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What is a Bluetooth codec? Part 2

The codec is a factor that determines the quality of the sound
It is sometimes said that the sound quality changes depending on the Bluetooth codec, but it is more accurate to think of it as “a factor that determines the sound quality”.

For example, the order in which sounds are transmitted when listening to music with wireless headphones can be simplified as follows.

Play music on your smartphone (playback device / software)
Music data is compressed and transmitted to headphones (codec)
Restore the data received by the headphones to the analog signal (DAC)
Amplify the analog signal (amplifier)
Send the amplified signal to the speaker (driver)
As mentioned above, there are many factors that determine the sound quality other than the Bluetooth codec, so it is good to understand that “the sound quality does not change with the Bluetooth codec alone.”

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Bluetooth codec list
We present the main Bluetooth codecs used in Bluetooth audio equipment.

Bluetooth codec list
Feature codec name
SBC Standard Bluetooth Audio Codec
CAA High quality sound codec mainly used in iPhone
aptX Higher sound quality and lower delay than SBC and AAC
aptX LL Sound quality equivalent to aptX and less lag
aptX HD High-quality sound codec supporting 24-bit / 48 kHz
Adaptive aptX Codec that achieves high sound quality, low lag, and connection stability
LDAC High-quality sound codec developed by SONY that supports up to 24-bit / 96kHz
Samsung scalable codec Achieves high sound quality and connection stability with the original Samsung codec
HWA High-quality, low-delay codec developed by Huawei
UAT 24-bit / 192 kHz ultra-high sound quality with original Hiby Music codec
SBC
SBC (Subband Codec) is a standard codec for Bluetooth audio.

The number of quantization bits / sample rate is 16-bit / 48 kHz, the latency (delay) is 220 ms (± 50 ms), and in principle it can be played on all Bluetooth audio devices.

At the beginning of its appearance it was said that the sound quality was poor, but it has been improving with the advancement of technology, and it is said that it has reached a level comparable to other codecs depending on the device.

CAA

Source: AirPods (2nd generation) -Apple (Japan)

AAC (Advanced Audio Coding) is a codec with lower delay and higher sound quality than SBC.

The number of quantization bits / sample rate is 16 bit / 48 kHz and the latency (delay) is 120 ms (± 30 ms) at 128 kbps, which is mainly used in Apple products (iPhone / iPad).

aptX

Source: Qualcomm® aptX ™ Audio

aptX is a high-quality, low-latency codec developed by CSR (currently purchased by Qualcomm).

The number of quantization bits / sample rate is 16-bit / 48 kHz and the latency (delay) is 70 ms (± 10 ms), which is used in the standard codec of Android smartphones.

aptX LL

Source: Qualcomm® aptX ™ Low Latency Synchronized Audio

As the name implies, aptX LL (aptX Low Latency) is a low latency codec.

The number of quantization bits / sample rate is 16 bits / 48 kHz, which is the same as aptX, but the latency (delay) is very small, less than 40 ms.

Since there is little discrepancy between video and audio, it can be said to be the best codec for watching videos and gaming.

aptX HD

Source: Qualcomm® aptX ™ HD Audio

aptX HD is a codec that improves the sound quality of aptX.

Although the latency (delay) is approximately 130 ms, which is less than aptX, the number of quantization bits / sample rate has been expanded to 24-bit / 48 kHz and the range of expression has been expanded.

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What is a Bluetooth codec?

The headphone jack has disappeared from the iPhone and wireless headphones have quickly become mainstream.

Bluetooth is used for wireless headphone communication, and the difference in the Bluetooth codec affects sound quality and sound delay.

This article describes the Bluetooth codec according to the following items.

What is a Bluetooth codec?
Main Bluetooth codecs and their characteristics
How to check the Bluetooth codec of your computer / smartphone
Please refer to that.

3 Smartphone / PC Bluetooth codec support information and confirmation method
3.1 How to check the supported Bluetooth codec on your Android smartphone
3.2 How to check the compatible Bluetooth codec on iPhone / iPad
3.3 Bluetooth codec compatible with Windows PC
3.4 Bluetooth codec for Mac
4 Choose the Bluetooth codec that suits your purpose

What is a Bluetooth codec? Audio compression method
The Bluetooth codec is a “method of compressing audio data”.

