CDs Not Lossy?

Discussion in 'Audio Hardware' started by lbangs, Mar 14, 2014.

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  1. Ham Sandwich

    Ham Sandwich Senior Member

    Location:
    Sherwood, OR, USA
    This thread is lossless. It will never die or fade away.
    Or maybe it's lossy because it is causing degradation of understanding.
    :p
     
  2. Schoolmaster Bones

    Schoolmaster Bones Poe's Lawyer

    Location:
    ‎The Midwest
    Agreed.

    I am now dumber for having gone through this thread.
     
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  3. SteelyTom

    SteelyTom Forum Resident

    Location:
    Boston, Mass.
    Your loss, their gain.
     
  4. MacGyver

    MacGyver Forum Resident

    Location:
    IRRIGON, OR. U.S.

    nah, just more Audiophile nonsense about the evils of the Redbook CD again, NVM that BS, YMMV...
     
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  5. Alice Wonder

    Alice Wonder Active Member

    Location:
    Redding, CA
    Close but I don't think that is completely true. When downsampling, it has to filter out frequencies above nyquest to avoid aliasing but those anti-aliasing filters do contain some drop-off below nyquest.

    For downsampling to 44.1 kHz I believe that the filters do impact some frequencies just below 20 kHz that some humans can hear, but by some humans I believe they are talking about young children, adults I believe (I'd have to research) generally can not hear above 16 kHz.

    So due to imperfections in the anti-aliasing filters, some frequencies below but near nyquest are also impacted by a downsample.
     
  6. Yost

    Yost “It’s only impossible until it’s not”

    Of course CDs use data compression. The 44/16 PCM data format used is not able to include all musical information from an analog master tape. In proper conditions the human ear can distinguish between an analog source and a CD. I read somewhere that at 96/24 the human ear cannot hear the difference with the analog source anymore. In practice, though, the listening environment and the state of our consciousness play I big role. So an AAC file in iTunes Plus format can sound fine too.

    The fact that CDs are not called "lossy" is a marketing ploy. When CDs were introduced, they were marketed as being better than vinyl, so no one wanted to tell there's actually less musical information on the disc (although I must state here that one huge advantage is that all that information stays on the disc, while records deteriorate with every playing session). The PCM format used is a compromise between what was technically feasible in the late 70's / early 80's and the fact that a German record company wanted the complete 9th Symphony of Beethoven on 1 disc.

    The term "lossy" was introduced when it became important that computers (and not dedicated CD players) could play music and file size was at stake. Data compression algorithms like MP3 and AAC were invented to make smaller files with enough information to reconstruct the original music (or, more correctly, the original music data file). Making use of the fact that most humans won't hear that you're reconstructing something that more or less sounds like the original, but is actually not an exact copy of the original. As small file size got less important, we finally arrive at the so called "lossless" files. These are data compressed files that can be decoded to reproduce the full uncompressed original file.

    So a CD quality audio file in 44/16 PCM format can be represented in a smaller Apple Lossless or FLAC file. We do this using data compression algorithms that weren't invented yet when the PCM format was engineered. But a CD quality audio file does not contain all musical info that the human ear is theoretically capable of hearing. For that you need a hires digital file in 96/24 format.
     
    Last edited: Apr 19, 2014
  7. ElizabethH

    ElizabethH Forum Resident

    Location:
    SE Wisconsin,USA
    'When CDs were introduced they were marketed as better .." Yeah. maybe no one remembers vinyl sales and cassettes PLUMMETED and CDs sales soared. as soon as CDs were introduced. They WERE better to most people.
    Easy to forget 'we' did that.
    It was not marketing 'fooling people' ... everyone, except a VERY few folks, loved CDs.
    I still do. I have a big record collection, and a big CD collection. CD for ease of use? ANY DAY ALL DAY..
     
  8. Rasputin

    Rasputin Forum Resident

    Location:
    Sweden
    Yost your post is so completely misinformed & wrong on every count. You should back up at least one of your misinformed claims with a link...

