBC codec, then you won’t be able to enable the Bluetooth codec LDAC, aptX, aptX HD!
How to enable the required Bluetooth audio codec on Android?
First, you need to make sure that your headphones or speakers support a more advanced audio codec. You'll have to do a lot of digging on the Internet to figure out what codec they support.
The second condition must be that your Android is version 8.0 or newer.
In order to activate one of the listed codecs, you will need to activate the “Developer Menu”. How to do it? You can read about this in the article "". Or you can watch two videos.
On bare Android:
Once you're in the developer menu, scroll down the menu to "Bluetooth audio codec" and select it.
Select the required codec - LDAC, apt, aptX, AAC, SBC. 
Codec activated! 
You can reboot Android! The sound over wireless headphones should improve!
Do you still have questions? Write them in the comments, tell us what you did or vice versa!
That's all! Read more useful articles and instructions in the section. Stay with the site, it will be even more interesting!
Smartphone manufacturers are gradually abandoning a separate headphone jack. So far this is happening sluggishly, but it is obvious that soon there will be no mini-jacks at all. It's no longer in the iPhone 7 and 7 Plus - and if Apple does something, it becomes standard.
You can listen to music without a separate headphone jack in two ways: via USB (Lightning) or via Bluetooth. The first option looks like temporary “crutches” until not everyone has wireless headphones yet. The future belongs to the second method.
“Bluetooth headphones are comfortable, but sound mediocre” is a stereotype.
There are technologies that wirelessly transmit high-quality sound that is pleasant to the average human ear. In this article we will talk about the protocol AptX, widely used now, and its improved version, which is already being slowly introduced.
Why did Bluetooth headphones sound bad?
The stereotype about the poor sound of wireless headphones appeared for a reason. They could be as advanced as they wanted in terms of hardware, but the limitations of Bluetooth turned high-quality sound into “brown”.
Blue tooth is a universal, widespread and economical technology, but its data transmission channel is very narrow. Therefore, you can’t just put Lossless into your headphones – you need to compress it.
The most common compression profile used in all smartphones is A2DP. Its base codec is called SBC. It greatly reduces the amount of data transferred, but the sound also becomes mediocre. For example, to simplify calculations (and therefore increase the speed of information processing), all frequencies above 14 kHz are simply cut off. Because of this, even with the same bitrate, the quality is worse than in MP3. And this format is far from standard.
The AAC codec is not so barbaric - the sound quality is already better than in MP3, but still worse than in CD.
AptX sounds almost like a CD
Here we come to the technology for which we gathered. AptX transmits audio over Bluetooth with a bitrate of 352 kB/s and does not cut off the range - it is 10 Hz - 22 kHz. This is achieved through complex algorithms, so the codec requires a processor that is three times more powerful than SBC. This is no longer a problem for modern smartphones, so AptX works on all Android devices.
However, it is required that both the smartphone and headphones support the technology.
Otherwise, compression will be performed through the base codec.
AptX is indeed comparable to CD quality, but still inferior. 4:1 compression is applied. That is, the range is narrowed four times compared to the original, high and low frequencies are lost. On the official website you will only find the wording “near-CD quality” - “close to CD quality”. Close, but not the same.
Before and after compression
However, look around - the majority listen to music on VKontakte through supplied or cheap headphones, not paying attention to the subtleties. They would live quite well with AptX.
AptX HD sounds better than CD
For those who still need better sound, we came up with AptX HD codec. Now let's figure it out what it is. The audio stream is also compressed four times, but the bitrate has increased from 352 to 576 kB/s. The official website promises us “quality better than CD.”
True, the technology is still very poorly distributed. Just as in the case of AptX, you need the codec to be on both the smartphone and the headphones. The list of phones supporting AptX HD is sparse:
- Vertu Constellation Octane
- Luna TG-L900S (have you ever heard of this one?)
LG Tone Active+ is one of the few headphones with AptX HD support
It is unlikely that you will buy any of the last two smartphones. To pair with the LG flagships, you will also need to purchase one of the four available headphones from the same LG and Audio-Technica. We recently reviewed one of these headsets -.
What does all of this mean?
The fact that wired headphones will soon fall into oblivion. Of course, not in the next year or two, but in the foreseeable future. This largely depends on how soon the technology comes to computers. After all, people listen to music not only from smartphones.
The main thing is that the necessary technology to eliminate wires already exists. It’s hard to imagine a person who needs even better quality or who considers wired headphones more convenient than wireless ones.
Of course, there will always be audiophiles who will listen to vinyl and use audio systems that cost a lot of money. AptX HD is not for them. This is a mass technology that will certainly become widely used.
