[HN Gopher] Encoding Data in Dubstep Drops ___________________________________________________________________ Encoding Data in Dubstep Drops Author : albertzeyer Score : 123 points Date : 2021-01-15 13:12 UTC (9 hours ago) (HTM) web link (blog.benjojo.co.uk) (TXT) w3m dump (blog.benjojo.co.uk) | iamacyborg wrote: | Whatever that music is, it sure ain't dubstep. | | I wonder how well it'd work with something like this | https://www.youtube.com/watch?v=VEAf_ZztCP0 | have_faith wrote: | I know the point of the article has nothing to do with the | definition of dubstep so it took a lot of restraint to not | write something about it ha, difficult when you grew up | listening to the early stuff. | | I'll take this as my only chance I'll probably get to post | dubstep on HN in a valid discussion: | | https://www.youtube.com/watch?v=rc85cGTlKLY | | https://www.youtube.com/watch?v=dwva123XBMk | | https://www.youtube.com/watch?v=l2n7w1H0pRQ | 1MachineElf wrote: | Skrillex is actually regarded as a leader in Brostep, a | subgenre and/or style of Dubstep. At least in the USA, Brostep | has practically supplanted Dubstep and co-opted the name. This | has been occuring for about the past 10 years. A big factor is | the "drop" part of Brostep sounding very attractive to non-EDM | people who head-bang, and to whom traditional Dubstep would be | percieved as "boring" or not stimulating enough (without | intoxication). This has led to a re-enforcing cycle where | domestic EDM festivals reach greater audiences, and so they | keep promoting Brostep as Dubstep. | | Personally, I'm not a fan of this shift. I prefer EDM from the | era of the track you linked to, and/or contemporary artists who | emulate the older styles. | iamacyborg wrote: | Oh I know, I just get irrationaly annoyed by people calling | this stuff dubstep. It feels like half the problem is people | and/or clubs don't have soundsystems appropriate for playing | bass-heavy music at the right level, so they end up listening | to stuff that's light on the low-end but still calling it | "dubstep". | blovescoffee wrote: | Pretty much every genre changes significantly over its | lifetime though. It seems like you could just say you like | early dubstep just like people say, "I like old school hip | hop" all the time. | iamacyborg wrote: | I get what you're saying but the sound is so completely | different it's not a simple evolution of style. | | Listen to dnb from two decades ago you can still see | where current stuff comes from. Compare early Digital | Mystikz stuff with Skrillex and you wouldn't call them | the same thing. | 1MachineElf wrote: | You are probably right. For EDM, cultural differences have | kept the US lagging behind Europe and the UK. EDM-specific | clubs are not common outside of major cities known for | nightlife. A lot of EDM tours end up at venues that aren't | designed for EDM. These are the conditions informing | people's tastes, so probably a big factor for why bass | isn't as prominent as elsewhere. There truly are fans an | places where it is very much alive, just not as strong as | other places IMO. | tomc1985 wrote: | The bass music underground is alive and well in many | parts of the US. | | Mainstream it is not, and THANK GOD for that | the_local_host wrote: | Brostep may be Dubstep Disneyland, but I'm not sure if | being unconcerned with filing music in the right | subcategory counts as "lagging". | rorykoehler wrote: | This still gets played on a weekly basis in our house | https://youtu.be/qwCr9QRNMc4 | | To save a click... It's the garage track largely credited as | the birth of dubstep | jk7tarYZAQNpTQa wrote: | "Zed Bias - Neighbourhood" is actually regarded as one of | the first dubstep songs, or at least a transition one. | | Here are some other "true" dubstep tracks, in no particular | order: | | - Burial - Archangel | https://www.youtube.com/watch?v=3J1gvgwHblI | | - Rusko - Jahova | https://www.youtube.com/watch?v=1OE_jjJkkD8 | | - Coleco - Taostic | https://www.youtube.com/watch?v=krGadL6Je6A | | - Kode9 - 9 Samurai | https://www.youtube.com/watch?v=1-rEAe4C8gk | | - Skream - Mignight Request Line | https://www.youtube.com/watch?v=vJGXRQ9vBoU | zebraflask wrote: | I'd make a case for El-B, too: | | Express: https://youtu.be/SLbXmPvtZXA | | A lot of proto-wobble in this one. | iamacyborg wrote: | I'd say Rusko is responsible for the