256 aac vs mp3 - which sounds better

Discussion in 'Music Corner' started by MikeP5877, Oct 18, 2012.

  1. fadingcaptain

    fadingcaptain Active Member

    Location:
    southeastern pa
    Good info, thanks guys. Maybe I'll do a 256/320 AAC VBR shoot-out, and see if I could even tell a difference.

    (For the lossless, I'm also doing ALAC rips - XLD lets you rip to multiple formats simultaneously, which is pretty cool).
  2. ShallowMemory

    ShallowMemory Forum Resident

    Location:
    GB
    I was genuinely shocked nay surprised when following the Led Zep Mastered for iTunes talk I installed iTunes, I did some test aac 256 vbr rips compared with 320 cbr and both over Mp3. I found I couldn't detect any difference with the iTunes version of secure rip on between 320 cbr and 256 vbr and for want a better word both were more 'organic' than Mp3. It was very hard for me to pick out my acc files played from my computer to the parent cds that suggests for me it's the same. You'd have lossless only as a absolute 'master' quality to compare and transcode for everyday usage from.
    I bought the Sensa clip zip player someone mentioned together with an extra micro card so I can enjoy my growing collection of aac albums in addition to legacy Mp3 and wma's on the move.
    Thurenity likes this.
  3. ShallowMemory

    ShallowMemory Forum Resident

    Location:
    GB
    That is a good site for variety plus a fair number of M4A titles that as far as I'm aware you can redownload up to 5 times if needs be. Additionally you can download whole albums without installing anything as an old school zip file.
  4. DrownedGod

    DrownedGod Member

    Interesting thread. First, the OP asked which is "better" - AAC or MP3? Then goes on to say that both are 256 kbps.

    First, "better" is subjective. If "better" means more universally compatible as a codec format, then MP3 is better than AAC because it is virtually universally playable on almost any mobile audio device.

    If "better" relates to sound quality, again, this is entirely dependent on bitrate and codec used. Both the latest LAME MP3 encoder (3.99 iteration) and iTunes AAC are widely considered "transparent" (indistinguishable from the source material) at 256 kbps and higher to 95% of the listening population. Double blind listening tests have convinced me that neither is distinguishable from the other consistently; if you haven't subjected yourself to one of these, you really can't honestly say that you always can tell a difference.

    The current iTunes AAC codec has come out generally on top for recent listening tests, over Nero's AAC codec, Vorbis, and WMA Pro, but IIRC, that test (done by some folks on Hydrogenaudio) did not use Coding Technologies AAC codec. The important thing to remember, however, is that this and most listening tests these days are done using much lower bitrates because that is where codec development advances are really occurring.

    No one in the lossy codec business (to my knowledge) is trying to improve sonic results at bitrates of 256 kbps or higher; instead, they are trying to deliver transparency at increasingly lower bitrates, with codecs such as AAC+, eAAC+, or MP3PRO. The AAC+ and eAAC+ codecs are often used for streaming audio over web apps to mobile devices and satelite radios; they provide an impressive degree of transparency at bitrates as low as 64 kbps (48 kbps for eAAC+).

    There are also newer codecs being developed and put out into the lossy coding world - a recent product is Opus, which I have not used or heard, only read about. It is designed to provide transparency at sub-150 kbps bitrates and, I believe, many have found it competitive with AAC+ and sub-100 kbps bitrates despite its (Opus') significantly different design principles.
    Vidiot likes this.
  5. DrownedGod

    DrownedGod Member

    Perhaps the MP3 codec used low-passed the source material during the encoding process. The LAME encoder does not use a lowpass filter at the highest (V0) setting, nor does iTunes AAC at 256 kbps. However, both LAME and iTunes do lowpass on encodes at less than 256 kbps...but I would be careful about judging sound quality in lossy files by looking at frequency graphs. There are other factors that influence how that lossy file will sound besides whether a lowpass filter was used.
  6. Stone Turntable

    Stone Turntable Forum Resident

    Location:
    New Mexico USA
    It's reassuring to hear all the positive words for 256 AAC files — like others here I 've been taking advantage of iTunes Match to upgrade lower-bitrate MP3s and to convert MP3s purchased from Amazon.

