APTX AND APTX HD: WHAT IS IT AND WHAT IS THE DIFFERENCE BETWEEN THEM?
Wherever we read about Bluetooth, in addition to the name itself, we also constantly come across all kinds of incomprehensible numbers and letters. Nowadays the designation aptX HD is “in vogue”, which has recently replaced the shorter aptX.
It is clear that HD means “high definition”, but how high and what does aptX mean? And how is aptX different from the new aptX HD?
In general, let’s find out.
So:
WHAT IS APTX?
aptX is a digital technology (also known as the Bluetooth codec) that allows audio to be transmitted at 16-bit / 44.1 kHz at a compression rate of 4: 1 and a data rate of 352 kbps.
This is brief. Actually, you can easily find all of this in any aptX codec description. And it will probably also be written that thanks to aptX your smartphone, laptop, AV receiver can transmit sound through a Bluetooth channel “with a quality close to that of a CD”. Which sounds a lot more encouraging than the boring spec numbers.
In general, aptX technology is capable of providing CD-like sound quality to music, and as a rule it does.
Another thing is that you need to distinguish between “near” and “true” CD quality. And the difference between these two “qualities” is only the level of compression (compression), which aptX, like any other Bluetooth codec, is used to reduce unavoidable delays. that arise during the encoding and transmission of stereo sound. Simply put, aptX always compresses the signal before sending it, and the receiving device (headphones, external speaker, etc.) decompresses this signal during playback. It takes time, otherwise nothing.
When you listen to music, any delay in the operation of the devices does not matter, and you simply do not notice them. Also, when transmitting a wireless audio signal, even between your smartphone and headphones, the delays can be very significant. But when you watch a video, the delays appear almost immediately. The actors suddenly stop “putting their lips to words”, the sound of the sequence clearly does not match what is happening on the screen, etc. If you watch Netflix or other video streaming services, then this is all familiar to you too.
Therefore, a special version of the codec, aptX LL, which stands for Low Latency, that is, “short delay”, has been developed specifically for the transmission of sound in video (and for all other cases where the minimum delay It is important). aptX LL also offers the same “CD-like” sound quality, but reduces the time required for data transfer and decompression to 32 milliseconds. Technically, this is also a lot, but the user’s brain does not notice such a delay. Therefore aptX LL is used in gaming headsets and headphones, where minimal latency is even more important than sound quality.
aptX and aptX HD: what is it and what is the difference between them?
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Now we can summarize: with aptX, Bluetooth headphones, earphones, external speakers and other devices sound better, moreover, aptX also works more efficiently than most other Bluetooth codecs, hence aptX support is provided in almost all devices that send and / or receive audio signal through the Bluetooth channel.
WHAT IS APTX HD?
aptX HD is the same Bluetooth aptX codec, but with an improved one, it can stream 24-bit / 48kHz audio at 4: 1 compression rate and 576kbps bitrate.
Yes, numbers again. But there are not many yet, and as we can see, they are somewhat different. It’s easy to see that aptX HD is capable of delivering higher quality audio at a much higher speed (less latency). And files in 24-bit / 48 kHz format already have real HD sound, which is so appreciated by owners of expensive wired headphones, and in which there is very little background noise and even the smallest sound nuances are clearly audible.
It should be noted that some “musical” smartphone models (eg the LG V series) can transmit such sound, but only in wired mode, that is, through a 3.5 mm “mini-jack” for headphones. , and the 24-bit / 48 kHz quality for them is actually the limit.
However, there is a difference between 24-bit / 48kHz cabling and 24-bit / 48kHz wireless (i.e. Bluetooth). And it consists of signal compression. The new aptX HD differs from the usual aptX in a more efficient compression algorithm (also called “smooth” in the descriptions), but not flawless.