whole brostep thing. | You can see how it all grew from his tunes. | monocasa wrote: | Yeah, Woo Boost was a divergence point for the genre for | sure. | oarabbus_ wrote: | It's still very garage/2steppy. I think Anti War Dub by | Digital Mystikz is generally considered the birth of | dubstep. Of course, ask 10 people and you'll get 10 | answers. | iamacyborg wrote: | Midnight Request Line is the one I hear most frequently. | henearkr wrote: | Same, I did not know Skrillex but I dislike this style. | | On the other hand I love Fonik, for example. | | I love even more Deadmau5, E.T.H, ... | tomc1985 wrote: | Skrillex ruined dubstep in the 'states. And he looks like a | total d-bag. | | I hate that guy. | ljm wrote: | Listening to the Skrillex samples in the article, it just | sounds like DnB but... obnoxious. | | The Loefah track in the parent comment though, I can get | behind that. | iamacyborg wrote: | It's even more obnoxious than breakcore, which is saying a | lot. | djxfade wrote: | Yeah, this is the American "Dubstep" commonly referred to as | "Brostep". Damn I miss the real Dubstep sound! | oarabbus_ wrote: | This fell out of style for the most part in America 5+ years | ago, FYI. | _underfl0w_ wrote: | Can confirm this is no longer the new thing, but FWIW, jazz | music similarly fell out of style ages ago, but that | doesn't make new stuff in the genre uninteresting to those | who enjoy it irrespective of hype value. | | That is, it's no longer nifty and fashionable to listen to | this type of "Brostep", but people who liked it without | regard to its social status may continue listening to new | material as though nothing changed, while others may have | grown tired of the sound or the social clout it may have | brought them to be "in the know" or part of some zeitgeist | and simply kept up with "today's hits". | | The same is true of lots of genres IMHO. | iamacyborg wrote: | Still some bangers being released on Sentry records, Deep | Medi, Bandulu and a bunch of other labels. | sneak wrote: | I was hoping that this would be encoding the data in the audible, | data-sounding part of the sound. | | The technique described could be used on any bass-heavy music, | and is in no way related to dubstep or its data-sounding-ness. | marcan_42 wrote: | The way the author went about doing and explaining this is | somewhat confusing. What he arrived through that strange band | split/merge process is actually ~identical* to: | | - Apply an EQ filter that lowers the volume of the 0-100Hz band | by 6dB (this happened because he halved the amplitude of the | 100Hz band) | | - Add a slow binary digital signal at around ~4 baud (2Hz | fundamental), with slopes smoothed to around 10% of the bit time. | | This has nothing to do with dubstep or bass drops - it would work | for any song. It's just modulating data in infrasound, at 2Hz, | which is well below the threshold of human hearing. The problem | here is that he's also needlessly reducing the level of the | 0-100Hz band to half the amplitude (6dB), which completely kills | the bass feel of the original song. Dubstep fans will not approve | (and he needs better speakers if he can't hear the difference). | | A much simpler, more sensible process would be to just do this: | | - Apply a steep highpass filter at 20Hz (the limit of human | hearing), to remove any inaudible low-frequency (infra)sounds. | | - Reduce the volume of the overall song by, say, around 1dB, to | make a bit of headroom for the modulated digital signal | | - Encode whatever you want in those 20Hz in the headroom you | created (the amplitude can be quite low, e.g. 5%, it doesn't need | to move the whole waveform over). | | Then to decode it just lowpass the signal at 20Hz and do your bit | detection after that - the filter will remove the audio, leaving | only your signal, so it doesn't matter that your signal isn't a | whole 50% of the output power. Now the song is only 1dB quieter. | You can use as simple or as fancy a modulation technique as you | want in that 20Hz band. You could use (normal) ASK as he did, | just lowpass it to remove any high frequency components. You | could use FSK. You could use QAM. Whatever. | | * His process actually also messes up the original 100Hz band by | modulating it with a ~4Hz square waveform due to the way he does | the modulation by inverting and interpolating, which is