Is it the music app or the phone that determines sound quality via bluetooth?

Researcher

Active Member
I can't get my head around this and am having conflicting thoughts! :rolleyes: Especially late at night!

I have a Samsung Galaxy S9 that supports SBC, AAC, aptX, LDAC. Samsung HD.
My headphones are Sony WH-1000XM3 that support SBC, AAC, aptX, aptX HD, LDAC and DSEE HX.
My current Samsung Music Player supports MP3, WMA, AAC, FLAC.

If I think of the Music app as a CD player (go with me here) it passes a signal to the Amplifier (my phone) which then transmits that signal on (via bluetooth) to the headphones. Staying with the comparison, If I used a basic phono cable I would not get a good quality signal passed through (CD to Amp) compared to using a coaxial cable. Back in the real world the conduit is (are) the sound codecs. Still with me - please?

Or does the Music app just literally pass the full range signal to the phone (physical connection) and the app codecs are only for what it can decode and hence pass on?

If anyone can confirm what actually goes on, my sleeping would be improved. Thanks.
 

Steven

Senior Moderator
Bluetooth is digital

The digital to analogue conversion takes place via the DAC built into the Bluetooth headphones

The Bluetooth codec (SBC, Aptx, Aptx HD, LDAC, AAC and so on) can potentially affect sound quality as each codec allows different bit rates i.e. data. The more of the file information preserved then in theory better sound quality

Software can affect sound quality depending on disclosed, and non disclosed, digital signal processing and equaliser settings the user may or may not be permitted to change
 

mjm2705

Active Member
On a similar theme, is there any justifiable benefit of having lossless music files on the phone when the BT headphones mainly used only support SBC or aptX?

Most of my phone listening is via lossless files (currently >200GB worth on a 512GB card) via various BT headphones (admittedly I sometimes used wired headphones) ... would I be as well just using Spotify?
 

Researcher

Active Member
Bluetooth is digital

The digital to analogue conversion takes place via the DAC built into the Bluetooth headphones

The Bluetooth codec (SBC, Aptx, Aptx HD, LDAC, AAC and so on) can potentially affect sound quality as each codec allows different bit rates i.e. data. The more of the file information preserved then in theory better sound quality

Software can affect sound quality depending on disclosed, and non disclosed, digital signal processing and equaliser settings the user may or may not be permitted to change
Oh, wow, thanks for that, I did not know that re headphone DACS - that probably accounts for some of the price difference between headphones.

However, it's what is happening between the Music player app and the phone that I also do not understand. Would whatever the phone is able to transmit be limited by the quality of the music player?
 

jamieu

Active Member
However, it's what is happening between the Music player app and the phone that I also do not understand. Would whatever the phone is able to transmit be limited by the quality of the music player?

More of importance (than the player) is the BT protocol/codec being used and how it is being routed.

If you're using a lossy BT protocol (ie. SBC) then your music will be getting transcoded to a low-res lossy format before transmitted to your headphone. In image terms think of a (lossless) TIFF being automatically converted to a (low res and lossy) JPG.

Next you have 'near lossless (lossy)' codecs like aptX-HD which are advertised as providing a encoding that you're unable to differentiate from the original lossless file — although this is also a lot of marketing speak. Think of this as a high-res JPG.

Finally you have 'very near lossless' codecs like LDAC which can transmit data at higher data/bit rates (990 Kbps at 24 bits/96 KHz). Which deliver you audio you are unlikely to be able to differentiate, but it is still getting transcoded and whenever you transcode using a lossy algorithm (however good) you run some risk of losing quality.

What codec you can use will depend on both your playback device and your headphones.

I don't think there is a true BT lossless 24 bits/96 KHz+ codec/protocol partly due to the bandwidth limitations of Bluetooth. But someone do correct me if I am wrong there.

---

In terms of the software/player, as @Stephen points out it should have little to no bearing on sound quality unless the software has been coded incorrectly or is routing/processing it's audio in such a way that the audio is resampled to a lower quality than the original. This can happen if your software is routing the audio via the devices operating system or audio framework which itself may have a fixed/limited bit-depth.
 
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Superaintit

Standard Member
I would recommend you try hifi cast as an app on your phone. Easy to use and bitperfect according to audiosciencereview. I hear a difference between it and other apps, although minor.
 

Researcher

Active Member
Thanks everyone!
 

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