Bluetooth audio is ubiquitous, and ultra-convenient, but it has two downsides: audio quality and latency. It’s unlikely that latency will ever be solved, but Qualcomm’s new aptX Lossless codec resolves the quality issue as it’s capable of streaming audio at CD quality and beyond. It’s even possible Apple was waiting on this codec for its next-gen AirPods, which are currently incapable of streaming lossless Apple Music songs. So, what are the challenges of squeezing such high quality into a protocol that’s also used to connect keyboards and mice? “It all comes down to two issues,” John Carter, sound engineer and inventor of Bose’s noise-canceling headphones, told Lifewire via email. “One, bandwidth for Bluetooth (it’s relatively slow), and then two, the time necessary to turn the aptX file into audio that can be routed as an audio waveform to speakers or headphones.”
Lossless?
When music is streamed, either over the internet or via Bluetooth, the audio is converted to a “lossy” format like MP3. Algorithms work out which parts of the audio can be thrown away without affecting the quality too much. In most cases, listeners can’t tell the difference between a good MP3 and the original. Lossless audio conversion also results in smaller files, but it does so without losing any information. You can convert back to the original format, and the result should be identical. And while it’s smaller than the original file, it’s a lot bigger than lossy compression. Now, Qualcomm has managed to create a codec (short for encode/decode) that can convert and transmit lossless audio fast enough for general use—in smartphones and Bluetooth headphones, for example. With 5G networks coming online, streaming lossless audio from the cloud is practical. Now, you can send that audio to your ears without wires. The aptX Lossless codec runs at 16 bit 44.1kHz, aka CD quality. It can stretch to 24-bit 96kHz lossy, too, which seems a little pointless. It can also detect a lossless audio source and auto-switch to CD-quality, as well as downgrade the quality to keep the music streaming. “Bluetooth operates in a highly variable RF-interference environment populated with Wi-Fi and microwave ovens that can impact signal transmissions,” audio engineer Sam Brown told Lifewire via email. “The challenge is in maintaining a high level of audio quality in all operating environments.”
Delay
Whenever you press play on a song sent over Bluetooth, there’s a short delay until the music hits your ears. It’s roughly tens of milliseconds, so you never notice—until you play a game, or use a music app like GarageBand. In those cases, the sound will lag ever-so-slightly behind your keypresses, and it’s enough to be annoying. This latency is caused by converting the audio to a digital wireless stream, then converting it back into sound at the other end. This is why gamers and musicians still use wired headphones and speakers—because they have a latency of zero. “What we will see is that Bluetooth management of audio will get better and better over time, as it has in the past,” says Carter. “The decoders that expand compressed files back into audio will get faster and faster. So, we should expect to see continual improvement, albeit slower than all of us would like.” But can it ever be as good as a wire? “The high-performance gaming threshold is about 40ms, so these solutions are getting closer and closer to the target of ‘zero-latency’,” explains Carter, but in the end, it might not be so much about engineering as priorities and marketing. Latency is a tough sell. You never notice it when listening to music. When watching movies, the video is also delayed, so it all syncs up.
AirPods
Apple Music’s recent lossless option doesn’t work over AirPods. We can guess that Apple will add some variant of aptX Lossless to any new AirPods, and the marketing message will be easy: better-sounding music. But would Apple license this tech from Qualcomm? That part is tricky because the two companies have been fighting in the courts for years. One thing is certain, though—Bluetooth audio is about to sound much better.
