Introduces technical terms related to sound and audio technology, essential physics in sound and audio research and development, terms used in mathematics, and terms on technology that are attracting attention as a trend of sound and audio technology.
Bluetooth Le Audio / LC3
"Bluetooth Le Audio" is a new standard that redefines the conventional Bluetooth audio standard (Classic Audio) that has been used for a long time. This standard has been formulated by a standardization organization called Bluetooth Special Interest Group (Bluetooth Sig), a standardization organization that supervises licensing related technology and trademarks.
This time, we will introduce Bluetooth Le Audio, the latest Bluetooth audio standard, and "LC3", which was adopted as a standard audio codec. If you understand the content of the audio standard based on the transition of Bluetooth audio standard formulation and the background, you can deepen your thoughts on how audio consumer equipment will be transformed in the future. I think.
1. The background of the changes so far and the standard formulation
We believe that knowing what is the standards formulated, its purpose and background, is very important because the future possibilities of audio consumer equipment can be seen. In order to know the background, it is necessary to understand the changes so far.
Since its announcement in 1998, Bluetooth audio standards have evolved significantly, such as improving data communication speed and low power consumption. Now, Bluetooth is commonplace with wireless headphones and wireless earphones. However, there were various changes to the current situation. Behind this is the change from mobile phone business tools to consumer necessities, innovative evolution from mobile phones to smartphones, and innovation from download regeneration in the music industry to music streaming.
Since 2014, the appearance of completely wireless earphones has led to the development of Bluetooth IC, as well as digital audio treatment technology such as MEMS Micro Hon, small transducer, active noise cancellation, and echocardian cells. Bluetooth Sig, a standardized organization of Bluetooth standard, has been examining the evolution of the standard in consideration of what is expected in the next 20 years. The base is actually a question that hearing aids have been solved for years. For example, low power consumption, conversation inspection, noise reduction, low delay, higher sound quality, stable connection, etc. It is expected that technical development will progress further as the evolution from a complete wireless earphone to a hyalreble device. Bluetooth Le Audio has been standardized to promote these long -term developments.
2. Characteristics
Bluetooth Le Audio features two functions: "low delay" and "high -quality codec", and two services: "Multi -Stream" and "Broadcast". These four features are compatible if you think of hearing aids. Now, I will explain each characteristic.
・ Low delay
The key that can achieve a low delay is the new transmission method called "LE ISochronous Channels". Details will be described later, but in this method, you can always send a certain amount of data continuously by sending the necessary data for real -time. Since it can be transmitted continuously in a certain cycle, it is possible to synchronize data transmission between smartphones and audio devices. If the data transmission cycle is set short, it is possible to achieve a lower delay than the conventional Classic Audio. However, it is necessary to be careful not to focus only on the delay, but to set it in consideration of the sound quality and the robustness of the connection. It is also necessary to consider that shortening the data transmission cycle between smartphones and audio devices may increase the processing load of the processor. Of course, real -time is an important factor in hearing. Therefore, the delay is not as low as possible.
・ High quality codec
This section describes "LC3" adopted as a standard codec. LC3 is characterized by the fact that the same sound quality can be achieved even at low bit rate compared to SBC, which is the standard codec in Classic Audio. So what is a good low bit rate? Let's unravel. First, the amount of transmission data can be reduced, so low power consumption. In addition, a stable transmission can be realized. If it is a hearing use, it is clear that long -term use will be used, and low power consumption will be one of the requirements. In addition, since the interruption of the audio should not be inhibited, it is understandable that stable transmission is a requirement. On the other hand, if you focus on pure audio playback, you need to be careful not to say that the sound quality is better than SBC, but that it is a LOSSY compressed codec.
