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Topic: Bluetooth headphones & AAC (Read 1163 times) previous topic - next topic
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Bluetooth headphones & AAC

Hello,

Sorry if I bring to the table an issue already discussed, but I’m still not sure about how to proceed.

I’ve recently bought my first pair of Bluetooth headphones, which support AAC. I’ve read that, despite being less energy efficient than SBC, AAC sounds better, so at the moment, I’m sticking with it.

I normally transcode my music from FLAC to Opus 128, but I was wondering about a possible boost of quality if I transcoded my music directly to AAC, though I’ve read that there’s still some kind of conversion applied when the audio file is transmitted by the Bluetooth protocol.

A few days ago, I found a thread comparing AAC codecs. I hope FDK is good enough, as it’s the implementation available in freac and Foobar.

If using AAC doesn’t make a noticeable impact on audio quality, I was also wondering if transcoding Opus to a higher bitrate (or even using FLAC directly, but my space is limited) would help. Maybe Opus at 192 kbps or even 320 kbps?

Any help regarding boosting the audio quality would be appreciated. My headphones are budget, so I know I can’t expect miracles.

Thank you in advance!

Re: Bluetooth headphones & AAC

Reply #1
It doesn't matter whether or not your source file is already in AAC; it will be converted.
To convince yourself, simply make the experience. Apply any effect (equaliser…) to the sound during playback: if the change is audible then it can't be your original file. Or if you hear from time to time an alarm, sound notification or something similar mixed within your music: again, it couldn't be possible if the original bitstream was streamed without change.

If you want the best audio quality then it's very simple: use a lossless source. You can even use a 24 bit high resolution file to increase the theoretical quality. The question is: is it worth? Especially if your disk space is limited?
Using a transparent lossy source won't probably make a huge difference. OPUS 128 should be fine: don't change it.

Re: Bluetooth headphones & AAC

Reply #2
You should return the Bluetooth headphones and go with wifi headphones if you want quality wireless.

Something like this Corsair Virtuoso
exhaleFLAC

Re: Bluetooth headphones & AAC

Reply #3
To convince yourself, simply make the experience. Apply any effect (equaliser…) to the sound during playback: if the change is audible then it can't be your original file.

I wonder why it wasn't designed better. Like, "here is an AAC stream and here is what you are supposed to do with it".
DSP instructions hardly take any bitrate to transfer, and for the device to apply a small set of instructions - like, volume, EQ and mixing with ringtones and whatnot - would be simple compared to the AAC decoding it anyway has to do.
High Voltage socket-nose-avatar

Re: Bluetooth headphones & AAC

Reply #4
Someone had done a test about how much the audio quality degrades each time the audio was reencoded with certain codecs.  Seems AAC isn't noticably degraded after multiple reencodes. https://hydrogenaud.io/index.php?topic=100067.0

I don't use Bluetooth much.  My phone and BT headphones only have the SBC codec in common.  I could only hear obvious degradation of the audio with AAC files below 96kbps.

Re: Bluetooth headphones & AAC

Reply #5
Hello,

Sorry if I bring to the table an issue already discussed, but I’m still not sure about how to proceed.

I’ve recently bought my first pair of Bluetooth headphones, which support AAC. I’ve read that, despite being less energy efficient than SBC, AAC sounds better, so at the moment, I’m sticking with it.

I normally transcode my music from FLAC to Opus 128, but I was wondering about a possible boost of quality if I transcoded my music directly to AAC, though I’ve read that there’s still some kind of conversion applied when the audio file is transmitted by the Bluetooth protocol.

A few days ago, I found a thread comparing AAC codecs. I hope FDK is good enough, as it’s the implementation available in freac and Foobar.

If using AAC doesn’t make a noticeable impact on audio quality, I was also wondering if transcoding Opus to a higher bitrate (or even using FLAC directly, but my space is limited) would help. Maybe Opus at 192 kbps or even 320 kbps?

Any help regarding boosting the audio quality would be appreciated. My headphones are budget, so I know I can’t expect miracles.

Thank you in advance!
You should return the Bluetooth headphones and go with wifi headphones if you want quality wireless.

Something like this Corsair Virtuoso

Great advice there. Really helping this member optimise his headphones and understanding of the technology. “Buy these cheap, gaudy headphones that don’t suit your needs”. Great stuff again HA!