When sending voice data from smartphone or PC to wireless headphones, etc., the amount of data is large and time consuming and delays occur.

Compression technology solves this problem.

There are several compression technologies, each with different delay, compression efficiency, sound quality, etc., and the general term for these compression methods is “codec.”

Delay, compression efficiency, and sound quality differ by codec
There are three main differences depending on the Bluetooth codec.

delay
Compression efficiency
Sound quality
“Delay” represents the time lapse between the sender and the receiver.

When watching a video, the smaller the lag, the smaller the gap between the video and the audio, and the more natural the video can be seen.

“Compression efficiency” indicates how efficiently the audio data can be compressed, and the higher the compression efficiency, the smaller the amount of data.

Codecs with high sound quality, low latency and high connection stability, such as aptX LL and aptX adaptive, can be said to have high compression efficiency.

The “sound quality” will be described later.

Is the sound quality of the Bluetooth headphones not good? Part 3

Correct use of high-quality sound codec to avoid deterioration of the sound quality of the Bluetooth connection!

With the expansion of Bluetooth, when listening to music on a smartphone such as an iPhone or Walkman, it is no longer necessary to connect a cable each time, making it extremely convenient.

But did you know that there are actually high and low quality Bluetooth connections that look the same?

Bluetooth high quality sound connection codec picture

There are several standards for high-quality Bluetooth connection methods.

However, even if the Bluetooth device supports a high-quality sound connection, if you make a mistake in pairing with the other party’s Bluetooth device, the connection may inadvertently lead to low-quality sound, so be careful.

For example, just like you feel that the sound has changed when you switch the headset from a wired connection to a Bluetooth connection, the sound quality improves depending on the connection partner even with the same Bluetooth compatible device, such as headphones, earphones, Portable speakers. , car navigation systems, car audio, etc. It can happen that it gets worse or worse.

Here, I will write about the method and precautions for connecting to high-quality sound via Bluetooth so that you can connect to Bluetooth with the best possible sound quality.・ High-quality sound codec support status list (link on page) of Bluetooth Compatible Devices.

Table of Contents

PR
What is the Bluetooth A2DP codec?
What is a codec?
First of all, what is a “codec” in general? As for, if you write it in English, it will be “codec”. When stripped, “codec = co der + DEC”, is made up of “oder”, which is a method of decoding data as a code (en).

With a Bluetooth connection, the music data is sent as a wireless signal, that is, a radio wave, but the data is compressed to transmit it efficiently when the radio wave is sent over the air. In other words, the Bluetooth codec is a method that compresses data before transmission and decompresses it after reception.

What is a high-quality Bluetooth codec?
As a Bluetooth codec, that is, a data compression method, the following four methods are a method that can achieve the necessary data compression while maintaining high sound quality, that is, a high sound quality codec.

AAC – Originally the format adopted by the iTunes Store. Widely used in Apple Bluetooth devices such as iPhone and iPod. Effectively up to 320 kbps.
aptX – Currently developed by CSR Limited, which was acquired by Qualcomm. Really up to 384 kbps.
aptX HD – Like aptX, developed by CSR Limited. Actually up to 576 kbps higher than aptX.
LDAC: developed by Sony. It is mainly used to connect high quality sound sources, such as high resolution. Really up to 990 kbps.
The higher the number, the greater the amount of data per second, so it can be said that the sound quality is higher.

Is the sound quality of the Bluetooth headphones not good? Part 2

Why is Bluetooth sound quality said to be poor?
Since Bluetooth headphones are connected wirelessly, the sound quality is said to be not as good as wired headphones.

The reasons for this are as follows.

There may be a delay in the voice
When transferring audio via Bluetooth, the sending device compresses the audio before making a call and the receiving data is decompressed again before playing the sound.

These occur instantly, but with a slight delay, this can manifest as a delay in the voice.

