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Music Media Technology (Apple) Technology

Hydrogenaudio AAC Listening Test Results 306

Posted by timothy from the picking-and-squeezing dept.
caffeine_monkey writes "Hydrogenaudio's AAC public listening test, previously posted on Slashdot, is now over and the results are in. The test compared five codecs at 128 kbps, including Psytel, Nero, Sorenson Squeeze, QuickTime, and FAAC. The winner? 'QuickTime is a clear winner, performing much better than the competition. Sorenson Squeeze, Psytel AACenc and Nero are tied, with Sorenson slightly higher than the others. Faac is clearly the worst.'"
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Hydrogenaudio AAC Listening Test Results More

Hydrogenaudio AAC Listening Test Results

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  • For the Audiophiles... (Score:3, Funny)

    by Michael's a Jerk! ( 668185 ) on Wednesday July 23, 2003 @08:33AM (#6510214) Homepage Journal
    I have the Ultimate Guide [rr.com]

  • Real competition absent (Score:2, Insightful)

    by weeble ( 50918 )
    While it may be relevant to have a comparison between different AAC encoders the trial would have much more relevance to real life if it had included ogg and mp3.

    A little extra work for a lot more sense in the results.

    Have fun
    Xander
    • Sure. That's like comparing the range of Fords against each other, when what you really want to know is whether they whup Cheveys. If it's Ford (or an interested party) doing the comparison, well, I'm inclined to believe the opposite.
      • No, this is more like comparing the quality of service at 4 ford dealerships, or perhaps testing performance kits on a ford from four different companies. As everyone else is stating...other formats, or brands of cars, are not relevent to this at all.

        • Re:Real competition absent (Score:2, Funny)

          by Anonymous Coward
          No. This would be like testing the quality of four different types of toilet paper and their comfort on your butt. Then someone comes along and asks why a bidet wasn't included in the comparison.

          I challenge anyone to come up with a shittier analogy than this.

    • Re:Real competition absent (Score:5, Insightful)

      by viktor ( 11866 ) on Wednesday July 23, 2003 @09:10AM (#6510435) Homepage

      Actually I do not agree with you at all. Comparing different encoders for a certain format is a complete test. In this particular case, the goal was to find out which AAC encoder is the best. The results answered that question.

      As an Open-Source (and open standards) advocate it is easy to look at such a test and say "but Ogg/MP3/whatever is better anyways, they should have included them". Actually saying so leads nowhere at all.

      If you want a comparison between Ogg, AAC, WMA and MP3, then do such a comparison. But this was not a test to find our which format/algorithm was the best, it was a test to find out which AAC encoder was the best, which is also what the test answered.

      Not every test in the world should always include all and every variant of the test subject in question. Just because you're comparing the quality of carrots from different farmers, you shouldn't automatically be expected to include potatoes in the comparison just because there are people that prefer potatoes over carrots. If the test question was "which is the best vegetable", then omitting potatoes could be considered careless.

      And, in very much the same way, if the test question is "which is the best AAC encoder", including MP3-or Ogg-encoders would be just as wrong.

      That's my view, at least.

      /Viktor...

      • Re:Real competition absent (Score:5, Insightful)

        by bill_mcgonigle ( 4333 ) on Wednesday July 23, 2003 @10:53AM (#6511315) Homepage Journal
        And to further your argument, if the question is 'which is the best sounding format, aac, ogg, or mp3?' then this test is a prerequsite. To compare the formats, one must pick an encoder to encode the samples. The only fair way to do this is to use the best encoder from each group. This test shows that it would be unfair to use faac, for example, to encode the AAC samples.

        So, the self-righteous open-standards advocates (no denegration intended) ought to be organizing a test just like this article talks about for ogg and mp3 if there's not a suitable prior study.

        Only then can they properly organize the audio-format bake-off.

    • Re:Real competition absent (Score:5, Informative)

      by thenightfly42 ( 166359 ) on Wednesday July 23, 2003 @09:31AM (#6510560)
      RTFA. This was onlyl the first step; next, HydrogenAudio will take the AAC winner (QuickTime) and compare it to what they consider the best encoders for the OGG Vorbis, WMA, MP3, etc.
    • Before you can compare mp3 encoders to aac encoders you have to find out which is the best aac and mp3 encoders to pit against each other.