Re: Bluetooth headphones & AAC

Reply #6
Hi!

Thank you for all your answers. I won't transcode to AAC in that case, as it seems it won't impact on the quality. I may switch from Opus 128 to Opus 160, as I've read some members of the forum indicate it's the sweet spot.

It's my first pair of true wireless headphones, and as I said, I didn't pay much. Now I have a reference for a future purchase in maybe of couple of years.

I had no idea there was such a thing as wifi headphones. They are interesting, but out of my budget, and I mostly use headphones when I'm not at home.

A few times a week, I browse the forum and read a few posts. I don't always get the technicalities, but I do appreciate that you've helped me learn a little bit about audio. For that, thank you!

Re: Bluetooth headphones & AAC

Reply #7
Quote
I had no idea there was such a thing as wifi headphones.

No surprise as they don't exist.
There are radio transmitters using the same band as the WiFi.
But headphones connected straight to the WiFi using protocols like UPnP, Airplay etc. don't exist.
TheWellTemperedComputer.com

Re: Bluetooth headphones & AAC

Reply #8
No surprise as they don't exist.
There are radio transmitters using the same band as the WiFi.
But headphones connected straight to the WiFi using protocols like UPnP, Airplay etc. don't exist.
There called 2.4GHz wireless or some call them wifi headphones for short.
2.4GHz wireless headphones sound a lot better than bluetooth.
https://www.electropages.com/blog/2019/07/wireless-audio-explained-bluetooth-vs-24ghz-audio
exhaleFLAC


Re: Bluetooth headphones & AAC

Reply #10
Someone had done a test about how much the audio quality degrades each time the audio was reencoded with certain codecs.  Seems AAC isn't noticably degraded after multiple reencodes. https://hydrogenaud.io/index.php?topic=100067.0

The A2DP specification was fixed in 2001-2003, at a time where having a portable device do an additional decoding+reencoding step - in real-time! - would probably tax the battery life quite heavily.  So even if you disregard the degradation - which I have no idea if you could with 2001-era portable-device encoders! - it appears to me as an unnecessary evil.
 
Mixing ringtone and music requires a DSP that might not have been for free, but the specification wouldn't need to make receiver-side DSP mandatory. Handshake, "dear device, can you do mixing? If no, then I'll do it".
High Voltage socket-nose-avatar

Re: Bluetooth headphones & AAC

Reply #11
Someone had done a test about how much the audio quality degrades each time the audio was reencoded with certain codecs.  Seems AAC isn't noticably degraded after multiple reencodes. https://hydrogenaud.io/index.php?topic=100067.0

The A2DP specification was fixed in 2001-2003, at a time where having a portable device do an additional decoding+reencoding step - in real-time! - would probably tax the battery life quite heavily.  So even if you disregard the degradation - which I have no idea if you could with 2001-era portable-device encoders! - it appears to me as an unnecessary evil.
 
Mixing ringtone and music requires a DSP that might not have been for free, but the specification wouldn't need to make receiver-side DSP mandatory. Handshake, "dear device, can you do mixing? If no, then I'll do it".

A2DP is being replaced by LC-Audio in Bluetooth 5.2. But it's still bandwidth limited. They're introducing a new codec, called LC3 (still lossy), and the protocol now supports streaming multiple channels at once, so you can have earbuds that pair as the left channel and the right channel. In theory you could pair 5 speakers and set them up in a surround sound setup.

LC3 is supposed to have a latency of only 5 ms, so that's an improvement. We'll see if that number holds up in real-world testing.

EDIT: I shouldn't say replaced.  Both protocols will be available side-by-side.  The goal is to have A2DP removed in a future version of Bluetooth.

Re: Bluetooth headphones & AAC

Reply #12
Someone had done a test about how much the audio quality degrades each time the audio was reencoded with certain codecs.  Seems AAC isn't noticably degraded after multiple reencodes. https://hydrogenaud.io/index.php?topic=100067.0

The A2DP specification was fixed in 2001-2003, at a time where having a portable device do an additional decoding+reencoding step - in real-time! - would probably tax the battery life quite heavily.  So even if you disregard the degradation - which I have no idea if you could with 2001-era portable-device encoders! - it appears to me as an unnecessary evil.
 
