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Well, AptX is shit (non-lossless), the only okay codec in use is LDAC, and it's by brute force - 990kbps is awfully close to flac typical bitrate (you'll also get connectivity issues for obvious reasons). Also legal reasons - everyone wants $$$$ for their shit codec

I don't know why the whole ecosystem is so fucked up, even AAC ~256kbps can pass double blind test against lossless source, assuming properly encoded and decoded - this assumption is not fulfilled in a slightest in Bluetooth land.

P.S. I really want to see some good and open codec, like .opus, properly implemented - this will close major source of frustration for everyone involved and will drive whole industry forward

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I feel like the real improvement in aptx is not the audio quality, but the latency for keeping audio and video in sync when watching tv (or computers for that matter). I used to work in the bluetooth chip industry and there really were very few players who were competitive in the audio headset business. I don't have any real insight into the players these days, but I would be very surprised if there were more than 4 chip makers who were competitive in that space. CSR was the dominant player for audio, so it's not surprising that Qualcomm who bought CSR offers this proprietary solution. So I think it's going to be really hard for someone to make an open codec solution that competes in terms of size, battery life, cost with an IC that's targeted to the market.

>but the latency for keeping audio and video in sync when watching tv (or computers for that matter).

realistically speaking latency only matters in games/calls. For any sort of media playback you can just delay the video stream to compensate.

Afaik that solution isn't available on any existing consumer electronics for legacy bt audio e.g. a2dp.

... Which are incredibly common everyday use cases for the majority of users. I don't see why latency should be sloughed off as unimportant.

There's also LHDC/HWA from Huawei/Savitech(?) for the two headphones that support it. It's approved by the Hi-Res society or whatever like LDAC.

Good luck finding a system that can play back LHDC though. At least thr LDAC encoder is free (to my knwoledge) and Android and PipeWire have support for it. LHDC, you'd better get the one of three phones that support it (from Huawei, Xiaomi, maybe OnePlus I think). I mean, Savitech has their forked fluoride Bluetooth stack + aarch64 LHDC binary blob and wrapper library source code on GitLab but I guess you'd have to hack something together to try it.

I'm very much in favour of Opus on Bluetooth and if you browse Reddit you will find someone has attempted to work on it but no details past that: https://www.reddit.com/r/hardware/comments/enad1t/comment/fd....

What is the latency for something like AAC? How much power does it take to encode and decode?

It seems to me like some of the big constraints on codec choice are power, latency and then quality. Maybe “spectral efficiency” too, but I don’t really know.

Could be why they are using a high rate lossless codec? Maybe said codec is super efficient to encode on a tiny airpod with a tiny power source?

I guess what I’m saying is maybe there are additional constraints specific to this problem domain that aren't a concern for the rest of us?

That doesn’t mean it can’t be an unencumbered, open source codec though. It just might mean the “common” ones out there don’t fit the constraints of the system.

AptX adaptive is an adpcm codec, so there is no artifact except for a higher noise level.

At 460kbps it's very very similar to LDAC at 990kbps.

It's also unlike AAC a truly adaptive codec.

If you really need it AptX also has a lossless mode iirc.

The best codec would obviously be to just use Opus, yeah. But AptX adaptive pretty much solves Bluetooth audio.

No idea how it supposed to work in theory, in practice every device combo i tried works noticably worse with AptX (than LDAC, even non-990 one). Don't have any device capable of AptX lossless.

Re: solve - as long as there are licensing issues, it can't solve BT Audio even if it was such great codec

P.S. Random link from google with measurements of some actual device using AptX, AAC, LDAC

https://www.audiosciencereview.com/forum/index.php?threads/t...

How are you able to know which codec is being used over the Bluetooth link?

E.g. my device (Fiio BTR5) tells me on its builtin display. Also for LDAC there's separate toggle in UI. Also Developer Tools stuff

Again, that is AptX, not AptX HD or AptX adaptive. I don't think the lossless mode is in any product yet.

Aptx is actually pretty good, certainly for ear pods. It's a time-domain codec which is great for acoustical instruments (the frequency-domain codecs can fail there, AAC too).

The signal-to-noise ratio is lower than CD quality but still good enough so that noise is not audible:

http://soundexpert.org/articles/-/blogs/audio-quality-of-blu...

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