What is the difference between DVD and Blu-ray and its resolution?

Background

DVD, also known as Digital Video Disc or Digital Versatile Disc, is an optical storage media format. It was invented and devloped by a number of companies in 1995. The main usage is for data and video storage. DVD's have the same dimentions as compact discs (CD's), but have the capacity of storing more than six times as much data.

The capacity of a DVD is 4.7GB (single sided, single-layer), 8.5GB (single-sided, double-layer) and 9.4GB (double-sided, single layer).

Blu-ray which was officially released in 2006 is named due to a blue laser reading the disc which is able to read data at a higher density then the red laser used to read DVDs. The capacity is also a lot higher with 25GB single, 50GB double.

Most DVDs and Blu-rays have region codes restricting the use to only one particular area of the world.

Type of DVD formats

DVD-R

These a write-once format that is compatible with many existing DVD Players, Recorders and DVD-ROM drives. This type of DVD can only be used in DVD Recorders and Burners that support DVD-R or multi-format recording (DVD+R). The storage is 4.7GB which is around 2 hours of MPEG-2 video on standard speed.

DVD-RW

These of similar to DVD-R but a re-writeable. Re-writing can be performed approximately 1,000 times before it is used up. DVD-RW disc are known to be less compatible then DVD-R. THey can only be used in DVD Recorders/Players that support DVD-RW recording or multi format recording. These also hold 4.7GB of data/video.

DVD+R

The DVD+ are a slightly different format although output and usage is the same. Only multi-format DVD Players/burners or DVD+ compatible players can use this type of DVD. Functionality wise it is the same as a DVD-R.

DVD+RW

Same as DVD-RW but only compatible with multi-format players or DVD+ Players.

DVD-RAM

This type of DVD comes in two varieties. There are both cartidge and non-cartridges, single sided or double-sided. If used like a Hard Drive they can be very usefull since you can erase/re-write up to 100,000 times, you can use it record your favourite TV shows and over write numerous times like how we did using VHS. Out of all the formats the DVD-RAM is the least compatible and is typically used for recording and playback in the same DVD player/recorder.

Other type of DVD

 For larger storage capacity there are DVD-DL (DVD 9). The DL stands for dual layer, within the disc itself there is a second layer underneath the top transparent layer. The drive is able to access the second layer by altering the focus of the pickup lazer so the focal point is a fraction deeper. Accessing the second layer will often cause a very brief pause in the viewing of video.

Dual Layer DVD's have a capacity of 8.5MB, almost twice that of a single layer.

Only Dual Layer compatible drives can read this type of DVD. Most computers nowadays are equiped with DVD-DL compatible drives.

Multi-Region DVD

DVD's have a regional which allow motion pictures to control aspects of a release, such as date and content.

A player will typicaly allow you to switch over regions a fixed number of times before it is locked in at one region. Of course there are many players on the market that are multi-region and can play any DVD.

Another way around this is to use software which not only copies the DVD, but actualy remove the region code, leaving the DVD regionless for use in any player. By searching around the net you should be able to find free versions of the kind of software.

Resolution

The resolution of a DVD is a large step up from VHS analogue however, on a large TV screen grainy areas can be noticeable, especially with darker shades. This is due to the resolution being 720 x 480 (480i), not HD.



Blu-Ray

A Blu-Ray video has a typical resolution of up to 1920 x 1080 which is full HD, and is very difficult to notice any grainy area on the screen, even in darker shades. The difference between DVD and Blu-Ray becomes very noticeable on larger TV sets. The frames per second is also faster and smoother with around 60 frames per second as opposed to around 25-30 frames per second on a regular DVD.

A Blu-Ray Disc holds 25 GB per layer as opposed to a standard DVD of 4.7 GB.

The next generation seems to be Ultra HD or 4k TV. 4k basically means a resolution of 4,000 pixels across the width of the TV which is 4x that of Full HD. Full HD may not be enough for larger TV's over around 50". Blue-Ray media and players will need to accommodate this higher resolution, but it should possible with newer compression CODECs.

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