DVD-Video recorders are also becoming available based on DVD-RAM & DVD-RW/+RW discs
The DVD Forum has defined the specification for video recording, which covers a range of applications including video camcorders, home recording and recording video on PCs. Basic features comprise Record, Playback, Delete and Edit. Addition of navigation data and the use of video objects (VOB) are also included.
Video files are labeled VR_MOVIE.VRO and are similar to VOB files and are contained in a DVD_RTAV directory. Video objects use MPEG-1 or MPEG-2 encoding with additional horizontal picture resolutions of 544 and 480 pixels. Audio encoding can be Dolby Digital, MPEG or LPCM but multi-channel is not possible with LPCM. Sub-pictures are as for pre-recorded DVD-Video, but with some restrictions for display control commands.
Real time recording and continuous playback are essential features and therefore a suitable buffer is used to ensure uninterrupted play even when skipping over defective sectors and jumping to another area of the disc.
Navigation data can include playlists and uses program chains like DVD-Video.
Both DVD-RAM and DVD-RW/+RW discs can be used for video recording and products are already available. These include both standalone video recorders and camcorders. Prices have fallen, allowing DVD to replace VHS as a recordable as well as a pre-recordable video format.