There are differences depending on the type of codec, headphone performance, distance and obstacles, but if there is a delay, the sound will not connect well and it will become unnatural, especially when watching a video, the image and the sound will match. how the disappearance occurs.

Insufficient codec capacity
The codec is an audio compression format, but compared to higher sound quality codecs like “LDAC”, “apt-X HD”, “apt-X” and “AAC”, it is connected with the standard codec ” SBC “. And the sound quality may be lower.

Note that it is pointless if one of the codecs is high performance and each device must support that codec.

If the headset or smartphone is a very old model, the sound quality may not be high due to insufficient codec capacity.

The latest Bluetooth headset situation.
It cannot be said that there are cases where there are problems with sound quality, but in recent years many high-quality and easy-to-use headphones have appeared, and headphones with specifications comparable to wired connections are attracting attention.

Let’s review the last situation.

Sound quality is improving
The Bluetooth version has also been updated, and the codec supports not only “SBC” but also “AAC” and “apt-X”, and the number of models that can enjoy music with high sound quality from Wireless way is increasing in recent times. years.

Make sure to choose headphones with multiple compression formats and high Bluetooth versions.

Easy to connect
It may seem that the connection (pairing) is more troublesome than wired headphones, but when pairing only for the first time, if the smartphone’s Bluetooth is ON the next time you use it, please turn on the headphones. Just connect it automatically.

You don’t have to plug and unplug the cable, and you don’t have to pull out your smartphone just to hear the sound.

Model with excellent resistance to water and impact.
The great advantage of Bluetooth headphones is that they do not get in the way during sports such as jogging because they have no cable and are difficult to break.

In such circumstances, I think the earbuds may have been spoiled by sweat or water droplets with conventional earbuds, but earphones with excellent water resistance that can be washed with water are also coming out.

You can confidently wear it for work and outdoor sports.

In this way, in recent years the latest models with improved quality and greater functions have appeared one after another in Bluetooth headphones.

When we think of sound quality as important, we think of wired headphones, but today, the number of Bluetooth headphones that are comparable to the wired types is increasing.

If you are thinking of changing models or replacing headphones, why not consider Bluetooth headphones?

Is the sound quality of the Bluetooth headphones not good?

Bluetooth headphones don’t need to be connected to wired smartphones, so there is less concern about cable disconnection, but many people wonder, “Isn’t the sound quality better than wired headphones?” .

But what about reality?

Here, I would like to present the latest situation regarding Bluetooth headphones.

What is Bluetooth?
Bluetooth is one of the standards for short-range wireless communication and it communicates wirelessly like infrared and Wi-Fi communication.

Bluetooth devices are connected by a method called pairing and can communicate with each other.

Bluetooth has several factors that affect sound quality, such as radio wave strength, audio compression format, and transfer rate, and high sound quality can be maintained by keeping them at a high level.

Let’s explain each of the factors that affect sound quality.

Codec
A codec is an audio compression format for transferring sound over Bluetooth.

If you transfer the voice data to the headset as is, the amount of data will be too large and it will be difficult to communicate.

Therefore, a mechanism is adopted in which the sound is compressed on the sending side, the data is cleared and transmitted, and then the headphone side decompresses it to produce sound.

This audio compression format is called a codec and is divided into several methods.
The standard codec was called “SBC”, but high-quality codecs such as “AAC” and “apt-X” are now being adopted.

In addition, higher sound quality codecs such as “apt-X HD” and “LDAC” that can communicate at high resolution have also appeared in recent years.

However, the codec has the characteristic that it cannot be used unless the sender and receiver correspond to each other.

codec

Class
The class represents the strength of radio waves and is a measure of the communication range.

As of 2018, there are three kinds of Class 1.2.3, and general smartphones and Bluetooth headsets have adopted the standard called Class 2.

Class1 has a maximum communication distance of approximately 100m, Class2 has a maximum communication distance of approximately 10m, and Class3 has a maximum communication distance of approximately 1m. The greater the communication distance, the higher the power consumption.

If the devices are too far apart, communication errors are likely, which can lead to poor sound quality and skipping.

