Tell the Difference Between a CD, DVD, or Blu-ray Disc

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Quick tricks to determine the type of optical disc you have
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CDs, DVDs, and Blu-ray discs can look a lot alike at a glance, especially if they’re blank. However, correctly identifying the type of media you’ve got on your hands is a breeze if you know what you’re looking for. In some cases, distinguishing features may be found on the disc itself—if not, your computer’s disc drive holds the answer. This wikiHow article teaches you how to identify a CD, DVD, and a Blu-ray disc.

How to Tell if a Disc is a CD or DVD

  • Most discs have "Compact Disc" for CD, "DVD," or "Blu-ray" printed on the disc.
  • CDs have a slightly green or green-gold tint, while DVDs have a slightly blue or purple tint.
  • Check the rim furthest away from the spindle hole. If you can make out a thin "trench" running through, it's likely a DVD.
Section 1 of 3:

Examining the Disc

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  1. If you’re trying to ID a commercial disc that’s been printed with a label or sticker, finding out what it is will be a piece of cake. Just give the bottom part of the label a quick scan. There, you should find a small symbol that reads “Compact Disc,” “DVD,” or "Blu-ray Disc." [1]
    • The “Compact Disc” symbol consists only of words spelled out in a stylized font, while the DVD symbol has the letters "DVD" over an image that resembles a disc. The Blu-ray symbol has a lowercase "b" next to a crescent over the words "Blu-ray Disc." Y
    • You should find a media symbol on all but the cheapest discs. Even blank CDs, DVDs, and Blu-rays are plainly stamped with identifying details.
  2. Not all CDs and DVDs are created equal. There are 3 varieties of compact discs and a whopping 7 DVD and Blu-ray formats on the market, each with a slightly different function. Your disc should say exactly what it is in or underneath its respective media symbol. [2]
    • CD formats: CD-DA (short for “digital audio”—in other words, ordinary, commercially-produced music CDs), CD-R, and CD-RW. The last two types are commonly used for burning music from other devices. CD-Rs can be written to once and only once, while CD-RW discs are rewritable and can be written over multiple times.
    • DVD formats: A DVD might be a DVD-ROM (movies and video games), DVD-R, DVD-RW, DVD-R DL, DVD+R, DVD+R DL, or DVD+RW. DVD-R discs are writable only once, while DVD-RW discs can be written over multiple times. If the disc says "DL," that means the disc has dual layers, allowing for more storage space.
    • Blu-ray formats: Blu-rays have also had the standard BD for Blu-ray Disc, BD-R for writable Blu-rays, and BD-RE for re-writable Blu-rays. They may also contain a number (i.e., BD-5, BD-9, BD-25, BD-50, BD-XL), which references how much storage space the Blu-ray disc can hold in gigabytes. BD-XL discs can hold over 100GB of storage space. [3]
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  3. If there is no printing on the disc, the underside color can tell you what type of disc it is. All optical discs reflect rainbow colors, but CDs will have a slightly green or green-gold tint. DVDs have more of a purple or blue tint, and Blu-rays have an even more distinct blue or purple tint. [4]
  4. Every now and then, you’ll come across a disc that has one or two lines of text printed around the hole in the middle. If you’re lucky, this string of characters might include the letters “CD," “DVD”, or "Blu-ray Disc." This should leave no doubt as to the disc’s purpose.
  5. Turn the disc sideways and zoom in on the “rim” section furthest away from the spindle hole. If you can make out a thin "trench" running through it, chances are good that it’s a DVD. If not, it’s most likely a CD.
    • A key difference in how CDs and DVDs are encoded can provide a helpful clue. Whereas the information on a CD is etched into tiny grooves on the bottom surface, on a DVD, it is nestled in between two separate layers of polycarbonate plastic, which can result in a “sandwiched” appearance. Blu-rays can have up to 4 layers and have harder plastic covering. [5]
    • The presence or absence of this feature is as close to a sure bet as you can get if you don’t have any other markings to go by.

    Tip: It’s impossible to differentiate a CD from a DVD by size or shape alone since both media types are manufactured using the same standardized dimensions. More specifically, they’re both 120 millimetres (4.7 in) in diameter and 1.2 millimetres (0.047 in) thick.

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Section 2 of 3:

Using Your Computer's Optical Drive

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  1. Press the button on or beside the disc-sized port to eject the drive tray. Set the disc on the tray and push the center hole down around the spindle, making sure the outer edges are aligned with the contours of the tray. Then, press the tray back in until it clicks. [6]
    • With self-loading slotted disc drives, all you have to do is slide the disc about halfway in and let the motorized rollers take it the rest of the way.
    • You may have to wait a few moments for the drive to read the data stored on the disc.
  2. Many computers have AutoPlay enabled by default, which can instantly pull up a program capable of decoding the information stored on a disc as soon as it’s inserted. If this happens, you should have no difficulty figuring out what sort of media it contains. [7]
    • For example, if after you put in your disc, you are shown the main menu for Monty Python and the Holy Grail, you’ll know that it’s a DVD-ROM or Blu-ray. If it starts playing music in your media player, you probably have a CD. If it has high-definition video, it is most likely a Blu-ray disc.

