AptX Adaptive is Qualcomm’s new Bluetooth audio codec which compresses audio at a variable bitrate

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Almost all of the manufacturers have been rushing to remove the 3.5mm headphone jack from their devices since 2016. While some of us may agree that wireless is really the future of technology, it still has a big flaw: quality isn’t as good and as consistent a wired connection. Users of wireless headphones often encounter stutters and other problems. That’s why Qualcomm decided to release a new audio codec standard called aptX Adaptive.

Even the name can tell what the new codec does: it adjusts the bitrate automatically based on what you’re listening to. Bitrate scales from 279kbps to 420kbps, which are used for CD and Hi-Res quality music. AptX Adaptive dynamically adjusts the bitrate when you’re gaming, watching a video, listening to high-quality music from the streaming service, having a video call, and so on. The codec optimizes audio quality and latency required for the specific tasks.

Automatically adjusting the bitrate also saves power. There’s really no point in transmitting sound at 420kbps when you’re playing Fruit Ninja. That’s when aptX kicks in and says “okay, let’s save some battery and playback time for the user.” Also, higher the unnecessary bitrate, the higher the chance that user encounters dropped packets, which result in stuttering audio. Qualcomm claims that aptX Adaptive “just works” and it doesn’t need a user’s configuration.

The SoundGuys reported that aptX Adaptive can scale the bitrate without even cutting out the audio. Other codecs, like LDAC, don’t really have scaling abilities, and in most cases, they make big 330kbps jumps. That’s why the difference in quality is much more noticeable than the aptX Adaptive. Here is the chart the SoundGuys put out. Notice how other codecs offer higher bitrates, but they don’t use them nearly as smart as aptX Adaptive does.

aptX Adaptive LDAC AAC SBC Max bit-depth 24-bit 24-bit 16-bit 16-bit Max sample rate 48kHz 96kHz 44.1kHz 48kHz Bitrate 279 – 420kbps

(dynamic) 330/660/990kbps

(switchable) 250kbps

(fixed) up to 345kbps

(fixed) Latency 50 – 80ms >200ms ~200ms ~200ms

As you can clearly see, aptX Adaptive is in no way the best audio codec when it comes to raw quality of sound. Alternatives like LDAC offer higher bitrates, which theoretically translates to the better audio quality, but it has big disadvantages, like lost packets while pushing unnecessary bitrates, higher latency, and so on. The whole point of aptX is that it is much more power efficient and user-oriented as it doesn’t need configuration or manual control, and offers more than decent sound quality while keeping many things in control automatically.

I’m sure many of you will agree that Qualcomm definitely made the right call. In the era of smartphones without dedicated audio jacks, we need to find the middle ground of wireless audio quality, where you sacrifice neither the quality of sound nor the convenience of using it. I think Qualcomm managed to find that middle ground. AptX Adaptive gives you an ability to listen to anything without worrying about whether you’ll have dropouts in connection, or if your device wastes packets and energy.

What’s better is that aptX Adaptive is backwards compatible with previous devices that support aptX and aptX HD codecs. The separate decoder will be available on the Qualcomm CSRA68100 and the Qualcomm QCC5100 series Bluetooth audio system-on-chips, which will be available by the end of September. Smartphones will start integrating the decoder by the end of the year. We’re looking forward to seeing the first smartphone which supports aptX Adaptive on the hardware level, without backporting the codec or depending on the backwards compatibility.