giant3 t1_jdb74sg wrote on March 23, 2023 at 3:21 AM

Reply to comment by AudiophileHeaven in Bluetooth Sound Quality, me trying to explore what is the difference between different bluetooth codecs, which sounds best, and why, along with how to get the most stable connection possible by AudiophileHeaven

> AAC codec and AAC bluetooth are two separate things

You couldn't be more wrong. The bit stream of AAC is very clearly documented and 2 different decoders should produce the same bit stream after decoding.

Any difference that exists is in encoding. There were differences 15 years ago when iOS encoder was superior, but now both Android and iOS are on par.

blorg t1_jdci6ny wrote on March 23, 2023 at 12:41 PM

This Soundguys comparison is from 2018, and it shows major differences in AAC encoding between iOS and Android, and for that matter between Android phones.

I don't think simply looking at the high frequency cut-off really tells much about audio quality, it's not the largest factor, and particularly when many of them are high enough that I know I wouldn't hear the difference personally. But it does indicate objectively that there were at least differences between the encoders as recently as 5 years ago, you don't need to go back 15.

AAC on my phone running Android 12 is also still truncated, I think around 17kHz. Subjectively, I think it sounds good, I don't think that's a problem. Arguably, cutting at 17kHz they don't have to waste as many bits on frequencies that most people can't hear. But it's lower than apparently iOS does it (Soundguys says it goes to 18.9kHz).

AudiophileHeaven OP t1_jdcr6ef wrote on March 23, 2023 at 1:51 PM

u/blorg - This is exactly how I documented it too, and rings true with my findings. Two Android phones can show significant differences between how they handle AAC and the same for iPhone vs Android. iPhone always has superior AAC encoding regardless of the test.

I also agree that the high cutoff won't always matter as it is likely that most people can't hear above 18kHz or even 17kHz, but it shows the difference, and if you place them side by side you can hear some differences, it is not just the high end cutoff that's different.

giant3 t1_jdd0v1t wrote on March 23, 2023 at 2:57 PM

I am very well aware of this article from sound guys.

BTW, I was talking about encoders while you are talking about difference in configuration. The Android encoder was developed by Fraunhofer Institute, the very people who invented MP3 & AAC, but the manufacturer can set the bandwidth of the encoder. If the phone is rooted, we could change the bandwidth.

Anyways, the cutoff doesn't matter much. There is very little energy in music beyond 13kHz except for cymbal crashes.

blorg t1_jdd3q6h wrote on March 23, 2023 at 3:16 PM

Right, but it doesn't matter whether it's the encoder or the parameters, the point is the result is different.

If you increase the parameters on SBC (SBC XQ) it can sound great too, but that doesn't help you particularly if the bitpool is artificially limited to a low bitrate as is done on Samsung buds (bitpool 37 rather than 53) and I believe, Windows.

That you could theoretically get a different result if the parameters were different, doesn't get you the different result, you get the result with the parameters chosen by the developers of the stuff you are using.

The Apple encoder is I believe different from the Fraunhofer one, and is supposedly, better. So there it's not just the parameters. But even if it was just the parameters, the average user isn't rooted and can't change the parameters. So it doesn't matter whether it's the "encoder" or the "parameters".

Personally- I think AAC sounds fine on Android, so I'm with your there.