[HN Gopher] The Ghost in the MP3
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The Ghost in the MP3
Author : Tomte
Score : 72 points
Date : 2021-02-12 17:24 UTC (5 hours ago)
(HTM) web link (theghostinthemp3.com)
(TXT) w3m dump (theghostinthemp3.com)
| KaiserPro wrote:
| one interesting artifact of MP3s in pop music is that symbols are
| transformed from a clean Crashhhhhhhhhhh, to a sound like a dog
| slurping water.
|
| However like Jpeg this is a tradeoff that we are used to. in the
| same way that tape has frequency inbalance, records just sound
| shit (sorry I know you like it, but they really don't sound
| better. they are great for evoking a feeling, but not for
| fidelity. Its lomo but for sound)
|
| I don't like the distortion that 128k mp3 introduces, but I
| imagine that in years to come it'll become a fetish for certain
| types of audiophile
| seanalexander wrote:
| > I don't like the distortion that 128k mp3 introduces, but I
| imagine that in years to come it'll become a fetish for certain
| types of audiophile
|
| This hasn't happened in almost 30 years of mp3s being a
| household format. The only feeling low resolution media evokes
| is frustration.
| dbatten wrote:
| I think the implication was that, once mp3 is no longer a
| household format, there will be a certain type of person who
| feels a nostalgia for the "sound" of mp3s, maybe even
| advocating that it was "better" in some way than the sound of
| whatever comes next...
|
| This is basically what's happened with vinyl records at this
| point, right? People have a nostalgia for their sound, even
| though by any scientific or technical measure a vinyl record
| represents music/sound less faithfully than, for example,
| lossless CD audio...
| 1996 wrote:
| As seen in the keyboard space! Try the latest XPS 15: low
| travel yet perfect feedback, better than mechanical
| keyboards!
|
| While we now have better technology, people prefer what
| they are familiar with.
| drzaiusapelord wrote:
| but we're drawn to "analog warmth" for whatever reason. We
| see it in guitars obviously with tube amps and analog
| effects pedals preferred over their digital counterparts.
| Vinyl has that messy analog-ish sound that we find pleasing
| in a similar way.
|
| Shrill low-bitrate, lower-fidelity digital sound just
| doesn't evoke that feeling in us. The same way no one is
| asking for RealMedia videos on their home theater system,
| but prefer film grain on video and 3D CGI to look "messy"
| (another analog noise characteristic). We humans love noise
| apparently! I guess evolution built us for a noisy and
| messy world and digital sound just seems off to us. We'll
| make an effort to get closer to analog warmth but do out
| best to flee digital shrill.
| igneo676 wrote:
| Supposedly, one of the big reasons people prefer vinyl is
| not because of the medium. It's because of the mastering
| process.
|
| CDs and/or Streaming services are victims of the "loudness"
| wars, resulting in music with low dynamic range. Since
| vinyl is often mastered by someone who specializes in the
| vinyl and is rather niche, they have full freedom to make
| it sound as good as it ever will be.
|
| That's also one reason why some people prefer Tidal or
| <insert HiFi music services of your choice> because
| sometimes they simply use better masters. At least, that's
| the only reason that can't be chalked up to placebo
| jim-jim-jim wrote:
| > As previously stated, the MP3 codec was refined using listening
| tests designed by european audio engineers and featuring the
| music they chose. In a sense, each of these songs acts as a
| resonant filter for every file encoded in the MP3 format
|
| Was thinking in the shower just the other day about genre-
| specific compression schemes. Could you get significant
| improvement if you knew something like the BPM or the spectral
| profile of common instruments ahead of time? Or is production too
| inherently complex for this to be worthwhile? Obviously no two
| hurdy gurdy recordings will sound the same, even though your
| algorithm knows wtf a hurdy gurdy is.
| underseacables wrote:
| Wow this is really fascinating. I've seen a lot of support for
| FLAC but I've never been able to get an iPhone or iPod to read
| them. I wonder why flac and other high end lossless file formats
| are not supported.
| LeoPanthera wrote:
| You can play ALAC (Apple Lossless Audio Codec) on your
| iDevices. If you have a Mac, the free XLD will convert FLAC to
| ALAC for you.
|
| https://tmkk.undo.jp/xld/index_e.html
| Mediterraneo10 wrote:
| 14 years ago, when the iPod Video was popular and it had an
| unlocked bootloader that allowed installing third-party
| software, lots of tech-inclined people replaced the Apple OS
| with Rockbox, which had support for FLAC. Unfortunately, with
| the next generation of iPods, Apple locked the device down, and
| the only lossless format supported was Apple's own.