    1. To call CD lossy is absurd.

    2. Can you please show some evidence that 24/96 is required for full bandwidth reproduction...

    Are you referring to some master tapes containing "information" up to 80kHz?
     
    Last edited: Apr 19, 2014
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  9. Stones_Fan_129

    Stones_Fan_129 New Member

    Location:
    Madison, WI
    There's nothing wrong with CD's. It's a great medium and when mastered right sounds pretty darn good. The trouble is, they're rarely mastered right. Or at least I'm not finding the well-mastered ones. I have a few that sound as good as the same thing on vinyl, but very few, maybe 3 CD's that compare (Steve Hoffman's Billion Dollar Babies is one I felt was worth every penny - loved it).

    I got a turntable recently, and aside from all the crackle present in the records I have, the music on them is much more pure - it's mastered correctly. It could just be that I'm hearing analog compared to a digital sampling, but I think it's got more to do with the music being mastered right.
     
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  10. shaboo

    shaboo Forum Resident

    Location:
    Bonn, Germany
    No.

    So vinyl offers full analog master tape quality, while CDs are missing some "musical information", because digital audio is always missing something because it's digital?

    Just a rumor ...

    This claim is as bold as it is unproven. Obviously you are aiming at another 20 pages of pointless discussion in this thread ...
     
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  11. kevintomb

    kevintomb Forum Resident


    Like I have said dozens of times. Back then it was the cool thing to dump vinyl and get stuff on CD. Very few did not find CD better in most ways.

    Today it is retro cool to like vinyl and say CD sucks.

    There is a lot of truth to that.

    Whether it applies to most, many, or all, who cares.

    That is the general consensus.
     
  12. shaboo

    shaboo Forum Resident

    Location:
    Bonn, Germany
    Today it's even retro cooler to like CASSETTES! But how much has this to do with SQ or fidelity?
     
  13. kevintomb

    kevintomb Forum Resident

    But oddly enough, a vinyl record, is not always able to fully capture what is on a CD.

    Analog is only Infinite in book theory. The infinite simply means, there is no set in stone line where noise, resolution or frequency will Always fall, but it is limited by the media and equipment type and chain.

    So theoretically there could be an "Infinite analog system", but in reality not a chance.

    Maybe 30IPS 2 track comes close, but it is not even perfect.
     
  14. Maggie

    Maggie like a walking, talking art show

    Location:
    Toronto, Canada
    This post simply suggests that you don't understand what the term "data compression" means. It also shows that you haven't read this thread (let alone anything else on the subject of data compression schemes like MP3, AAC, and FLAC).

    I used to record 11 khz/8 bit audio on an old computer. It sounded like ****, but it wasn't "lossy" and did not use "data compression." Again, you need to read the whole thread before you contribute. "Fidelity" isn't the same thing as "losslessness." One is a technical/mathematical term, one is not.
     
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  15. Stones_Fan_129

    Stones_Fan_129 New Member

    Location:
    Madison, WI
    I agree to a point. Vinyl can sound better. I find that it's due to the mastering. CD's are a lot more convenient, and hopefully they'll start mastering digital downloads the way they master vinyl - to sound outstanding, rather than just being the loudest album on the block.
     
  16. Yost

    Yost “It’s only impossible until it’s not”

