June 21, 2012
Lately I've been trying to rid my life of as many physical artifacts as possible. I'm with Merlin Mann on CDs:
Although I'd extend that line of thinking to DVDs as well. The death of physical media has some definite downsides, but after owning certain movies once on VHS, then on DVD, and finally on Blu-Ray, I think I'm now at peace with the idea of not owning any physical media ever again, if I can help it.
My current strategy of wishing my physical media collection into a cornfield involves shipping all our DVDs to Second Spin via media mail, and paying our nephew $1 per CD to rip our CD collection using Exact Audio Copy and LAME as a summer project. The point of this exercise is absolutely not piracy; I have no interest in keeping both digital and physical copies of the media I paid for the privilege of
owningtemporarily licensing. Note that I didn't bother ripping any of the DVDs because I hardly ever watched them; mostly they just collected dust. But I continue to love music and listen to my music collection on a daily basis. I'll donate all the ripped CDs to some charity or library, and if I can't pull that off, I'll just destroy them outright. Stupid atoms!
CDs, unlike DVDs or even Blu-Rays, are considered reference quality. That is, the uncompressed digital audio data contained on a CD is a nearly perfect representation of the original studio master, for most reasonable people's interpretation of "perfect", at least back in 1980. So if you paid for a CD, you might be worried that ripping it to a compressed digital audio format would result in an inferior listening experience.
I'm not exactly an audiophile, but I like to think I have pretty good ears. I've recommended buying $200+ headphones and headphone amps for quite a while now. By the way: still a good investment! Go do it! Anyhow, previous research and my own experiments led me to write Getting the Best Bang for Your Byte seven years ago. I concluded that nobody could really hear the difference between a raw CD track and an MP3 using a decent encoder at a variable bit rate averaging around 160kbps. Any bit rate higher than that was just wasting space on your device and your bandwidth for no rational reason. So-called "high resolution audio" was recently thoroughly debunked for very similar reasons.
Articles last month revealed that musician Neil Young and Apple's Steve Jobs discussed offering digital music downloads of 'uncompromised studio quality'. Much of the press and user commentary was particularly enthusiastic about the prospect of uncompressed 24 bit 192kHz downloads. 24/192 featured prominently in my own conversations with Mr. Young's group several months ago.
Unfortunately, there is no point to distributing music in 24-bit/192kHz format. Its playback fidelity is slightly inferior to 16/44.1 or 16/48, and it takes up 6 times the space.
There are a few real problems with the audio quality and 'experience' of digitally distributed music today. 24/192 solves none of them. While everyone fixates on 24/192 as a magic bullet, we're not going to see any actual improvement.
The authors of LAME must have agreed with me, because the typical, standard, recommended, default way of encoding any old audio input to MP3 …
lame --preset standard "cd-track-raw.wav" "cd-track-encoded.mp3"
… now produces variable bit rate MP3 tracks at a bitrate of around 192kbps on average.
(Going down one level to the "medium" preset produces nearly exactly 160kbps average, my 2005 recommendation on the nose.)
Encoders have only gotten better since the good old days of 2005. Given the many orders of magnitude improvement in performance and storage since then, I'm totally comfortable with throwing an additional 32kbps in there, going from 160kbps average to 192kbps average just to be totally safe. That's still a miniscule file size compared to the enormous amount of data required for mythical, aurally perfect raw audio. For a particular 4 minute and 56 second music track, that'd be:
|Uncompressed raw CD format||51 mb|
|Lossless FLAC compression||36 mb|
|LAME insane encoded MP3 (320kbps)||11.6 mb|
|LAME standard encoded MP3 (192kbps avg)||7.1 mb|
Ripping to uncompressed audio is a non-starter. I don't care how much of an ultra audio quality nerd you are, spending 7× or 5× the bandwidth and storage for completely inaudible "quality" improvements is a dagger directly in the heart of this efficiency-loving nerd, at least. Maybe if you're planning to do a lot of remixing and manipulation it might make sense to retain the raw source audio, but for typical listening, never.
The difference between the 320kbps track and the 192kbps track is more rational to argue about. But it's still 1.6 times the size. Yes, we have tons more bandwidth and storage and power today, but storage space on your mobile device will never be free, nor will bandwidth or storage in the cloud, where I think most of this stuff should ultimately reside. And all other things being equal, wouldn't you rather be able to fit 200 songs on your device instead of 100? Wouldn't you rather be able to download 10 tracks in the same time instead of 5? Efficiency, that's where it's at. Particularly when people with dog's ears wouldn't even be able to hear the difference.
But Wait, I Have Dog Ears
Of course you do. On the Internet, nobody knows you're a dog. Personally, I think you're a human being full of crap, but let's drop some science on this and see if you can prove it.
When someone tells me "Dudes, come on, let's steer clear of the worst song ever written!", I say challenge accepted. Behold The Great MP3 Bitrate Experiment!
As proposed on our very own Audio and Video Production Stack Exchange, we're going to do a blind test of the same 2 minute excerpt of a particular rock audio track at a few different bitrates, ranging from 128kbps CBR MP3 all the way up to raw uncompressed CD audio. Each sample was encoded (if necessary), then exported to WAV so they all have the same file size. Can you tell the difference between any of these audio samples using just your ears?
1. Listen to each two minute audio sample
(update: experiment concluded; links removed.)
2. Rate each sample for encoding quality
Once you've given each audio sample a listen – with only your ears please, not analysis software – fill out this brief form and rate each audio sample from 1 to 5 on encoding quality, where one represents worst and five represents flawless.
Yes, it would be better to use a variety of different audio samples, like SoundExpert does, but I don't have time to do that. Anyway, if the difference in encoding bitrate quality is as profound as certain vocal elements of the community would have you believe it is, that difference should be audible in any music track. To those who might argue that I am trolling audiophiles into listening to one of the worst-slash-best rock songs of all time … over and over and over … to prove a point … I say, how dare you impugn my honor in this manner, sir. How dare you!
I wasn't comfortable making my generous TypePad hosts suffer through the bandwidth demands of multiple 16 megabyte audio samples, so this was a fun opportunity to exercise my long dormant Amazon S3 account, and test out Amazon's on-demand CloudFront CDN. I hope I'm not rubbing any copyright holders the wrong way with this test; I just used a song excerpt for science, man! I'll pull the files entirely after a few weeks just to be sure.
