Highest possible AAC quality

Discussion in 'Digital Audio' started by vladobizik, Feb 11, 2014.

  1. vladobizik macrumors 6502

    Joined:
    Aug 21, 2012
    Location:
    Slovakia
    #1
    TLDR: Is there a higher theoretical AAC quality level than “VBR Constrained, 320-381kbps”?

    I appreciate music in as high quality as possible, although I cannot be described as a true audiophile by any means – for example, I value convenience about as high, if not slightly higher than sheer quality - I am an iTunes Match subscriber and I stream my music from it, even on my Mac. As you may know, if you have any lossless tracks in your collection, it automatically converts them to a 256 kbps AAC file, whether it is matched or uploaded. There is nothing inherently wrong with that, but at least for the tracks that are not available on iTunes, I would like to upload them in higher bitrates – if the codec used is lossy, iTunes doesn’t convert the file, regardless of the bitrate. At first, I used to rip all my CDs to 320 kbps AACs in iTunes. Later, I started using a great piece of software called Pro Audio Converter (highly recommended and available here: https://itunes.apple.com/us/app/pro-audio-converter/id445279797?mt=12 ) it has tons of these handy settings and the mode which seems to produce the highest bitrates and largest AAC file sizes is the “VBR Constrained” mode which keeps the bitrate between 320 and 381 kbps at all times. The files produced with this mode have nominally highest bitrates I could ever achieve. Since I discovered this mode, I have been ripping new CDs and also re-ripping some old ones (those that iTunes Match didn’t find a match for; and I have tons of those) to this quality level. I know many of you will say that it’s a waste of space and effort, especially if the difference is virtually inaudible and if tons of my music is matched and “only” in iTunes Plus quality anyway. But I would like to ask – is this really the highest theoretical quality I can get from AAC or can I still squeeze something more out of the format?
     
  2. MacUser2525 macrumors 68000

    MacUser2525

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #2
    Best you can do with AAC is Apple lossless encoding. As the name implies you lose none of the information contained in the resulting file after conversion from your CD. It uses the same idea as when compressing a text file or similar it strips out the redundant 1 and 0 leaving you with the same information as was contained in the original file. Files are going to be huge (roughly 4-5 times larger) though for example below lossless AAC and mp3 from my collection, I use the mp3 on my iPod.


    Code:
    MacUser2525:~$ ll /Volumes/WD_4/Music/AAC/3_Doors_Down/3_Doors_Down_2000_The_Better_Life/3_Doors_Down-The_Better_Life-01-Kryptonite.m4a 
    -rw-r--r--@ 1 MacUser2525  staff    27M 20 Nov 03:27 /Volumes/WD_4/Music/AAC/3_Doors_Down/3_Doors_Down_2000_The_Better_Life/3_Doors_Down-The_Better_Life-01-Kryptonite.m4a
    
    MacUser2525:~$ ll /Volumes/WD_4/Music/MP3/3_Doors_Down/3_Doors_Down_2000_The_Better_Life/3_Doors_Down-The_Better_Life-01-Kryptonite.mp3 
    -rw-r--r--  1 MacUser2525  staff   5.5M 22 Oct 01:31 /Volumes/WD_4/Music/MP3/3_Doors_Down/3_Doors_Down_2000_The_Better_Life/3_Doors_Down-The_Better_Life-01-Kryptonite.mp3
    If you go the lossless route XLD is a nice little program for ripping your CD to it.
     
  3. vladobizik thread starter macrumors 6502

    Joined:
    Aug 21, 2012
    Location:
    Slovakia
    #3
    I am of course aware of Apple Lossless (although technically it's not AAC, although they come in the same container format), but since iTunes Match converts all lossless audio to lossy 256kbps AACs, it's not really a route I can take. I am okay with a lossy compression, just looking for the best quality "AAC proper" can give.
     
  4. Johbremat macrumors regular

    Joined:
    Feb 8, 2011
    #4
    If you have a Windows machine, neroAAC codec allows you to encode at 512kbps.

    Haven't done an AB, so wouldn't know if any increase in quality can be perceived.
     
  5. Julien, Feb 16, 2014
    Last edited: Feb 16, 2014

    Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #5
    ....but why go lossy at 512kbps when ALAC is only a small amount more, usually 700kbps to 900kbps (even lower for classical music)?