| hctaw wrote:
| Lossless is only useful as an archival or intermediary format
| during production/recording where you can't tolerate lossy
| encoding.
|
| For listening purposes lossy codecs are all capable of being
| perceptually lossless for trained or untrained listeners,
| including MP3. MP3 gets a bad rap because low bitrate mp3 does
| sound awful. 320kbps or higher is sufficient for 99% of
| listeners, including audiophiles. Most listeners can't pass a
| double blind study in pristine conditions, let alone average
| ones.
|
| It's a lot like 192kHz 32 bit recordings. 96kHz audio bandwidth
| and almost 200dB of SNR has a purpose, but that purpose is not
| for day to day listening. Your ears, brain, speakers and
| amplifiers cannot reproduce or perceive the extra information.
| toast0 wrote:
| > MP3 gets a bad rap because low bitrate mp3 does sound
| awful.
|
| It's also the case that MP3 encoders got better over time,
| and if you're considering the sound of a 128kbps (or 96kbps)
| MP3 encoded by the Fraunhofer encoder you got from IRC in the
| late 90s; it's just not going to be good.
| Mediterraneo10 wrote:
| There are reasons to prefer seeking out lossless, though,
| even if you could just as well convert them to lossy once you
| have downloaded them. First of all, sometimes the lossy
| versions of downloads have "loudness wars" compressed
| dynamics, since the label assumes that anyone listening to it
| will be using earbuds in some loud public space. The same
| recording sold in lossless from an audiophile-focused source,
| however, will preserve the original mastering that preserves
| all that nice dynamic range.
|
| Also, if you want music that was recorded in 5.1 surround
| sound, sometimes the surround version is only available from
| lossless sources, while lossy sources sell only the stereo
| downmix.
| hctaw wrote:
| Masters will differ for target platforms, sure, but do you
| have any examples of records with a different master for
| MP3 for digital distribution and a lossless record from an
| "audiophile-focused source"?
|
| > sometimes the lossy versions of downloads have "loudness
| wars" compressed dynamics
|
| The loudness war has been over for years, and it was
| precisely due to lossless CD audio that it existed in the
| first place.
| [deleted]
| maxton wrote:
| iOS has supported ALAC (Apple Lossless Audio Codec), I think
| since day one, but at least for a long while. You can convert
| FLACs to ALAC without any loss in quality obviously, but the
| coding tends to be a bit more efficient for FLAC.
| chungy wrote:
| I'd be surprised if they don't support ALAC, Apple's lossless
| codec. Can't say I have any iPods or iPhones to try it out
| myself though.
|
| Apple generally has a very strong case of NIH.
| Malic wrote:
| I was under the impression that Apple chose to develop ALAC
| because it was less CPU/battery intensive to decode. This is
| going back to iPod Rev.1 days, mind you. Processing power for
| simply decoding audio CODECs hasn't been a challenge for some
| time now.
| LeoPanthera wrote:
| ALAC (and Sony's ATRAC) can be decoded using only integer
| math, which makes them very power efficient. It's the
| reason they exist in the first place.
|
| MP3, FLAC (and I assume AAC) requires floating point math
| to decode.
| didsomeonesay wrote:
| Flac decoder does not require floating point math since
| 2005:
|
| https://xiph.org/flac/changelog.html
|
| Come to think of it, that still might have been one of
| the historic reasons for ALAC's creation. Its development
| started before.
| spotyoufi462881 wrote:
| Maybe VLC app can read them?
| 8bitsrule wrote:
| "I am planning a series of related compositions, constructed
| first from the other songs involved in the listening tests, but
| then probing the space of MP3 compression in different ways,
| attempting to highlight even more explicitly the filtering effect
| of this codec.... Composing with these sounds and injecting them
| back into contemporary listening spaces is one possible act of
| resistance, one available mode of cultural critique."
|
| MP3's unwitting/unintended uncovering of the possibilities of
| weird filtering schemes points to the hugeness of unexplored
| timbre space. We are so familiar with our usual collection of
| instrumental timbres ... we have assumed that this galaxy is the
| whole universe. Timbre is waiting for its Hubble.
| kleer001 wrote:
| > Timbre is waiting for its Hubble.
|
| Jesus fucking Christ, man. I'm going to remember that phrase
| for the rest of my life. Good show, good show.
|
| standing_ovation.gif
| enriquto wrote:
| > We are so familiar with our usual collection of instrumental
| timbres ... we have assumed that this galaxy is the whole
| universe.
|
| Some references you may enjoy:
|
| * _Music: a Mathematical Offering_ , Dave Benson. Explains the
| mathematical theory of how to compute the timbre of an
| instrument given its shape. Also how the timbre of the
| instruments determines harmony.
