Feature image for the blog : Differences Between a CD, DVD and Blu-Ray Disc

Differences Between a CD, DVD and Blu-Ray Disc

The hyper-convenience of streaming platforms, with their minimal monthly charges, has completely transformed the way people listen to music and view films. However, it can be argued that the rapid pace at which media consumption has changed over the years has taken away from the experience of appreciating its true value. While the nostalgia market has brought about the resurgence of vinyl, most overlook the other form of physical media that was the dominant choice in the pre-streaming era: discs. 

There are three broad categories of discs: CDs, DVDs and Blu-Ray. Each of these are used to store data, yet they all come with different features. Neo-Online provides a detailed comparison of them below. 


Compact Disc (CD)

As a computer device would usually be at risk of getting affected by malware, CDs became a primary medium for saving audio in digital form. Introduced in 1982, a standard CD has a capacity of around 650-700 MB — which seemed like a huge upgrade after the floppy disc drives, in which only less than 2 MB of data could be stored. 

They were initially read-only, but technology eventually allowed users to record on them as well. Towards the end of the decade, they became the industry standard for audio recordings.

There are many CD variations, including Quality CD-R Discs (in which the data cannot be erased) and CD-RW (on which data can be rewritten), among others. 

A CD works when the beam of a semiconductor laser (of 780-nanometer wavelength) is focused on its rotating surface. It measures the light that is reflected off the polycarbonate layer on the CD’s bottom side. This is then converted into sound. 

Although lightweight and portable, CDs have the disadvantage of being fragile and prone to scratches. Even if they can be repaired, disc readability might still be affected. 


Digital Versatile Disc (DVD)


Picture for Digital Versatile Disc


DVDs were introduced in the market in 1995. Although physically similar to CDs, they have a higher storage capacity of 4.7 GB (which is about 7 times more data than a standard CD). They are usually used to store standard-definition videos. These had led to the growth of the music and film industries when they first became available. 

There are two popular formats of DVDs: Quality DVD-R Discs and DVD-RW — both of which allow the recording and rewriting of data. These are a bit pricier than CDs. 

A DVD has several layers of plastic around 1.2 mm thick, each of which consists of polycarbonate plastic. Data is in the form of small bumps and pits on the disc’s surface, arranged as a long and single spiral track of data. The DVD’s design enables the laser to focus through the outer layers and onto the inner layers, and scan the data. 


Blu-Ray Disc (BD)

Blu-ray discs quickly became a replacement for both CDs and DVDs when they were first developed and released in 2005. They have a capacity of 25 GB (5-10 times more than that of other discs), which enables the storage of high-definition videos (making them more expensive than CDs and DVDs). The hard coating also makes them scratch-resistant. 

Blu-ray discs come with a better reading capability; the data is placed on a 1.1 mm thick layer of polycarbonate, which prevents any readability issues. They use a different type of laser (of 405-nanometer wavelength) to read the discs, with the smaller beams focusing more precisely on the information recorded in the pits (which are more than twice as small as those on a DVD). 


The Bottom Line

Discs come without the hassle of playing a vinyl record or the unsolicited recommendations from online algorithms. They are proof that the analog experience still holds appeal today. 

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