      NOw they know which is the better AAC encoder, so next time someone does a general encoder compairison AAC will be properly represented.
      • Only problem I see is: in this fast evolving softwareworld, if they sequentially test encoders for different formats, the first one tested has a really good chance to be less than state-of-the-art, by the time they finish testing. So when it comes to a head to head comparison of the formats themselves, it is possible that in the mean time there were better encoders developed for (in this instance quictime,) giving it a disatvantage. I hope they keep an eye open for new releases.

  • be careful (Score:3, Insightful)

    by borgdows ( 599861 ) on Wednesday July 23, 2003 @08:36AM (#6510235)
    Do not confuse FAAC and FLAC [sourceforge.net] (the lossless audio format from Xiph).

    Btw, why does this test compare only proprietary formats and not free (as speech) formats like Ogg Vorbis or FLAC ?

    • Re:be careful (Score:4, Informative)

      by IamTheRealMike ( 537420 ) on Wednesday July 23, 2003 @08:38AM (#6510250)
      Well, it seems it's not comparing formats, it's comparing encoders for AAC, to find out which is the best. The "QuickTime" encoder (exactly where it comes from, or what it is doesn't seem to be mentioned) won. If you aren't interested in AAC audio though, this set of tests doesn't really interest you.

      • Re:be careful (Score:2, Informative)

        by Anonymous Coward
        Apple uses Dolby's AAC Codec.
        Sorenson uses Fraunhofer IIS AAC.

      • Re:be careful (Score:3, Informative)

        by TheRaven64 ( 641858 )
        The "QuickTime" encoder (exactly where it comes from, or what it is doesn't seem to be mentioned) won.

        The AAC encoder used in QT 6 is a slightly hacked version of the Dolby `consumer' codec. I am quite surprised by these results, since the dolby consumer codec is noticable inferior to the PsyTel one, which is closer in quality to the Dolby `Pro' (read `expensive') encoder. I suspect that Apple may have tuned it a little...

    • Btw, why does this test compare only proprietary formats and not free (as speech) formats like Ogg Vorbis or FLAC ?

      What would be the point of a FLAC listening test? The only thing it would do is give us the opportunity to pummel any "expert" who says it sounds different from the original.

      Since this test is only for different AAC encoders, any Vorbis comparison will be the subject for a different test.

  • Things I've heard from Audiophiles... (Score:3, Funny)

    by Michael's a Jerk! ( 668185 ) on Wednesday July 23, 2003 @08:36AM (#6510236) Homepage Journal
    The following are actual quotes I've read from audiophiles on the net. Enjoy.

    "Pulling harmonics together from a jumbled auditory stream to form a coherent harmonic envelope."

    "Image outlines were sharply focused in space with believable palpability."

    "There was plenty of bass detail to behold."

    "The music flows with gusto and verve. It squeezes instrumental images into incredibly palpable outlines."

    "...more muscle and definition, and a heart that is pure gold."

    "Most preamps when pushed hard change their sonic signature."

    "Harmonic colors were somewhat on the dark side."

    "By using the $450 gold plated RCA stereo jumper cables for all line-level connections, and the newly available $1200 gold plated XYZ speaker wires, we were able to achieve a distinct improvement in highs and the deepest rich bass lows I have ever heard. A massive improvement over ordinary old copper."

    "These cables deliver big time! The sound is surprsingly smooth and spacious, with particularly sweet upper octaves."

    "If you connect a ground to the chassis of your power amplifer and use 4 gauge wire connected to a bucket of salt water with a copper coil in it, your mids and highs will be the sweetest you have ever heard. Works with car audio systems too. Place the bucket in the trunk and reduce speed on corners and when braking, to avoid spillage."

    "Special wooden resonator disks made in Asia from a special tree, only found in one area. Placing these under EACH of your components, at strategic locations will remove 'unwanted resonances', and DRAMATIC improval tonal quality. The difference is astounding. These disks of wood sell for around $100 to $400 EACH (depending on size)." (See the top of this web page!)

    "somewhat fuzzy portrayal of image outlines."

    "Harmonic textures ebbed and flowed with startling dynamic nuances and the sort of liquidity and purity one only comes to associate with world-class audio products."

    "Harmonic textures are painted slightly gray in color."

    "Spatial detail was painted with a fine brush that readily resolved massed voices and the air around individual instruments."