    Not sure what the OP is trying to accomplish. You either go lossy to save space or you go lossless to get the best possible SQ/archive. You can always take lossless and make any version of lossy out of it any time you want but you can't do it the other way. Once you go lossy you have lost it forever (unless you re-rip).

    EDIT: After rereading the OP it looks like he/she wants to upload to Match higher bit rate songs. I don't believe this is possible. I think Match will only allow an upload max of 320kbps MP3's or 256kbps AAC. Anything higher will be converted to 256kbps AAC.
     
  6. Johbremat macrumors regular

    Joined:
    Feb 8, 2011
    #6
    Just providing a public service, giving the OP information relative to their query, rather than passing opinion.


    One of the takeaways from http://support.apple.com/kb/HT4914 is that "ongs encoded in ALAC, WAV, or AIFF will be transcoded to a separate temporary AAC 256 Kbps file locally, prior to uploading to iCloud. The original files will remain untouched".

    OP realises that lossless is transcoded before upload to iCloud, but is under the belief that AAC won't be. As such, they're asking after a higher bitrate in the hope that they can stream back at something higher than 256.
     
  7. RoboWarriorSr macrumors 6502a

    Joined:
    Feb 23, 2013
    #7
    Sorry to bring this up but I didn't want to start another thread. Does iPhone support 512 kbps AAC or is it limited to 320 kbps AAC like in the technical specs?
     
  8. scilix macrumors newbie

    Joined:
    Jun 26, 2014
    #8
    iTunes Mastering Droplet

    The Best way to make lossy file with high quality (and bitrate) is use iTunes Mastering Droplet (Apple Mastering Tools), IMHO. Everyone can download it from Apple site.
    But it needs a little refinement. It is necessary to change the bitrate AAC file from 256000 to 320000 in the Script Editor:

    " -d aac -f m4af -u pgcm 2 --soundcheck-read -b 320000 -q 127 -s 2 "

    You can also change CAF file settings sample rate with 44100 to 48000 (if you want to convert Vinyl Rip):

    " -d LEF32@48000 -f caff --soundcheck-generate --src-complexity bats -r 127 "

    With that changes you get VBR Constrained AAC file with max bitrate. I saw that in my files 460 kbps bit rate reached the peak. You can see the real time bitrate via VLC. (But in the file you see in iTunes will be written 320 kbps).

    It is really very good sound quality.
    And some more thing: a lot of poorly recorded music, music on CD recorded with a cutoff frequency above 15 kHz.

    P.S. If you have OS X 10.10 it needs (with Script Editor) change in iTunes Mastering Droplet systemVersion from 10.6 to 10.10. It does not work in other way. (Search it with Find/Replace tool)

    Good luck!
     
  9. RoboWarriorSr macrumors 6502a

    Joined:
    Feb 23, 2013
    #9

    Is this the same encoder that XLD uses? I would hate to re-encode all my music once again.
     
  10. MacInTO macrumors 6502a

    MacInTO

    Joined:
    Apr 25, 2005
    Location:
    Canada, eh!
    #10
    I've been converting/encoding all of my CDs to 320kbs VBR. It seems to be fine. I have a mid-range audio setup. I think the biggest improvement for sound is the amplifier and speakers.
     
  11. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #11
    What is the point since it doesn't save any significant space? You can use ALAC and go completely lossless and it will only be an average of about 30% or less larger files. Some music will even take less than 512Kbps to be lossless.
     
  12. RoboWarriorSr macrumors 6502a

    Joined:
    Feb 23, 2013
    #12
    All my lossless music are at least 768 Kbps so no worries there. Yeah, I encode at 320 Kbps "CBR" AAC
     
  13. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #13
    Actually is goes in cycles. If you listen to the iPad with the built-in speaker then 128K MP3 is good enough. But then you upgrade to decent speakers or even cheap headphones and you decide 128K MP3 is not so good. This keeps going each time you get better audio gear until finally you think you need the lossless files. After all ONLY the lossless files capture ALL the detail that is on a CD.

    It should be obvious that only lossless is without some loss of quality.

    It makes perfect sense however to compress music when it is placed on you iPod/iPhone and iTunes will do this. It will compress as it downloads so you can keep the lossless on the computer and the compressed on the phone.

    That said, many people, maybe most people will NEVER invest in a good HiFi audio system. Few people care enough about sound to spend over $1K. That is kind of the breaking point between the low and higher end of audio.
     

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