Tag: does bluetooth audio loss quality

Reasons why Bluetooth can reduce sound quality

While Bluetooth technology offers an easy way to listen to wireless audio through speakers and headphones, some people are opposed to Bluetooth because in terms of audio fidelity it is better to choose one of the Wi-Fi based wireless technologies such as AirPlay, DLNA , Play-Fi or Sonos. … While this understanding is generally correct, there is more to using Bluetooth than meets the eye.

A little about Bluetooth technology

Bluetooth was not originally created for audio entertainment, but rather to connect speakerphone and phone headsets. It has also been designed with a very narrow bandwidth, which forces data compression to be applied to the audio signal. While this format may be ideal for phone calls, it is not ideal for playing music. Additionally, Bluetooth can apply this compression over existing data compression, such as digital audio files or sources streamed over the Internet.

Bluetooth 5.0 standard – a new level of wireless communication

But one important thing to keep in mind is that the Bluetooth system should not apply this additional compression. That’s why:

All Bluetooth devices must support low complexity subband encoding. However, Bluetooth devices can also support additional codecs, which can be found in the Bluetooth Advanced Audio Distribution Profile specification. Additional codecs listed: MPEG 1 and 2 Audio, MPEG 3 and 4, ATRAC and aptX.

In fact, the familiar MP3 format is MPEG-1 Layer 3, so MP3 is included in the specification as an additional codec.

Additional Bluetooth codecs

The official Bluetooth standard in section 4.2.2 states: “The device can also support additional codecs to maximize usability. When both SRC and SNK support the same subcode, that codec can be used instead of the required codec. ”

In this document, SRC refers to the source device and SNK refers to the destination (or receiver) device. So the source would be your smartphone, tablet, or computer, and the receiver would be your bluetooth speaker, headset, or receiver.

By design, Bluetooth does not necessarily add additional data compression to material that is already compressed. If both the source and receiver devices support the codec used to encode the original audio signal, the audio can be transmitted and received without change. So if you are listening to MP3 or AAC files that you have saved on your smartphone, tablet, or computer, Bluetooth should not degrade the sound quality if both devices support this format.

This rule also applies to Internet radio and music streaming services that are encoded in MP3 or AAC format, which covers most of what is available today. However, some music services are experimenting with other formats, for example Spotify uses the Ogg Vorbis codec.

According to the Bluetooth SIG, the organization that licenses Bluetooth, compression remains the norm for now. This is mainly due to the fact that the phone has to transmit not only music, but also calls and other notifications related to calls. However, there is no reason why a manufacturer cannot switch from SBC compression to MP3 or AAC if it supports the Bluetooth receiver. This will apply compression to the notifications, but the original MP3 or AAC files will be transmitted without modification.

What about aptX

The quality of stereo sound transmitted via Bluetooth has improved over time. The current aptX codec, which is marketed as an upgrade to the mandatory SBC codec, provides CD-like audio quality via Bluetooth wireless technology.

Just remember that both your Bluetooth source and receiver need to support the aptX codec in order to benefit. However, if you are playing MP3 or AAC material, it is best if the manufacturer uses the proprietary format of the original audio file without additional transcoding via aptX or SBC.

Bluetooth 5.0: new power saving mode

Most Bluetooth audio devices are not made by companies whose employees wear their brand on their chest, but by an original design that you have never heard of. And the Bluetooth receiver used in the audio product was probably not made by ODM, but by another manufacturer. The more complex a digital product is and the more engineers work on it, the more likely it is that no one knows everything about what is actually going on inside the device. One format can easily be transcoded to another and you will never know, because hardly any Bluetooth receiver will tell you what the incoming format is.

A must-have brief on Bluetooth, from the basics to daily practice in audio land, was posted on HiFi.nl this summer. That raised a number of questions for readers, which, in short, are almost the same: “Great, that wireless connection, but what is left of the quality of the source file when you send audio over Bluetooth?”

We know that since the introduction of the current standard in the field of wireless connection, things have evolved considerably. While Bluetooth was never primarily intended to send or receive audio signals, but rather to allow hardware like the mouse and keyboard to communicate with each other, quite a few steps have been taken to exploit and enhance those capabilities. Consider Bluetooth version 4.0 and the arrival of the now-familiar aptX codec. However, the transfer is not (yet) loss-free. Is the quality of the source file sufficiently preserved with a wireless connection via Bluetooth? In other words, does it make sense to play FLAC instead of MP3, for example if you use Bluetooth to send the music to your speaker?

Codecs

The wired versus wireless discussion will likely always persist. After all, there are numerous hi-fi manufacturers that specialize in audio cables and tell a very good story about it (and besides, of course, there’s the good digital cable twist). When talking specifically about wireless audio over Bluetooth, there is always the element of compression. Due to the limited bandwidth of the connection, by definition there will be data compression and therefore loss of quality. (Not to mention, Bluetooth operates within the 2.4Ghz frequency that many other equipment in the house are also ‘connected’ to.)

aptX

The algorithm used also depends on the codecs supported by both the sender and the receiver. The only one that always works is low complexity subband encoding, or SBC. SBC is still used if, for example, the smartphone supports aptX, but the headphones do not; is the backup option. aptX, which has already done a lot to limit compromise, is certainly not the official standard and is still quite rare, regardless of the fact that there are so many different variants of su. What aptX also does exactly to ensure the ‘lossless CD quality’ of the connection is known only to the creator CSR and owner Qualcomm (you know, the American telecom giant), and their interpretation is, at best of the cases, vague. to name. In any case, the transport of audio data is still dependent on the bandwidth of the connection, which does not have the lossless qualities of transmission over optical cables, for example. The essence: With Bluetooth audio streaming, the audio stream is encoded with a lossy algorithm. After all, Bluetooth has insufficient bandwidth for lossless, let alone high resolution.

“It is always recommended to work with lossless FLAC or ALAC files”

Now what?

Well then there is loss of audio quality. And it’s no secret that hi-fi enthusiasts aren’t fans of compression. However, is the commitment so present that there is as much to horrify as with MP3? No, because thanks to innovations in the quality and bandwidth of a Bluetooth connection, much is being done to minimize the audible effect of compression, as this study shows between SBC, the younger aptX, and 320 mp3 Kbps. So the question is whether it can still be heard in an a / b test with, for example, optical cabling as an alternative. However, the main question is whether an a / b test with different source files via Bluetooth has any effect. The answer is really simple: do you prefer the loss of a good file or a less good file? After all: the better the source, given the (for the moment) inevitable but increasingly marginal loss of quality via Bluetooth, the better the end result. So it is always wise to work with lossless FLAC or ALAC files, because no matter what happens behind the scenes with Bluetooth streaming, you certainly won’t have to deal with double lossy compression, which is always a downside.

Finally, you have to put the Bluetooth app in perspective. After all, for many seasoned audiophiles, the above won’t be a discussion at all, for the simple reason that the listening room isn’t set up for an audio connection via Bluetooth (“Wired! Wired! “). Therefore, the use depends on the circumstances.