|
| * _Tuning, timbre, spectrum, scale_ , William Sethares. A deep
| exploration of the relationship between timbre and harmony. It
| starts by exhibiting a (synthetic) instrument whose octaves are
| dissonant, and the music that you can do with it. Then it
| doubles down on this idea to obtain a lot of fun.
|
| * _The Topos of Music_ , Guerino Mazzola. Really hardcore
| mathematical music theory, too scary for simple people like me.
|
| EDIT: regarding telescopes for seeing timbre... have you ever
| seen an spectrogram? You can install a spectrogram app in your
| phone and see the spectra of sounds around you. There's a lot
| of things! My favorite is opening a rusty old door.
| tomcooks wrote:
| There's a music album, Most Beautiful Design by Bienoise (cited
| in the PHD of the author of the site as a great example of how to
| work with MP3 compression artifacts and glitches) that is made of
| heavily compressed mp3s so that it sounds great while still
| fitting in a standard 1.44mb floppy.
|
| https://forceincmilleplateaux.bandcamp.com/album/most-beauti...
| rubatuga wrote:
| Um, that sounds absolutely horrible.
| gwbas1c wrote:
| A few years ago I did a much more detailed comparison of lossy
| audio codecs:
| https://andrewrondeau.herokuapp.com/objectively_comparing_au...
|
| TLDR: If you need to go lossy, use Opus. At higher bitrates, it's
| the only lossy codec that has a flat frequency response.
| hctaw wrote:
| You cannot objectively analyze the performance of perceptual
| audio codecs. They exploit subjective perception of audio
| signals... I haven't dug into your analysis but on the surface
| it appears quite biased against MPEG codecs that exploit
| masking to determine quantization levels (one of the major
| advantages being that humans can't perceive quantization error
| in the presence of loud/noisy content, which can be exploited
| to use far fewer bits for the same samples!).
|
| The closest thing to an objective analysis tool is PEAQ which
| is also pretty terrible, but its universally terrible so that
| makes it useful as a benchmark.
| nayuki wrote:
| The author posts clips like "Example 1. White, Pink, and Brown
| Noise - Uncompressed", but the audio files are hosted on
| SoundCloud. My experience on SoundCloud is that no matter what
| format you upload as, they always stream it down to you as a 128
| kb/s MP3 or something like that. I think the author is better off
| self-hosting the WAV files?
|
| > Listening tests, primarily designed by and for western-european
| men, and using the music they liked, were used to refine the
| encoder.
|
| > As previously stated, the MP3 codec was refined using listening
| tests designed by european audio engineers and featuring the
| music they chose. In a sense, each of these songs acts as a
| resonant filter for every file encoded in the MP3 format.
|
| Through a simple accusation of racial bias, the author seeks to
| undermine the technical work that went into the development of
| the MP3 codec.
| danbolt wrote:
| I didn't really get that impression that the author was seeking
| to do that, to be honest. I think he was interested in the
| context developing the codec and how that influences the media
| that can be produced/expressed.
| fao_ wrote:
| > Through a simple accusation of racial bias, the author seeks
| to undermine the technical work that went into the development
| of the MP3 codec.
|
| I'm always surprised when pointing out that something has
| design limits, and often limits imposed by racial bias in
| testing, is seen as such an evil thing. Acknowledging the
| limits is the first part of making use of something properly,
| wouldn't you say? Understanding that MP3 is likely (Although it
| would have to be confirmed via testing) to have poorer encoding
| on non-white artforms is important to choosing a media
| encoding, no?
|
| I'm not sure how acknowledging the limits they created is
| "undermining the work that went into it", can you explain why
| you feel that is the case?
| cardamomo wrote:
| The ways in which biases can be encoded in an algorithm are not
| trivial. The author takes pains to describe how the lossiness
| of MP3 encoding is audible. The codec's authors made aesthetic
| decisions, shaped by their own taste, to determine what sounds
| could be acceptably removed from the audio. That should be a
| significant point in almost any discussion of MP3. The author
| of this piece does not, however, challenge the technical merit
| of the codec, as you claim. Instead, its biases are simply
| acknowledged and plainly described.
| apostacy wrote:
| I for one find the idea that there is a "white" way to hear
| music to be pretty offensive. Does he have any evidence for
| his race-realist perspective? I wish we could move past these
| outdated ideas.
|
| Of course mp3 is limited by the people who made it,
| everything is. It certainly wasn't done with any bad
| intentions.
| kruxigt wrote:
| Personally Im quite offended that blacks haven't
| contributed with almost any technical invention.
| kevin_thibedeau wrote:
| That is _cultural_ bias. It is just easier to play the other
| card and get attention.