    I didn't call it lossy, I said it uses a kind of data compression because an analog/continuous signal is sampled to discrete data points. Just like movies that are actually just a lot of pictures shown very fast in sequence. So the original continuous audio signal is not completely present on a CD. When I talked about the marketing ploy, I put "lossy" between quotation marks because I know its a term from the digital audio data compression realm. When staying strictly in that realm, CD's aren't lossy because they contain all the digital audio data needed and don't need additional decoding before entering a DAC.
    First, "The dynamic range of human hearing is roughly 140 dB". On 16 bit PCM, the dynamic range is 96-98dB, and with some proper dithering can be manipulated to give the listener the impression of a dynamic range of 120dB. "24-bit digital audio calculates to 144 dB dynamic range". Quotes and info from Wikipedia. So 24 bit is a save word length for reproduction of full dynamic range.
    Second, "When it is necessary to capture audio covering the entire 20–20,000 Hz range of human hearing,[4] such as when recording music or many types of acoustic events, audio waveforms are typically sampled at 44.1 kHz (CD), 48 kHz (professional audio), 88.2 kHz, or 96 kHz.[5] The approximately double-rate requirement is a consequence of the Nyquist theorem. Sampling rates higher than about 50 kHz to 60 kHz cannot supply more usable information for human listeners."
    "One advantage of higher sampling rates is that they can relax the low-pass filter design requirements for ADCs and DACs…"
    "The Audio Engineering Society recommends 48 kHz sample rate for most applications but gives recognition to 44.1 kHz for Compact Disc and other consumer uses, 32 kHz for transmission-related application, and 96 kHz for higher bandwidth or relaxed anti-aliasing filtering."
    Quotes from Wikipedia.
    Also Bob Katz talks about 96 kHz as a save limit for processing digital audio in his book "Mastering Audio - The Art and the Science".

    No. Sampling at 96 kHz indeed has the effect that you can sample higher tones, but that's not the point. Those very high frequencies cannot be heard by humans, and need to be filtered out to remove any sound "anomalies" from being heard. The point is that a 96 kHz sample frequency gives you more than twice the data points for the audio signal between 20 Hz - 20 kHz, and thus a closer representation of the original analog continuous signal. And it gives enough room to exclude all kind of audio artefacts that originate from digital data processing, whether recording, mixing, processing or converting the bits.
     
  17. Yost

    Yost “It’s only impossible until it’s not”

    Vinyl is an analog/continuous medium and once the whole playing/recording/pressing chain was completely analog. Of course this chain has its problems, with noise and distortion being added along the way, or simply using low-quality gear. But sampling a continuous signal to a discrete signal always filters out data. Above a certain sample frequency your ears cannot differentiate between the original analog audio and a digital copy of that audio. As I said in the post you're replying to, this is partially a theoretical discussion. In practice even AAC files will "fool" you into believing you hear the "full" signal.

    Funny is that nowadays vinyl records are pressed from digital recordings. :winkgrin:
    Yeah, probably marketing again: "The original target storage capacity for a CD was one hour of audio content, and a disc diameter of 115 mm was sufficient for this, however both parties extended the capacity to 74 minutes to accommodate a complete performance of Beethoven’s 9th Symphony." Quoted from the official Philips news site.
    It's a discussion forum, isn't it? :shh:
     
  18. Yost

    Yost “It’s only impossible until it’s not”

    Yes, I completely agree that sound quality is mostly influenced by good recording, mixing and mastering. And not only vinyl, but even a CD can sound gorgeous. When people complain about the harshness of CD's, I always play them Kate Bush's Lionheart (Japanese first pressing cd). Most are astonished.
     
  19. Goratrix

    Goratrix Well-Known Member

    Location:
    Slovakia
    Why did you leave out the next sentence from your Wikipedia quote? "The dynamic range of music as normally perceived in a concert hall doesn't exceed 80 dB".
     
  20. Yost

    Yost “It’s only impossible until it’s not”

    Because I make a distinction between theory and practice. That sentence is a practical remark. Rock performances, studio recordings and sound effects can exceed that 80 dB. Nice that you're reading, BTW.
     
  21. Don Hills

    Don Hills Forum Resident

    This is mostly right, except for the bit about 96 KHz giving you a closer representation of the original analogue continuous signal. Given a perfect system, 44.1 KHz is as accurate as 96 KHz at capturing and reproducing everything between 20 Hz and 20 KHz. Nyquist proved it. As you said, all that a higher sample rate offers is "room" to implement real world (less than perfect) filters.

    Whether 16/44.1 is enough for audible transparency is another story. I strongly suggest reading the following article:
    https://www.meridian-audio.com/w_paper/Coding2.PDF
     
  22. Master_It_Right

    Master_It_Right Forum Resident

    With more and more of these MFiT albums coming out and sounding awesome, and me slowly running out of storage space for my CD collection, I think I am at a point where it's not worth it to keep buying CDs except for the audiophile ones every now and then.
     
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