Mixing ringtone and music requires a DSP that might not have been for free, but the specification wouldn't need to make receiver-side DSP mandatory. Handshake, "dear device, can you do mixing? If no, then I'll do it".




A2DP is being replaced by LC-Audio in Bluetooth 5.2. But it's still bandwidth limited. They're introducing a new codec, called LC3 (still lossy), and the protocol now supports streaming multiple channels at once, so you can have earbuds that pair as the left channel and the right channel. In theory you could pair 5 speakers and set them up in a surround sound setup.

LC3 is supposed to have a latency of only 5 ms, so that's an improvement. We'll see if that number holds up in real-world testing.

EDIT: I shouldn't say replaced.  Both protocols will be available side-by-side.  The goal is to have A2DP removed in a future version of Bluetooth.

Yep the problem with A2DP is the packet size and general protocol overhead limiting the throughput over bluetooth, and thus limiting the codecs/bitrates available. A new profile should solve this issue.
I've yet to see lossless audio over bluetooth, you have Sony's LDAC which can theoretically go to 990kbps but due to A2DP is rarely does. Best solution I found, at least on a mac, is go to the bluetooth explorer, disable aptX, enable/force AAC and whack the datarate to the highest VBR setting with the expense of range and possible battery life, increase the buffer a bit to avoid dropped frames. Runs about 300kbps.
Audio Engineer from the UK

Re: Bluetooth headphones & AAC

Reply #13
Someone had done a test about how much the audio quality degrades each time the audio was reencoded with certain codecs.  Seems AAC isn't noticably degraded after multiple reencodes. https://hydrogenaud.io/index.php?topic=100067.0

The A2DP specification was fixed in 2001-2003, at a time where having a portable device do an additional decoding+reencoding step - in real-time! - would probably tax the battery life quite heavily.  So even if you disregard the degradation - which I have no idea if you could with 2001-era portable-device encoders! - it appears to me as an unnecessary evil.
 
Mixing ringtone and music requires a DSP that might not have been for free, but the specification wouldn't need to make receiver-side DSP mandatory. Handshake, "dear device, can you do mixing? If no, then I'll do it".




A2DP is being replaced by LC-Audio in Bluetooth 5.2. But it's still bandwidth limited. They're introducing a new codec, called LC3 (still lossy), and the protocol now supports streaming multiple channels at once, so you can have earbuds that pair as the left channel and the right channel. In theory you could pair 5 speakers and set them up in a surround sound setup.

LC3 is supposed to have a latency of only 5 ms, so that's an improvement. We'll see if that number holds up in real-world testing.

EDIT: I shouldn't say replaced.  Both protocols will be available side-by-side.  The goal is to have A2DP removed in a future version of Bluetooth.

Yep the problem with A2DP is the packet size and general protocol overhead limiting the throughput over bluetooth, and thus limiting the codecs/bitrates available. A new profile should solve this issue.
I've yet to see lossless audio over bluetooth, you have Sony's LDAC which can theoretically go to 990kbps but due to A2DP is rarely does. Best solution I found, at least on a mac, is go to the bluetooth explorer, disable aptX, enable/force AAC and whack the datarate to the highest VBR setting with the expense of range and possible battery life, increase the buffer a bit to avoid dropped frames. Runs about 300kbps.


Honestly, I don't think you'll ever see lossless audio over Bluetooth. If they wanted to add it, they would have provided enough bandwidth to handle it in LC-Audio, and they don't.

I have to say that I am impressed with their claim of 5 ms of latency using the LC-3 codec. That's pretty impressive. It even beats OPUS, which was the low latency codec to beat.

I don't know of any device that supports LC3 yet. But it looks like you HAVE TO support LC-3, if you're going to support Bluetooth 5.2. I wonder if Bluetooth 5.0 devices can be upgraded to 5.2 with a firmware update, or if you'll need new hardware.

Re: Bluetooth headphones & AAC

Reply #14
My question is if there's going to be also an updated HFP replacement, cause the current one, even wideband, sucks.

 

Re: Bluetooth headphones & AAC

Reply #15
Bluetooth is a proprietary radio frequency that makes it limited.  20 years from now it will be the same.
exhaleFLAC

 
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