    Tip: If you don’t already have AutoPlay enabled on your computer that runs Windows, you can set it up by heading to the “Devices” hub in your “Settings” menu and switching on the “AutoPlay” option.

  3. Use your computer’s file explorer feature to navigate to the folder corresponding to your disc drive. On most PC computers, it will be the one labeled “D:” or “E:”. The icon will not only tell you whether it’s a CD, DVD, or Blu-ray but also display any specific suffixes it carries, such as CD-R, CD-RW, DVD+R DL, etc.
    • Sometimes, disc-related functions may be assigned to drive “F:” or even "G:", depending on the total number of drives your computer has.
    • It’s also possible to view what’s in your disc drive by loading the disc manually through any media player.
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Section 3 of 3:

Differences Between CDs, DVDs, and Blu-rays

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  1. CDs, DVDs, and Blu-rays all have different storage capacities:
    • CDs: CDs can hold between 650 - 700 megabytes (MB) of data.
    • DVDs: A single-layer DVD can hold up to 4.7 gigabytes (GB) of data, while a dual-layer DVD can hold up to 8.5 GB of data.
    • Blu-rays: A single-layer BD can hold up to 25 GB of data, while a dual-layer can hold up to 50 GB. A quadruple-layer BD can hold up to 120 GB of storage space.
  2. CD, DVD, and Blu-ray players can read discs at different speeds:
    • CDs: CD players and CD-ROM drives can read CDs at a rate of 150 Kilobytes per second (Kbps) at 1x speed.
    • DVDs: DVD players and DVD-ROM drives can read discs at a rate of 11.08 Megabytes per second (Mbps) at 1x speed.
    • Blu-rays: Blu-ray players and Blu-ray ROM drives can read discs at a rate of 36 Mbps at a 1x speed.
  3. Since CDs, DVDs, and Blu-rays have different storage capacities and transfer rates, this makes them suited for different purposes:
    • CDs: CDs are the oldest optical disc, introduced in 1982 and primarily used for music. They can hold up to 80 minutes of uncompressed audio, which is typically enough for a full album. Since CDs can hold more data than a floppy disk, by the 90s, CDs became popular for software for computers and game consoles. CDs were also ideal for storing low-resolution graphics, video, and audio.
      • Early game consoles that used CDs include the Philips CDi, Sega CD, Saga Saturn, Panasonic 3DO, Amiga CD32, and the original Sony PlayStation. [8]
    • DVDs: DVDs were introduced in 1995 and initially used for standard-definition movies and videos. DVDs eventually replaced VHS tapes as the primary format for home video because they were able to produce sharper images with better sound and bonus features. Like CDs, DVDs were also used as media for computers and game consoles. DVDs became the standard format when Sony made DVD the primary media format for the PlayStation 2.
    • Blu-rays: Blu-ray was introduced in 2005 as a competitor to the DVD. With their large storage capacity, Blu-ray discs were primarily used for high-definition video. A 50 GB Blu-ray disk can hold up to 3 hours of 1080p high-definition video, while a Blu-ray XL can hold 4K HD video. They also support more high-end audio formats, like Dolby and DTS surround sound. Like previous optical disc formats, Blu-rays can also be used to store computer data. Sony, once again, led the charge when it made Blu-ray the primary format for the PlayStation 3 console. [9]
  4. CD and DVD players are read by red nanoconductor lasers. CDs use a 780-nanometer wavelength red laser, while DVDs use a 650-nanometer wavelength red laser. Blu-rays use 450-nanometer wavelength blue laser, which allows Blu-ray players to read more data compressed into a smaller area.
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      Tips

      • If all else fails, you could also try sticking an anonymous disc in a CD or DVD player to see what happens. Keep in mind, though, that the disc won’t play if it’s blank or if its encoded information doesn’t match the format of the player.
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      • It’s rare to encounter a disc with no markings whatsoever, so you shouldn’t have too much trouble solving your digital media mystery.
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      References

      1. ↑ http://cdn.cnetcontent.com/e8/0b/e80b7343-bdc3-4378-b282-6487cb10d5ca.pdf
      2. ↑ https://www.bemuso.com/musicbiz/cdmediabasics.html
      3. ↑ https://www.tipard.com/blu-ray/blu-ray-disc-types.html
      4. ↑ https://support.discmakers.com/hc/en-us/articles/205395358-How-can-I-tell-blank-CDs-and-DVDs-apart
      5. ↑ https://www.scientificamerican.com/article/whats-a-dvd-and-how-does/
      6. ↑ https://support.lenovo.com/us/en/solutions/ht004167
      7. ↑ https://docs.microsoft.com/en-us/windows/win32/shell/autorun2k-intro
      8. ↑ https://obsoletemedia.org/data/video-game-console-media/
      9. ↑ https://www.theverge.com/2019/12/4/20992215/playstation-3-ps3-blu-ray-disc-hd-dvd-sony-25th-anniversary

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