You'll get no argument from me that the old standby of 128kbps constant bit rate encoding is not adequate for most music, even today, and you should be able to hear that in this test. But I also maintain that virtually nobody can reliably tell the difference between a 160kbps variable bit rate MP3 and the raw CD audio, much less 192kbps. If you'd like to prove me wrong, this is your big chance. Like the announcer in Smash TV, I say good luck – you're gonna need it.
So which is it – are you a dog or a man? Give the samples a listen, then rate them. I'll post the results of this experiment in a few days.
Posted by Jeff Atwood
I agree that 192kbps is fine the vast majority of the time but it still makes perfect sense to rip your collection to FLAC especially if you are dumping the original media. While we can sit and argue whether 192kbps or 320kbps is better, I'm sure most would agree that re-encoding a compressed file into another compressed format is a bad idea. That means if you have any intention of encoding those songs in a different format in the future it's really in your best interest to keep a lossless copy around.
I agree about MP3 bit-rate too. But what if I throw a party and I have really big speakers? I heard that if you amplify an MP3 with really big speakers, you get distortion. Please some fancy DJ corroborate this.
the warez scene did a great job in figuring out the best mp3 encoding presets and this info can be found in their mp3 scene rules. You can check them out here http://sceper.eu/2006/06/the-scene-rules.html. Basically they choose LAME and VBR (best quality/compression ratio):
- LAME 3.97 (final version!) with preset V2 and VBRNEW ("-V2 --vbr-new")
- LAME 3.90.3 (modified version preferred) with preset APS ("--alt-preset standard").
Why is it so important to minimize the size of the tracks? Storage space is cheaper than ever. A 100$ 1TB hard drive lets you store 1,500 CDs in raw format. And the prices aren't exactly increasing, either (at least not over the long term). So, you're really not losing anything on ripping these files in raw format.
I would not spend time worrying over which bitrate to use, but rather just rip everything in raw format, and then if availability on portable media is an issue I would just make MP3 copies of these files to carry around on portable media.
I hate to be "that guy" but using the song "We Build This City" in the experiment is not really fair. That song was created with 80s drum machines and synthesizers. The quality of the original samples wasn't very good to begin with. It would be like connecting an old NES to a stereo system and then complaining about it sounding just like mono.
Dave's comment at #1 goes to the heart of the matter: For archival purposes, always use lossless compression. Re-encoding to a spiffy new future format MAY render some MP3 artifacts audible. And storage space is cheap. I have a collection of ~1200 CDs ripped to FLAC - it's below 500GB, and it really doesn't matter to me if this could be reduced to 100GB.
I am sure I can rate all of them in order consistently; I am also quite sure I could show people what to listen to in order to rate the versions correctly.
I will not do so in order not to impact the experiment, however listen carefully to:
2. hats and crashes
3. the small hi-hat that plays on the eights
4. the splash cymbal (it only comes in at times)
I found these parts to change very noticeably in the 5 versions. There were only two versions which I had trouble placing: I was unsure about which was the third best or fourth best.
Listened on: iMac speakers and Sennheiser reference headphones. Didn't need to bring out a proper audio card and reference headphones.
Adolfojp makes a very good point here. I really really REALLY like the idea of this test, but it's flawed.
I grabbed an uncompressed WAV copy of the chosen track and gave it a listen for comparison, and found myself hearing what my ears identify as compression artifacts. I've trained myself to be able to hear them, which is probably a bad thing for consuming media, but it also means I get false positives on old tracks that use analog recording equipment and low-fi synths.
A much better track to use would be something like Aerials by System of a Down. It's modern, mastered using high quality digital processes, has a huge harmonic range at both low and high amplitude. It's my test track of choice.
Ignoring my own criticism of the experiment, here's my reasoning for avoiding MP3:
1) At low bitrate, it sounds significantly worse (to me, at least) than other codecs, such as AAC.
2) Too many vendors of MP3 files use old versions of LAME, have it configured badly, or just use a low bitrate. 256Kbps MP3 produced from a poorly configured codec can sound worse than 160Kbps MP3 produced from a properly configured codec.
3) I've noticed that MP3 has difficulty handling very complex audio, such as speed metal / black metal. For example, it tends to make that strange phasing noise over the top of heavy downtuned rhythm guitars during fast-paced high-frequency guitar solos. This may be my ears, or it may be the configuration of the codec, but I've heard it frequently (pun not intended).
4) Every media device I own or have access to supports AAC, OGG or FLAC, all of which my ears seem to enjoy more.
5) 1TB of storage space is ludicrously cheap. Heck, I've got just under 7.5TB worth of drives on my desktop machine. I could encode my entire collection in 32-bit 192KHz PCM and still fit it in there with plenty to spare. 320Kbps CBR AAC is more than small enough, and has a good quality margin.
Argh, typo: I user Sennheiser HD380 pro headphones, did not use AKG reference.
You mentioned that the playback fidelity of 24-bit/192kHz is slightly inferior to 16-bit/48kHz. What is the reason? After all you can map the 16/48 values exactly into 24/192, so it should be equal or better.
I think this audio quality experience poll is nice:
Well, except that it presupposes electrical music sources and (re)mastered originals, so it is rather hard (for me) to tell which artefacts were (deliberately) introduced in the original studio, and which ones were added/amplified by compression
I spent less than 15 seconds listening to the five different versions of the tracks and there were two clear winners (that I could listen to). I'm absolutely convinced I have picked the ones with the least compression (e.g. raw PCM and 320kps, allthough it is entirely possible the 'second pick' is in fact flac -- I didn't spend so much time vetting it)
Listened with puny Phillips in-ear buds and crappy work PC SoundMAX integrated audio... :)
@Roman I can only venture to guess that audio equipment is actually better able to smooth out the aliasing and samplefrequency distortions at 44.1kHz than at 192kHz... I wouldn't be surprised that driving the conus with sample 'steps' at 192kHz actually doesn't work out that nicely (forcing the exact curve from hardware that just doesn't allow for that?)
Anyways, you could follow the link to the research quoted
They all sound identical on my cell phone speaker on the subway.
I'll agree with you that space is important, especially if you copy everything on a smartphone. That is why I keep everything as uncompressed audio. Huh? Well, mp3 is not the most effiency audio format. 256kbps mp3 is like a 128kbps AAC or ogg file. But what if you change your phone or music player? The iPhone don't play ogg. So what are you gonna do? Rerip your ogg to AAC, and have double the compression artifact? Use mp3 and waste some space on your limited device?