    "Image outlines, however, are more precisely focused within the soundstage and in general the Accordance is capable of sketching out a convincing 3-D acoustic impression."

    "It felt like I had crawled into a warm and inviting sonic womb."

    "Not content with straight S.E.X. (the single-ended experimenter's kit), the Doctor introduces the "69" tapered pipe loudspeaker. Sounds like a recipe for a mind-blowing sonic orgasm."

    "The impression of speed and control was strong."

    "Bass lines were fleshed out with excellent definition."

    "It is less lush sounding than..."

    "...force feeding the listener an earful of detail; more accurately, a barrage of in-your-face zingers that becomes almost an instant irritant."

    "Each tube brand seems to have a unique flavor of its own."

    "Certain busy passages of music get congested."

    "... sounds either euphonic or bright."

    "The Equilibre ($8,475) - nominally a 60-watt stereo amp."

    "It could well explain the sweet sounds that come from using passive preamps straight into the power amplifiers."

    "...with an easy-to-drive impedance magnitude."

    "Rendition of harmonic colors was suave and smooth, with a believable sugar coating."

    "Exposure of low-level detail, even in complex passages, without leaving anything to the imagination."

    "The mids are vivid in spades with wave after wave of honey-coated harmonic bliss."

    "The midbass region is "fun"

    "the upper mids are a bit more laid back than I would like."

    "the low bottom end is not there..."
    • :) now that's amusing.

      seriously, audiophiles are indeed full of s&*t. sorry to say, but when they have to listen and compare stuff, they are very inconsistent.

      mostly audiophile gear is a jerk-off session of wannabee music expert wealthy bast^H^H^H^H guys who can afford to spend large anounts of money on equipment

      what also strikes me as interesting is that most musicians i know don't give a shit about their hifi set. as long as they can get the general idea of what a song sounds like and what the diff

      • Re:Things I've heard from Audiophiles... (Score:5, Funny)

        by sevensharpnine ( 231974 ) on Wednesday July 23, 2003 @09:15AM (#6510453)
        As a musician myself, I can tell you that one of the most important aspects of a stereo to me is its ability to be manipulated with my toes. Makes transcribing music much easier.
        • Yah, I'm an audiophile and I like to maniuplate my stereo with my toes too.

          Frees up my hands so I can better appreciate the masturbatory experience that is spending massive amounts of money on only marginal (and imaginary) improvements in sound quality.

    • Re:Things I've heard from Audiophiles... (Score:4, Insightful)

      by e1618978 ( 598967 ) on Wednesday July 23, 2003 @09:20AM (#6510487)
      About half that stuff makes sense to me. Many of the things you wrote seem reasonable and valid - I don't see what you are making fun of. For example, many pre-amps (not mine) change character during loud transients. Opera singers seem to jump out at you when they hit the really high/loud notes. A lot of the quoted statements make perfect sense - it is just that they are having trouble explaining their experience, and you are taking the quotes out of context to make them look stupid. Slashdot is not capible of discussing high end audio - stick to your MP3 players and surround sound computer speakers.
      • I'd like to see some psychophysical analyses of these things. Failing that, see what blind test/retest data are like. I do a get a bit puzzled when audiophiles claim to be able hear differences between things outside the ability of people tested with very high level equipment in laboratory conditions to discern or discriminate between. I'm not saying they are necessarily lying or imagining things, but on the other hand at the present time some (not all) claims made by audiophiles are akin to those made by p
      • And to think, I thought "high-end audiophiles" was a synonym for "self-rationalizing snob".

        Boy was I mistaken!

      • Re:Things I've heard from Audiophiles... (Score:4, Funny)

        by Jeff DeMaagd ( 2015 ) on Wednesday July 23, 2003 @12:54PM (#6512531) Homepage Journal
        Some of it sounds valid.

        About half of the list consisted of using B.S. adjectives to describe things they never were meant to describe. In short, it mostly reads like clips from a wine taster's guide.

        One of my biggest objections to high-end audiophilia is that the subjects more often than not refuse to try double-blind tests concerning the difference between two products.

        They all claim that the difference is so stinking obvious, but if that were so, then they shouldn't be afraid to prove it. Pshych experiments show that even changing the color of a product's box changes people's perception of performance, so I want factors like that removed through a proper double blind test.

        How all this connects to an AAC test, I don't know, but I hope that was properly administered as well.
      • A huge percentage of audiophile nonsense is focused on speaker cables, and thus far no double-blind test has shown a discernible difference between speaker cables, unless you are comparing with some particularly horrid wire you purposedly made as bad as possible.
    • however, all of those quotations you've 'collected' are found at http://home.cfl.rr.com/happysurfer/audio_bs.htm

    • Those quotes remind me of Allmusic.com's review of Miles Davis' 1969 album, Bitches Brew [allmusic.com] . Here is a highlight:

      "A three-note bass vamp centers the entire thing as three different modes entwine one another, seeking a groove to bolt onto. It never finds it, but becomes its own nocturnal beast, offering ethereal dark tones and textures to slide the album out the door on."
    • "...Place the bucket in the trunk and reduce speed on corners and when braking..."

      Reduce speed when braking? Ingenious.

      • "Place the bucket in the trunk and reduce speed on corners and when braking, to avoid spillage."

        Putting a lid on the bucket would apparently ruin the sound quality.

        Is there any logical reason why grounding into a bucket would be any different from grounding to a car frame or water pipe?

        -B
    • If you want real fun, investigate Peter Belt.

      He's a British hi-fi looney who sells all kinds of silly things, such as pens and stickers, for marking CDs and audio equipment, which supposedly make the equipment sound better. All of the, naturally, are sold at very silly prices, but some people do buy them. The most expensive item he sells is a crocodile clip called "The Quantun Clip" that retails at £500, and supposedly improves the sound of anything it has been attached to.

      Absolutely barking mad! Ye
      • Wow! That stuff will go great with the V-tec and TypeR stickers I got for my beige 1984 honda civic hatchback! After I put those stickers on it I was able to totally outrun mustangs, corvettes, almost anything! I bet if I put these stickers on my 8 year old altec lansing surroud sound system it will sound just like the $3500 system from hi-fi buys that I was looking at! I'm ordering a dozen right away!!!!!

        Kintanon
      • thanks for the link, i haven't laughed so much in ages :)

        'The P.W.B. Quantum Clip is specifically designed to produce an energy pattern that is neutral and in a state of equilibrium. The crocodile clip is under tension at all times and we have applied techniques that equalise the mechanical pressure variations. This results in an energy pattern which is in a high state of gravitational energy equilibrium. Attached to the clip is a specially twisted, multi-strand combination of copper and the pattern of the

  • QuickTime codec (Score:4, Interesting)

    by MacGod ( 320762 ) on Wednesday July 23, 2003 @08:41AM (#6510271)
    Would I be correct in assuming that it is the QuickTime codec that is used in iTunes? I can't imagine Apple would go to the trouble of writing two different codecs.

    • Re:QuickTime codec (Score:3, Interesting)

      by shunnicutt ( 561059 )
      According to the article, this same QuickTime AAC codec is used in iTunes, but for this test, the encoding was done at the 'best' setting, while iTunes encodes at the 'better' setting.

      • QuickTime codec parameters (Score:4, Informative)

        by benwaggoner ( 513209 ) <ben.waggoner@mic ... t.com minus poet> on Wednesday July 23, 2003 @12:28PM (#6512309) Homepage
        There are three speed/quality settings in QuickTime. The first is fast and cheap, and really only meant for real-time broadcasting. For this, we're interested in "Better" and "Best" modes. The only real difference between then is when working with more than 16-bit source. Better uses every quality optimization technique that works when the source is only 16-bit. Best uses additional techniques that improve quality with higher bit sources (like 20 or 24 bit, common in audio mastering).

        iTunes is tuned for CD ripping, so using "Better" mode by default is just fine.

        AAC-LC can also decode at more than 16-bit in some implementations. This means it's possible to make a AAC-LC encode that is better than CD quality, if the source is more than 16-bit. I gather Apple does this with the iTunes music store, using better than CD quality masters for the encode when available.

    • Re:QuickTime codec (Score:3, Informative)

      by Henriok ( 6762 )
      Yes! Since it states as much in the article. Before asking questions, it might be good to actually read the article.