Bluetooth version
The Bluetooth version is fixed for each model and cannot be updated later.

The newer the version, the lower the power consumption, the greater the communication power and communication range, and the addition of extended functions.

As of 2018, the latest popular version is 5.0.

When buying Bluetooth headphones from now on, it is recommended to choose one with 4.2 or higher, which is widely used now.

Profile
A profile is a standard that defines what can be done with Bluetooth communication, and there are several types, such as those that can be operated simply by listening to the sound, those that can be operated as play and stop, and those that can be communicated. each other with a microphone. There is something.

There are four profiles used in Bluetooth headsets: “A2DP” which allows you to listen to music with stereo sound, “AVRCP” which allows you to control play and stop, and “HFP” and “HSP” which allow you to transfer and make and receive voice during a call.

Why is Bluetooth sound quality said to be poor?
Since Bluetooth headphones are connected wirelessly, the sound quality is said to be not as good as wired headphones.

Bluetooth sound bad?

Today, everything is connected wirelessly and the wave is running in the world of audio.

In particular, the technological progress of Bluetooth headphones and speakers is wonderful, and “wireless sound quality deteriorates” is said to be a thing of the past.

But is that true?

From a “convenience” standpoint, Bluetooth is very good. The nickname of smartphones is outstanding. However, when I consider it from the “sound quality” aspect, I am skeptical of its ability.

Therefore, this time, we will thoroughly investigate Bluetooth. How was Bluetooth born and what about the latest Bluetooth? We will introduce the good and bad sound quality.

Bluetooth overview
Bluetooth® is one of the short-range wireless communication standards for digital devices. It consists of Bluetooth Basic Rate / Enhanced Data Rate (BR / EDR) and Bluetooth Low Energy (LE).

The frequency channel used is the 2.4 GHz band. It is used in various products, mainly smartphones, PC-related devices, headphones, and speakers.

Especially in recent years, Bluetooth headphones have become very common in the city. The reason for its widespread use is that you can listen to the music played on your smartphone without a cable, and if you use Bluetooth, the headphones will not get tangled in the bag.

Bluetooth is also very popular when making calls while driving. If it is a hands-free call, you will not be charged with violating the use of mobile phones. Therefore, Bluetooth headset microphones that are very easy to use are very popular.

In addition, it is used for wireless communication of low-speed digital information, such as PC mouse and keyboard, such as notebook computers, text information, and voice information on mobile phones, PHS, smart phones, and tablets.

2. Derived from the name of Bluetooth
Bluetooth directly translates to “blue teeth”.
So why are the teeth blue? And what is the reason for that mark with the Bluetooth logo?

This chapter introduces the origin of the Bluetooth name and logo.

2-1. The godfather is Ericsson
The father of the name “Bluetooth” is an engineer from Ericsson (Telefonaktiebolaget LM Ericsson) in Sweden. A telecommunications equipment manufacturer based in Stockholm, Sweden, is a well-known manufacturer of fixed land equipment for mobile communications (mobile phones) in the world.

Approximately 20,000 engineers are engaged in research and development in 17 countries around the world, and the company is said to account for about 15% of annual R&D expenditures. Notably, GSM is used by more than 80%. of the world’s mobile phones and is practically the worldwide standard technology for wireless communication.

There is also a Japanese corporation called “Ericsson Japan Co., Ltd.” in Japan, which primarily provides ground binding equipment to SoftBank Mobile and EMOBILE. Due to such circumstances, Ericsson Japan Co., Ltd. has signed a helmet sponsorship contract with Fukuoka SoftBank Hawks since the 2012 season.

2-2. The motive is the king of Denmark “Harral Sprout Gormson”
Harald Blåt and Gormsen / Haraldr blátǫnn Gormsson is the first Danish king to negotiate a bloodless integration of Norway and Denmark to unite culture. The chronicle “Chronicon Roskildense” written in Latin around 1140 has the nickname of “Blue Tooth (in Danish: Blåtand, in English: Bluetooth)”, for which the King of the Blue Teeth There is a story that came to be called.