・ Multi stream
Left and right independent transmission is essential for complete wireless earphones that have swept the earphone market in recent earphones. Until now, chip vendors have developed their own transmission methods and have responded to this request. And although we have differentiated with the connecting and robust performance of left and right independent transmission, the selection of Bluetooth IC has been restricted. In the conventional Classic Audio, only single streams could be transmitted between smartphones and audio devices, but multi -streams can transmit multiple streams, simultaneous streams to left and right independent and multiple speakers. Transmission can be realized. The standardization of multi -streams is expected to improve the degree of freedom in the Bluetooth IC selection.
·broadcast
Compatible with broadcast that can be transmitted simultaneously to many people. Until now, the standard was one -on -one communication, albeit in both directions. It is expected to be used in various usage cases by responding to broadcasts. For example, if you transmit it from a TV to multiple headphones at the same time, you will be able to enjoy the same content with multiple people. In addition, public facilities will be able to communicate the same information at the same time, such as commercial use at theaters and stores, and announcements at places such as square, station and airports. It may have a big impact on society as a whole.
3. Transmission technology and protocol
Bluetooth Le Audio has two key technologies. It is "Le Isochronous Channels" and "Enhanced Attribute Protocol (Eattt)".
In particular, the former LE ISochronous Channels is a new transmission method for realizing multi -streams and broadcast functions. Trying to create a flexible system based on a long -term development can increase the flexibility of the specifications, that is, to reconsider the architecture itself. Le Ischronous Channels can build many Ischronous Audio Stream that can transmit all kinds of audio signals. Multi -stream can be realized by Connected Ischronous Stream (CIS) as shown in the figure below, and a broad cast function can be realized by BroadCast Ischronous Stream (Bis). Also, the time synchronization is completely different from the A2DP, which was used in the conventional stereo audio transmission. In this transmission method, you can send audio data at a time synchronization for each interval. By setting the interval, you can control the delay by audio transmission.
Time -synchronous multi -streams can be realized by performing data communication between Central, which refers to source equipment such as smartphones and audio devices such as earphones for each interval called ISOCHRONOUS INTERVAL (ISO Interval). Central, peripheral, and Central, and Central, are called SubEvent, and the interval to the next subEvent is called Sub International. In addition, multiple SubEvents are combined and are called Cis Events.
By performing data communication between Central, which refers to source devices such as smartphones and audio devices such as earphones for each interval called ISOCHRONOUS INTERVAL (ISO Interval), you can realize time -synchronous broadcast functions. The peripheral single -directional communication from Central is called Bis Subevent, and the interval to the next Bis Subevent is called Sub Interval. Multiple Bis Subevent is called Bis Event.
The latter "Enhanced Attribute Protocol (Eattt)" is an extension of Bluetooth Low Energy standard attribute protocol (ATT) so that multiple ATT protocols can be executed at the same time. ATT is a one -on -one communication protocol between Central, which refers to source devices such as smartphones and audio equipment such as earphones. It is a protocol that has attribute (attribute) data, respectively, and exchanges the attributes for both sides. Conventional ATT assumes that only one command is generated at a time. Therefore, if multiple commands occur, the second command could be delayed. To avoid this, Eatt is added, and multiple commands can be communicated simultaneously. The fact that each other's attributes can be performed at the same time in two -way communication is the foundation of multi -stream and broadcast function.
4. Implementation in products
So far, we have explained Bluetooth Le Audio. So how will it be implemented in the products surrounding us? Can the conventional Classic Audio and the new audio standard LE Audio be compatible, or will it be replaced? How will the codecs for audio use evolve? How long will the source equipment side such as a smartphone go, and what is the response of the audio device that receives it? We believe that evolving can contribute to improving the quality of life by users' audio experiences and sounds. We will continue to develop products while watching the market trends.
Nick Hunn
"Introducing Bluetooth Le Audio"
RELEASED JANUARY 2022
ISBN-13: 979-8727237250
https://www.amazon.co.jp/dp/B09PKRXRLQ
Bhalla, Himanshu/ Haggai, Oren
"UNRAVELING BLUETOOTH LE AUDIO"
RELEASED MARCH 2021
ISBN: 9781484266588
https://product.rakuten.co.jp/product/-/259fb1e1b63d4c0c5bfb677f1309bdf2/
Shake
Bluetooth Le Audio / LC3
"Bluetooth Le Audio" is a new standard that redefines the conventional Bluetooth audio standard (Classic Audio) that has been used for a long time. This standard has been formulated by a standardization organization called Bluetooth Special Interest Group (Bluetooth Sig), a standardization organization that supervises licensing related technology and trademarks.
