APTX audio compression decoding technology completely subverts Bluetooth stereo listening experience, providing high-quality wireless audio for a Bluetooth stereo headset, various speakers and other consumer electronics applications. The APTX technology starts from the initial application of radio broadcast until 4 years ago. Its application enables the device that supports the stereo Bluetooth A2DP connection to output CD quality audio.
Although APTX technology overcomes the lower sound quality problem of Bluetooth audio, developers still need to solve the latency of Bluetooth audio, in order to develop high-quality wireless headphones and speaker products for consumers who use mobile to watch movies or play games. Delaying means that the audio stream is transmitted from the audio source (smartphone, media player, computer or console) to the wireless receiving device (speaker or headset).
When wearing a wireless headset, when watching a movie, the user does not want to encounter the phenomenon of no synchronization with the picture; and the game player also hopes when operating the fierce action game of shooting, explosion and other intermittent accidents on wireless devices. Get intuitive audio responses. In order to achieve synchronization between sound and action, the delay must be controlled within 40 ms. Since the latency of traditional Bluetooth technology exceeds 100ms, its performance cannot achieve real-time synchronization of white and game real-time. Therefore, various patented radio frequency solutions (most of which require adapters) should be delivered to fill huge giant gaps in this field, but there are fewer successful cases.
CSR's recent low-delay APTX audio compression decoding technology allows developers to easily solve delay problems without using a complicated adapter. The new low-delay APTX audio compression decoding technology not only provides lossless high quality audio through Bluetooth, but also provides low-delay output performance of up to 40ms. APTX breakthrough technology has many advantages, including:
● Use standard RF technology and compatible with Bluetooth
● Because Bluetooth 100% compatible smartphone, tablet and notebook, there is no need to use the adapter
● You can run in an existing chip design system via a simple software update.
Low delay audio compression code decoding technical problem
The key to this problem is the advancement or lag of the audio and the video signal. According to the European Broadcast Recommendation Standard R37-2007, the slot range between the sound and image components transmission of the television signal is: "The sound should not be higher than 40 ms before the image signal is exceeded and the lag should not be higher than 60 ms." In stereo audio transmission In the Bluetooth transport layer, the A2DP protocol supporting standard SBC codecs and coding algorithms based on psychological sensational techniques are used. However, based on SBC and perceived compression techniques use frame compression, the overall delay time is up to 100 ms to 500ms, which is mainly attributed to the following three factors:
1. Coder delay: Each audio codec causes a certain internal delay before encoding the data and transmits it. The conventional codec has been detected by up to 50ms of the codec delay.
2. Transmission delay: The A2DP transport layer uses a data packet structure. Engineers When filling packets based on SBC or perceived frames, they have two options: one is to place a frame into a large Bluetooth packet; the second is to decompose a frame into two Bluetooth packets. The first scheme will reduce the robustness of the data transmission, and in the second scheme, the decoder can only decode the decomposition frame after receiving the two Bluetooth packets, so the transmission delay time will be significantly increased.
3. The codec is received throughout the packet or frame before starting decoding.
Further, since the bit rate setting features, the audio quality provided by the SBC and the perceived codec is highly variable. That is to say, even if a plurality of the same codec are employed, a stable audio effect cannot be provided.
A2DP transmission cannot be two suites. To achieve low delay performance, the robustness and sound quality of the audio will be reduced. Therefore, many special RF solutions have been launched on the market to meet the needs of consumers on wireless transmission.
APTX low delay technology
The APTX codec based on sampling mode has two major advantages over the A2DP codec: it provides 1.9 ms ultra-low-neckline delay, and more importantly, there is no need to adopt a frame format. Therefore, in the decoding process, the APTX codec can fill the Bluetooth packet without waiting, that is, once it receives the data package, start the decoding process. In addition, the APTX adopts a fixed compression ratio algorithm, which can always provide the same bit rate during transmission, thereby ensuring that each product equipped with an APTX output is the same sound quality.
A series of unique features with APTX provide professional audio performance and robustness while also guarantees end-to-end delays in 40ms. 40ms meet the standard requirements for dialogue and action synchronization in accordance with the European Broadcasting Union (EBU).
TV and games
Since the birth of the flat-panel TV, engineers have been working on narrowing the border of the TV, mainly to better mount the TV to the bedroom wall. However, the lightweight design of the television is inversely proportional to its sound quality, and the sound effect of the speaker is proportional to its volume, that is, the cable is thinner, and the sound quality is worse. For the 5mm thickness flat-panel TV on the current market, we offer two optional options based on low-delayed Bluetooth connections:
1. Manufacturers can make independent speakers, built-in APTX low-delay technology in the TV case and embed the decoder in the speaker
2. The TV buyer can use the receiver from the linear output port to transmit the signal to the three-dimensional sound system of the existing APTX technology.
The game is also an application area that grows. When the traditional indoor game machine market is still strong, the mobile game market has greeted flourishing. The modern operating system allows all smartphones and tablets on the market to run 3D games, which will create potential users in the game market.
Players wearing Bluetooth headset on the road will definitely do not want to encounter delay problems, they want to keep synchronization with the game screen and handled action through the sound heard through the headset. If the trigger and the time interval of hearing the guns exceed 50ms, the delay caused is more obvious, and this game has become a taste.
APTX low-delay technology and its 40ms low delay performance ensure that game players get the required audio synchronization effect. In addition, the APTX can also open a dual-channel audio stream to return signals in the headset to the game console, providing a wireless voice chat function for the game team, enhancing the gaming experience.
Built-in APTX's headphones can be used to play games, listen to high quality music, hands-free calls, and create a variety of beautiful experiences for users.
How to use APTX low delay technology
The two ends of the APTX low-delay technique are: compression / encoder / source and decompression / decoder / complimentary. It is adapted to use various encoders based on Linux, Android Jelly Bean and Kit Kat, and compatible with Bluez and BlueDroid Blueta protocol stacks. Once the output signal is accurate, the data integration can be completed within two working days.
In the decoding end, the user can use CSR chips such as BC05MM and SR8670, which are compatible with KalIMBA onboard DSP. Users can then integrate APTX low delay technology to Kalimba DSP platforms. In addition to the APTX, CSR chips also provide other variety of enrichments, including high performance DACs and ADCs, capacitive touch, input / output functions (SPDIF, I2S, I2C and GPIO, etc.). If used, CSR8670, Provide Bluetooth Smart connectivity.
What is your choice?
The beginning of this article has been explained: Since the codec based on the SBC and other frames has certain constraints in the Bluetooth connection, the A / V industry has no choice of other private programs. Given that the CSR technology successfully solves the latency problem, manufacturers can consider using Bluetooth connections in their ecosystem design, not only easy to use, save costs (chips and systems), but also ensure that their products are never.
Abandoning a private program and choosing a standard-based program is conducive to the manufacturer to enjoy the research and development results of each Bluetooth semiconductor company, and the benefits include:
● Accelerate design flow
● Form a scale economy to ensure advantageous price
● In addition to Bluetooth radio, you can also enjoy all kinds of rich features, including onboard DSP, ADC, DAC and sample rate converters, etc.
The Bluetooth standard has been adopted by the majority of consumer electronics manufacturers, and the sales of Bluetooth chips have exceeded 3 billion in the past decade. All smartphones, tablets, and most features on the market are equipped with a Bluetooth function and compatible with the A2DP protocol to provide broadband stereo audio. User Opening When watching a smartphone, you can listen to high quality audio with the speaker through the wireless headset and the speaker, which will be a thousand-stricken career.
Be
Source: Wiku Electronic Market Network
Our other product:
