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Music Media

Linux Based Stereo Components 57

davidu writes "MP3.com has a really cool interview with Joseph Mesterhazy, the creator of the LCDAT Linux-based MP3 player. If you haven't seen it, it is extremely cool. The interview also talks about how open standards make projects like this easier. This is is one of the first, not vapor, stereo quality, MP3 players out there, and it runs Linux! " I wonder how many of us have duct taped perl scripts together for our MP3 playing.
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Linux Based Stereo Components

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  • >I don't want a harddrive in my car.
    >A CD/DVD drive is a safer and cheaper solution.

    Don't hold your breath waiting for this to happen.
    The designer of the empeg said that he had considered a cdrom drive during the design of the empeg. He ruled it out because car cd components don't have data capability (so they can't read CDROM) and CDROM components aren't engineered ruggedly enough for in car usage. The are rather flimsy designs suitable only for stable desktop use.
  • Only one nit: you've confused bits and bytes. mp3 records generally at 128k_bits_per second etc, and the CD is approx 1400 kbits/sec.
  • Certainly a true statement. Of course, this reminds me of my theory about that "girls don't care about important things." When was the last time you heard a girl say,
    "Sure, the iMac has nice colors, but this Dell has 256 MB of RAM!" or "I just brought my Conrad-Johnson amp home; I found the bass on the Krell to be too
    muddy."? :)


    For God's sake, should you ever find a supply of these women, let me know!!! :)


    Also, fwiw, I think that there are quite a number of audiophiles who might beinterested in this kind of equipment for convienience sake; notably, audiophiles that tend to leave music playing in the backgroud when they're not doing some serious listening. Of course, when the urge to really *listen* to some music comes, off go the digitally compressed tunes, and out comes the vinyl, or HDCD, or 30IPS tape, or what have you.


    BTW, I would guess that much of the degridation you see in sound qualities for MP3s is due to loss of timing information. This is why it's quite easy to tell the difference between CD and analog on a good system. I wonder if anyone has taken any measurements.


    Now if only they'd gone with the Sony system instead of AC3 for DVDs... maybe we would have found out how good music that's been lossily compressed could sound :/

  • Certainly a true statement. Of course, this reminds me of my theory about that "girls don't care about important things." When was the last time you heard a girl say, "Sure, the iMac has nice colors, but this Dell has 256 MB of RAM!" or "I just brought my Conrad-Johnson amp home; I found the bass on the Krell to be too muddy."? :)

    For God's sake, should you ever find a supply of these women, let me know!!! :)

    Also, fwiw, I think that there are quite a number of audiophiles who might beinterested in this kind of equipment for convienience sake; notably, audiophiles that tend to leave music playing in the backgroud when they're not doing some serious listening. Of course, when the urge to really *listen* to some music comes, off go the digitally compressed tunes, and out comes the vinyl, or HDCD, or 30IPS tape, or what have you.

    BTW, I would guess that much of the degridation you see in sound qualities for MP3s is due to loss of timing information. This is why it's quite easy to tell the difference between CD and analog on a good system. I wonder if anyone has taken any measurements.

    Now if only they'd gone with the Sony system instead of AC3 for DVDs... maybe we would have found out how good music that's been lossily compressed could sound :/

  • Certainly a true statement. Of course, this reminds me of my theory about that "girls don't care about important things." When was the last time you heard a girl say, "Sure, the iMac has nice colors, but this Dell has 256 MB of RAM!" or "I just brought my Conrad-Johnson amp home; I found the bass on the Krell to be too muddy."? :)

    For God's sake, should you ever find a supply of these women, let me know!!! :)

    Also, fwiw, I think that there are quite a number of audiophiles who might be interested in this kind of equipment for convenience sake; notably, audiophiles that tend to leave music playing in the background when they're not doing some serious listening. Of course, when the urge to really *listen* to some music comes, off go the digitally compressed tunes, and out comes the vinyl, or HDCD, or 30IPS tape, or what have you.

    BTW, I would guess that much of the degradation you see in sound qualities for MP3s is due to loss of timing information. This is why it's quite easy to tell the difference between CD and analog on a good system. I wonder if anyone has taken any measurements.

