iPhone AAC vs. Aptx and Aptx-hd real world
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LajostheHun

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aptX is superior to AAC because it uses time domain ADPCM instead of perceptual encoding (which are based on psychoacustic models) which are commonly used by MP3, AAC and WMA. This makes aptX more efficient than other lossy codecs.

aptX sounds more like WavPack Hybrid Lossy, since the compression artifacts sounds identical on low frequencies (mild distortion + cassette like hiss)

So if there any AAC file that has been transcoded into aptX, there will be minimal changes to SQ as aptX will not "shave" off very high or low frequencies like what MP3 does, rather it varies the size of the quantization step, to allow further reduction of the required data bandwidth for a given S/N ratio.

So a 16 bit AAC file will be transcoded by the BT device into a 6 or 8 bit ADPCM file - which is 99% indistinguishable from the original file, and that is what you are going to hear when using an aptX device.
I consider APTX superior too, so I'm not sure why you quoted me, but in any case the differences are extremely subtle IMO, not worth losing sleep over it.
 
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Also in your earlier message that i quoted, you said that aptX splits the signal into four sub-bands. Does that mean that the signal encoding of aptX is the same as SBC? And does it also applies to LDAC as well?
 
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I consider APTX superior too, so I'm not sure why you quoted me, but in any case the differences are extremely subtle IMO, not worth losing sleep over it.
The difference between AAC and MP3 is subtle and probably impossible to ABX at 256 kb/s. aptX causes audible degradation which ruins the listening experience in particular songs if you know what it's supposed to sound like. This happens only in particular notes in particular songs, so it's a non-issue 95% of the time. I have not heard aptX HD yet so I can't comment on its subjective quality.

This document shows other flaws of aptX.
https://docs.wixstatic.com/ugd/fb72a4_a6a76213617c46c38213e298784bff55.pdf
 
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https://www.head-fi.org/threads/radsone-earstudio.867366/page-22#post-14086297
My take away from this is that aptX and aptX HD are barely better than SBC. They are essentially just low bit-depth ADPCM with variable noise floor across bands. The audible artefacts are probably due to implementation flaws rather than the codec itself.

AAC and MP3 are vastly superior codecs and it's laughable to even compare them to low bit-depth ADPCM. It's like comparing FM radio to a modern digital connection.

SBC and aptX are relics from an era where manufacturing low-power chips was challenging.
 
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https://www.head-fi.org/threads/radsone-earstudio.867366/page-22#post-14086297
My take away from this is that aptX and aptX HD are barely better than SBC. They are essentially just low bit-depth ADPCM with variable noise floor across bands. The audible artefacts are probably due to implementation flaws rather than the codec itself.

AAC and MP3 are vastly superior codecs and it's laughable to even compare them to low bit-depth ADPCM. It's like comparing FM radio to a modern digital connection.

SBC and aptX are relics from an era where manufacturing low-power chips was challenging.
Ironically, SBC is the core technique used in popular lossy audio compression algorithms including the entire MPEG 1 Audio Layer family (MP1/PASC, MP2/Musepack, MP3 and MP4/AAC).
 
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Waiting for the day they make Bluetooth audio SQ the same as wired + a good DAP + FLAC/lossless files ~
 
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Waiting for the day they make Bluetooth audio SQ the same as wired + a good DAP + FLAC/lossless files ~
Let see if the upcoming Bluetooth 5.1 can permit true lossless audio streaming using true lossless compression and not aptX.
 
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Audible transparency is the goal. There’s more than one way to skin a cat.
 
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Audible transparency is the goal. There’s more than one way to skin a cat.
Yes, and aptX HD achieves audible transparency at 1/4 of the bitrate of a standard audio CD.

(4/4 or full CD quality = 1411.2 kbps, while 1/4 = 352.8 kbps)
 
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AAC is transparent at around 256
 
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AAC is transparent at around 256
For you maybe, Apt X HD is a transmission protocol, which means is better to use higher bandwidth hardware to achieve better transparency. 576 Kbps is a step forward than assuming everyone's gear can only handle no better than AAC. Come on , it's obvious, to pretend the math is out is revealing what you think about Apple.
 
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For you maybe, Apt X HD is a transmission protocol, which means is better to use higher bandwidth hardware to achieve better transparency. 576 Kbps is a step forward than assuming everyone's gear can only handle no better than AAC. Come on , it's obvious, to pretend the math is out is revealing what you think about Apple.
True that, and FYI AAC is "transparent" at 256 kbps due to the fact that it is "psychoacoustically" equivalent to CD quality. However if an audiophile has the right equipment as well as the basic knowledge about what to hear in AAC then they can differentiate which (lossy) codec are transparent at certain bitrates as well as comparing the codecs via an ABX test, etc.

Just my 2 cents...
 
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Also in your earlier message that i quoted, you said that aptX splits the signal into four sub-bands. Does that mean that the signal encoding of aptX is the same as SBC? And does it also applies to LDAC as well?
Aptx predates all of the lossy encodes currently in use, as it was developed in the late 80's for broadcasting, since then it was sold several times, currently owned by Qualcom. Don't know if it works the same exact way as SBC, I doubt it just from the patent POV but APTX HD does, LDAC does not as it is Sony's brain child.
 
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True that, and FYI AAC is "transparent" at 256 kbps due to the fact that it is "psychoacoustically" equivalent to CD quality. However if an audiophile has the right equipment as well as the basic knowledge about what to hear in AAC then they can differentiate which codec are transparent at certain bitrates as well as comparing the codecs via an ABX test, etc.

Just my 2 cents...
Can you please point me to ANY peer reviewed test which shows this to be true please. A group of us tried this on Head-Fi years ago (one had a Stax set-up, and was able to successfully ABX MP3 320 from FLAC - most of us couldn't). The same guy failed repeatedly on aac256. As long as it was the same master recording, and double-blind volume matched ABX (with no transcoding errors) - I'm yet to find anyone who can reliably do this. I've searched and I can't find any definitive tests either.

I know in my own double blind volume matched tests - aac256 is transparent to me. I still archive everything in FLAC (may as well have a lossless copy right) - but all my listening (portable) is done with aac256.
 
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