Why not just keep the "lossless" on your computer and reencode it to your hearth content? For me, that's THE reason to keep a lossless copy. That is also why I keep all my picture as RAW file, so that I can re export them all I want to any format I desire. Hard drive are so cheap these day... You don't need to put that kind of file on a SSD.
@Roman it's worth a read if a bit hard to get (even if you understand a lot of the basics). It mainly just points out that most hardware doesn't have such a wide frequency range and is not perfect, so some of that (inaudible) higher frequency signal is going to bleed into the audible range and cause distortion, actually making the experience worse. I'm skipping all the details here.
Also 24 bit is unnecessary because psychoacoustics and proper encoders. So it just wastes space.
I'm sorry, but I have to say I couldn't get past your second paragraph. You say this not being about piracy. Then, you mention donating the ripped physical media. Whether you buy, rip, then sell/donate or borrow, rip, then return the physical media, once you no longer have the physical media, you no longer have a license to the "software" and it would be wrong to hang on to the digital copy. I don't know nor care about the legal versus non-legal copy argument, but this is just wrong.
Well, with only 5 samples of a single track there's a chance of 1/120 of someone giving the right answer by random picking.
You'll won't be able to rule out that people with dog ears do have the ability to tell the difference between them...
I support the lossless strategy many have presented. I keep everything from Bandcamp in FLAC, and am considering reripping what few CDs I have (comparatively to most people) to FLAC. As for the rest of my collection, 80+% is in Ogg Vorbis, much of it from Jamendo. I often pass up downloading MP3 if another format is available, due to MP3's age and technical inferiority. Storage and trnasfer is cheap nowadays. (until all your factories are belong to flood!)
@Romulo Did you consider that the poll was out of general interest?
Perhaps the poll shows that people clearly prefer a specific version - regardless of technical quality. Perhaps on average, people would think a 128kpbs is superior to a 256kpbs? Who knows.
Of course, that is not what we expect.
The test, however, is _clearly_ not designed to identify individuals with perfect ears. It is therefore a poll, not a test.
What about gapless playback? There still no general standard for this in MP3.
This discussion feels rather akin to discussing the quality of Bluray encoding whilst ignoring the capabilities of your television. The best encoding or lossless storage in the world won't help if your playback equipment is introducing all sorts of noise, clamping and/or artefacts all by itself. The same can be said of the choice of encoder and the material given to it - any resampling needs to make sure it avoids clipping, normalising, or any other common older tricks to reduce file size or you absolutely will create noticeable differences.
The correct assertion is to encode to the quality of your intended playback equipment & scenario, with the right encoder (configuration) for the job. That is why, as the linked Neil Young article states, encoding for recording is done at 24-bit - because in recording you need to fully capture the signal without guessing the 16-bit range in advance.
That said, this test is deliberately goading the tester to find differences, and as the same article highlights, the human brain is great at hearing things that aren't really there when it's looking for them.
I notice with interest that the audiophile discussions revolve entirely around the 20Hz - 20Khz range because that's what the ear hears, whilst completely forgetting that we are not just our ears. Has anyone done any studies on the sub/super-sonic effects on the physical body and how that may or may not influence the listener? I could easily imagine that an orchestra might produce e.g. 4Hz waves that might affect the physically present listener that a filter would entirely remove. Of course, that might be a good thing (3Hz being known to induce resonance in the stomach)!
Regardless I'd certainly rather have a lossless file so that I can choose to encode it to my hearts content for the right situation, to the file format that my given player supports.
I think you didn't touch on an important side of the issue here. While MP3 is the most popular format now in the future it may fall completely by the wayside and you might have a device that doesn't support it or simply want the advantages of another format. By storing all of your music using a lossy codec and getting rid of the reference media you've lost your ability to re-encode it without reducing the quality further.
A lossless codec such as FLAC does take more storage space but it also allows you to re-encode to something else without any quality loss. Personally I'd much rather take the space hit to store my music as FLAC on my home server (Running out of space with 6TB would take a LOT of music). Encoding from FLAC to MP3 (or another format of choice) is fast enough on a modern system that I'll simply re-encode the playlist of choice and then sync that to my phone where space actually does matter.
If you're going full MP3 I would reconsider getting rid of the physical CDs, they may be fine for listening (depending who you ask of course) but it is not a good archival format.
Damn! i'm must admin i wasn't able to tell the difference on any :(
128 should be transparent to me, so I suspect you included one at an even lower rate.
At this point I'm keeping 128k rips (iTunes AAC on that computer, MP3 on Linux) + media for physical CDs, and whatever comes off Amazon MP3. Higher bitrate stuff gets recoded to 128k en route to portable devices.
Wait, you expect me to listen to John Cage - 4:11 in a less than perfect quality and not recognize the difference? I refuse to take part in such an abysmal experiment, sir, this is exactly why this internet will never take off.
I agree a better song should have been selected that had more range and less synthesized sounds. None-the-less, I could hear a difference on my setup. I have USB cable connected to a Nuforce Icon2 and the Windows 7 passes it as 24 bit / 96000 Hz. The speakers connected to the Icon2 DAC are Paradigm Mini Monitor v.5.
I ripped my collection to FLAC, under the assumption the equipment I use to listen to my music will likely increase in quality, so using a lossless format means I wouldn't have to rip again to hear a better sound.
I couldnt get the files to play. Just loaded forever. I will admit that on most equipment I use I will not be able to hear a difference after the 160VBR (differs from track to track), but on my desktop I will. More importantly though, if you are getting rid of your CDs, please rip to FLAC. You can change that into anything and not lose anything. Also MP3 is pretty crap, it creates artefacts by itself.
One of the benefits of having noise-induced hearing loss: I can't tell the difference between ANY of the files. Woot! They all sound just fine to me. But I still ripped all my CDs to variable 192kbps mp3s (before throwing them out) any way.
A poll with a value for the quality of each piece (instead of ranking them) would've been better. Now when people can't hear the difference they still have to 'rate' them differently. This means your poll results are now not only determined by the perceived quality but also biased by the answering method. The best you can hope for is that people on average choose a random ranking for the tracks they can't distinguish - something I doubt.
Have you ever converted an MP3 file to another format, say AAC? The result is significantly worse than encoding AAC from the original. My hearing is pretty average but CD -> MP3 -> AAC I ended up with malformed music. I think these conversions don't stack well.