    Now if only they'd gone with the Sony system instead of AC3 for DVDs... maybe we would have found out how good music that's been lossily compressed could sound :/

  • by Paelon ( 69063 ) on Thursday July 29, 1999 @04:38AM (#1777450)
    Hopefully this can come of some use to people who know little about mp3s and CDs. I forget the exact number, but audio on CDs takes up somewhere around 1400 kilobytes per second. The majority of mp3s don't even reach 256 kilobytes per second. The reason that mp3s can sound so close to CD audio with the savings in size is through the masking of frequencies.

    The phenomenon is almost equivilant to the difference between newsprint advertisements and a painting (not in quality, but in terms of perception). With the newsprint, the picture is actually made up of tiny dots which, when viewed from afar, blend together to make a seamless looking picture, even though there are gaps if you look up close. Mp3s use the same principle, only with sound. Say you have a sound with a frequency of 80hertz at 60decibels; because of how our hearing works, that sound being played will mask out sounds around it. So for instance, if you had that sound playing, and suddenly you played a frequency of 75hertz at 30decibels, there would be no audible difference (note: these are numbers I'm making up to illustrate the general idea. I don't know the actual mathematics of it).

    What mp3s do is allocate a certain amount of space (128kilobytes/sec or 256kilobytes/sec), break down a second of music into a number of frames (usually 44.1) and then for each frame looks at what the frequencies are, and gradually and more agressively gets rid of the sound that is most likely to next be masked.

    The problem that can arise with this fixed bitrate encoding is that the encoder is not making an overall judgement based on what the quality of each frame should be, it merely knows how much it MUST cut out of each second of music. The solution to this is VBR or variable bitrate encoding, which has not been very widely accepted as far as I've seen. The difference with this style of ecoding is that you specify to the encoding program a quality level to set the song, and then it will go through each frame and cut only enough sound to fit your preference for sound quality, not some arbitrary number.

    Anyhow, I think that's enough of me rambling. Hopefully someone found that at least slightly informative and interesting.

    Paelon
  • Can anyone recommend a digital-out only soundcard?

    Living in a small house allows me to connect the PC to the stereo, but the sound quality is rather poor.

    I was going to buy a seperate DAC, but I can only justify the expense if I can find a sound card that outputs digitally (either coax or optical)

    Excuse the PC/soundcard ignorance, but living on Planet Linux for the past couple of years means that I don't really know what's available nowadays.

  • I totally agree, I listen to MP3s rarely, because the quality is so apparent. Especially on my very pricy audiophile system. On a cheap bookshelf system it's not a big deal, but on high-quality components its VERY noticable. Before you all start telling this guy that he's a loser and no one can possibly hear it, try it yourself. Here is a simple test that shouldn't take too long. Take any CD with a song that has lots of detail, preferablly something you know well. Just about anything thats not thrash metal or should work well. Take a song of the CD, MP3 it (try a couple different bitrates, the standard 128 is a lot worse then 256), and record it to a blank CDR. Now go to a stereo store that sells nice stuff. The nicer the equipment, the more revealing of the source limitations it is. Play both the original CD, and the MP3 on CD. Tell me which one sounds better.

    There are other formats out there that are MUCH better vqf [vqf.com] is one of my favorites, too bad there is no linux player :-( I think the reason why is mostly due to the licensing agreements (Yamaha owns the tech, but its free). Maybe someone can look into that more. Hopefully MP4, which uses a conglomeration of AAC (another better format) and VQF will improve the quality of MP3s.

    Spyky
  • by eric2hill ( 33085 ) <{eric} {at} {ijack.net}> on Thursday July 29, 1999 @04:53AM (#1777459) Homepage
    I'm putting this in the main thread 'cause the MD article I read (posted by Foxman98 [mailto]) was buried a level.

    I used to work at a high-end stereo shop, and we sold everything from Sony cheapo stuff to Sony ES to Denon and up. I got the chance to play around with an MD versus a CD. After some rigging, I was able to switch to and from the MD and CD, and I had the exact same music playing simultaneously. On cheaper speakers ($300/pr) it wasn't real easy to tell the difference, however on more expensive speakers ($1800/pr) the difference was night and day. Compared to the CD, the MD was a little shrill, and the base was a little "boomier". All in all, the MD would probably sound better in a car than a CD, simply because a car stereo usually doesn't reproduce quality highs and lows (mids are good tho :). Even the $4000 stereo I put in my car didn't sound as good as a properly set-up soud stage in a home room. There's something about a larger room that just gives more ambiance.

    Anywaze, on to MP3. From what I read about the compression technologies, it seems like the MD and MP3 algorithims are similar, but MP3 is designed to run at 128K/s to 256K/s data streams, where MD's are about 512K/s. (Correct me if I'm wrong, it's been a few years) I'd bet that an MD compared to an MP3 in a car would sound identical, but on a quality home system the difference would be night and day. Now say we got a better MP3 player (XAudio extensions anyone?) that supported a mic-feedback EQ so the system could be tuned, it'd probably sound damn good -- especially for the price!

    Just my $.02.
  • It might be overkill, but the TB Fiji has an optional S/PDIF daughtercard, and is supported under Linux. (I've verified that both digital in and digital out work) I'm not entirely sure this is needed, though, as the analog out from the Fiji is _very_ good as it is. Better than any of the portable CD players I have, and probably comparable to a $4-500 player. These might be a bit tough to find now, but well worth the effort, IMHO.

  • Hmm, lemme see... my cheap speakers/stereo

    B&O audio components....
    Bose 901's, 601's and 301's ($1600,$800,$500 repectively)
    CD's and Mp3's sound the same on the normal enjoyment level...
    Now, If I sit down and listen closely, being extremely picky and anal... I can hear the swiching and bit artifacts..

    Final conclusion... dont use mp-3 if you are anal-retentive... the type that can tell that a record was played once already or that a current diamond cartridge has been used more than 10 times, use bi-wire to the speakers that is 50 conductor ribbon 00 gague to enhance the sound.

    If you cant tell the difference between lamp cord or $100.00 a foot audio speaker cable (99.9% of all humans) then mp-3's will sound perfect to you

    There is one thing on this planet I cannot stand... an audiophile...
  • The site says that it is not a commercial product, but rather a build-one-yourself-from-these-specs type of thing.

    It seems to me that for a product to be vapor it has to be commercial and not shipping. As Joe's office-mate I can assure you that the player is quite solid, nothing gaseous about it.

  • The unencoded ripped wav should be identical to the CD quality, although playing it through your computer might (read: definitely will) give lower quality output than if you played it through your stereo system. Once the wav is encoded a lot of information is tossed out, and that is what causes the biggest quality loss. Another thing to watch out for is that all bitrates are not created equal. It's almost as important what program is used to encode an mp3 as it is what bitrate is allocated to it, because some encoders use dirty encoding tricks (cutting off any frequencies over 16khz, etc.)

    Paelon
  • The funny part is that Sony et al are hoping to crush MP3 by controling audio hardware, forcing a/v component makers to build in pay-for-play SDMI crap (through threat of lawsuit or through outright ownership).

    They haven't yet realized that audio hardware is as dead as physical audio media.

    The only Hi-fi equipment that will exist 10 years from now are amps, speakers, and headphones.

    -bonkydog

  • Actually, to jump back in and nitpick again myself, I think you've got them reversed again. Perhaps you've seen differently, but in my experience a Bps is a bit per second and a bps is a byte per second. I could be wrong about this though, and encourage someone to quote someone who is sure :).

    But yeah, in the original post I mixed up bits and bytes and all. For all who care: CD audio is exactly 1408 BITS per second, or 176 BYTES per second. It also appears that if you take the bits per second (1408) divide by number of channels (1408 / 2 = 704), and divide by the refresh rate (704 / 44 = 16), you'll get 16 which is why you commonly refer to cd audio as 16bit/44khz wheras DVD is 22bit/(i forget the refresh exactly, either 44 or 76 I believe). Fun with cd audio stats.

    Paelon
  • Let me preface by saying that I mean no disrespect, I simply disagree. I do see strong potential for this product, but only in a certain market. Hell, a lot of my friends send MP3s to their stereos through analog sound cards and cheap RCA connectors. Anyway, on to my opinion:

    In short, for me [the audio quality issue] isn't one.

