[paulguru]

Sorry, I have questions for curiosity regarding this topic, that is about the using with BT headphones / earphones with PC, specially with USB bluetooth dongle.

I've seen that some USB Bluetooth dongles have specific codecs like AAC, APTX (in different versions) or A2DP.
I'd like to know if :



1) The devices need to support these codecs or is it necessary that only the source supports it ?

For example these: https://www.bang-olufsen.com/en/hea...Link&cjevent=186537c9538e11e98360025e0a18050e
According to the specification: Bluetooth 4.2 · Codec AAC, do not report anything else, does it mean by chance that if I had an Aptx HD support it would not be exploited?


2) Will the sampling frequency and depth always be limited to that of the CD (hence 16bit and 44Khz) where the Aptx HD or Aptx Adaptive codecs could not be exploited between one of two ( source - device ).


3) The audio codecs in the PC depends by the dongle or by operative system ?
This is a parte that i dont understand.
To have these codecs i must looking for a special dongle or is sufficient to buy a simple BT dongle ?

 

[Roseval]

It takes 2 to tango: both must support the same codec.
If B&O supports AAC it won't work with a APTx sender
Well it will work as all Bluetooth audio devices support SBC (mandatory) but that is not AAC or APTx

None of the present codecs can play CD quality without lossy compression
Codec kbps
SBC 328
APTX 352
APTX-HD 576
LDAC (Connection priority mode) 330
LDAC (Normal mode) 660
LDAC (Quality priority mode) 990
LHCD 900

The PC sends raw PCM to the dongle
The dongle does the coding hence look for one supporting the codecs you need.

A bit more on my website: http://www.thewelltemperedcomputer.com/HW/Bluetooth.htm

 

[paulguru]

So, if the B&O of the example support only AAC following the product specifics, it will works with AAC or SBC ( because this one is mandatory ), right ?

Into the USB Bluetooth dongle usually there's nothing in the productor specifics about codec supported, this what means ?

 

[Roseval]

it will works with AAC or SBC

Correct

When buying a dongle make sure A2DP (Bluetooth stereo audio) is supported.
Often additional codecs are mentioned e.g.
https://us.creative.com/p/accessories/creative-bluetooth-audio-bt-w2-usb-transceiver
https://www.aptx.com/products?field_product_category_tid=128

 

[paulguru]

Audio quality between source and device can depends also by other factors exclusing the supported codecs ?

 

[Roseval]

It is digital signal transmission hence I don’t expect any quality issue due to the transmission.
As a headphone is a device with a receiver, a DAC , an amp and drivers I do think the quality of the headphone itself is far more dominant than the codec.

 

[paulguru]

Can you tell me someone about latency ?
If i'll not use AptX LL i will have the latency in specifics purpouses like movies or games ?

 

[Roseval]

See this page for the latency of various codecs: https://www.rtings.com/headphones/learn/sbc-aptx-which-bluetooth-codec-is-the-best