The actual DVD is to use MPEG-2 format. Both picture and sound produced by this format is much better than CD or VHS.
But unfortunately sometimes to save on production costs rather than MPEG-2 format obtained but MPEG-1 format. MPEG-1format has a quality that is not comparable with MPEG-2. MPEG-1 the same quality similar to VHS. MPEG-2 format using a compression system that removes Lousy Compression unimportant information, such as some areas in the image that does not change at all or eliminate some of the information will not be captured by the human eye.
Audio quality is also owned by a high-quality DVDs. Much better than CD Audio, for audio on DVD using the size and sampling rate greater than CD Audio. On DVD Video, Audio files do not become one with the image file. And the audio quality which is owned by the same audio on DVD video quality available on the theater space, namely multi-channel surround sound using Dolby Digital. Or DTS. In terms of compression, Dolby Digital or DTS can have the same quality or even better than CD Audio.