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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. bigshot
    You can feel free to dismiss compressed audio, but the fact remains that the lion's share of the music business consists of compressed audio... iTunes store, Amazon, streaming services like Spotify, Pandora and Tidal... The vast majority of music listeners are listening to music on compressed formats. I think it's kind of important to know how compression works and what it's thresholds are. My library in lossless would span many TBs. It would require a lot more work to backup and manage. And all that extra trouble wouldn't result in one iota of better sound quality. For a small library, it might be different. But most people with small libraries have just turned to streaming so they can have a wider selection of music.

    And repeating again... datarate is not a good measure of sound quality. There are voice codecs that you can boost up to the same data rate as a CD and they still won't achieve transparency. And AAC is able to reach transparency much lower than PCM. The codec is what matters, not the numbers.
     
    Last edited: Jul 22, 2018
  2. shortwavelistener
    Tidal does offer a lossless option if you are subscribing to their premium Tidal HiFi service. BTW i'm a Tidal HiFi subscriber myself. And you forgot Qobuz which also offers hi res compressed music streaming.
     
    Last edited: Jul 23, 2018
  3. PiSkyHiFi
    I don't use hard drives much these days, they are delegated to be archive devices.
    I was a huge advocate for AAC when it was useful, fairly transparent, but not fully - it's lossy.- you've encoded a whole library, same as myself, you would have had it done automatically of course, maybe you could stop making assumptions about how much other people know.

    I still have MP3's in my collection and I use streaming services that use compressed music like Google Play Music.

    It's just that I have nearly my entire collection of FLACs on a micro SD card now... storage is cheap. Doesn't make me rest any differently knowing that.

    Plus there's those automatically converted 1080P HEVC files.... I don't think we'll ever dispense with video compression.
     
    shortwavelistener likes this.
  4. bigshot
    AAC is fully transparent at AAC 256 VBR. The only way to know that is to do a test. If you refuse to do a test, you don't know for yourself. I know. I've done the test. If I tried to put my entire library in lossless on SD cards, I would need about 70 SD cards. Lossless is fine for smaller libraries. But the more music you're storing, the more file size matters. And when you're listening to music, all that matters is what you can hear. High data rate audio and lossless don't affect the way music sounds. I don't need them.
     
    Last edited: Jul 23, 2018
    shortwavelistener likes this.
  5. PiSkyHiFi
    I see a pattern here... people that love AAC are in a situation where they need to compromise in order to listen functionally at all.... storage space, streaming services these days make it too easy to accept lossy as good enough.

    I've been there.... out of all the lossy codecs short of Opus, AAC is fantastic... no doubt, but this thing about it being transparent at 256KBps.... that's just loaded - it's true for most people on your average equipment.

    On most equipment, especially portable equipment, ABX testing on FLAC and AAC will result in no better than random guessing mostly. It's because the differences really are exceptionally small and to hear the difference, you would need to use equipment that can reveal the differences.

    The differences between AAC and PCM are going to be present in phase analysis, compressed audio doesn't focus on recovering phase details like instrument positioning and room timbre - these are very subtle details and they are just examples of what can be heard with the right equipment, human ears can be trained to do rudimentary sonar, they are actually good enough for that.

    This forum is so full of inaccuracies - people generalising about complicated codec algorithms as if there is a clear winner if we just all paid attention to it. There isn't, the math is difficult and relevant and there will be a final word based on statistics when someone finally gets around to it.

    So... to all those people who are probably Apple shills claiming that 256 KBps AAC is simply transparent and so ends the argument, are you prepared to admit that perhaps there exists a sound setup that would reveal the differences to the average listener? Do you just simply think that no equipment, no matter how good could possibly be that revealing?
     
    LajostheHun likes this.
  6. bigshot
    If something sounds the same, to me it *is* the same. I don't "love" any format. I am focused on function. What can do the job in the most efficient way? If you think that I am shilling for any format or company, I'm not the one that is biased in my opinions, you are. I'm simply telling you that if you took a blind listening test to compare AAC 256 VBR to lossless, you wouldn't be able to tell the difference. For the purposes of listening to music in the home there are many audibly transparent formats to choose from. Some are just more efficient than others. AAC is among the most efficient codecs that are able to achieve complete transparency. You can choose to use a less efficient one than another simply because the bigger numbers make you feel more comfortable, but it doesn't make a lick of difference to how it sounds. Both lossless and AAC 256 VBR sound the same.

    Here in sound science, we are allowed to ask for proof. I offered you a test to prove what you say. You declined. That pretty much answers it. You aren't interested in knowing one way or the other. You just want to do whatever you've decided. That is perfectly fine for you. I support your right to pack hard drives and SD cards full of inaudible sound. All I am saying is that transparent is transparent. There is no "better transparency".

    Also, the only time that AAC might have phase problems is if you choose joint stereo at too low of a data rate. No one uses joint stereo any more because just about everyone is using the regular stereo setting at a data rate that supports complete transparency.
     
    Last edited: Jul 23, 2018
  7. PiSkyHiFi
    So, your answer is no then, you don't believe that with the right equipment, you might be able to hear the differences.

    Also, just because shills exist, gives you no basis to assume I am one, who for and why?
     
  8. bigshot
    I have the right equipment and that's what I've used for my testing. All of my equipment is audibly transparent too. The signal coming in is what comes out. Before you ask... yes, I test for transparency with every piece of equipment I buy.

