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iPhone AAC vs. Aptx and Aptx-hd real world

Discussion in 'Sound Science' started by neil74, Oct 4, 2017.
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  1. LajostheHun
    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.
  2. shortwavelistener
    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?
  3. Monstieur
    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.
    Last edited: Jul 16, 2018
    Jearly410 likes this.
  4. Monstieur
    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.
    Last edited: Jul 20, 2018
  5. shortwavelistener
    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).
  6. Colors
    Waiting for the day they make Bluetooth audio SQ the same as wired + a good DAP + FLAC/lossless files ~
  7. shortwavelistener
    Let see if the upcoming Bluetooth 5.1 can permit true lossless audio streaming using true lossless compression and not aptX.
    Colors likes this.
  8. inspectah_deck
    I don´t see any data about aptX HD in this post to conclude that.
    Although I´m thankful for your informational posts, I notice a pretty agressive pro AAC, contra aptX tone in your posts, which I find unnecessary.
    shortwavelistener likes this.
  9. bigshot
    Audible transparency is the goal. There’s more than one way to skin a cat.
  10. shortwavelistener
    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)
  11. bigshot
    AAC is transparent at around 256
  12. PiSkyHiFi
    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.
    shortwavelistener likes this.
  13. shortwavelistener
    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...
    Last edited: Jul 21, 2018
  14. LajostheHun
    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.
  15. Brooko Contributor
    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.
    Jearly410 likes this.
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