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Audio over Bluetooth: most detailed information about profiles, codecs, and devices...

BillG

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#1
Somewhat technical in parts, but nicely summarized - I can't attest to the validity of their findings, though. From a personal, and purely subjective, perspective I don't find SBC, AAC, or aptX to be particularly bad sounding codecs when I occasionally stream via Bluetooth. No... they don't sound as good as my streaming via WiFi, but they don't sound awful, either... :cool:

Conclusion
"Can Bluetooth completely replace wired headphones and headsets? Probably, but at the cost of low quality voice, increased latency in sound transmission, which can be annoying in games, and a multitude of proprietary codecs that require license fees and increase the final cost of both smartphones and headphones. The marketing of alternative codecs is very strong: aptX and LDAC are presented as a long-awaited replacement of the “outdated and bad” SBC, which is far from as bad as it is commonly thought of. As it turned out, the artificial limitations of Bluetooth stacks on SBC can be bypassed, so that the SBC will be on par with aptX HD. I took the initiative and made a patch for LineageOS firmware: Modifying Bluetooth stack to improve the sound on headphones without AAC, aptX and LDAC codecs."

https://habr.com/en/post/456182/
 
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#3
After reading that article and doing a thorough listening test myself, I noticed that out of AptX, (high quality) SBC, and LDAC, AptX actually sounded the worst. On busy sections it would get congested and muddy, lacking in dynamics.

I ran some measurements through RMAA that I detailed here: https://www.reddit.com/r/headphones/comments/ci7gqt
TL;DR yikes:

That's all noise rather than IMD on the AptX squiggle. Dynamic range gets crushed really hard when you push AptX with complex music. AptX HD does the same thing, to a lesser extent, though I can't do any listening tests with it at the moment.

By contrast, SBC has some distortion products in the highs which AptX does not. So SBC highs sound brighter and harsher than direct wired, but there is no muddiness or congestion like with AptX.

LDAC is practically imperceptible.
 
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Jimmy

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#5
Trouble is that LDAC, and AptX, too, are propietary licensed technologies, in my experience different devices (even different bluetooth adapters with standard Windows 10 drivers) produce vastly different results, so it's hard to make a judgement.

In my opinion what the market for wireless audio needs is a new open standard that allows lossless capabilities, and less companies making profits from licensing technologies that could be easily replaced by open alternatives.
 

BillG

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#7
wireless audio needs is a new open standard that allows lossless capabilities
Lossless on Bluetooth? I don't think that's going to happen just yet because of the energy usage restrictions of the technology as utilized by the cellular industry. Additionally, the Bluetooth standard contains bit rate fallback requirements in relationship to signal degradation, etc.
 

Jimmy

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#8
Right, oreo and later has it, but what about headphones, receivers, etc.?, what they get is a larger user base, at the beginning only sony smartphones were enabled.

As I understand it Sony has given ldac away for use on Android, so it's free for that. Apple are not going to start using it even if it was really free.
 

Jimmy

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#9
With bluetooth 5.0 it is possible, it can transmit at 2 Mbps (short range, though), and there's also bluetooth AMP (uses wifi to transmit data), so the hardware should be capable as of today.

Lossless on Bluetooth? I don't think that's going to happen just yet because of the energy usage restrictions of the technology as utilized by the cellular industry. Additionally, the Bluetooth standard contains bit rate fallback requirements in relationship to signal degradation, etc.
 
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#11
Thanks for this! I recently got back into wireless music for the occasional travel, and I honestly feel that such a use-case is typically where Bluetooth serves its purpose at its best; and usually you'll have much bigger problems to worry about (ambient noise and all) that the codec should really be the lowest order of concern. Like my Bose QC35II aren't the best sounding headphones in the world, but the Active Noise Cancellation more than makes up for whatever shortfalls in audio quality it may possess. Not to mention not having to deal with cables getting tangled up and caught on random everyday objects while moving around is a huge plus as well!
 

maxxevv

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#12
And that's why it won't be used in a lossless transmission scheme would be my guess - the energy requirements when using WiFi would be too high for practical day-to-day usage.
On a portable device perhaps but on a desktop one, such as the popular Topping DX3 Pro and now the D50S, it shouldn't be a problem.
 

