Bluetooth Codecs Explained: Which Gives You The Best Audio Quality?

Now that most smartphones don't have headphone jacks, if you want wireless, you need Bluetooth. But something equally important as wireless capabilities is the type of digital codec it supports, which determines the quality of the audio shared. Your device may play high-resolution audio through whatever app or service you use, but if you're connected via Bluetooth using a low-quality codec, you're not getting the best experience. While the "best" codec is subjective, aptX Lossless is widely considered the highest-quality option, with the best audio, followed by LDAC, which is more widely used. AAC is another big one.

To make sense of it, you must 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, reducing file size for performance. Thanks to compression, there's less latency or hiccups in transmission. However, when compressed, files can drop a small amount of data. Ultimately, that loss in data, however minuscule, can mean the difference in sound quality on the other end.

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 denotes the data transfer rate of a codec, measured in kilobits per second (kbps) or megabits per second (mbps). A higher bitrate means greater "bandwidth" and generally better, more efficient transfer speeds. Thinking of a codec as a container of sorts, like a capsule, the higher the bitrate, the more data it can fit inside, as well. More data, better performance, and fewer bits lost during transfer mean better audio quality on the other side of the connection. Bit depth and sample rates also play a role, ranging from 16-bits to 24-bits and from 44.1kHz to 96kHz for high-resolution audio, respectively. Higher depth and sample rates give the 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 that also means that if you want a codec capable of high-resolution audio, you need one with a comparable bitrate. The codec in use must be able to handle the larger file size, higher bit depth and higher sample rate frequencies. 

This is grossly oversimplified, but it's the abridged version to make it quick and easy to understand and help choose the best codecs.

aptX, which comes in various standards and formats, is a next-generation codec designed to enhance wireless media playback. The original aptX was introduced commercially in the '80s and has undergone many iterations since. aptX Lossless came in 2021, with consumer-product support more widely available from brands in 2022. To date, aptX Lossless is one of the best codecs available for devices that support it. The bitrate scales dynamically between 1.1 Mbps and 1.2 Mbps for true CD-quality audio up to 16-bit/44.1kHz. However, Qualcomm says "no data is lost" when audio is encoded or decoded using the format, making it truly "lossless" in function.

LDAC, another high-resolution Bluetooth codec commonly used today, was developed by Sony and supports a 990 kbps bitrate for high-res audio up to 32-bit/96kHz. LHDC, created by Savitech as a viable alternative to LDAC, supports a 1,000Kbps bitrate for up to 24-bit/192kHz audio quality. In a useful audio update, Android 17 Pixel devices now support the LHDC codec.

Finally, AAC supports a bitrate of 320 kbps and up to 24-bit/44.1kHz audio quality. It was originally developed as a higher-quality format and as a successor to MP3, and was popularized by Apple. There are other formats — LC3 is an up-and-comer, but the three core 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 which you prefer in terms of the sound experience. Above all, you'll want to pair the codecs supported by your device and your listening devices, whether that's headphones, a speaker, or something else. You want both your smartphone and headphones to support aptX Lossless, for example. That applies to any audio devices you might buy, so it's important to check codecs when shopping. This information is commonly 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, then it won't matter if aptX Lossless is considered the best-of-the-best, savvy? A perfect example is how iPhones and iOS devices don't natively support aptX or LDAC, only AAC. In most cases, if you're pairing an iPhone with anything via Bluetooth, AAC is the best you get. But you can find third-party adapters that will expand support.

That's why one of the tricks you can use to stream higher-quality audio from your phone to headphones, or from any media playback device really, is to be mindful of the higher-quality formats available to you. Look for lossless media formats, like WAV, FLAC, and beyond, as well as higher bitrates and, when streaming via Bluetooth audio, higher-quality codecs. In the end, that's what makes a true enthusiast or audiophile: someone involved and interested in those finer details to achieve the best possible experience they can muster.