DVD Audio

DVD-Audio (commonly abbreviated as DVD-A) is a digital format for delivering high-fidelity audio content on a DVD. DVD-Audio is not intended to be a video delivery format and is not the same as video DVDs containing concert films or music videos.

DVD-Audio was in a format war with Super Audio CD (SACD), another format for delivering high-fidelity audio content. Neither has gained a strong position in any consumer market.

DVD-Audio offers many possible configurations of audio channels, ranging from single-channel mono to 5.1-channel surround sound, at various sampling frequencies and sample rates. (The ".1" denotes a Low-frequency effects channel (LFE) for bass and/or special audio effects.)

Compared to the Compact Disc, the much higher capacity DVD format enables the inclusion of either:

With the introduction of the DVD-Audio format, some kind of backward compatibility with existing DVD-Video players was desired, although not required. To address this, most DVD-Audio discs also contain DVD-Video compatible data that allows the standard DVD-Video Dolby Digital 5.1-channel audio track on the disc (which can be downmixed to two channels for listeners with no surround sound setup). Some discs also include a native Dolby Digital 2.0 stereo, and even a DTS 96/24 5.1-channel, audio track

Since the DVD-Audio format is a member of the DVD family, a single disc can have multiple layers, and even two sides that contain audio and video material. A common configuration is a single-sided DVD with content in both the DVD-Video (VIDEO_TS) and DVD-Audio (AUDIO_TS) directories. The high-resolution, Packed PCM audio encoded using MLP is only playable by DVD players containing DVD-Audio decoding capability. DVD-Video content, which can include LPCM, Dolby or DTS material, and even video, makes the disc compatible with all DVD players. Other disc configurations may consist of double layer DVDs (DVD-9) or two-sided discs (DVD-10, DVD-14 or DVD-18). Some labels have released two-sided DVD titles that contain DVD-Audio content on one side and DVD-Video content on the other, the Classic Records HDAD being one such example.

Unofficial playback of DVD-Audio on a PC is now possible through freeware audio player foobar2000 for Windows using an open source plug-in extension called DVDADecoder Cyberlink's PowerDVD Version 8 provides an official method of playing DVD-Audio discs. This feature was dropped from version 9 onwards. Creative also provide a dedicated DVD-Audio player with some of its Soundblaster products, but this latter option is not compatible with versions of Windows later than XP.

From a purely technical standpoint, the audio resolution of a DVD-Audio disc can be substantially higher than standard red book CD audio. DVD-Audio supports bit depths up to 24-bit and sample rates up to 192 kHz, while CD audio is 16-bit, 44.1 kHz. In both cases, the source recording may have been made at a much higher bit and sample rate, and down-converted for commercial release.

DVD-Audio discs may optionally employ a copy protection mechanism called Content Protection for Prerecorded Media (CPPM) CPPM, managed by the 4C Entity, was designed to prevent users from extracting audio to computers and portable media players.

Because DVD-Video's content-scrambling system (CSS) was quickly broken, DVD-Audio's developers sought a better method of blocking unauthorized duplications. They developed CPPM, which uses a media key block (MKB) to authenticate DVD-Audio players. In order to decrypt the audio, players must obtain a media key from the MKB, which also is encrypted. The player must use its own unique key to decrypt the MKB. If a DVD-Audio player's decryption key is compromised, that key can be rendered useless for decrypting future DVD-Audio discs. DVD-Audio discs can also utilize digital watermarking technology developed by the Verance Corporation, typically embedded into the audio once every thirty seconds. If a DVD-Audio player encounters a watermark on a disc without a valid MKB, it will halt playback. The 4C Entity also developed a similar specification, Content Protection for Recordable Media (CPRM), which is used on Secure Digital cards.