K Video Compression Dynamics

From Wikipedia, the free encyclopedia

K Video Compression Dynamics (KVCD) which is a non-standard modification of the MPEG-1 and MPEG-2 video standards for encoding digital video. It is compatible with a number of standalone DVD players, though it is not universal.

1 Technical description
2 VCDs and KVCDs
3 KSVCD (SKVCD) and KDVD
4 External links

[edit] Technical description

KVCD is a modification to the standard MPEG-1 and MPEG-2 GOP structure and Quantization Matrix. It enables storing up to 120 minutes of medium SVCD or DVB approximate resolution video on a single 80 minute CD-R/CD-RW.[1]

These specifications have been published as KVCDx3, the standard resolution which produces 528x480 (NTSC) and 528x576 (PAL) MPEG-1 variable bit rate video, from 64 kbit/s to 3,000 kbit/s. Using a resolution of 352x240 (NTSC) or 352x288 (PAL), it's possible to encode video up to about 360 minutes of VCD quality on a single 80 minute CD-R.

[edit] VCDs and KVCDs

The main difference between a KVCD and an ordinary Video CD is in the way the video data and audio data are encoded. Videos on a VCD are encoded at a constant bit rate (1150 kbit/s video, 224 kbit/s audio) which mirrors the overall bit rate of an audio CD. This allows for almost exactly the same amount of VCD video and audio data to be stored on a CD as the amount of CD audio data that could be stored on that same disc. (e.g. Approximately 80 minutes of VCD video can be stored on an 80 minute CD)

KVCDs deviate from this standard by employing a variable bit rate set by the encoder. The video data on a typical KVCD will range from a minimum of 64 kbit/s to a maximum of 3000 kbit/s[3mbps]. The bit rate of the audio is downsampled to a lower bitrate, eg. 128kbps, in order for more video to be stored on a CD than would normally be allowed according to the VCD standard.

This, however, also means that in order to create a lengthy KVCD with higher quality, one must be proficient at encoding video at variable bit rates. This ultimately creates a steep learning curve to the process of creating a KVCD, whereas most software capable of encoding ordinary VCDs have the specifications readily available. For this reason, many people prefer to spread a lengthy video across two or more VCDs rather than the extra effort required to encode that same video into KVCD format, though video files can be converted to KVCD parameters using custom templates for TMPGEnc, the Tsunami MPEG Encoder, in order to alleviate some of the difficulties associated with the creation of KVCDs.