    However, I'm still going to rip everything I possibly can in Apple Lossless as my best shot at future-proofing my digital music. Drive space is too cheap and plentiful not to.
  7. hogger129

    hogger129 Well-Known Member

    Location:
    Madison, Wisconsin
    Sorry to revive an old thread. I was ripping all my stuff to AIFF but I've just found that iTunes Plus sounds good enough and I save a ton of space using it. If you got the space, backup to lossless (FLAC or ALAC) and then just make 256 AAC versions to put on your device.
  8. swedgin

    swedgin Well-Known Member

    There is an option on iTunes now to down sample lossless files to 256AAC when you sync with your IDevice, no need to keep lossless and lossy files.
  9. RoyalScam

    RoyalScam Luckless Pedestrian

    I've tried to switch to AAC several times, and always wind up going back to LAME mp3. There's something in the AAC algorithm that my ears just don't like. Can't put my finger on it, and I've ABX'd several times with consistent wins going to LAME. I've tried AAC 256 and TVBR 110 and 90. LAME -V 2 works better for me.
  10. Paul Saldana

    Paul Saldana Forum Resident

    Location:
    Hallandale Beach
    Buy some new tweeters!
    Grant likes this.
  11. ricks

    ricks Well-Known Member

    :righton:
  12. Saint Johnny

    Saint Johnny Well-Known Member

    Location:
    Asbury Park
    :biglaugh:
    Though in my experience it seems that the lower the bit rate, it's more that the lower frequencies suffer, than the higher ones. :shrug:
    Grant likes this.
  13. Paul Saldana

    Paul Saldana Forum Resident

    Location:
    Hallandale Beach
    I did notice this very thing when I dubbed some files at 192k mp3 as an experiment.

    A 256k .m4a sounds rolled off or muffled up top compared to a source cd to me. I have ribbon tweeters at home, titanium ones in my headphones and in the car . . . so it's always detectable.

    Some harsh sounding cds (either through clipped mastering or stupid;y bright eq) sound less harsh when dubbed off as .m4a's. In such cases the lossy file is actually easier to listen to.
  14. Thurenity

    Thurenity Wood Fill and Non Glue

    Location:
    Eastern PA, USA
    Since I last posted in this thread I've actually started using the MFiT droplet for OSX to convert my needledrop FLAC's to 48khz 320kps AAC's (I tweaked their Applescript). Basically for my on-the-go and day-to-day listening and I honestly cannot tell a difference between it and my original FLAC. The FLAC is the backup / storage track while the AAC gets copied between my PC and DAP and music server.
  15. Chris C

    Chris C Music was my first love and it will be my last!

    Location:
    Ohio
    I download all my music to i-Tunes via 192 AAC and I've yet to hear one single person, including myself, to complain with the sound, that has heard my sound system. Sure, I have a few tracks in my library that have a "sound" that doesn't please me as much as the rest, like, The Beatles "Twist & Shout" (from the Lennon "Imagine" soundtrack) and "Soul & Inspiration" by The Righteous Brothers (probably from that Rhino 2-CD set), otherwise you just can't prove the sound much less than the real CD, in my opinion.

    The same people who will say that 192 AAC is crappy sounding, will listen and pay for, with no complaints, to satellite radio and I will never understand that nonsense..., talk about crappy sounding???

    AAC over mp3 every time, in my book!
    GetHappy!! likes this.
  16. TheGenuinePig

    TheGenuinePig Member

    Location:
    Earth
    Interesting thread, I thought I'd post some frequency spectrum images (using Izotope RX) of the track 'Apocalypse Dreams' by Tame Impala, converted in different formats. First is the lossless WAV file ripped from the CD, second is that WAV file converted to AAC at 320 CBR, and last is that WAV file converted to MP3 at 320 CBR (LAME codec) - It is mind blowing to me that the frequency spectrum of the 320 AAC file appears identical to that of the lossless WAV file

    Attached Files:

    coffeetime likes this.
  17. McLover

    McLover Forum Resident

    Location:
    East TN
    AAC every time. Higher quality for any given bitrate, will handle multiple generation cascading algorithms better, and really the logical compressed, lossy medium which sucks the least. Even OK for broadcasting use. MP3 is not.
  18. Thurenity

    Thurenity Wood Fill and Non Glue

    Location:
    Eastern PA, USA
    To get the MP3 frequencies up to close to 22khz, I believe you have to use VB0, not CBR 320kps for LAME -- going on what I recall from a few years back. With AAC I think you can use either VBR / CBR 320kps to get the frequencies up to near max.
  19. DrownedGod

    DrownedGod Member

    The psycho-acoustic principles behind lossy encoding pretty much render frequency graphs meaningless for assessing perceived sound quality.