      Quotefrom the article:
      <blockquote>" It's important to note that the QuickTime codec used in this test is the same one used in Apple iTunes(but using a different coding mode). The samples were encoded in QuickTime's "Best" quality mode, while iTunes uses the "better" setting. This setting reportedly produces the same quality as "best" on 16-bit material. (Best is targeted at 24bit materi

    • Re:QuickTime codec (Score:3, Informative)

      by JPelzer ( 202626 ) *
      The individual sound files for iTunes are encoded by the various record labels, not by Apple, and so could be encoded by any one of the encoders. Apple receives raw .aac files, then puts them into a DRM'ed quicktime wrapper.

      In general, I believe most iTunes music is actually NOT encoded directly with the Quicktime encoder, because Quicktime for Windows didn't handle AAC encoding at the time of the launch (Only Mac Quicktime did), and most of the record labels actually use Windows for their conversions.

  • Interesting results (Score:4, Interesting)

    by thatguywhoiam ( 524290 ) on Wednesday July 23, 2003 @08:48AM (#6510300)
    I'm a little confused as to why the article just references 'QuickTime' when really we're talking about only one codex out of the (what, 200?) media types QT understands.

    What I'm curious about is, there was some discussion before about the differences between the original AAC encoder that came with QT, and the newer one that now ships with QT 6.3 (and ties to iTunes). The original encoder was said to have sucked. This one, if I'm reading this right, is now very good...?

    Anyways, I must have lead ears. I used to rip my MP3s at 160kbps, now I do 160kbit AACs, and cannot really tell the difference. AAC seems a tiny bit better maybe but could be a placebo effect.

    • > I'm a little confused as to why the article just references 'QuickTime' when
      > really we're talking about only one codex out of the (what, 200?) media types
      > QT understands.

      -nod- I was wondering that, too... last time I checked, QuickTime was a file format, and not a codec at all? Has Apple muddied the waters even further by making a codec named QuickTime ?

    • Re:Interesting results (Score:5, Interesting)

      by Winterblink ( 575267 ) on Wednesday July 23, 2003 @09:41AM (#6510652) Homepage
      "Anyways, I must have lead ears. I used to rip my MP3s at 160kbps, now I do 160kbit AACs, and cannot really tell the difference. AAC seems a tiny bit better maybe but could be a placebo effect"

      Heh, I hear ya. (pun alert!) In my experience, two major factors affect your being able to discern quality differences between audio codecs: environment, and equipment. Listen to the stuff on a crummy pair of computer speakers and you'll hardly be able to tell the differences between bitrates, much less formats. Listening in a room with ten computers with their fans whining away doesn't help either. Myself personally, if I'm listening for differences between formats I'll put on a decent pair of headphones, and close my eyes while listening. But that works for me. :) Others are different, and that's the trick with encoding-- music registers quite differently with everyone.

      I also like to use music I've listened to for YEARS. If I take a song that I've listened to a zillion times in the past and run it through various codecs it's much easier to tell if the song sounds "right", to me. :) If you recognize every note being played it's easier to tell if an encoder's stripping some bits out that wreck the harmonics more than another one does. But that's just me!

    • Anyways, I must have lead ears. I used to rip my MP3s at 160kbps, now I do 160kbit AACs, and cannot really tell the difference. AAC seems a tiny bit better maybe but could be a placebo effect.
      That may be true, though from what Apple says you should be able to rip at 128 kbit AAC and have it still be just as good or better, and then save disk space.

      Have you tried that comparison?
    • The higher the data rate, the more transparent the encode, so differences between codecs will shrink. Since 160 MP3 sounds "close enough" to lossless for most listeners, there isn't that much room for a better codec to pay off. But while I can't really listen to 128 MP3 for for, 128 AAC-LC sounds great, even though headphones. And compare them at 96 Kbps at 44.1, the difference is huge.

  • What's AAC (Score:5, Informative)

    by nsushkin ( 222407 ) on Wednesday July 23, 2003 @08:48AM (#6510307)

    From Apple's AAC page [apple.com]

    Because of its exceptional performance and quality, Advanced Audio Coding (AAC) is at the core of the MPEG-4 and 3GPP specifications and is the new audio codec of choice for Internet, wireless, and digital broadcast arenas. AAC provides audio encoding that compresses much more efficiently than older formats such as MP3, yet delivers quality rivaling that of uncompressed CD audio.

    AAC was developed by the MPEG group that includes Dolby, Fraunhofer (FhG), AT&T, Sony, and Nokia--companies that have also been involved in the development of audio codecs such as MP3 and AC3 (also known as Dolby Digital). The AAC codec in QuickTime 6 builds upon new, state-of-the art signal processing technology from Dolby Laboratories and brings true variable bit rate (VBR) audio encoding to QuickTime.