Today MP3 is something of a world standard. So this would only come into play if there are devices that require a different encoding.
Just adding my voice to those complaining about the material we're supposed to rank. Without being given a reference track (by identifying the lossless one), I have no idea what the original synthesized drums should sound like. I can tell you which clip I like best but not which one is most faithful. An important distinction in my humble opinion. Now, nicely recorded acoustic drums/cymbals that have been artifacted via mp3 compression? Sadly, I do know what that sounds like.
Furthermore, to add to the complaints, the sample has also ripping errors. At the beginning of every version, in the pauses, you can clearly hear scratching introduced by missed sectors while grabbing. That is imho the worst offense of a lot of DL music. There's no point in all the fancy lossless formats (flac, wv, ape) or high-quality lossy formats (AAC, OGG, MP3-320k) if the grab is ridden with audio gaps.
To me two of them sounded quite good, the other three were okay, but didn't seem to have as much depth... but I couldn't really point out why. I flipped back and forth between them for a bit, but gave my best guess as to which was good/bad :p
I am not an audiophile, and I have terrible speakers, so it probably didn't help much!
This test asks us to compare each track with what we expect to hear. How can that be meaningful with a pop recording, which has no real-world referent?
If you want to hear MP3 fail most obviously, listen to recordings of a capella chorus or string orchestra. At mid to high volumes (of the performers, not the playback device) you can often hear what used to be called "flanging".
Also: you obviously never listen to opera, or other continuous music split (gaplessly) into tracks. Everyone can hear the glitch at each track change, it's that obvious. This glitch is an artifact of the mp3 encoding format, and it cannot be corrected.
Also: since you're including FLAC, including uncompressed (WAV) obfuscates the question.
Personally: Since I frequently edit and/or mix, I store as FLAC and downsample to suit the playback device. I can't hear the difference between 192 and FLAC, but re-encode that 192 a couple of times and the result is disgusting.
I can't hear the difference, until I can..
that is, on mediocre headphones with on-board audio, listening to over-produced 80s pop/rock like this, I cannot tell the difference between the encodings. Using a DAC to a decent high fidelity system and listening to opera, the lower quality encodings are blatantly horrible.
Like most others here, I keep archival copies for listening when concentrating on the music, and everyday copies for the mp3 player, car, etc. In the old days that meant LPs and cassettes, now it means FLAC and mp3.. truth be told, I have mp3s made from cassettes made from LPs that no longer exist..
Your nephew should be punished for not keeping a lossless copy while ripping your CD collection :-)
I can't say I generally hear a huge difference on headphones, but when I listen on real speakers (70s Sansuis) through a real amp (http://tubedepot.com/diy-k12g.html) at a decent volume, mp3s are lacking. This is especially true compared to vinyl. I personally didn't really get why Black Sabbath were so heavy until I cranked it up on vinyl, at which point it was clear the mp3s and radio cuts were mere shadows of how it should really sound.
The point being is that I'd wonder if mp3 vs. lossless might be a bit too headphone focused.
They all sound exactly the same to me.
If you want a real torture test to compare encoding methods, while still being something fairly recognizable, go grab the Peter Gunn Theme off the Blues Brothers soundtrack. All that brass wreaks havoc on inferior encoders.
Interesting test! I used AKG K240 monitor headphones on a mobo sound card and could pretty clearly pick out the 2 best and 2 worst sounding encodings. The real kicker will be whether what sounded good to me was the highest quality encodings.
Like others I ripped all my CDs to FLAC for a lossless copy that can be encoded to any other format without transcoding.
I get the convenience of lower quality encodings, though, and I'll buy or stream lower quality from time to time for the same reasons I'll watch a movie on Netflix streaming instead of buying the BluRay.
I whole-heartedly agree with @Bob Meyer. I was very surprised to read that "[t]he point of this exercise is absolutely not piracy," followed by your plan to donate or sell your entire CD collection, thus giving up your legal rights to the content. I keep my collection of about 1,000 CDs in boxes in my basement so that I can prove I have a right to all of the music I've ripped from them. Without those rights, you would be a thief, just like everyone else who downloads or shares music illegally.
Destroying them isn't a good option either, for two reasons. First, it's wasteful and clogs up our landfills. More importantly, someday you may want to donate/sell some of your CDs (after deleting the bits from your computer, of course).
I hope you'll update your post so that it doesn't encourage piracy.
@Eric Larson: Vinyl sounds the way it does because of the turntable rumble. The low frequencies of the rumble, combined with the music, result in what are called "sum" and "difference" tones. They're very quiet, but we experience the effect as "richness" or "fullness".
It's a pleasant kind of distortion, but it is distortion.
24/192 can be slightliy worse than 16/44 if your system cannot handle high frequencies well and you get nonlinearities anywhere in the signal chain. Then you can get intermodulation distortion from signals in the non audible range which could lie in the audible range. With 16/44 those signals are just not there and distortion disappears. From a theoretical standpoint, the best combination would be around 20 bit/50 kHz, this would be good enough for even very young listeners who might be able to hear up to 22 kHz and the dynamic range would be that of the very best microphones and converters.
I was so excited about this test. Then I heard the song. I'm sorry, but that was probably the worst song choice for this test. The original is highly-compressed, synthesized audio. Converting it to "uncompressed" "raw" audio is like playing a VHS tape on a 60" TV. It still looks like crap.
> Furthermore, to add to the complaints, the sample has also ripping errors. At the beginning of every version, in the pauses, you can clearly hear scratching introduced by missed sectors while grabbing. That is imho the worst offense of a lot of DL music.
Hmm, I don't think so -- I used the most severe (accurate) mode of Exact Audio Copy when ripping the track from CD, and it reported a perfect copy.
Your brain, especially your senses, are inaccurate and imprecise sensors. Furthermore, our ability to analyze flaws in audio is even less dependable. Our brain is designed to fill in holes in our senses, and it does an extremely good job of it. Indeed, this is why mp3 and other perceptual audio encoding techniques work so well.
However, one must always keep in mind—you can just as easily fool yourself that you can't hear any differences, as you can fool yourself that you can.
You're right in the general case. One cannot hear a difference between the original CD and a bitrate of about 160kbps. But that's because your ears adapt to it. They readily fill in the gaps; and they want to! But that does not mean there is no difference, and certainly the difference can be heard in untestable ways, not necessarily when focused on the details of short segments of specific tracks, but instead at the overall sound and feeling of the music over extended periods of listening.
