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Old 2nd April 2021, 13:54   #1  |  Link
FranceBB
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Bluetooth codecs in 2021, which one to pick

Hi there,
although I'm very familiar with normal audio codecs like AAC, AC3, AC4, Opus, PCM, Vorbis etc, I'm not really familiar with bluetooth codecs.
Here is the thing, when I connect my bluetooth headsets, the computer is asking me which codec to use among the following using the A2DP Sink:

- SBC
- AAC
- aptX
- aptX HD
- LDAC

It doesn't specify anything like bitrate, sample rate, bit depth etc, so I have no idea about the specs, which annoys me... a lot.
Doing a bit of research, it looks like all of the support the output of my sound card setting, so 48'000Hz passthrough (with 44100Hz resampled automatically to 48kHz), however not all of them support 32bit (which is my output).
If I got that right, it should be:

SBC: 16bit 48'000Hz 345kbit/s CBR 2ch Stereo
aptx: 16bit 48'000Hz 384kbit/s CBR 2ch Stereo
aptX HD: 24bit 48'000Hz 576kbit/s CBR 2ch Stereo
LDAC: 32bit 48'000Hz 990kbit/s CBR 2ch Stereo

So, although I don't know the codec implementation, what's their psycho-acoustic, which transform they use etc, it looks like LDAC is the clear winner here as it's the only one that can actually output a 32bit precision stream. I also gladly noticed that it uses a modified version of the classic DCT, so it looks good. I actually tried to listen to those codecs myself and although I wasn't able to hear any difference between aptX HD and LDAC while playing AAC radio stations like BBC Radio 1 or Capital London or YouTube Music, but I was able to hear the difference while playing commercially available PCM files from CDs. So... should I just pick LDAC and go ahead with it?

I'm sorry for all those questions but I'm really not familiar with bluetooth codecs...

Last edited by FranceBB; 2nd April 2021 at 14:04.
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Old 2nd April 2021, 15:23   #2  |  Link
tebasuna51
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Is normal don't hear differences with these bitrates, I recoded to flac a Cat Stevens CD and I obtain an average bitrate of 792 Kb/s, for stereo sources AAC encodes at 192 Kb/s are considered transparent.

aptx and LDAC are proprietary audio codecs, if you have already pay to use it don't worry and use the best LDAC
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Old 2nd April 2021, 16:34   #3  |  Link
hajj_3
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LC3 and LC3 Plus are new codecs which were added in Bluetooth 5.2: https://www.iis.fraunhofer.de/en/ff/...ation/lc3.html

I don't know if any headphones are out yet that support bluetooth 5.2 yet.

Last edited by hajj_3; 2nd April 2021 at 16:37.
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Old 2nd April 2021, 19:24   #4  |  Link
FranceBB
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Quote:
Originally Posted by tebasuna51 View Post
aptx and LDAC are proprietary audio codecs, if you have already paid to use it don't worry and use the best LDAC
Got it. I'll stick with LDAC then.

Quote:
Originally Posted by hajj_3 View Post
LC3 and LC3 Plus are new codecs which were added in Bluetooth 5.2.
I don't know if any headphones are out yet that support bluetooth 5.2 yet.
Dunno, but definitely not mine, otherwise it would have been listed in the option.
Anyway, I'll stick with LDAC which is the best one I can pick with my bluetooth version, but thanks for the heads up anyway.
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