    But for many it is. Sure, some people moved from cassette to CD because there's no rewinding, etc. But sound quality is the real selling point. (Yes, I'm aware that many audiophiles use their turntables instead of their digital equipment quite frequently).

    In the interview I stated I built this machine to replace my *analog* equipment. I don't think anyone can argue that a 256kb/s MP3 (on a digital output) sounds worse than a cassette tape. Perhaps if you bought a $1000 tape deck, but if this is the case I am sure you could care less about MP3.

    Good point, but I feel that such a device is mostly competing for market share against CD-Rs and the like. But I'd still say a good turntable will sound better than a 256 kbps MP3. Of course, to whom it will sound better is a very (!) small minority... and like you said, those folks could care less about MP3.

    Yes, if you listen for it, you can hear the compression of the audio. Especially in the rear channels if you place your receiver in a surround mode

    Why anybody would put an audio track designed for 2-channel listening into surround mode is beyond me. In two channel mode, can put you "there," where the sound doesn't appear to be coming from a couple of speakers. When fed into more than 2 channels, all imaging and soundstage qualities disappear. Of course, (reversing what you said above), the people who care about MP3 don't care.

    As far as I am concerned it sounds *close* enough to a CD, that I don't mind if there is a little swishy-ness in the cymbals. The advantages of having all my music at at the touch of a button far outweigh this.

    For me, the convenience advantages don't outweigh the sonic disadvantages. But then again, I place more emphasis on how my amp sounds than how many watts I can claim it's rated at. (Dude, my new Sony pumps out 200x5!) It's also the reason I have a single-disc CD player rather than a two million disc changer - better sound quality.

    It is all a matter of personal preference

    Certainly a true statement. Of course, this reminds me of my theory about that "girls don't care about important things." When was the last time you heard a girl say, "Sure, the iMac has nice colors, but this Dell has 256 MB of RAM!" or "I just brought my Conrad-Johnson amp home; I found the bass on the Krell to be too muddy."? :)

    Please excuse my generalizations, I mean it only in jest. And Joe, if you want to send me an LCDAT and prove me wrong about sound quality, please do. :) Even if I wouldn't buy one, it truly is a good idea for a large segment of the population.

    -Drew Boyles-
    dboyles@resnet.gatech.edu

  • I'm gonna pick one more nit. CD audio is in fact 176400 BYTES/sec, not 176. its 44100 samples per second times 4 bytes per sample (16bits, 2 channels). Also, this comes out to 1411200 BITS/sec. I don't know much about DVD, but I doubt the bitrates are comparable, since DVDs usually hold compressed data, whereas CDs are uncompressed.
  • I'm waiting for a mobile (mountable in an automobile) version of one of these things that can work with CD-ROMS with MP3s on them, play traditional or standard audio CDs, and also includes a radio tuner. This should be technically possible, right?
    Using a serial connection to (slowly) upload a set of songs is not for me...
  • I wonder how many of us have duct taped perl scripts together for our MP3 playing.

    Guilty as charged. I spend most of my time in the X Window System, but running xTerms (or their equivalent). It's much easier to control my MP3 listening from a cobbled together Perl script than to switch to the mouse and manipulate a GUI player, then switch back to a keyboard and resume work...

    I thought I was the only person silly enough to do this...

  • by anewsome ( 58 ) on Thursday July 29, 1999 @04:19AM (#1777473)
    Joseph is a member of mp3stereo@lists.gofast.net. If you're at all interested in issues about building your own stereo components, then you need to join the list. Send a message to mp3stereo-help@lists.gofast.net to learn how to sign up.

  • by Anonymous Coward
    is that ever since I got sensitive speakers/ amp (paradigm monitor 3's/ NAD) I can't really enjoy mp3s anymore. Even at 256kbps, I can hear some noises. I think 256 is actually good enough but changes of voltage in computer, interference from peripherals, etc, make it fall *way* short of quality I get from any $200-300 cd player. As I said, the difference is so big I can't really enjoy mp3s anymore. So, does this thing take care of that or not?
    - Rainy
  • Do unencoded ripped songs sound better than the encoded songs? What type of sound card are you using?
  • You know what, I think, nah, I definately remember seeing something like this on the web. I forget a link for it, but it was like a DiscMan, but one could load in Burned MP3 CD's and then the player wopuld player them as if the CD was just a regular Audio CD.... Sorry for the lack of info but I do know I saw it *somewhere*.
  • Egads, you must be able to hear the dust mights crawl around the floor right now w/ that kinda hearing!
  • The site says that it is not a commercial product, but rather a build-one-yourself-from-these-specs type of thing.