BillG

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#13
On a portable device perhaps but on a desktop one, such as the popular Topping DX3 Pro and now the D50S, it shouldn't be a problem.
And Bluetooth's primary domain is portable devices in the context of this discussion. The vast majority of people seeking wireless streaming in stationary environment, where energy usage and signal degradation are of less concern, would choose WiFi for audio because of its ability to transmit lossless.
 

Krunok

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#14
And Bluetooth's primary domain is portable devices in the context of this discussion. The vast majority of people seeking wireless streaming in stationary environment, where energy usage and signal degradation are of less concern, would choose WiFi for audio because of its ability to transmit lossless.
I agree. BT has capability as WiFi (which btw also falls back to lower transmit rates when signal degrades) to transmit lossless, but as BT was from the start designed to be short range/low energy technology I don't think it is reasonable to expect lossles over BT - WiFi is a more suited technology for that and SBC codec can produce decent results if implemented carefully.
 

JJB70

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#15
Very interesting. I think that within its limits BT works extremely well. As has already been said, for mobile use its positive attributes outweigh its negatives and BT headphones like the QC35 and 1000X series are very good. However for wireless hifi in home applications then WiFi does seem to be a better option.
 

Jimmy

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#16
Lossless audio over bluetooth 5.0 (red book) is perfectly possible 1.4 < 2.0 Mbps, however there's nothing new for audio in sight, the new capabilities are advertised for other means, but the hardware is already there.

Wifi is just a tradeoff, bluetooth is much less power hungry, but I'm pretty sure that headphones like the Sony 1000XM3 with a 1000 mAh battery would still be able to provide decent autonomy if fitted with that technology.

And that's why it won't be used in a lossless transmission scheme would be my guess - the energy requirements when using WiFi would be too high for practical day-to-day usage.
 

Krunok

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#17
Lossless audio over bluetooth 5.0 (red book) is perfectly possible 1.4 < 2.0 Mbps, however there's nothing new for audio in sight, the new capabilities are advertised for other means, but the hardware is already there.

Wifi is just a tradeoff, bluetooth is much less power hungry, but I'm pretty sure that headphones like the Sony 1000XM3 with a 1000 mAh battery would still be able to provide decent autonomy if fitted with that technology.
I'm not sure if you understand that, no matter how smart power management you implement, power consumption of the BT, and every other wirelss technology, is proportional to the ammount of data been sent plus some overhead to keep the connection alive. That means that the moment you start to stream app 1Mbps, which you need for compressed losless audio like FLAC, BT will start to consume much more energy than what it is consuming now and most devices simply wouldn't be able to handle that.
 

maxxevv

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#18
The vast majority of my FLAC files are under 800kbps. So for BT 5.0 throughput, it shouldn't be an issue. However, it would mean more processing power needed to decode the compression. Which in itself is an energy consumption issue.

So it will still be an trade-off until chips get more processing power at the same or lower power consumption levels. OR batteries have a higher storage density than what is currently available economically I guess ?
 

Krunok

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#19
The vast majority of my FLAC files are under 800kbps. So for BT 5.0 throughput, it shouldn't be an issue. However, it would mean more processing power needed to decode the compression. Which in itself is an energy consumption issue.

So it will still be an trade-off until chips get more processing power at the same or lower power consumption levels. OR batteries have a higher storage density than what is currently available economically I guess ?
It's about batteries, not about chips. And the consumption is about high transfer rate, not about chips doing the decoding.
 

BillG

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#20
So it will still be an trade-off until chips get more processing power at the same or lower power consumption levels. OR batteries have a higher storage density than what is currently available economically I guess ?
With the current thinness wars going on in the smartphone industry, we're going to need new battery technology to compensate for that. They're working on it, as outlined in the article below, but we're not quite there yet... :cool:


https://www.pocket-lint.com/gadgets...in-seconds-last-months-and-power-over-the-air

In all honesty, lossless over Bluetooth isn't a real concern of mine - I rarely use it anyway, and prefer my USB-C earphones at the moment for on-the-go. However, audio transparency is. We appear to be getting quite close to that, and I suspect we'll see it within two - four years, if we've not already with LDAC. But I've no products that receive it, so I can't say for myself.
 
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