    I'm not the one accusing you of being a shill, you said I was one. I think you have a definite bias though.
     
    Last edited: Jul 23, 2018
  9. PiSkyHiFi
    Well, I'm accusing general people in this forum and elsewhere of not admitting to their own bias when they make a claim that some lossy codec is audibly transparent.... it is biased by definition because it assumes that the threshold for transparent is non-zero.

    You test for transparency... that's great, are you aware that it is impossible to buy a system anywhere that is actually audibly transparent?

    AAC is a fantastic codec ... I said that, maybe I was being biased or just honest.

    So, let me get this right, you put a lot of work in to making a library and you spent a fair amount of time deciding which codec to use and you went with a lossy one.

    That's fine... I've have been there fully myself, but you are now convinced that no one else could possibly ever experience something you haven't, simply because they haven't gone through this process that you have?

    What equipment did you test on?
     
  10. bigshot
    Everyone has biases. The way you eliminate that from consideration is to do controlled listening tests. I’ve done that with three compressed audio codecs and I’ve discovered that they can achieve audible transparency. I don’t care what brand of audio file I use, I just want transparency, convenience and efficiency. The key word there is transparency. I wouldn’t have selected the codec I chose if it wasn’t audibly identical to the original CD.

    I have a 5.1 system in my theater/listening room and for headphones I have Oppo PM-1s and an Oppo HA-1. I have lots of other equipment too. I’ve tested all of it to make sure the electronics are audibly transparent.
     
    Last edited: Jul 23, 2018
  11. PiSkyHiFi
    You and I will never agree, we can't even agree on a definition of audibly transparent.

    Good luck with your library.
     
  12. bigshot
    Quoted from the audio myths thread pinned to the top of this forum...

    49. Trust Me I'm a Scientist - Audio Poll: Neil Young and High-Definition Sound, May 2012

    A bind test of a high def WAV file version of Neil Young's self titled debut album against some standard AAC files.

    "The majority of you are audio engineers, professional musicians, and ambitious hobbyists, and I figured that if anyone would be able to tell these file types apart, it would be you guys.
    So, how did you do?
    Well… please accept my warm congratulations to the 49% of you who guessed right.
    That’s right: even among our readers, the results came out no better than a coin flip. And we didn’t even need a huge sample size to get a result that’s consistent with the tremendous mountains of research already done in this field."

    Another blind test that foiund pretty much the same thing....
    https://cdvsmp3.wordpress.com/cd-vs-itunes-plus-blind-test-results/

    "Notice that, despite deviations, both distributions have similar bell shapes. Furthermore, all reliable p-values are in favor of the null hypothesis stated, some of them in high agreement. So, based on the data obtained, the most reasonable conclusion is that we can’t hear the difference between CD audio and iTunes plus. And this is true in all the cases considered—being young, with our sense of hearing at its peak, having musical training or using excellent audio gear doesn’t seem to help."
     
    Last edited: Jul 23, 2018
  13. PiSkyHiFi
    I pretty much agree with most of what you're saying, since as I mentioned earlier, I have been through all of this before years ago when it was important because space was expensive. I first had MP3, then recently I used libfdk AAC for my portable player - at 320 Kbps.

    For the higher res files, I actually encoded to 640 Kbps, just to preserve stuff I couldn't hear every time - probably not necessary on the portable player because it doesn't have the analog quality level to reveal possible differences.

    You've made a commitment to AAC at 256 Kbps, that's fine, but it was a compromise despite your efforts to convince yourself it wasn't - it allowed you to save money on storage and now you can say things like audibly transparent, but audibly transparent means sounds the same as no electronics at all, so I think you shouldn't be using that term unless you can define it better.

    Those times are over though.... there is no need to justify lossy any more, because it will disappear eventually.

    It's simple, I have a FLAC and I have an AAC mpa file, which one do I use if I can now store either one in my phone without issue?

    It's a no brainer. My phone storage (a 256 GB Micro SD) is now about 80% FLAC and about 5% MP3 for the tracks I don't have FLACS for.
     
  14. bigshot
    I've compared AAC 256 VBR to lossless on high quality equipment using careful controls. I posted a couple of published tests that showed that there was no audible difference to trained ears or on high end equipment. That is evidence to support my statement that AAC 256 VBR sounds every bit as good as FLAC. Why have files that are 5 to 10 times larger if they don't sound better?

    You say that lossy is going to disappear. The opposite is true. Compressed audio and video dominates the market and there's no indication that it won't continue to do so. I haven't seen you present any evidence that AAC 256 VBR isn't audibly identical to lossless, and I haven't seen you cite any evidence to support your argument that compressed formats are going away. Do you have anything to back that up? I'm actually curious to see what you base those ideas on.
     
  15. PiSkyHiFi
    How about the dwindling 5% of my collection that is still stored lossy?

    I'm not that atypical, not even rich - I'm here because people were picking on AptX HD and I've already been through this mill - it's not a better codec than AAC, but given it's using 576 KBps data rate and lossless equivalent is only 50% more than this for Redbook, I'm pretty much done with anything less completely.

    So, I use Google Play Music happily at 256 Kbps AAC - re-encoded by AptX HD sometimes when I'm out and about.

    But when I want to stretch my dynamic range and hear something I haven't heard before - like I do every time I pick up my home audio equipment, I have absolutely no need for compressed audio at all. I do listen for things I haven't heard before and sometimes I get lucky, but they need to be there for me to hear them.

    Right now. 2018.
     
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