ABX is flawed. It's using the most inaccurate sensor ever designed: the human ear. I don't trust it, and prefer to go with the highest quality available for that reason. Because I know exactly how the mp3 algorithm works, I know it's designed to fool me, I know it does it quite well, I know I can't hear any difference, and I know better than to trust it.
Well I must be a dog. Those five samples were as different as night and day on quality. I listened using my stock EVGA mobo sound card and the only headphones nearby: a crappy skype headset that came with my webcam. No challenge to identify which quality was better or worse.
would like to see you try this again with some symphonic classical, which generally has orders of magnitude more harmonics than typical pop/rock. in my experience, on good speakers, i can absolutely tell the difference between 192 and 320kbps mp3, and in at least one i could even tell the difference between 320kbps and flac.
There are a lot of misconceptions about lossy music, unfortunately. I've never done a test like this myself, but I tend to trust the listening tests of the folks over at Hydrogenaudio, who've consistently found that people can't tell the difference between the original track and V2-encoded LAME MP3 (which is ~192kbps VBR), and that many people can't even tell the difference with 128kbps VBR LAME MP3. (And I believe they have a lot of audio engineers on board, as well as people with really good equipment.) With that said, I keep all my music in FLAC format, just for the archival benefits and the pleasure of having the "definitive" version.
I'm interested to see what the results of your informal poll will show.
"Also: you obviously never listen to opera, or other continuous music split (gaplessly) into tracks. Everyone can hear the glitch at each track change, it's that obvious. This glitch is an artifact of the mp3 encoding format, and it cannot be corrected."
This was actually fixed years ago. Modern MP3s have extra metadata to avoid the gap, supported by all but the most obscure music players.
In terms of HD movies, though, I can't agree with you yet. A Blu-Ray is generally 30GB—40GB whereas a compressed video is often 4GB—8GB, and it's far easier to see compression artifacts with our eyes than it is to hear them with our ears. In addition, Blu-Rays offer director's commentary, multiple languages, different audio configurations, bonus snippets, chapter selection, subtitles, etc. — none of which are supported by any of the leading digital video stores. (Of course, the pirates have had this stuff for years.) And what about 4k, when it becomes more mainstream? That's almost 4x as many pixels! I doubt most people have enough storage for that.
You should have given us an opportunity to say "I have no idea" in the survey. They all sounded basically identical. But I also think that that was a poor choice of song.
So anyway, I didn't submit the survey.
Brian: if only people who can hear a difference submit the survey, then the results will be inaccurate. It's important that everyone who takes the survey submits their results, especially if they can't hear a difference.
Jeff, are you still using Mediamonkey? I've been using it for ages, still love it.
Jeff, I'm listening on nice studio monitors (the ones I mixed my last album on) and was really excited about this test until I heard the sampled material. ALL of the files sound compressed, hissy and noisy to me. I then checked my original CD of this song and it sounds the same. The song is just . . . old. Recording technology has become so dramatically better, clearer, and more complex since then.
Complexity within the original file really seems to matter in compression, at least according to my experience. Today's commercial volume wars have pushed the limits of "real estate" within the sonic spectrum - there's a lot less "space" available in a modern rock recording as opposed to something like the Starship recording you chose for the test.
I highly recommend using a song recorded in the last 10 years with modern technology and re-issuing the test for more valid results.
The main problem is the white noise that is introduced while reproducing at low bitrate, most audiophiles don't bother if the original content was crappy that is why they still listen to really old music.... any way to troll a bit 24531.
i never thought blog writer like gouda the best, but who knows :P
I would not consider CD to be reference quality, as you point out they are 44.1 and studios work at a multiple of 48. Every time I've mastered a track and put it on a CD it's ended up with aliases because you can't match the frequency of a CD to studio sound cards.
So it's pointless worrying about this sort of thing.
I think this runs the risk of "pepsi challenge" issues. The basic premise here is that being able to consciously determine differences between a few samples is an adequate substitute for judging subjective listening experience over a lifetime. I don't think that premise holds up. I think if you present a handful of songs with different encodings to people and ask them to say which encoding they think is better you're going to get different results than, say, if you ask people to listen to different songs repeatedly over a long period of time. There are subtle effects that may not be noticeable on a single listen but become quite noticeable on repeated listenings.
As a case in point, have you ever listened to Pink's "Raise Your Glass"? Have you ever noticed the high pitched beeps in that song? I've noticed that most people don't notice them, but can hear them if they listen carefully. For example, http://www.youtube.com/watch?v=XjVNlG5cZyQ#t=58s "... raise. your. (feep) glass."
The same thing happens in lots of other music. If you're not paying attention you may not notice that sibilant s's are a little distorted or that high-hat hits are muddy. More so if you don't always listen to music with those sounds. But repeated listenings may make it more and more obvious, and then suddenly you'll wish you had a better copy.
Encoding can be forever, it's important to be extra cautious. Personally I think 192kbps VBR is an excellent encoding format, and for the most part it's indistinguishable from uncompressed audio to my ears. But I've noticed that even 128kbps CBR is hard to tell from the original for many songs, though I would be hesitant to pay money to lock myself into such a format for life.
Ok, to all the folks alleging piracy:
Can anyone point me to a EULA from my Best of Berlin CD I bought back in '88 that says I no longer own the rights if I sell the physical media? Because, according to property rights as far as I can tell, just because I made a legal, fair use copy of something I paid for, once the physical media dies, I do not lose the rights that I bought. If I have the receipt, I bought it. Selling it onwards != unbuying. Also, since I bought the CD *well* before the DMCA, I believe ex post facto law says you can't go back and change terms of a sale. So, at best, that might apply to CDs purchased after the DMCA in 1998. Might.
Absolutely +1 for trying to rid your life of as many physical artifacts as possible!
However, for me as a music producer, it is unacceptable to produce lossy audio. The media of today is about remixing and mashing up - reencoding audio in a lossy way at every new version is what I call disastrous.
Also note that the perception of lossy compression greatly depends on the kind of music. I play the organ, and organ music is especially prone to the artifacts due to MP3 compression.
If the aim is to get rid of the CDs, or at least not have to re-rip them again in this lifetime, then the only rational response is that you should store them in a non-lossy format which has an open-source decoder, say FLAC. Storage is cheap. Encoding is fast. Then you re-encode to the lossy format that is best for you at the time you need it (say in 20 years).
