Qualcomm aptX Bluetooth Review: Improving Wireless Sound

Megalith

Megalith

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Here is a good article for those of you who are wondering where we’re at in regards to wireless sound quality. You’ve probably heard of aptX, which is basically a codec that tries to get around the limitations of Bluetooth with compression. Based on this reader’s experience, aptX, when coupled with a pair of quality headphones, provides quality that is nearly indistinguishable compared to a wired set. Obviously, sound is super subjective and your mileage will vary, but I will say that wireless quality is pretty trivial to me. The only time that I go wireless is when I'm out and about, and I definitely don't need the best quality when I'm just sitting in a subway car or something.

…how can aptX make a difference, considering it is still operating within the restriction of the 345 Kbps Bluetooth audio streaming specification? The difference is in the way the signal is compressed before being transmitted, as aptX does not use psychoacoustic techniques to achieve its compression. It is still considered “lossy”, but aptX uses time domain-based, not frequency domain-based, compression using ADPCM (adaptive differential pulse-code modulation). With the ADPCM compression used in aptX Bluetooth streams, the difference between the quantized samples can be transmitted and used to reconstruct the original signal on the receiving end, saving data, and therefore valuable bandwidth.
 
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OK, I'll bite.

Compressing Bluetooth audio is one thing, but what you have to keep in mind is that nearly all music is already compressed, MP3, AAC etc. So what happens when you compress something that's already compressed? Answer - It will sound even worse, and WILL be audible to the end user, ever more so with better quality headphones.

It's the same as copying a VHS videotape, with each copy, it just gets more and more terrible.
 
True, but there's more than one way to compress audio, with AptX being a lot less harsh than the way Bluetooth traditionally compressed audio, which are ATRAC, MP3, and MPEG 3/4 and are psychoacoustic. The negatives in this case being that the device and the headphones need to be AptX aware.

It's also is worth mentioning there is a lossless version of AptX, with the same limitations.
 
I would be interested in wireless for my everyday usage. The dog going under the desk and catching on the cable is the number one thing that destroys my headsets. Being half deaf from to many Iron Maiden concerts sound quality is a thing of the past, but really I am not an audiophile but do appreciate quality sound.
 
I heard of apx before which is a proprietary codec that requires a license. My S3 had it, my nexus 5 did not. There was a noticeable difference but it's annoying when technologies can't stay consistent.
 
Yeah, it's been around for years. In some ways since the 80s in fact, and you heard about it off and on on Android devices for years. Qualcomm probably has just decided to get some press out of their purchase of the technology a few years back.
 
I've been using an aptx BT dongle in my car for years. Through my car's marginal BOSE OEM system, it's indistinguishable from a cable. Previously, I tried a cheap BT dongle, and the audio was absolutely horrible.
I'm sure if you had some high dollar gear, aptx would show shortcomings, but for most, it does the job perfectly.
 
The only thing I will be using aptX for is with my digital receiver I can simply put my compatible device down near it and stream music to the stereo system. Since that means I could leave the source files as FLAC, the quality loss shouldn't be an issue. I have yet to try it out though as I've been spending way too much money on other things lately to buy a much bigger microSD card.
 
Articles like this is why people keep overpriced Beats. Who cares about sound quality over wireless? Get outta here.
 
Ryokurin said:
True, but there's more than one way to compress audio, with AptX being a lot less harsh than the way Bluetooth traditionally compressed audio, which are ATRAC, MP3, and MPEG 3/4 and are psychoacoustic. The negatives in this case being that the device and the headphones need to be AptX aware.

It's also is worth mentioning there is a lossless version of AptX, with the same limitations.
Click to expand...


Yeah, I'll get on board with Bluetooth audio when they support uncompressed CD quality audio streams. Until then, I'm keeping my handy dandy cable.
 
Stimpy88 said:
... So what happens when you compress something that's already compressed? Answer - It will sound even worse, and WILL be audible to the end user, ever more so with better quality headphones...
Click to expand...

Sorry, that isn't true. Trivial to give examples. You can zip an MP3. Nothing is lost. You can compress a wave form using sampling (say a CD) and then apply a delta sampling compression. If the data in the CD is 10234, 10236, 10237, 10238, etc. You can represent it as 10234, +2, +3, +4, etc. After decompressing... It is exactly the same as the CD file.

Digital compression is not copying or sampled recording ... like VHS or tapes. Any loss in the signal depends solely on its algorithm. An MP3 would be uncompressed prior to AptX/BT recompressing it. You can test this using a BT transmitter with an analog input. Feed in a signal from an MP3 player and record the output. Then play the same MP3 from a BT device. You'll get the same output... plus a bit of noise from the audio line.
 
Stimpy88 said:
OK, I'll bite.

Compressing Bluetooth audio is one thing, but what you have to keep in mind is that nearly all music is already compressed, MP3, AAC etc. So what happens when you compress something that's already compressed? Answer - It will sound even worse, and WILL be audible to the end user, ever more so with better quality headphones.

It's the same as copying a VHS videotape, with each copy, it just gets more and more terrible.
Click to expand...


Agreed. I won't go bluetooth audio until it can support full frequency range uncompressed audio, or at least something lossless like FLAC, so you aren't introducing compression artifacts over compression artifacts in your stream.
 
Ryokurin said:
Yeah, it's been around for years. In some ways since the 80s in fact, and you heard about it off and on on Android devices for years. Qualcomm probably has just decided to get some press out of their purchase of the technology a few years back.
Click to expand...

The topic of discussion is aptX Bluetooth wireless audio, not blanket facts you pulled from Wikipedia.
 
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