The Ultimate Guide to AptX and More

Bluetooth technology has evolved significantly over the years, and as cell phones have been updated, Bluetooth has become increasingly common and widely used. In the early days of Bluetooth, the most commonly used codecs were SBC and AAC, which are both lossy compression protocols.

These codecs were not able to deliver the same level of sound quality as wired audio, and they are now mostly found in low-end audio products.

In recent years, one of the most talked-about developments in the Bluetooth world has been the introduction of aptX lossless sound. This codec is able to deliver lossless audio quality over Bluetooth, which is a significant improvement over the lossy codecs that were previously used.

In this blog post, we will take a closer look at the evolution of aptX technology and explore the various standards that have been developed over the years.

The aptx Family

aptX is a family of proprietary audio codecs developed by Qualcomm. The codecs are designed to provide improved audio quality over traditional Bluetooth audio codecs, particularly in the areas of low latency and better fidelity.

There are several different versions of aptX, each with its own specific features and capabilities:

aptX: This is the original aptX codec, which was designed to provide improved audio quality over Bluetooth. It has a bitrate of 352 kbps and can support up to 48 kHz audio.
aptX HD: This codec is designed to provide even higher audio quality than the original aptX codec. It has a bitrate of 576 kbps and can support up to 48 kHz audio.
aptX Adaptive: This codec is designed to provide the best possible audio quality, depending on the available bandwidth. It can automatically adjust its bitrate and other parameters to provide the best possible audio quality in a given situation. It has a maximum bitrate of 960 kbps and can support up to 48 kHz audio.

To use aptX or any of its variants, both the transmitter (e.g. a smartphone or laptop) and the receiver (e.g. a pair of wireless headphones or a soundbar) must support the same codec. If both devices support aptX, for example, they will be able to use the aptX codec to transmit audio between them. If only one device supports aptX, the audio will be transmitted using a different, lower-quality codec.

aptX: The First “High Quality” Bluetooth Encoding

AptX is a digital audio compression algorithm that was developed by Audio Processing Technology and later purchased by Qualcomm. It is based on Subband ADPCM technology and was proposed by Dr. Stephen Smyth in the 1980s. AptX supports 16-bit, 44.1/48kHz audio with a bit rate of 384kbps and is backwards compatible with SBC.

It has a higher bit rate than SBC and AAC, which results in improved sound quality. AptX was the first Bluetooth audio codec that was able to offer sound quality that was slightly closer to CD quality in the early days of Bluetooth audio. However, some devices, such as the iPhone, do not support AptX due to the Qualcomm license fee.

AptX is a lossless transmission technology that is used to solve various problems in Bluetooth transmission, such as transmission delay. Although it is referred to as lossless, it is actually also lossy. However, AptX is able to greatly reduce audio delay, which makes it suitable for use with Bluetooth headsets for gaming and other applications where high sound quality is desired.

Originally used in the professional audio and broadcasting fields, AptX has more recently replaced SBC in the field of Bluetooth wireless audio transmission due to its low latency, good fault tolerance, and high quality. The AptX family includes AptX Bluetooth, AptX Enhanced, AptX Live (released in 2007), and AptX Lossless (released in 2009).

AptX is mainly used in Bluetooth headsets and speakers, and both the device and the headset or speaker must support AptX in order to utilize its capabilities. AptX is able to minimize audio and video latency in Bluetooth transmission.

Many devices already support AptX, and cell phone manufacturers can provide support by updating their systems (although hardware support is also required). The main benefit for everyday users is that the Bluetooth device connection delay is reduced, and the improvement in sound quality for cell phones is significant.

aptX HD: Bluetooth listening with high sound quality evolution

AptX HD is a codec that has been developed to improve the sound quality of Bluetooth audio. While AptX is able to offer sound quality that is close to that of a CD, it is still a significant distance away from “high resolution” or the quality of a wired connection.

Many people feel that listening to music with Bluetooth headphones inevitably means sacrificing some sound quality, and AptX HD may be the best solution to address this issue.

What is AptX HD? AptX is a codec that has been increasingly applied to cell phones, headphones, amplifiers, speakers, and other equipment in recent years as more and more people use Bluetooth to listen to music. It has helped to change the previous perception that Bluetooth audio has poor sound quality.