At the World Heritage site “Jelly Stones”, there is a runestone monument marking the achievement of the unification of Denmark by Haral. And, in relation to the achievements of Ericsson engineers, starting from the idea that “it will be a wireless communication standard that can be used in common in various fields regardless of the difference in industry and device”, Blåtand lo I called “Bluetooth” which is an English transliteration.

Bluetooth – the most convenient way to listen to music wirelessly. Part 2

Sound quality comparison of conventional Bluetooth coding

⬤

SBC
Bluetooth “default” transmission code
SBC (Subband Codec) is an audio codec configured for the Advanced Audio Distribution Profile (A2DP) by the Bluetooth Special Interest Group (SIG), an organization that customizes various Bluetooth standards and specifications. Since it is part of the standard, almost all Bluetooth devices support it. SBC encoding. SBC supports mono and stereo transmission, with a sample rate of up to 48 kHz, while the highest bit rate for mono is 342 kbps and stereo is 345 kbps. The sound quality is approximately equal to that of medium quality MP3. SIG announced the SBC at CES in 2020. The following LC3 (Low Complexity Communication Codec) code, in theory, has better sound quality and less distortion than SBC.

⬤

AAC
The successor to MP3
Advanced Audio Coding (AAC) is a technology jointly developed by Dolby Lab, Sony, Nokia, and other major brands. It was designed as the successor to MP3. With the same bit rate, AAC is usually better than MP3. Sound quality. Spotify, Apple Music, and KKBOX use AAC encoding to stream music, and they are also widely used on different devices and platforms such as PS3, iPhone, and YouTube. Since iPhone, iPad, etc. will use AAC as Bluetooth music streaming, most headphones, speakers, etc. Bluetooth will support AAC, and the sound quality is roughly equal to medium to medium-high quality MP3.

Bluetooth (Bluetooth) is believed to be the most familiar wireless way of streaming songs. Although the connection is quite convenient, the sound quality is slightly lower. However, with the version upgrade and Bluetooth technology, different codes have been introduced so that this convenient and fast connection method can also provide better and better sound quality.
IPhone Bluetooth streaming has always used AAC and is not equipped with encryption technologies like LDAC or even aptX.

⬤

aptX
The first “high sound quality” Bluetooth codec
aptX was also called “apt-X” before, but this encoding algorithm was invented as early as the 1980s and was eventually bought by the famous mobile phone processor manufacturer “Qualcomm”. aptX supports 16-bit, 44.1 / 48 kHz audio, bit rate up to 384 kbps, backward compatible with SBC. Since the bit rate is higher than that of SBC and AAC, it also has better sound quality.In the early years, it was the first Bluetooth music codec with slightly close to CD sound quality. However, due to the need to pay Qualcomm’s license fees, some devices, such as iPhones, are not equipped with aptX.

Bluetooth (Bluetooth) is believed to be the most familiar wireless way of streaming songs. Although the connection is quite convenient, the sound quality is slightly lower. However, with the version upgrade and Bluetooth technology, different codes have been introduced so that this convenient and fast connection method can also provide better and better sound quality.
In 2009, Sennheiser launched the first headset equipped with aptX encoding technology and also began the development of Bluetooth for high-quality wireless music streaming.

⬤

aptX-HD
Nearly “lossless” Bluetooth music streaming
aptX HD is an “evolutionary version” of aptX, which can provide a bit rate of up to 576 kbps and a bit depth of up to 24 bits and an audio stream with a sample rate of 48 kHz. Although the name has “HD”, it is still a lossy encoding method, but it can already provide almost lossless music quality, providing audio frequencies of up to 20 kHz and a dynamic range of at least 120 dB. And the encoding delay is quite small, which can be less than 5 milliseconds, which is especially beneficial for applications such as Bluetooth as hands-free communication. Of course, listening to music is helpful. In terms of high-quality Bluetooth transmission, the main opponent is LDAC developed by Sony.

Other readings:
▸ [SPILL Encyclopedia] aptX HD: The Evolution of High-Quality Bluetooth Music Listening
Bluetooth (Bluetooth) is believed to be the most familiar wireless way of streaming songs. Although the connection is quite convenient, the sound quality is slightly lower. However, with the upgrade of the Bluetooth version and technology, different codes have been introduced to make this connection method convenient and fast.