going to | create harmonics and other ickiness around the transitions, as | well as does not guarantee the absence of clipping due to the way | he only reduced the amplitude of the low 100Hz band (this process | can actually _increase_ peak levels, as can happen any time you | use frequency filtering - try his high-pass filter command on | this file and watch sox complain of clipping, even though the | original file does not clip: | https://mrcn.st/t/filtering_clips.wav ), so I would not recommend | trying to emulate his approach precisely even if you want to | achieve the same actual effect, since it's actually quite a silly | way of going about doing it :) | dylan604 wrote: | Isn't this precisely what some ad tracking people or rights | management are doing? Aren't they adding audio that is out of | range for human consumption but things like Alexa can hear them | so that, or so the broadcaster can tell that a pub is | broadcasting a match without paying for it, etc? | blovescoffee wrote: | Do you have a link? I assumed a low pass filter was applied | to the signal to reduce unnecessary data transmission. I have | heard about what you're saying and I'm not dismissing it. One | could run their television through a low pass filter to get | around such tracking, right? | dylan604 wrote: | That's kind of what I was implying with one of my other | replies. This filtering is something that Alexa/Googs | should be doing on thier end. Their mics should only be | listening in the frequency ranges of what human voices | exist. | marcan_42 wrote: | This kind of modulating data in infrasound or ultrasound is | common, yes. It has been used in toys too, e.g. things that | respond to certain sounds from a show. chibi-tech stuck some | reverse engineered ultrasound triggers for a certain line of | toys in some of her songs :) | | https://twitter.com/chibitech/status/1237326756672983040 | | Infrasound only works digitally because no speaker system can | reproduce frequencies that low, and many analog systems will | corrupt them (e.g. AC coupling). Ultrasound is therefore used | most of the time in practice, but I believe infrasound has | been used in digital song watermarking for DRM/copyright | tracking purposes. | GuB-42 wrote: | Not really, unless you are doing a 1:1 digital copy, | frequencies outside the range of human hearing are often | removed. | | Frequencies outside the range of a speaker are often filtered | out as it can create distortion or even damage. And the job | of lossy compression is to remove everything that you can't | hear in order to save bytes, and limiting the bandwidth to | what you can hear is the most basic step. | | Instead, DRM systems typically encode data over a wide range | of frequencies (spread spectrum), well within the audible | range. It is designed in such a way that you could hear it in | theory, but don't notice it because it blends with background | noise. It is very robust, resisting compression, recording | and even deliberate attacks. In fact, it is one of the | techniques used by the military radios to resist jamming. | _underfl0w_ wrote: | You can also trigger wake words like "Ok Google" or "Alexa" | by using _harmonics_ of normal human voices that are outside | the range of audible sound. The key is that the mic can't | differentiate between the harmonics and actual speech of | normal human pitch and so the trigger is set off, but the | sound isn't audible to humans. | | I don't have a link to the paper handy (sorry!) but IIRC I | found a white paper on ArXiv called "Dolphin Attack" or | similar that demonstrated this. It was a fun read. | dylan604 wrote: | While technically that sounds like a cool hack, it sounds | like a dumb thing to actually allow to happen. "Okay | Google" or "Hey Alexa" outside of the frequencies | reproducible by human voices should be filtered out | completely. At least, from my comfy chair nit picking | someone else's work. Of course, by not filtering the | acceptable bands allows them to do all of the ad | tracking/rights management things they are allowing to | occur. The fact that Alexa/Google is able to do these ad | tracking/rights management is just another example showing | that the mic is listening 100% of the time. | IIAOPSW wrote: | The limit of human hearing is a bit above around 20KhZ. | Emphasis on the K. It is totally possible to hear 20Hz