HOW GOOD is DVD?

Basic Information

This document applies to PAL DVD. The data storage requirements pertaining to the PAL DVD coding scheme are outlined in this document.

DVD stands for Digital Versatile Disc. It is suitable for data backup purposes and good quality video storage. It is available in pressed DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW and rewritable DVD-RAM (Matsushita\Panasonic) in single layer (4.7Gb) and dual layer (9.4Gb) formats.

Total maximum data rate: 9100 kbits/sec=9318400 bytes/sec
Audio: 320 kbits/sec=327680 bytes/sec

This means and average of 9318400/25=372736 bytes per frame for video.

Audio will usually be encoded in AC3 or Dolby 5.1. Audio is rarely encoded in uncompressed linear PCM format except in some high quality DVDs.

Compression comparison and data storage requirements

The standard PAL DVD resolution is 720 pixels wide by 576 high at 25 frames per second. Audio is often encoded at 256kBits/s.

If video at that resolution is stored in as uncompressed 24-bit RGB values that would require
For video: 720*576*25*3=31,104,000 bytes/sec
For audio: 44.1kHz, stereo, 16bit = 44100*2*2=176400 bytes/sec
=31,280,400 bytes per second in total uncompressed.

This means that the compressed data on DVD takes up a fraction of the uncompressed data.

(9318400/31280400)*100=29.7899%
That gives us a 70.2101% saving!

The video compression techniques used by DVD are 16*8 macroblock encoding, intra-frame GOP generation, colour quantization, DCT encoding and at the lowest level Huffman encoding.

Summary

DVD-Video provides excellent picture and sound quality at a good price for film releases. Copy protection is normally implemented using CSS (Content-Scrambling System), MacroVision, weak sectors or a combination of these. All of these copy protection systems can be overcome with special software. Region locking is also implemented on videos and games although these can be overcome with firmware changes, unlock codes or hardware modifications.

DVD-Video provides excellent picture and sound quality at a good price for films.

The DVD-Video coding scheme allows basic interactive menus, multiple language and subtitle support, commentary soundtracks all on even the most basic disks. DVD-Video is good for archiving vintage material from VHS using commonly available set top boxes and PC based authoring software.

DVD in general is a very versatile and affordable way to archive data.
There is a variety of good DVD writing software and DVD-Video authoring tools available for the home user.

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