Besides, hydrogenaudio.org have already been doing these sorts of listening tests for years, and better.
Third, if you're the one who will be listening to these songs, how does what anyone else think matter? Only bad things can come from listening to what others say. That is, you may learn to hear artifacts which you did not previously detect. Is your life now better or worse for it? Personally this is one domain in which I'm happy to not have 'golden ears'.
I usually encode to ~80kbps vorbis for portable.
Generally I find MP3s acceptable. But, there are some cases where they are really bad.
When I compare my MP3s of Sade to the actual CDs the CDs win out by a large margin. There's just something about the quality of her voice on the CD that doesn't translate to the MP3s.
I took @Gsuberland's comments to heart, and tried encoding Aerials at different bitrates. Upon careful listening, I could pick out the 128kbps version. CBR 192, ABR 160, ABR 192, and CBR 320 sound exactly the same as the FLAC to me.
Casually, I can only tell whether it is 56kbps and below, or "good enough". 64-128 CBR sound good enough to me.
That said, I always use ABR 192 to encode.
I wrote a simple PHP script to do the double-blind encoding, just generates X random numbers in an array, writes that array to a file, and then encodes using the value at each array index as the filename. Random enough for me.
Ripping to a lossy format looks like a misguided optimization, I think.
The hard labor-part is the ripping: you only want to (have your nephew) rip your CDs once in a lifetime and never again, so you want to get the most out of that manual process. If you let EAC rip to FLAC you loose nothing and can always batch-encode all songs to MP3 with whatever lossy settings that suits you and your player. I've ripped my entire CD-collection to Flac and use dbpoweramp to batch-transcode it from FLAC to MP3 for storing on my iDevices and it works really great - the entire library can be converted completely unattended overnight. And if a better format comes along in 10 years I'll just convert to that. Sweet.
Let's look a a few numbers, based on my own FLAC-converted CD-collection:
My 517 CDs takes up 169 GB. That is 0.33 GB/CD.
A new 2TB harddrive costs $120. That is $0,06/GB.
This means that storing a CD as FLAC costs $0.02.
That's 2 cents for each album. You're paying your nephew $1 per album just to rip it. Does it really make sense not to rip it in a lossless format that adds 2% to that price? (Disregarding the admittedly extra hassle of storing both an archived format and also eg an iPod-friendly mp3 format)
First off, saying something like "I [..] think I have pretty good ears" is a ridiculous statement. The only way to know is to get your hearing checked. Hearing is not binary (as in hearing vs deaf), and you can easily loose a large spectrum of your hearing before you actually realize it.
Also, I agree with most of the other posts here. Not ripping to FLAC or WAV is just plain idiotic. The cost of the space is nothing compared to the time it would take to re-rip everything. In 5, 10 or 20 years, a few 100G will be the sample space on Google drive or equal to what you carry around on your credit card. Considering the cost and time to rip (not to mention the limited shelf life of physical media), its not worth the risk for literally zero gain.
Anybody who claims that lossless formats are _never_ better is just as ignorant as anyone who thinks that 192KHz is better. Also, if you must have lossy audio, go with a format (ogg) that doesn't require licensing.
"Not ripping to FLAC or WAV is just plain idiotic. The cost of the space is nothing compared to the time it would take to re-rip everything. In 5, 10 or 20 years,"
In 20 years time I'll care even less about audio quality. Meanwhile, the likelihood is high that lossless copies will be around for future generations because someone else will have cared enough to make them.
20 years ago I was mostly using computers that didn't have hard drives, but -- as far as music goes -- things have been at the 'good enough' stage for ages.
There doesn't seem to be much point with accurate ripping if you are going to throw data accuracy away altogether by using MP3. It is like measuring a piece of metal to 10 decimal places and then cutting it with an axe rather than a laser.
The flaw in the argument against higher resolutions is that it presumes that all equipment is theoretically perfect. Although CDs are theoretically perfect to 20KHz, the entire upper half of the spectrum comes out smeared across time in practice. This is why a cymbal sounds like a cymbal on a high resolution recording and merely an undefined hissing sound on a CD. In any case, there is so much more to music than mere frequency response.
Also, the claim of "inaudible difference" is merely "inaudible on my current equipment". A bit like assuming 8-bit colour is fine for archival photographs in 1995 because that's all your monitor can do.
Here's an interesting aside: if your sound card supports 24-bit, try switching to this mode for playing 16-bit CDs (Windows 7 Control Panel). I am amazed at the difference, even on small computer speakers, that using a more accurate decoding path can make. It is this accuracy that makes the difference — higher resolution audio is easier to decode cleanly than lower resolution, because the unwanted artefacts are further separated from the signal to begin with and do not need such harsh and harmful measures to be rid of them. (BTW iTunes does not seem to support 24-bit playback, you need to use WMP to hear a difference).
Far from the claim that some diehards do not understand sampling theory, those who say "it makes no difference" often do not understand the practical limitations and trade-offs of physical implementation. This error has been going on for years: people (even in the industry) saying that all digital sources are perfect and sound exactly the same.
Actually, the reason to use EAC is because problematic disks produce pops and cracks on ripping. Very audible no matter what encoder you're using.
I tried to participate, but the sample material is intolerable. Seriously, "...worst-slash-best rock songs of all time..."? No "slash-best"! Definitely worst song of all time and definitely not rock. I can't take it, the heinousness of the song completely taints any objective evaluation of the sound quality.
Also, unless your CD collection numbers in the tens of thousands, the space usage is insignificant by today's standards. I have around 500 (perhaps not an "audiophile" size collection, but more than most people I know) and I store them in their natural .wav format. Only consumes ~210 GB. Only slightly more than 10% of the drive upon which they reside.
1. "Uncompromised studio quality" has more to do with conversion flexibility, forwards compatibility than it does some "holy grail" of SQ.
2. Whether or not you can hear the difference depends heavily on a) your equipment (most people's is subpar) b) the kind of music you're listening to c) how that music was recorded and mixed and d) whether you've trained your ears to be sensitive listeners or not.
and I personally suspect 3) Just like there are "supertasters" out there, there are also "superlisteners" out there.
and 4) "good enough" is not a constant baseline in analog reproduction, and never has been, be it sound or vision. What was "good enough" in 1950 is not "good enough" now, and what's "good enough" now isn't going to be "good enough" in 2050.
Who cares if you can hear the difference between "good enough" and "absolutely uncompromised"? If there's no significant downside to the latter then the relative quality of the former becomes moot, as does the former itself.