Bluetooth – the most convenient way to listen to music wirelessly.

Bluetooth (Bluetooth) is believed to be the most familiar wireless song transmission method.

Although it is quite convenient to connect, it is a bit inferior in terms of sound quality compared to AirPlay, Chromecast, DLNA, Play-Fi, and other technologies that use network methods to stream music. However, with the version upgrade and Bluetooth technology, different codes have been introduced so that this convenient and fast connection method can also provide better and better sound quality.

Chi
Bluetooth (Bluetooth) is believed to be the most familiar wireless way of streaming songs. Although the connection is quite convenient, the sound quality is slightly lower. However, with the version upgrade and Bluetooth technology, different codes have been introduced so that this convenient and fast connection method can also provide better and better sound quality.
Version 1.0 to 5.2: Reduce Power Consumption, Increase Bandwidth, and Increase Features
This technology was developed by the telecommunications company Ericsson in the 1990s. After almost 30 years of development, Bluetooth has undergone many version changes. Bluetooth uses a radio frequency of 2.4GHz, from the initial Bluetooth 1.0 with a slow speed of 723.1kbps, to Bluetooth 3.0, it has increased considerably to 24Mbps, which is enough to transmit more data and higher quality music; the later Bluetooth 4.0, 4.1, 4.2 are It is a very popular version with much improved functions. Among them, version 4.0 adds Bluetooth low energy technology, version 4.1 adds smart connection and supports connection of multiple devices, version 4.2 can connect to the Internet, and even the current Bluetooth-enabled devices are quite similar and part of them they still use Bluetooth version 4.x.

Bluetooth (Bluetooth) is believed to be the most familiar wireless way of streaming songs. Although the connection is quite convenient, the sound quality is slightly lower. However, with the version upgrade and Bluetooth technology, different codes have been introduced so that this convenient and fast connection method can also provide better and better sound quality.
The AVR-X2600H amplifier released by Denon in 2019 still uses Bluetooth version 4.1, which is sufficient to support two-way Bluetooth and other functions.
Other readings:
▸ [Evaluation] Denon AVR-X2600H: Decentralization of real flagship machine technology!
Bluetooth 1.0
The original version of Bluetooth had quite a few compatibility issues, and was prone to crashing when connecting and leaking data. The speed of the later version 1.2 was increased to 723.1kbps, and the transmission distance was only 10 meters.

Bluetooth 2.0
With the incorporation of “skip-free narrow-band channel” (skip-free narrow-band channel) technology, there is no need to exchange feedback signals with each Bluetooth-connected device, so Bluetooth signals and data can be stream to multiple devices.

Bluetooth 3.0
The data transmission speed increases up to 24 Mbps, which is 8 times that of Bluetooth 2.0, which is enough to transmit high-quality music signals. The current conventional Bluetooth transmission speed is probably at this level. In addition, the power control has been improved to significantly reduce power consumption when idle.

Bluetooth 4.0
Although the speed remains the same as in 3.0, the transmission distance has been greatly increased to 50 meters, or even up to 100 meters, and three modes of “Bluetooth Low Energy”, “Traditional Bluetooth” and “Bluetooth” have been incorporated. Of high speed”. 4.2 is the most popular version of Bluetooth.

Bluetooth 5.0
It supports indoor positioning and navigation functions, combined with Wi-Fi to achieve indoor positioning with an accuracy of less than 1 meter. It is possible to receive unmatched data such as advertisements, location information, etc., the transmission speed increases to 48 Mbps, and many underlying optimizations have been made for the Internet of Things.

Bluetooth 5.0, released in 2016, doubles the bandwidth to 48 Mbps and supports features like indoor navigation and positioning. The recently announced Bluetooth 5.2 in 2020 adds LE Audio technology, running on Bluetooth Low Energy, which allows headphones to connect to multiple audios, or multiple sets of headphones to connect to one audio, using the LC3 (Audio Codec). low complexity communication