noise. | In fact 20KhZ is better for this because you can use a higher | bit rate and that band is going to have very little intentional | noise to begin with. | marcan_42 wrote: | Wrong side of the spectrum. The lower limit of human hearing | is 20Hz. It is not possible to hear <20Hz noise. It is, | however, possible to _feel_ it, if the sound pressure is loud | enough and you actually have a subwoofer capable of | reproducing those frequencies, but that is rather unlikely | unless your subwoofer is a cut-out in your room 's wall with | a fan in it. | | https://en.wikipedia.org/wiki/Rotary_woofer | | If you feed a 20Hz signal to a typical home subwoofer (or | even most club systems) and hear something, you aren't | hearing 20Hz. You are hearing a bunch of high frequency | rubbing noises as the speaker cone moves at 20Hz, trying and | utterly failing to couple any amount of energy at that | frequency into the air. This is why many songs these days are | produced with "bass maximizers" and why modern laptops can | sometimes have "decent bass". It's not bass, it's a filter | that purposely distorts the bass, which your speakers can't | reproduce, into higher frequencies, which it can and which | we've learned to associate with heavy bass played through | systems that can't reproduce it but distort instead. | | Just for reference, I believe these are the subs we use at | Euskal Encounter. I can vouch for the fact that they can make | the floor shake in a massive event hall venue. Low end | response: down to 28Hz. No more. | | https://jblpro.com/en/products/vtx-b18 | | It is indeed better to modulate data in ultrasound since you | have a lot more bandwidth - except for the fact that any | lossy compression applied to your file is going to completely | destroy your data. This is one thing the author got | absolutely right. | corytheboyd wrote: | Big shout out to the ideas like this that are just someone having | fun and being excited enough about the outcome to share with the | world :) | have_faith wrote: | a "Big shout out" is very appropriate for a post about dubstep | petercooper wrote: | Ben's blog is full of this stuff, it's fantastic, definitely my | favorite 'doing fun stuff with tech' blogger of recent years. | | https://blog.benjojo.co.uk/post/dns-filesystem-true-cloud-st... | is one of my favorites. | adamddev1 wrote: | This is really cool. Can the author or anybody else tell me how | he made those gif sketches with the moving waveforms and | equations? | arilotter wrote: | A DC offset, which amplitude-shift keying like this introduces, | isn't so nice to your speakers. It might cause them to heat up as | the offset waveform holds the magnet out in one direction. I do | love the idea of hiding data in "messy" audio, though :) | arcticbull wrote: | Aren't all speakers AC coupled? Should be filtered out by | somthing as simple as a blocking capacitor no? | arilotter wrote: | Yes, it's unlikely to cause problems in any real-world setup, | but it's theoretically possible :P I've edited my original | comment to clarify that it won't always be the case. | lostlogin wrote: | Signal that can damage hardware is something that used to | be discussed with CRT monitors back in those ancient times, | and rumours existed of a virus that played on this. | | Having damaging audio signal is a new one for me. | Unklejoe wrote: | Not necessarily. The amplifiers sometimes are though. | | In a normal 2 or 3 way speaker cabinet, you'll have an analog | crossover which consists of something like a capacitor in | series with the tweeter (high pass filter), and an inductor | in series with the woofer (low pass filter). | | In that case, the tweeter is protected from DC, but the | woofer isn't. | arcticbull wrote: | Very cool thank you! | isoprophlex wrote: | Also, if the data rate is low enough, compression will probably | also remove such dc components? | tekstar wrote: | If it's audio rate how is it different than a squarewave? | | Edit: looked closer at the post, the DC offset lasts for over | 100ms per cycle.. yeah that's a problem | virgil_disgr4ce wrote: | The problem is not the waveform, it's the DC offset requiring | more constant current to the voice coil. | mkr-hn wrote: | All waves are made of sine waves. DC offset is when the | signal is too much one way or another. | dylan604 wrote: | Maybe in analog, but in digital, they are