    From Via Licensing [vialicensing.com]

    MPEG-4 AAC has been specified as the high-quality general audio coder for 3G wireless terminals. Apple Computer has incorporated MPEG-4 AAC into QuickTime 6 and iTunes 4, as well as the latest version of its award-winning iPod portable music player. The Digital Radio Mondiale system (the next-generation digital replacement for radio broadcasting under 30 MHZ) builds on the audio coding of MPEG-4 AAC. These exciting platforms represent the state of the art in audio coding--and Via Licensing is pleased to offer the MPEG-4 AAC Patent License Agreement.

    The MPEG-4 AAC standard incorporates MPEG-2 AAC, forming the basis of the MPEG-4 audio compression technology for data rates above 32 kbps per channel. Additional tools increase the effectiveness of MPEG-2 AAC at lower bit rates, and add scalability or error resilience characteristics. These additional tools extend AAC into its MPEG-4 incarnation (ISO/IEC 14496-3, Subpart 4).

    A copy of the MPEG-4 Audio standard can be purchased from the ISO online store (search for "14496-3").

    • The Digital Radio Mondiale system (the next-generation digital replacement for radio broadcasting under 30 MHZ) builds on the audio coding of MPEG-4 AAC.

      A ha! They said their files have very little DRM. But, LOOK, right there! They said that DRM is the next generation! The future! Ahrg!

  • WAY back in the day Ken Thompson was interviewed for Wired and he played music on his computer using a lossy compression called PAC which he had coded in C from Fortran with the original developers. This was WAY before MP3.

    Just a short time back, it seems, he claimed it was still way better than MP3.

    How come it wasn't in this contest and in fact I cannot find anything more about it anywhere??

  • Just how many more audio codecs do we need??
    • Well, the authors of FAAC recommend (or did, they may not anymore) that you don't use it, and generally point to the PsyTel encoder (written by Ivan who has been known to contribute to FAAC/FAAD). The more interesting part of the FAAC project is the decoder, FAAD, which provides the basis for XMMS and Winamp plugins for playing .aac and .mp4 files.

  • Flawed samples (Score:2, Flamebait)

    by bukharin ( 344329 )
    Whilst the listening test is interesting, look at the styles of music tested:

    1) "Rock"
    2) Solo Harpsichord
    3) Quiet intro with acoustic and electric guitars followed by loud metal riffs
    4) IDM [??]
    5) Electronic mix
    6) Metal, complete with screeching vocals
    7) drums and bass in the far left, guitar in the far right. Female vocal in the center.
    8) rock/metal riffs
    9) Drums and ride cymbals intro, followed by bass and female vocals.
    10) Intro consists of guitar in far left with male vocal in center.

    Hardly a broad r
    • I'm sure someone will correct me if I'm wrong (this is Slashdot, after all), but a lot of these are considered "stress tests" for encoders. That is, they usually cause audible artifacting in the compressed version, even at high bitrates.

      This makes them ideal tests when comparing encoders, because you don't need "golden ears" to spot the differences. It also gives you a good idea of a worst-case scenario for the quality of the music you encode.

      Nathan
    • I think that this sample group is actually quite good. It doesn't exactly cover the whole spectrum of music - where's country and disco?! - but, it covers a few areas which I've noticed horrible problems with encoding in the past.

      For example, the IDM choice(which stands for "intelligent dance music." btw) is an excellent stress test, as the genre tends to be oriented around completely synthetic, rapidly changing sounds. Hard to describe, but in my experience with this genre, there's a pretty impressive

  • Clear Winner? (Score:3, Informative)

    by Anonymous Coward on Wednesday July 23, 2003 @10:39AM (#6511150)
    The article claims the QuickTime audio format as a clear winner. Yet in most graphs the 95% confidence markers overlapped with other formats. Most statisticians would then say "Not Enough Data!!"

    OK The results suggest that Quicktime was better but its not a clear winner until the 99% confidence intervals don't overlap, let alone the 95% ones. As one other poster said. You need a bigger sample size.
    • No, most statisticians would have never done something so ridiculous as compute standard deviations based on subjective rankings. The entire study became total bullshit the moment they tried to do any analysis of the results.