AptX HD is essentially the same as the AptX codec that has been in use for a few years, but it has a higher bit rate of 576kbps, compared to 352kbps for the original AptX Classic. This allows for a compression ratio of 4:1, which is higher than the 16-bit/44.1kHz CD sound quality. However, as with any compression, the sound quality will depend on the specific implementation.

Compatibility with AptX The new AptX HD codec is compatible with the original AptX codec, so if a phone supports AptX HD and a headset also supports it, the user will be able to listen to songs wirelessly in high quality after establishing a Bluetooth connection.

Alternative to AptX HD If you want to listen to songs with Bluetooth but do not want to wait for AptX HD to become more widely available, there is already an alternative option in Sony’s LDAC technology. This has a highe bit rate of 990kbps and supports a 24-bit/96kHz music signal, which is theoretically better than AptX HD.

It is supported by a range of Sony equipment, including the h.ear series headphones and the ZX-2 Walkman. However, it is currently limited to Sony products and is not compatible with other headphones or phones.

aptX Adaptive: New aptX Technology for Best Sound Quality at Lower Bit-rates

AptX Adaptive is a new version of Bluetooth encoding technology that is designed to offer the highest sound quality at lower bit rates. It is one of the latest developments in the aptX codec family, which also includes aptX, aptX HD, and aptX LL.

AptX Adaptive is characterized by its ability to adapt the bit rate of Bluetooth transmission dynamically according to the usage. It is backward compatible with aptX and aptX HD, and has a bit rate range of 279kbps to 420kbps.

Although the maximum bit rate of AptX Adaptive is lower than that of AptX HD (576kbps), the more efficient encoding technology allows it to deliver the same high sound quality as AptX HD at 420kbps, and support Hi-Res audio at up to 24-bit/96kHz. At 279kbps, it delivers the same sound quality as AptX.

While there may not be a significant increase in sound quality compared to AptX HD, AptX Adaptive is more efficient and saves bandwidth.

AptX Adaptive is also more resistant to interference, providing a more stable Bluetooth connection in today’s complex wireless environment. It supports Qualcomm’s TrueWireless Stereo technology and Dual Mono mode, making it easy to use in true wireless headsets.

The QCC5100, QCC302x, and QCC303x series Bluetooth chipsets already support AptX Adaptive, and the TWS Neo from Vivo is the first true wireless headset to support it.

Other aptx standards

there are several other standards in the AptX codec family, in addition to the original AptX, AptX HD, and AptX Adaptive. There are many different AptX standards because each one was developed to address a specific need or problem in the realm of Bluetooth audio. These include:

AptX Low Latency (AptX LL): This standard was developed to reduce the audio delay in Bluetooth transmission, making it suitable for use in applications where real-time audio is important, such as gaming and video.
AptX Live: This is a codec that was specifically designed for use in live performance and broadcasting applications, where low latency and high sound quality are essential.
AptX Lossless: As the name suggests, this codec is designed to deliver lossless audio quality over Bluetooth. It is able to compress audio signals at a ratio of 1:1, resulting in audio that is identical to the original source.
AptX Enhanced: This is a codec that was designed to improve the sound quality of Bluetooth audio in noisy environments. It uses advanced noise reduction techniques to eliminate background noise and improve the clarity of the audio signal.
AptX Adaptive Voice: This is a codec that was specifically developed for use in voice applications, such as phone calls and voice assistants. It is able to optimize the audio quality for speech and is designed to be used in devices with limited processing power.

These are just a few examples of the various AptX standards that have been developed over the years. Qualcomm, the company behind AptX, has continued to innovate and expand the AptX codec family in order to meet the evolving needs of Bluetooth audio users.

Conclusion

AptX, AptX HD, and AptX Adaptive are all digital audio compression algorithms that have been developed to improve the sound quality of Bluetooth audio. AptX was one of the first high-quality Bluetooth encoders, and AptX HD was developed to offer sound quality that is closer to Hi-Res audio.

AptX Adaptive is the latest version of the AptX codec and is able to adapt the bit rate of Bluetooth transmission dynamically to deliver the same sound quality as AptX HD at a lower bit rate. All three versions of the AptX codec are widely used in a variety of devices, including headphones, speakers, and phones.

AptX Adaptive is also more resistant to interference and provides a more stable Bluetooth connection. Overall, the AptX codec family has been instrumental in improving the sound quality of Bluetooth audio and has helped to change the perception that Bluetooth audio is inherently of poor quality.