    You want something way cool that is NOT vapor? The empeg car [empeg.com].

    This thing makes me salivate. A removable in-dash MP3 player. Connect it to your PC to download music, create playlists, etc. Put it back in your car and use the remote to select your song/playlist. Store 476 hours of music on it (that's three weeks straight without a repeat). It has an awesome LED GUI including real-time visuals. And, it runs Linux. If you know a little Python, you can create your own custom GUI for it!

  • I think you're 100% right. MP3's are good when you've got mediocre equipment. If you've got good ears and high end equipment, they'll drive you nuts. I listen to them all the time at work on my crappy Polk speakers that came with this PC.

    At home? They're tolerable, but no comparison really to the quality from a CD played in my DVD player (which outputs digitally to the receiver).

    In my car? Not a chance. If I'm driving on the highway or something, I won't notice the quality as much, but on side streets there's not enough road noise to mask it. Drives me crazy.

    Try saying that on rec.audio.car though and see how quickly you get flamed. :) Lot of people don't understand that LOTS of people CAN hear the difference even at 256k.
  • This article seems to imply the empeg unit doesn't exist. Strange that mine is shipping as I speak.

    I submitted an article last week about how they're shipping unit now, but it was /dev/null'ed.

    The empeg car player is *not* vapourware.
  • The only time I've noticed quality issues over regular CD tracks is when screwing with the encoder's settings, or with a very dynamic audio source (loud, quiet, loud...)

    I've gotten around the latter problem by encoding everything VBR. I achieve a *miniumum* level of 128kbps, but when there is a quiet part to the music I've seen it hit ~376kbps if I'm not mistaken to keep the quality up.

    I use LAME, BTW. It seems to me that the encoder is the problem if you're hearing artifacts of encoding.

    I won't step out and say there is no difference, but with what I listen to and with what I listen to them through I haven't found anything that would make me want to cringe. At the *very* worst, it sounds like listening to a perfectly tuned FM stereo radio. At best, I can't tell the difference from the CD I cut it from.
  • Well the page seems to indicate that he's offloaded the digital-to-audio conversion to his receiver using optical audio output, so yeah. But if your soundcard is a decent one, you shouldn't really be hearing much interferance... And at 256 kbps, you're getting as much quality as possible. Are you using DAE to rip the songs off CDs or are you copying them through the soundcard?



  • There are a few things you can do to improve mp3 playback. The site said it used a SPDIF connector on the sound card / motherboard with a TOSLINK adaptor to a reciever. If you use the analog link, you're more likely to get noise as analog electronics and DACS in sound cards are pretty cheap.

    Another is to max the bitrate. I thought 512k rates were possible, but I never tried. There are also better encoders available. I'd say which ones, but I really don't remember. Some encoders do better than others.

    But if you already believe that CDs are crap, then you're screwed, as entropy dictates any transfer will only be as good as the source, no better, and likely worse, and I guess there are enough people that believe MP3s are crap at any rate, so I can't help on that.

  • Am I the only one who thinks that the quality of MP3-encoded audio is not up to par? Even if we're talking 256 kbps stuff, the quality loss is definitely noticeable if played through anything more than cheap speakers. Until these types of players have the storage capability to store audio in a format without quality loss, I don't see any serious music listeners really buying into it. However, for the junior high school girl who wants to listen to the latest Britney Spears (mmm) pop single, an MP3 player might be just the ticket.

    -Drew Boyles-
    dboyles@resnet.gatech.edu

  • by Casshan ( 4998 ) on Thursday July 29, 1999 @05:36AM (#1777487) Journal
    Hi, I am the author of this project, and would like to share my opinion about this whole MP3 audio-quality issue that a lot of people have brought up:

    In short, for me it isn't one.