This time, we will introduce Bluetooth Le Audio, the latest Bluetooth audio standard, and "LC3", which was adopted as a standard audio codec. If you understand the content of the audio standard based on the transition of Bluetooth audio standard formulation and the background, you can deepen your thoughts on how audio consumer equipment will be transformed in the future. I think.
1. The background of the changes so far and the standard formulation
We believe that knowing what is the standards formulated, its purpose and background, is very important because the future possibilities of audio consumer equipment can be seen. In order to know the background, it is necessary to understand the changes so far.
Since its announcement in 1998, Bluetooth audio standards have evolved significantly, such as improving data communication speed and low power consumption. Now, Bluetooth is commonplace with wireless headphones and wireless earphones. However, there were various changes to the current situation. Behind this is the change from mobile phone business tools to consumer necessities, innovative evolution from mobile phones to smartphones, and innovation from download regeneration in the music industry to music streaming.
Since 2014, the appearance of completely wireless earphones has led to the development of Bluetooth IC, as well as digital audio treatment technology such as MEMS Micro Hon, small transducer, active noise cancellation, and echocardian cells. Bluetooth Sig, a standardized organization of Bluetooth standard, has been examining the evolution of the standard in consideration of what is expected in the next 20 years. The base is actually a question that hearing aids have been solved for years. For example, low power consumption, conversation inspection, noise reduction, low delay, higher sound quality, stable connection, etc. It is expected that technical development will progress further as the evolution from a complete wireless earphone to a hyalreble device. Bluetooth Le Audio has been standardized to promote these long -term developments.
2. Characteristics
Bluetooth Le Audio features two functions: "low delay" and "high -quality codec", and two services: "Multi -Stream" and "Broadcast". These four features are compatible if you think of hearing aids. Now, I will explain each characteristic.
・ Low delay
The key that can achieve a low delay is the new transmission method called "LE ISochronous Channels". Details will be described later, but in this method, you can always send a certain amount of data continuously by sending the necessary data for real -time. Since it can be transmitted continuously in a certain cycle, it is possible to synchronize data transmission between smartphones and audio devices. If the data transmission cycle is set short, it is possible to achieve a lower delay than the conventional Classic Audio. However, it is necessary to be careful not to focus only on the delay, but to set it in consideration of the sound quality and the robustness of the connection. It is also necessary to consider that shortening the data transmission cycle between smartphones and audio devices may increase the processing load of the processor. Of course, real -time is an important factor in hearing. Therefore, the delay is not as low as possible.
・ High quality codec
This section describes "LC3" adopted as a standard codec. LC3 is characterized by the fact that the same sound quality can be achieved even at low bit rate compared to SBC, which is the standard codec in Classic Audio. So what is a good low bit rate? Let's unravel. First, the amount of transmission data can be reduced, so low power consumption. In addition, a stable transmission can be realized. If it is a hearing use, it is clear that long -term use will be used, and low power consumption will be one of the requirements. In addition, since the interruption of the audio should not be inhibited, it is understandable that stable transmission is a requirement. On the other hand, if you focus on pure audio playback, you need to be careful not to say that the sound quality is better than SBC, but that it is a LOSSY compressed codec.
・ Multi stream
Left and right independent transmission is essential for complete wireless earphones that have swept the earphone market in recent earphones. Until now, chip vendors have developed their own transmission methods and have responded to this request. And although we have differentiated with the connecting and robust performance of left and right independent transmission, the selection of Bluetooth IC has been restricted. In the conventional Classic Audio, only single streams could be transmitted between smartphones and audio devices, but multi -streams can transmit multiple streams, simultaneous streams to left and right independent and multiple speakers. Transmission can be realized. The standardization of multi -streams is expected to improve the degree of freedom in the Bluetooth IC selection.