    Looking at those pics - are you sure these aren't the same picture mislabeled? A 256 kbps encode should not look exactly like a .wav file, even if it may sound like one.

    Second, there was (is) a switch setting on older versions of the LAME encoder that will manage how it encodes frequencies above 16khz in order to conserve bit usage. Because of the design of the original MP3 codec, these frequencies lack certain encoding scale controls (controls that were subsequently incorporated into the AAC codec design spec).

    This means that MP3 encoders would use more bits in this frequency range. That said, the LAME codec has been modified to restrict the bit usage in this range at certain settings (perhaps all CBR settings?), but to do so in a psycho-acoustically sophisticated way (via low-pass filtering) that maintains perceived sound quality.

    In reply to the previous post, yes, using the -v 0 setting will turn off the LAME polyphase low-pass filter completely. iTunes 256 kbps VBR (and above) is also not low-passed in any way to the best of my knowledge. Anything lower than that, however, is....

    I would agree completely that MP3 has no real sound quality edge over AAC; at very high bit rates, they're statistically equal and at lower bitrates (under 128 kbps) AAC is definitely better. MP3's main advantage is its universality in terms of compatibility. Everything out there will play an MP3 file. That's not likely to change for quite a long time and that's why I use LAME (-v 0) for almost all my lossy encoding.
    boiledbeans and RoyalScam like this.
  20. Vidiot

    Vidiot Faded to Black.

    That's pretty much my experience as well. Back in the summer/fall of 2004, I did about a solid week of tests between WAV, Lossless, MP3, and AAC at different bitrates with a dozen different songs, purely subjective, just using decent headphones (Sennheiser HD600's). After going back and forth for at least 25 or 30 hours, I finally opted to go for 320kbps AAC for all my portable listening, and Apple Lossless for archiving. I still use that method to this day.

    I honestly didn't know that the roll-off stopped with 256kbps files, but I can say that the difference between 256K and 320K is so negligible as to be meaningless. I go for 320K just for the psychological reassurance that I've gone to the minimum amount of compression I possibly could.

    I've mentioned this before, but I think the 4:1 compression rate (which is not far off for 320kbps compared to 1,440 for WAV) appears to be a "magic" number. It's also very close to the compression rate used for Digital Betacam videotape, HDCam-SR videotape, and it's around the rate used for some pro 4K production cameras. I draw a lot of parallels between video compression and audio compression, because when you get down to it, it's the same thing: trying to cram 10 pounds of entertainment into a 2.5 lb. bag. It's amazing that it works as well as it does... but despite the difficulty in differentiating 320kbps from Lossless, I'm not willing to rely on 320K alone just on principle.
    coffeetime likes this.
  21. RoyalScam

    RoyalScam Luckless Pedestrian

    Just curious...how does using (and tweaking) the MFiT droplet differ from just ripping with iTunes and using the AAC iTunes Plus preset (or tweaking to custom settings there)?
  22. mando_dan

    mando_dan Well-Known Member

    Location:
    Salem, MA
    Let's cut straight to the specs bypassing the "it certainly sounds better" and "look at the spectrogram for indefatigable proof" stuff. From Wikipedia:

    AAC's improvements over MP3

    Advanced Audio Coding is designed to be the successor of the MPEG-1 Audio Layer 3, known as MP3 format, which was specified by ISO/IEC in 11172-3 (MPEG-1 Audio) and 13818-3 (MPEG-2 Audio).
    Blind tests show that AAC demonstrates greater sound quality and transparency than MP3 for files coded at the same bit rate.[2]
    Improvements include:
    • More sample frequencies (from 8 to 96 kHz) than MP3 (16 to 48 kHz)
    • Up to 48 channels (MP3 supports up to two channels in MPEG-1 mode and up to 5.1 channels in MPEG-2 mode)
    • Arbitrary bit-rates and variable frame length. Standardized constant bit rate with bit reservoir.
    • Higher efficiency and simpler filter bank (rather than MP3's hybrid coding, AAC uses a pure MDCT)
    • Higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 or 960 samples, allowing more efficient coding than MP3's 576 sample blocks)
    • Higher coding accuracy for transient signals (AAC uses a blocksize of 128 or 120 samples, allowing more accurate coding than MP3's 192 sample blocks)
    • Can use Kaiser-Bessel derived window function to eliminate spectral leakage at the expense of widening the main lobe
    • Much better handling of audio frequencies above 16 kHz
    • More flexible joint stereo (different methods can be used in different frequency ranges)
    • Adds additional modules (tools) to increase compression efficiency: TNS, Backwards Prediction, PNS etc... These modules can be combined to constitute different encoding profiles.
    Overall, the AAC format allows developers more flexibility to design codecs than MP3 does, and corrects many of the design choices made in the original MPEG-1 audio specification. This increased flexibility often leads to more concurrent encoding strategies and, as a result, to more efficient compression. However, in terms of whether AAC is better than MP3, the advantages of AAC are not entirely decisive, and the MP3 specification, although antiquated, has proven surprisingly robust in spite of considerable flaws. AAC and HE-AAC are better than MP3 at low bit rates (typically less than 128 kilobits per second)[citation needed]. This is especially true at very low bit rates where the superior stereo coding, pure MDCT, and better transform window sizes leave MP3 unable to compete.
    While the MP3 format has near-universal hardware and software support, primarily due to MP3 being the format of choice during the crucial first few years of widespread music file-sharing/distribution over the internet, AAC is a strong contender due to some unwavering industry support.[31]
  23. Pizza

    Pizza Forum Resident

    What would be the space savings in regards to AAC vs Apple Lossless?
  24. Thurenity

    Thurenity Wood Fill and Non Glue

    Location:
    Eastern PA, USA
    The droplet adds an intermediate step which is creating a 32/44 CAF file (or, in my case, a 32/48 CAF file). That CAF file is supposed to help with dithering instead of going directly from 24/96 to a 48khz AAC.

    For a CD to AAC conversion it may not be a big deal since the source is already 16 bit, but I believe for 24/96 to 48khz AAC's it might help a bit with overall SQ. I would think an HDTracks source would also apply. What I do is convert my FLAC to AIFF's in Foobar to a MacOS shared temp folder and then that's where OSX takes over to run the scriplet -- it takes a little time to convert these but I have the storage and time since I'm just doing needledrops.

    Apple's droplet is just an Applescript file wrapped in a GUI, so I went into the file and tweaked it a bit, changing the CAF settings from 44khz to 48khz and the end result AAC from 256kps AAC to 320kps AAC. I also copied the original elsewhwere so I can use that CD rips as I see fit.

    ALAC is similar to FLAC, so I would say it's about a 4:1 size ratio in general (which I believe was already stated).
  25. DrownedGod

    DrownedGod Member

    Interestingly enough, there used to be a publicly available AAC encoder (Nero) that would allow VBR encoding above 320 kbps. Using Nero on it's highest setting, one could get to 400 kbps or so, which is pretty close to a typical Dolby DVD movie bit rate. Nero's public development has ceased, however, but I think the codec is still available for free on-line at Hydrogenaudio. At those bit rates, it's easily equal to iTunes, so if you use EAC, you could probably download Nero as well. If you use iTunes, no such luck.

    You know, there's one other good reason to consider LAME if one is concerned about space (which should always be a concern) - using a "pure" VBR versus Apple's "constrained" VBR will generally get you smaller file sizes, even with MP3. The reason is that not all frames need to be at or above a specific bit rate to maintain consistent perceived sound quality - more complex musical passages likely will require higher bit rates, but sections with pure tones (such as piano) can be encoded at lower bit rates with no perceptual difference. Thus the "pure" VBR encoders offer the best of both worlds - the ability to encode as high as necessary to maintain quality, but also the flexibility to encode lower where possible. It's essentially a more sophisticated way to control bit allocation. I'm certainly not trying to be critical when I say this, but CBR wastes space and gets you nothing in return for it!

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