In the world of disappearing 3.5mm connectors, aptXHD can fix things.
Original material
When reading anything about Bluetooth, you invariably come across a bunch of numbers, letters and other obscure characteristics. One such technology is aptXHD, which adds 'HD' to the mysterious characteristics of the previous version of the codec. We all know what 'HighDefinition' is behind this shorthand, but what about 'aptX'? And what is the difference between aptX (in fact, also an HD codec) from its successor?
Don't worry if you are not sure about the answer, you are not alone in this matter. Let's go through each of the codecs in detail and together determine what's what.
What is aptX?
This means Bluetooth – an audio codec capable of transmitting 16 bit / 44 kHz audio with a 4: 1 compression ratio at 352 kbps. Not to say that this can remove all the questions, but this is the result that the search for known characteristics of aptX will bring. Its presence means that the device (phone, computer, A / V-receiver or anything that supports audio transmission over Bluetooth) can transmit audio in 'CD quality'. It sounds better because the audio source is at or above CD quality.
Have you noticed the contrast between CD quality and 'like on CD'? It's all about compression. AptX, like any Bluetooth – audio codec, before sending the audio compresses it, and the receiving device (headphones or other speaker) plays it during the decompression process. Compressing the information and transmitting it are necessary steps because Bluetooth 'cannot' send a stereo audio stream at a speed sufficient for the raw information to sound good. The aptX codec was created to reduce the delay – the time between sending and starting playback of an audio file.
If you are listening to music, then the latency does not matter. There can be quite a significant lag between the phone and the headphones, but you won't notice it. But you are more likely to notice a delay when watching a video. Streaming broadcasts in which words are out of sync with the speaker's articulation will not be a revelation to anyone.
For cases where minimum latency is important, the aptXLL (low latency) codec has been developed. This technology reduces the latency to 32 milliseconds, which our brains cannot hear. AptX LL is present in headphones for gamers where minimum latency prevails over sound quality, although aptXLL is also capable of transmitting 16-bit / 44 kHz.
What is aptX HD?
This Bluetooth is an audio codec capable of delivering 24 bit / 48 kHz audio with a 'light' 4: 1 compression ratio at 576 kbps. And again the numbers, but now they are useful to us. First of all, a higher quality audio stream can be sent over aptX HD without interrupting the stream or increasing the delay. 24-bit / 48 kHz files are actually HD files that are appreciated by people with expensive wired headphones and that minimize background noise and sound crisp every single part. Phones such as the LG V range can send high quality audio over the 3.5mm jack, but those numbers have almost reached the point where recoil is reduced when reaching 24 bit / 48 kHz.
The difference between a 24 bit / 48 kHz audio stream over a wired connection and over Bluetooth is compressed. AptX HD offers an improved compression algorithm than standard aptX (and therefore a 'light' ratio), but any compression ends up with a buzz and sibilance. You've heard this effect without even realizing it – extreme compression is used by rock guitarists to make their guitars sound more 'heavy' and 'loose', and it works. The compression used by aptXHD has been specially designed to avoid such distortion in the sound, but noise is added anyway.
The last difference is the most important. AptX transmits audio at 325 kbps, and aptX HD at 576 kbps. The higher the bandwidth, the more information will be sent, which means that there is no need for heavy compression, or, as we can see with the aptX HD example, a relatively 'lighter' algorithm can be used.
Where to find aptX HD
Not all devices support this codec. It was developed by Qualcomm, like aptX and all its variations, and will require the company's proprietary software and hardware to use it. Their current top-end solution, the CSR8675 Bluetooth Audi o single-chip microprocessor, supports aptX HD, Bluetooth 5, active noise cancellation on Bluetooth and stereo Qualcomm TrueWireless technology. Like any hardware with aptX HD support, it is backward compatible with aptX.
The first phone sold with aptX HD support was LG G5. The company LG became the pioneer of this movement and therefore the mentioned codec can be found in V20, G6, V30 devices. Sony included it in the Xperia XZ1 and XZ1 Compact, OnePlus in the 3, 3T, 5 models. Many lesser-known manufacturers followed suit.
In terms of listening equipment, aptX HD is supported by headphones from Sony, Audi o Technica, LG and other brands. The codec provides a comparatively better sound without any additional involvement from the manufacturers who use it in their devices. Consequently, the list of supported devices will grow.
By Jerry Hildenbrand
The same cannot be said about the Sony LDAC (Losless Digital Audi o Coding) codec. The technology is superior in performance to the solution from Qualcomm, but for some reason Sony continues to keep an area of mystery around it and refuses to license it to other users. If it is interesting, then the next article will be devoted specifically to the features of LDAC.
In general, for a long time I was skeptical about Bluetooth – headphones, I considered them a temporary measure for playing sports and nothing more. Familiarity with more expensive wireless models changed this opinion. The final pros are the difference in the sound of inexpensive wireless sports headphones Xiaomi on the OnePlus 5 using the aptX HD codec. Therefore, I cannot consider myself to be 100% adherent of one of the mentioned approaches. How do you feel about Bluetooth – headphones and aptX HD? Do you think support for this codec is a significant advantage?