| drzaiusapelord wrote:
| This isn't "racial bias" and has nothing do with race, but the
| types of music MP3 developers, who were western men, decided to
| use as a reference. Famously, Karlheinz Brandenburg focused on
| making 'Tom's Diner' sound good, which suggests the mp3 model
| is strongly optimized to rock music and, as others have
| claimed, sounds sub-optimal when encoding non-Western music.
|
| Your comment was good until you got into an unfounded and
| reactionary "reverse racism" accusation.
| apostacy wrote:
| I read a paper that asserted that the internet was racist
| against SE Asian people because it didn't have support for
| eastern languages out of the box.
|
| Never mind that the Chinese still have not completely made up
| their minds about exactly how to represent their language in
| digital form. It is ludicrous to think that in the 1960s they
| could have somehow anticipated how Chinese people wanted to
| communicate in digital form, and just have support for that.
| Essentially invent Unicode first.
|
| Of course the authors don't understand any of that, they just
| saw that there were limits of how Chinese characters could be
| represented digitally (this was in 2012) and they took an
| ignorant and antagonistic tone, and threw out accusations of a
| racist conspiracy by ISO and ASCII. And this paper was part of
| a curriculum at a major university.
|
| Accusations like this are almost always wrong, and actually
| damaging. In today's climate, it is especially damaging to
| throw out accusations of racism.
|
| I can not imagine how the designers of MP3 could have satisfied
| this person. The had to start somewhere. They had to start with
| what they knew, and work their way out, which they did.
|
| Text started out being only upper case only, and then lowercase
| and extended western characters, and then more complexity was
| added over the years. Photo codecs started out calibrated for
| Lenna[1], so that they would have a common reference, and
| worked from there. Were they supposed to be able to perfectly
| capture every skin tone, all at once, the first time? Should
| they have started with a picture of a non-white person first?
| What ethnicity then?
|
| This kind of antagonistic critical mentality is toxic, and
| should just be dismissed without consideration. At this point,
| if someone says that some technology is racist, I assume they
| are a grifter and ignore them.
|
| [1]: https://en.wikipedia.org/wiki/Lenna
| ardy42 wrote:
| > As previously stated, the MP3 codec was refined using listening
| tests designed by european audio engineers and featuring the
| music they chose. In a sense, each of these songs acts as a
| resonant filter for every file encoded in the MP3 format. Tom's
| Diner by Suzanne Vega, Fast Car by Tracy Chapman, a Haydn Trumpet
| concerto... these songs carved out the space of sounds that could
| be successfully encoded as MP3's.
|
| Does anyone have a full list of the recordings they used for
| these listening tests?
| tabtab wrote:
| Compressing white noise and other "hissing" kinds of sounds is
| not something MP3 is good at. Compression perhaps can be split
| into frequency vectors and noise vectors. Frequency vectors would
| be plotted lines of specific frequencies and intensity.
|
| White noise could be represented by a grid with frequency. Or
| perhaps use vectors with less frequency precision. That way the
| same mechanism can be used for both types, but with frequency re-
| scaled for noise to reduce data size. A given noise vector would
| represent an approximate frequency range rather than a specific
| frequency.
|
| A frequency vector would probably need about a quarter note step
| in precision for a typical compression level (but adjustable). If
| it allows interpolation between vector nodes[1], then it can
| handle frequency tremolo fairly well. A vector node can have
| flags saying whether to interpolate frequency and/or volume, or
| just do a direct step jump, which ever best fits the original.
| (Noise vectors can also have interpolation flags.)
|
| The noise vectors may only need a half-octave or octave range of
| precision. I'm guestimating only 4 to 6 bits are needed for the
| default precision, whereas the frequency vectors need around 11
| bits.
|
| As far as how to process the sound to produce such vectors, the
| encoder would have to "look" at the time/frequency plot, and
| divide artifacts (areas) into frequency "lines" and noise lines.
| I'm not an expert on such algorithms, but it probably can be
| refined from experimentation. Maybe make a rough guess start, and
| use a genetic algorithm to breed a vector set that best recreates
| the original, given a data size constraint.
|
| If there's a lot of sound going on in one spot, then precision
| can perhaps be reduced for that spot. Human ears can't typically
| isolate details when the rock band is going all out, for example.
| Maybe give more precision to the loudest vectors, but slack on
| the lessor ones to save space.
|
| [1] I'm thinking of segmented lines. Each segment node would
| contain a frequency value, volume value, frequency interpolation
| flag, and a volume interpolation flag. The range and meaning of
| each value would depend on the type (voice vs. noise) and
| precision specified for that line. "Voice" vector may be a better
| term than "frequency" vector.
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