squares and what | not type of waves. | layoutIfNeeded wrote: | Sigh... No, digital signals are not "square waves". | https://youtu.be/cIQ9IXSUzuM | bhj wrote: | I always laugh when vinyl is described as more "pure". | There's nothing more pure than math, and that's digital | PCM audio. Sure, it's stored as discreet samples, but | that's not how it comes out of speakers. The | digital->analog converter will give you 1:1 perfect | representation of the original waveform as long as you | sample at 2x the highest frequency desired and there's a | low-pass filter in place. | anamexis wrote: | For the record, I don't think vinyl enthusiasts ever | describe vinyl audio as more pure. "Pure analog," yes, | but that's different (and true). It's generally | acknowledged by vinyl enthusiasts and audiophiles that | vinyl introduces a lot of imperfections, which some | people prefer. | | Also worth noting that an _ideal_ D /A converter will | give you the exact waveform back, but such a device does | not exist (but you can get pretty close). | dylan604 wrote: | Have you ever played with an Arduino or similar device? | Comparing inputs signals on a digital pin vs an analog | pin? Hopefully, you'll agree it's the same concept. If | you haven't, I'd encourage you to try one out. They are | loads of fun. I am a huge fan of analog, yet digital is | just so damn convenient. If you have played with one, | you'll understand why your comment makes me smile and | chuckle. | grkvlt wrote: | Not strictly true, you must sample at 2x the frequency | _and_ at sufficient resolution in the amplitude domain, | i.e. an ADC that samples at 44 kHz but with only one bit | of resolution (outputs a 1 for positive input voltage and | 0 for negative, say) would be pretty awful... | dylan604 wrote: | Sigh... you are wanting to show me that we can do A/D and | D/A again? Thanks, I was totally unawares that we could | do that. I've never heard an audio signal played back | once it was digitized. My life is now complete. | | What this guy is showing is not a digital signal. It is | an analog signal that has been generated from digital | data. Not sure what the point of all of this was, but | thanks, I needed a break from finding this bug I've been | trying to squash. | _underfl0w_ wrote: | Your comment might be more helpful (i.e. more likely to | be read by others who could use the information you're | providing) without the snark. | magicalhippo wrote: | In a traditional amplifier the DC should be blocked by the DC | blocking capacitors, but I guess with modern full-bridge | class-D amplifiers which don't require those it'll have to be | done on the software/digital side? | dimnsionofsound wrote: | I was thinking it'd be something more like this: | http://www.windytan.com/2015/10/pea-whistle-steganography.ht... | TheActualWalko wrote: | Hey cool! Here's essentially the same encoder in a few lines of | JS, you can run this on https://wavtool.com by pressing cmd+; | (() => { const message = 'asdf'; const | messageBinary = message.split('').map(c => | c.charCodeAt(0).toString(2)).join('').split('').map(Number); | const bitDurationSeconds = 0.1; const shiftSize = 0.1; | return wavtool.mapSamplesCommand((sample, index, channelData, | settings, context) => { const bitIndex = | Math.floor(index / (bitDurationSeconds * context.sampleRate)); | const shift = bitIndex < messageBinary.length ? (2 * | (messageBinary[bitIndex] - 0.5)) // [0,1] => [-1,1] : | 0; return sample + shift * shiftSize; }); | })() | tekstar wrote: | Reminds me of Aphex Twin (and some other artists) embedding | images in the spectrograph render of their songs: | | https://www.magneticmag.com/2012/08/the-aphex-face-visualizi... | 1vuio0pswjnm7 wrote: | I have read that is quite common in, e.g., file carving, CTF | challenges. | tekstar wrote: | Stenography is common, but usually it's just modifying the | last bits of an image or hiding the extra payload after the | image data. This is "drawing" within the audio spectrum, | making the image out of audio that will be audible. | BugsJustFindMe wrote: | Steganography. Stenography is something else. :) | tekstar wrote: | This gets me every. Time. Lol | brianzelip wrote: | Just going to drop this here then, | https://www.youtube.com/watch?v=eTNx_SsApu4 ___________________________________________________________________ (page generated 2021-01-15 23:00 UTC)