video encoding formats

Not surprisingly there are a large number of CD and Internet video formats - those listed here are the most popular and most widely supported. Not all are cross-platform compatible, and most require the installation of additional software on the playback machine.

AVI

Now virtually obsolete as a distributable format (the DivX MPEG-4 codec being a major exception), but still used for proprietary specialist uses such as video capture or legacy applications.

MPEG-1

This non-proprietary format is probably the most popular for CD delivery. It has the advantage of being supported 'out-of-the-box' by both PC's (running Windows 95 and later) and Apple Macs, and requires no additional software to be installed. Some time and effort spent in the encoding stages can result in truly excellent picture quality although file sizes can become quite large. Files are traditionally encoded at 1/4 screen resolution but can be resized to play at 'full-screen' with only moderate degradation of image quality. If the delivery method is local (i.e. CD) and the playback machine reasonably new and powerful, then files can be encoded at 1/2 screen resolution or larger, giving even better picture quality.

MPEG-2

The native format for video material encoded to DVD. It creates very high quality full-screen pictures but with very large file sizes (a CD has a storage capacity of approximately 650 Mb, a DVD has approximately 4.7 Gb). Rarely used for CD's because of the file-size and data throughput requirements, although two CD based hybrid formats do exist: SVCD & miniDVD.

  • An SVCD disc is a documented and recognized standard based on MPEG-2 technology and offers approximately 30 minutes of running time at a somewhat reduced quality. The SVCD format is supported by most modern stand-alone DVD players and computer systems.
  • A miniDVD disc is not a documented and recognized standard, but is simply DVD quality MPEG-2 video recorded onto a CD. It offers approximately 15 minutes running time. Very few stand-alone DVD players support this format but most modern computers do, although a fast CD drive is required for smooth playback.

Be aware that in order to play either true DVD's or one of the hybrid formats, a PC must have a DVD software player installed. This is in addition to the physical drive.

MPEG-4

Claimed by many to be the successor to MPEG-1, MPEG-4 offers the potential of very high levels of compression with 'negligible' loss of quality. Unfortunately there are (still) serious licensing and compatibility problems at the moment, so this format is only useful in a closed system where the specification of target machines is closely controlled.

Apple Quicktime

This format is supported 'out-of-the-box' by Apple Macs, but requires the installation of the Quicktime player on PC's. That said, it is an extremely powerful and flexible format and is capable of excellent quality video playback from medium sized files. Files are traditionally encoded at 1/4 screen resolution but can be resized to play at 'full-screen' with only moderate degradation of image quality. If the delivery method is local (i.e. CD) and the playback machine reasonably new and powerful, then files can be encoded at 1/2 screen resolution or larger, giving even better picture quality. This format also supports both pseudo and true streaming (the controlled and negotiated delivery of video data across a network), and is therefore suitable for delivering video across the Internet. However, to support true video streaming, the web server delivering the video feed must have the necessary Quicktime Streaming Extensions installed.

Microsoft Audio/Video Format

Currently in various incarnations, but the most recent (creating files with the .WMV extension) is the most flexible. Designed primarily for web streaming, it is supported by Windows Media Player 7.x and beyond (and also version 6.4.x with additional software codecs available from Microsoft). This format is capable of producing excellent quality images from relatively small files, and supports both pseudo and true streaming (the controlled and negotiated delivery of video data across a network), and is therefore suitable for delivering video across the Internet. However, to support true video streaming, the web server delivering the video feed must have the necessary Microsoft Streaming Extensions installed.

Sorenson Spark & On2 VP6

The Sorenson Spark codec is the default codec for video clips encoded within a Macromedia FlashMX file, whilst the On2 VP6 codec is usable within Macromedia Flash 8 files. Both require the installation of the Flash plugin on the users browser for playback (this installation is automatic when a client browser loads a web page containing a Flash animation). They are primarily used for delivering video across the Internet and are capable of extremely high compression and good to excellent picture quality. They support both pseudo (progressive download) and true streaming, however to support true video streaming, the web server delivering the video feed must have the necessary Flash Streaming Extensions installed.

RealMedia

This proprietary format is ideal for the creation of web streaming video because even though it creates very small files, the resulting sound and picture quality is still reasonably acceptable (even at 56k modem connection speeds). It does however require the installation of (somewhat intrusive) additional software on both PC's and Apple Macs for playback purposes. Just as with Apple Quicktime and the Microsoft Audio/Video Format, to support true video streaming the web server delivering the video feed must have the necessary RealMedia Streaming Software installed.