I have FLACs in my music library. I don't give a crap about what bitrate they are or how heavily they're compressed because I don't have to. I can encode them to any format I want without worrying, be it MP3 or Apple's format du jour or Microsoft's own special format.
I don't have to worry if in 10 years all those 160kbps files I can't re-encode sound lackluster compared to the new baseline, like all those 128kbps files from the 90's.
As tech changes, so does people's expectations, and I suspect also their ability to perceive relative quality differences. It's called change, and adaptation. It happens.
The question is not "why FLAC", the question,as tech and perceptions change over time, is increasingly "why not"?
I did the test, didn't notice much difference, but have noticed big differences between 128kbps and FLAC before, which your sample songs don't show. So I think the sample song is flawed. It uses synths heavily, which are already samples, this is a big problem.
A live acoustic recording with multiple instruments would've been a better test (and preferably one that's known to be a good reference recording). One way HQ audio is better is good instrument separation and a sense of 3-d space, you feel more like you're in the room (whereas with LQ you get a more mushed together sound that sounds like it's coming from one place). With the recording you've selected, this difference can't be highlighted, even on the best recording, it sounds like it's coming from the same place.
Like most people here, I store my audio in FLAC, and for similar reasons. When I have 7+TB of space, then a few 100GB for FLAC is a no-brainer. I encode down to OGG normally to put on my phone, and stream from the server when I'm at home (no point duplicating the data) since I have a gigabit network that handles it fine.
I agree that nobody can hear the difference between 160 and 192Kbps, especially VBR, though some people can hear the difference between 160 FBR and lossless FLAC but they are few and far between.
I completely understand the desire to rid oneself of excess physical artifacts, but Jeff, you CAN NOT get rid of the CDs that you ripped. When you rip a CD, you're shifting the format of the music, but since you still own it, that's a perfectly reasonable thing to do.
If you then sell or donate the CDs, then you DON'T OWN THE MUSIC ANYMORE.
If you rip then sell, you're a pirate just as if you'd pulled the album off a torrent.
Think of it like this: Would it be OK to copy the CDs with your burner and then sell them on? Of course not! But if you rip and then sell them on, how is it any different? It's not!
Or think of this: You buy a CD new and then rip the CD and sell it. The next guy buys it used, listens to it. You've just created extra copies of the music. Not cool.
If you really need to minimize the physical artifacts, then just dump the discs on a couple of spindles and throw the cases in the trash.
I agree with your sentiment, Jeff: It is time to do away with media and concern ourselves only with the information.
I agree with posters that flac is the only sensible way to blanket archive the audio information of CDs: Flac (and wave) represent the base data of the CD, and for an insignificant storage cost, we can entirely avoid the debate of the ability of lossy formats to accurately represent the audible information of a CD, and, particularly, to maintain quality through transcoding.
But I'm intrigued that noone has mentioned the other qualities of a CD album - the liner notes. I buy CDs instead of mp3s because, apart from wanting a lossless copy, I feel I am missing out on an important aspect of the album if I just get the mp3s and a cover image jpeg. Sometimes this is misguided (a 2 page booklet), but sometimes it is the artist themselves who has produced the artwork, and it is a significant part of a concept album. Does anyone care about this part of the experience? Has everyone been iTunesd?
Also, I can hear no difference between the sample tracks. (Foobar 24bit to Sennheiser HD280Pro via Audigy front panel. I am 26 though. Hearing going.)
Haven't bothered to give this a shot, mostly cause I don't have confidence in my audio analysis. But what about the subconscious effects? It seems entirely plausible to me that listening to compressed tracks, where your mind sometimes fills in the details, might be more mentally taxing, or slightly stressful. I'd love it if anyone knows of any research in the area.
The reason I keep my audio in FLAC is because I want to keep it forever. For me, it's a question of compatibility.
If you encode in a lossy format today, what will happen in the future when a new encoding format is released, or when devices stop supporting MP3? Your only choice if you wish to update will be to use lossy encoding on your lossy encoding, resulting in further degraded quality. What happens when your awesome new proprietary (e.g. Apple) device only supports AAC5 and not MP7?
Encoding in lossless means that you can encode in any other lossy format at any time in the future.
I have submitted rates; no cheating, I heard that the two top rated samples have different compression level and the other three have different high frequency cut but with almost the same compression setting. used my $35 creative earplug headphones, with my wife snoring beside, heavy trucks 50 ft. away, and boeing airplanes 1000 ft. above about landing
Shenanigans! This can't possibly be a valid test, proper audio tests must be TEH DOUBEL BLINED!
Your influence is clear in your choice of cheese, Everyone knows which cheese is the best and which is the worst in that list. You even tried to cover it up by REVERSING TEH ORDER! Best Cheese = worst quality!
New test, this time use boy band member names, no-one likes boy bands. Or Vegetables! Animals! No, wait, Animals have Order, breeds of rat!
This all hinges around a supposition of how you'll interact with digital recordings that you have paid for in the future.
I have about 800 CDs in boxes under my bed now and a bit more living space in home, which I quickly filled with a new turntable and all my old vinyl.
I am worried though that when my descendants all have genetically engineered super-ears, that great granddaddy's record ripped record collection is going to sound like a load of old wax cylinders!
Couldn't complete the survey, sorry (two minutes of that song is enough for a lifetime :) ). First sample sounded quite good actually. But to equalize (unconditionally) the bitrate, judging by only one song (or even one genre), is a bit of a stretch, don't you think?
PS What's wrong with 'Rikki don't lose than number' http://www.soundonsound.com/sos/sep03/articles/testcd.htm ?
I also don't think this is a very good way to test the quality of the encoding. Since we don't have a reference (the uncompressed CD audio) what you're really testing is if any particular encoded version sounds the most appealing to the majority of people. That is not the same thing as an accurate representation of the original. Say for instance you would produce a truly horrible and annoying set of sounds. The encoding of that may remove some of the frequencies that are causing it to be horrible, and people would then rate that version higher. But it's not what you originally intended.
A better way to test this is, in my opinion, to give us the uncompressed version to compare against. Then the uncompressed version would be among the compressed ones we compare with. Then you would see if people really could tell a difference or not.
@Jeff: I must say I'm very surprised that you, of all people, would post something like this? You where the one to blog about preserving everything, and yet you want to throw information away?