·broadcast
Compatible with broadcast that can be transmitted simultaneously to many people. Until now, the standard was one -on -one communication, albeit in both directions. It is expected to be used in various usage cases by responding to broadcasts. For example, if you transmit it from a TV to multiple headphones at the same time, you will be able to enjoy the same content with multiple people. In addition, public facilities will be able to communicate the same information at the same time, such as commercial use at theaters and stores, and announcements at places such as square, station and airports. It may have a big impact on society as a whole.
3. Transmission technology and protocol
Bluetooth Le Audio has two key technologies. It is "Le Isochronous Channels" and "Enhanced Attribute Protocol (Eattt)".
In particular, the former LE ISochronous Channels is a new transmission method for realizing multi -streams and broadcast functions. Trying to create a flexible system based on a long -term development can increase the flexibility of the specifications, that is, to reconsider the architecture itself. Le Ischronous Channels can build many Ischronous Audio Stream that can transmit all kinds of audio signals. Multi -stream can be realized by Connected Ischronous Stream (CIS) as shown in the figure below, and a broad cast function can be realized by BroadCast Ischronous Stream (Bis). Also, the time synchronization is completely different from the A2DP, which was used in the conventional stereo audio transmission. In this transmission method, you can send audio data at a time synchronization for each interval. By setting the interval, you can control the delay by audio transmission.
Time -synchronous multi -streams can be realized by performing data communication between Central, which refers to source equipment such as smartphones and audio devices such as earphones for each interval called ISOCHRONOUS INTERVAL (ISO Interval). Central, peripheral, and Central, and Central, are called SubEvent, and the interval to the next subEvent is called Sub International. In addition, multiple SubEvents are combined and are called Cis Events.
By performing data communication between Central, which refers to source devices such as smartphones and audio devices such as earphones for each interval called ISOCHRONOUS INTERVAL (ISO Interval), you can realize time -synchronous broadcast functions. The peripheral single -directional communication from Central is called Bis Subevent, and the interval to the next Bis Subevent is called Sub Interval. Multiple Bis Subevent is called Bis Event.
The latter "Enhanced Attribute Protocol (Eattt)" is an extension of Bluetooth Low Energy standard attribute protocol (ATT) so that multiple ATT protocols can be executed at the same time. ATT is a one -on -one communication protocol between Central, which refers to source devices such as smartphones and audio equipment such as earphones. It is a protocol that has attribute (attribute) data, respectively, and exchanges the attributes for both sides. Conventional ATT assumes that only one command is generated at a time. Therefore, if multiple commands occur, the second command could be delayed. To avoid this, Eatt is added, and multiple commands can be communicated simultaneously. The fact that each other's attributes can be performed at the same time in two -way communication is the foundation of multi -stream and broadcast function.
4. Implementation in products
So far, we have explained Bluetooth Le Audio. So how will it be implemented in the products surrounding us? Can the conventional Classic Audio and the new audio standard LE Audio be compatible, or will it be replaced? How will the codecs for audio use evolve? How long will the source equipment side such as a smartphone go, and what is the response of the audio device that receives it? We believe that evolving can contribute to improving the quality of life by users' audio experiences and sounds. We will continue to develop products while watching the market trends.
Nick Hunn
"Introducing Bluetooth Le Audio"
RELEASED JANUARY 2022
ISBN-13: 979-8727237250
https://www.amazon.co.jp/dp/B09PKRXRLQ
Bhalla, Himanshu/ Haggai, Oren
"UNRAVELING BLUETOOTH LE AUDIO"
RELEASED MARCH 2021
ISBN: 9781484266588
https://product.rakuten.co.jp/product/-/259fb1e1b63d4c0c5bfb677f1309bdf2/
Shake
