VCD is an mpeg1 based format, with a constant bitrate of 1150kbit at a resolution of 352×240 (NTCS). VCDs are generally used for lower quality transfers (CAM/TS/TC/Screener(VHS)/TVrip(analogue) in order to make smaller file sizes, and fit as much on a single disc as possible. Both VCDs and SVCDs are timed in minutes, rather than MB, so when looking at an mpeg, it may appear larger than the disc capacity, and in reality u can fit 74min on a CDR74.
SVCD is an mpeg2 based (same as DVD) which allows variable bit-rates of up to 2500kbits at a resolution of 480×480 (NTSC) which is then decompressed into a 4:3 aspect ratio when played back. Due to the variable bit-rate, the length you can fit on a single CDR is not fixed, but generally between 35-60 Mins are the most common. To get a better SVCD encode using variable bit-rates, it is important to use multiple “passes”. this takes a lot longer, but the results are far clearer.
These are basically VCD/SVCD that don’t obey the “rules”. They are both capable of much higher resolutions and bit-rates, but it all depends on the player to whether the disc can be played. X(S)VCD are total non-standards, and are usually for home-ripping by people who don’t intend to release them.
DivX / XviD
DivX is a format designed for multimedia platforms. It uses two codecs, one low motion, one high motion. most older films were encoded in low motion only, and they have problems with high motion too. A method known as SBC (Smart Bit-rate Control) was developed which switches codecs at the encoding stage, making a much better print. The format is Ana orphic and the bit-rate/resolution are interchangeable. Due to the higher processing power required, and the different codecs for playback, its unlikely we’ll see a DVD player capable of play DivX for quite a while, if at all. There have been players in development which are supposedly capable, but nothing has ever arisen. The majority of PROPER DivX rips (not Re-Encs) are taken from DVDs, and generally up to 2hours in good quality is possible per disc. Various codecs exist, most popular being the original Divx3.11a and the new XviD codecs.
CVD is a combination of VCD and SVCD formats, and is generally supported by a majority of DVD players. It supports MPEG2 bit-rates of SVCD, but uses a resolution of 352×480(ntsc) as the horizontal resolution is generally less important. Currently no groups release in CVD.
Is the recordable DVD solution that seems to be the most popular (out of DVD-RAM, DVD-R and DVD+R). it holds 4.7gb of data per side, and double sided discs are available, so discs can hold nearly 10gb in some circumstances. SVCD mpeg2 images must be converted before they can be burnt to DVD-R and played successfully. DVD>DVDR copies are possible, but sometimes extras/languages have to be removed to stick within the available 4.7gb.