Bluetooth codecs explained: which one gives you the best audio quality?

Now that most smartphones no longer have a headphone jack, if you want wireless, you need Bluetooth. But something as important as wireless capabilities is the type of digital codec supported, which determines the quality of the audio shared. Your device can play high-resolution audio through the app or service you’re using, but if you’re connected via Bluetooth using a low-quality codec, you’re not getting the best experience. Although the “best” codec is subjective, aptX Lossless is widely considered the highest quality, best-sounding option, followed by LDAC, which is more widely used. CAA is another important issue.

To understand this, you need to understand how Bluetooth codecs work. Digital audio is nothing more than digital information. Data shared over Bluetooth is compressed for efficiency and decoded on the other side of the connection. Compression naturally shrinks data, thereby reducing file size for performance reasons. Thanks to compression, there is less latency or hiccups in transmission. However, once compressed, files may contain a small amount of data. Ultimately, this data loss, no matter how small, can cause a difference in sound quality on the other end of the line.

A codec is the format used to compress data, with higher quality codecs like LDAC or aptX designed to preserve audio fidelity. Some codecs lose more data than others — this is how “lossy” (some data lost) and “lossless” (no data lost) formats differ. Bitrate is also important.

Bitrate refers to the data transfer rate of a codec, measured in kilobits per second (kbps) or megabits per second (mbps). A higher bit rate means greater “bandwidth” and generally better and more efficient transfer speeds. Thinking of a codec as a sort of container, like a capsule, the higher the bit rate, the more data it can also hold. More data, better performance, and fewer bits lost in transfer mean better audio quality on the other side of the connection. Bit depth and sample rates also play a role, ranging from 16-bit to 24-bit and 44.1 kHz to 96 kHz respectively for high-resolution audio. Higher depth and sample rates give audio a higher overall quality ceiling.

The higher the audio quality, the more data it requires and the larger the resulting file. This is why, for example, CD-quality audio at 16-bit has much smaller file sizes when stored as MP3s or digital files, and high-resolution audio qualities at 24-bit are much larger. But this also means that if you want a codec that can produce high-resolution audio, you need one with a comparable bit rate. The codec used should be able to handle larger file sizes, higher bit depth and higher sample rates.

This is extremely simplistic, but this is the shortened version to make it quick and easy to understand and help choose the best codecs.

aptX, available in various standards and formats, is a next-generation codec designed to enhance wireless media playback. The original aptX was introduced commercially in the 1980s and has gone through many iterations since. aptX Lossless arrived in 2021, with support for consumer products more widely available from brands in 2022. As of today, aptX Lossless is one of the best codecs available for devices that support it. Bit rate dynamically scales between 1.1 Mbps and 1.2 Mbps for true CD-quality sound at up to 16-bit/44.1 kHz. However, Qualcomm claims that “no data is lost” when audio is encoded or decoded using the format, making it truly “lossless.”

LDAC, another high-resolution Bluetooth codec commonly used today, was developed by Sony and supports a bit rate of 990 kbps for high-resolution audio up to 32-bit/96 kHz. LHDC, created by Savitech as a viable alternative to LDAC, supports a bit rate of 1000 Kbps for audio quality up to 24-bit/192 kHz. In a useful audio update, Android 17 Pixel devices now support the LHDC codec.

Finally, AAC supports a bit rate of 320 kbps and audio quality of up to 24-bit/44.1 kHz. It was initially developed as a higher quality format and successor to MP3, and was popularized by Apple. There are other formats – LC3 is a newcomer, but the three main codecs mentioned above are widely available in products on the market.

Ultimately, what matters most is what’s available to you and your devices, and what you prefer in terms of sound experience. First and foremost, you’ll want to match the codecs supported by your device and your listening devices, whether headphones, speakers, or otherwise. You want your smartphone and headphones to support aptX Lossless, for example. This applies to any audio device you might purchase, so it’s important to check codecs when shopping. This information is usually listed on product pages or in user manuals.

If the devices you want to pair, like a phone and speaker, only support AAC or LDAC audio over Bluetooth, who cares if aptX Lossless is considered the best of the best, wise? A perfect example is how iPhones and iOS devices don’t natively support aptX or LDAC, only AAC. In most cases, if you pair an iPhone with anything via Bluetooth, AAC is the best you get. But you can find third-party adapters that will extend support.

That’s why one of the tricks you can use to stream better quality audio from your phone to headphones, or from any media playing device, is to consider the higher quality formats available. Look for lossless media formats, like WAV, FLAC and beyond, as well as higher bitrates and, when streaming over Bluetooth audio, higher quality codecs. Ultimately, that’s what makes a true enthusiast or audiophile: someone involved and interested in those smallest details to achieve the best possible experience.