      Had they just plotted a histogram of the rankings, this might have been a respectable attempt. But they just made themselves look like morons.

      What they should have done is asked a series of binary questions: "Is there perceptable pre-ringing?" "Did you perceive any audio clicks?" "W

  • The article states (near the bottom) that the files used in the test were encoded using iTunes' `best' setting, while iTunes uses the `better' setting. Presumably, this only affects the amount of time taken, since it's all 128kbps anyway.

    Now, does anyone know how to encode using Quicktime's `best' setting? I have Quicktime Pro 6.3, which is supposed to have an `enhanced AAC encoder', but I see no difference in iTunes' preference panels. I've assumed that the encoder has been transparently upgraded, but hav

    • Re:iTunes settings (Score:2, Informative)

      by Anonymous Coward
      For Mac users the simple solution would be to use AACelerator, AAChoo or makeminempeg4. iTunes actually uses the "good" not "best" settings. Also in Quicktime there is an export/movie to mpeg-4/options/audio setting for doing it file by file. Browse the AAC forum over at Hydrogen Audio.
  • For anyone who encodes in AAC. Because AAC is only supported by the iPod as far as portable devices are concerned, its a useless codec to people who own other devices that support MP3 only, which while a 128kpbs AAC file sounds a tad better than an MP3, most people would be better off encoding a higher bitrate MP3 file with a quality mp3 encoder(Lame) so their music will be compatible with just about every little player on the market. Is there a device that doesn't support MP3?

    I think OGG as a format soun

    • Yeah, but as of March 1 in 10 MP3 players could play AAC, and as of June, thanks to the additional sales of 304,000 iPods in this one quarter, as compared to the 3/4 million in the past two years... I wouldn't be surprised if Apple now had one in 7 or 8 players in the market right now ^^

      So the better question is if 1 in 8 players support AAC, and those players happen to have 100 to 300 times the storage of the 4 nearest competitors (for a total of 50% of the market), then it seems to suggest that a *lot* o
      • First off there are plenty to hard drive based portable players have between 5-15 GB of storage and there are also plenty of bigger devices similar to nomads that offer 30+ GB. There are millions of cheap, less than $100 mp3 portables sold. The ipod while being the by far the best device on the market probably only has a 2-5% share of the portable market. Not many people are willing to spend more than $100 for a device to replace their walkman.

        The biggest problem with AAC is that lack of support from the

        • Found here [macobserver.com]

          Of course I can't verify they are *right*, but as of beginning of 2003, it seems Apple had 1 in 10, and what with the iTunes music store, it has been implied they have 1 in 8...

  • Wait. (Score:3, Insightful)

    by pclminion ( 145572 ) on Wednesday July 23, 2003 @01:04PM (#6512626)
    They asked people to rank things on a subjective scale, and then they did statistics with the results? I'm sorry, but that's a scientific faux-pas. The moment they tried to compute a standard deviation, they became pseudoscientists. Sorry, the "hard" stats are worthless. The only even possibly meaningful thing would be a histogram of the rankings.

    Just to make it clear why you can't do this: There is a certain incremental difference in subjective quality, that will cause listener A to rank something 4 instead of 3, for example. Will that same incremental difference in subjective quality case listener B to also rank something 4 instead of 3? We don't even know if the scale is linear, much less whether the different increments are even the same for different listeners.

    Example: on the Kuro5hin blog site, if I really like a comment I will rate it 5. If I hate it, I will rate it 1. I never use the ratings in between. Thus, sometimes a 1 is bad, and sometimes a 1 is really bad. The same could happen here. Even if different listeners perceive similar subjective changes in quality, they might assign different changes in rank to those changes in quality.

    God, this entire thing is bullshit, now that I think about it.

    • Re:Wait. (Score:3, Informative)

      by ff123 ( 514860 )
      There is a whole field of science which deals with the statistics of subjective measurement. Here's a reference to a book which you might pick up to inform yourself:

      Sensory Evaluation Techniques [amazon.com]

      Subjective tests of codecs are not new or particularly controversial. See the MPEG group's own subjective test of AAC:

      Report On The MPEG-2 AAC Stereo Verification Tests (PDF File) [uni-hannover.de]

      The statistics in the hydrogenaudio test treats each listener as a "block," which takes into account the fact that different list

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