This is actually the first time I've read a blog post by you that I really disagree with, for reasons stated multiple times by other commenters (Brent Maxwell and Ben Leggett just to name two), but oh well, nobody's perfect. ;)
Thank you for a very great blog though, and it's actually the only one I recommend others to read, but do so a great deal, because of the very high quality of posts, and all the information you manage to cram into them! :)
My kids listen to vinyl and say it has nuances that CDs and MP3s don't capture. Like clicks and pops I can only imagine.
>This is actually the first time I've read a blog post by you that I really disagree with, for reasons stated multiple times by other commenters (Brent Maxwell and Ben Leggett just to name two), but oh well, nobody's perfect. ;)
I wholeheartedly agree with Johny Woller Skovdal's comment.
Henrik was the first person to get this right.
Ripping lossless isn't really about audio quality, but rather generational quality.
If I convert my CD collection to 192kbps MP3 format, I'll be very happy to listen to it... for as long as MP3 remains a viable format. Given that (a)it's patent-encumbered, and (b)technology very rarely regresses, I can imaging wanting all my music in a different format at some point in the future.
Transcoding a 192kbps MP3 to something else causes *another* round of loss -- one you can definitely notice. Transcoding the new file to a third formation would be yet another round of loss; and the quality degrades rapidly with each generation.
As you yourself point out (https://www.google.com/search?q=site:codinghorror.com+hard+drives+cheap), hardware is cheap; including storage. Why would you not make yourself a lossless copy of your collection somewhere, and then carry around your lossy files for listening to?
MP3 = LOSS at any bitrate. 320 kbps is great for earbuds - that's it. I will not waste time comparing cds to mp3. There is none. Buy vinyl and a decent table if you want to hear the recorded track in it's purest form. Until you jarheads start MAKING digital music (and some crap I hear these days sounds like 2 notes over and over... 010101010) you will always need to convert to analog to hear it.
Go ahead and settle for micro speakers and video on phones. Bigger is better.
1: Limburger - Sounded Nice (Could be uncompressed)
2: Cheddar Sounded worse than Limburger
3: Gouda sounded OK
4: Brie Sounded Nice (Could be uncompressed)
5: Feta Sounded the worst of the lot.
2,3, and 4, were pretty similar to me. I don't know if I was imagining things or not. I tried not to put too much thought into it, but just give my impressions. I am an audio engineer, and not an audio snob. I want the best audio of course but if I can't hear a difference it's not biggie to me. I want of course to archive music with an uncompressed format of course. I encode all my MP3s of my music as LAME. I have to put most stuff up on Reverb nation at 160kbps due to size constraints, and I thought I heard a hit in quality over my 320kps files. They sounded more dull. Now that I think of it, I am exporting recent MP3s out of the Cubase project, rather than using WaveLab as I used to. Hmmmm. Maybe Cubase isn't doing LAME?
That was a really interesting post, and a really fun test to boot. Good timing too, now that my audio system is setup :)
I really hope you aren't pulling our legs though and they all end up being exactly the same.. By the way, are you going to normalize for stockholm syndrome?
Woof, woof, woof. Woof woof woof, woof woof!
@Tristan Harward: That sort of misses the forest for the trees. You're saying the sound quality *is* better, even if the human ears cannot distinguish between the two. But what's the point of having better unless you are going to be listening with something other than your ears?
Best = 5, Worst = 1;
WOOF WOOF WOOF WOOF WOOF!!!
I totally agree that decent-quality MP3s are "good enough" for listening, even on decent equipment. I tend to go for 256kps on average myself, just because "hey storage is cheap". However, to me that's still not argument for ripping straight to MP3. The point of ripping your collection to FLAC is that you can toss the CDs and never worry again, forever. You have the full fidelity original recording digitized faithfully, and you can then encode that to MP3 or any future standard at-will.
Re-compression with multiple codecs *does* degrade quality. If you rip to 192K MP3s and toss the CDs, in ten years (or more!) you might decide you want your music collection to be in 128K MZ6 format, because it's even smaller and better sounding, and one of your newest listening devices has dropped support for that old MP3 format. With a FLAC library you can do that. With only your 192K MP3 library you're hosed, you'd keep losing quality every time you transcode to a new format.
My recommendation, if you want to keep digital audio around at all: Rip to FLAC for archival purposes. You can put those on slow drives or backup media or whatever suits your fancy. These are your permanent archives. Then encode the FLAC data down to your MP3 flavor of choice for your live library that you actually share around the house and listen to on devices/computers, or upload to a music locker service, etc.
I guess you made your point about having really-good audio equipment.
I think that the sample chosen for the experiment is biased towards the point wanted to be made. I pass.
I believe it's quite hard to differentiate it -because we have no base ground on how he actual sounds are, when uncompressed- that's not how you do AB tests.
If you want to challenge us about sounds difference, it's better if you give us the very same track, compressed on different bitrate. Not different song, which may or may not bad recording from the very start, this can lead to different results.
The Great MP3 Bitrate Experiment may be worth doing with classical music---the results of reproducing a 100-piece natural-instrument orchestra (especially if live, not postprocessed/edited significantly) may be more striking than a small band with much of the sound electronic (or electronically post-processed).
Another poster was right---cymbals are a way of distinguishing quality. Is it live or is it Memorex? You can tell with cymbals.
I am actually surprised by the advances in modern MP3 codecs and disappointed by aging of my hearing. Many years ago I performed non-blind test and I could easily hear the difference between CBR 160 and CBR 192; and I believed I could distinguish 192 and 256.
But in this test I don't hear any real meaningful difference (old Audigy + AKG K390). Will try next week with high quality sound card and good headphones.
Well then. They all sounded roughly the same (Baad) except for one which was terrible.
I'd be interested to see a comparison like this done with some Black Metal, one live track comes to mind: Satyricon - Mother North (Live from Gjallahorn).
It features a brass section, crowd noises (chanting), slow drumming, fast drumming, even faster guitars.
Here's a crap version on YouTube: http://www.youtube.com/watch?v=1gye4XCFAmo
If you want to store as many songs on a portable device as possible, but also want to enjoy the confidence of future proof lossless format, why not give WavPack's hybrid mode a shot? It allows you to encode a song into two files: one .wv file at any bitrate you set, and one .wvc correction file containing all the rest of bitrate data. When both files are present, it plays as a lossless format. If only the wv file is present, it plays as that bitrate. The only downside is that you need a portable device which support WavPack