    In the interview I stated I built this machine to replace my *analog* equipment. I don't think anyone can argue that a 256kb/s MP3 (on a digital output) sounds worse than a cassette tape. Perhaps if you bought a $1000 tape deck, but if this is the case I am sure you could care less about MP3.

    Yes, if you listen for it, you can hear the compression of the audio. Especially in the rear channels if you place your receiver in a surround mode. If this distracts you to the point you cannot listen to the audio, fine. Don't use MP3. I encoded most of my MP3 at 160kb/s, and my classical music and ambient music at 256kb/s. As far as I am concerned it sounds *close* enough to a CD, that I don't mind if there is a little swishy-ness in the cymbals. The advantages of having all my music at at the touch of a button far outweigh this.

    How many people do you know record TV shows at SLP speed on their VCR? Probably a lot. For them the advantage of being able to record 6 hours of video on a 2 hour (SP) tape makes up for the loss in video/audio quality.

    It is all a matter of personal preference.
  • Ah yes, but if your speakers are vifa components driven by very expensive LEAP designed crossovers using frequency response charts produced from the specific drivers you're using in custom built 1" thick MDF enclosures that together produce the auditory quality of $20,000 home speakers, you can shut them up pretty quick. :) My only complaint is I'm running a MT configuration and the tweeter is a bit too off-axis for my taste, and I haven't gotten around to fixing it.

    When car audio is good, its *good*. But most people who think they've got something good have never heard a $20k set of speakers, much less a $250k set of speakers. :)

  • by sdt ( 7606 )

    Hmm, I guess I qualify as one of those duct-tape people.
    I've got a cgi script (in perl of course), running on Apache, that gives me a nice listing of my songs and lets me pick the ones I want. Also it plays random songs and a kind of "radio"-streaming (it just streams random songs after each other. Currently I'm thinking of implementing song-titles via festival. All the hooks are there, I just need some time to implement it ;).

    Anyways, these things are really neat, I especially like those empeg car players.... now if I just had a car ;). -- sdt

  • Try saying that on rec.audio.car though and see how quickly you get flamed. :)

    Try saying that you've got a car stereo that sounds good in rec.audio.opinion or rec.audio.high-end and see how quickly you get flamed. :) I consider the term "good car stereo" to be an oxymoron, unless it's used in a relative sense (better than OEM, etc.).

    -Drew Boyles-
    dboyles@resnet.gatech.edu

  • I think the main issue is taste in music. While I think the different is negligable when listen to rock music w/ loud drums / guitars, the sound quality becomes evident when one listens to say, classical or opera. MP3 encoders aren't too kind w/ that kinda thing, they tend to tear off a lot of important bytes. Which would not be noticed in rock but would in anything less.

    Somehow I think some people wouldn't mind the loss of quality in their cars. Cars w/ tainted windows, hydrolics and subwoofers come to mind. When was the last time you heard Pavarotti coming from the windows?

    I think MP3's are usefull. Obviously, sinc eI can sit ay my computer and listen to any of my cd's. And they sound good. But not perfect. That brings me to the issue of minidiscs (I know I know, offtopic) Does anyone here know if the quality is the same as to CD's? It sounds like it..... Does it depend on thje encoder version?
  • You may want to take a look at the Hoontech 4D Wave NX card, which uses the trident chipset of the same name. Trident has released a GPL'd driver, so it should work "out of the box" with ALSA ( Advanced Linux Sound Architecture [alsa-project.org]). The Hoontech card has S/PDIF out (optical & coaxial). You can buy it from http://www.audiencedp.com [audiencedp.com] for $47 plus $5 S&H (I did). You can also try to buy direct from Hoontech [hoontech.com], but I am not sure how they handle the oversea shippings (unless you live in Korea :).
  • One thing that makes direct bitrate comparison difficult is that the MD recorder must of course be a real-time encoder implemented on a relatively modest DSP, whereas MP3 can take arbitrary amounts of time (and memory). As with any compression scheme (music, files, video etc), the more time you have and the more signal you can look at, the better job you can do. I've never done a direct MD vs MP3 comparison, but it wouldn't surprise me at all if 256k MP3 was comparable if not better.

"An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup." - H.L. Mencken

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