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DVD-Audio (commonly abbreviated as DVD-A) is a digital format for delivering high-fidelity audio content on a DVD. DVD-Audio uses most of the storage on the disc for high quality audio and is not intended to be a video delivery format. DVD-Audio has much higher audio quality than video DVDs containing concert films or music videos. The first discs entered the marketplace in 2000. DVD-Audio was in a format war with Super Audio CD (SACD), and along with consumers' tastes tending towards downloadable music, these factors meant that neither high-quality disc achieved considerable market penetration; DVD-Audio has been described as "extinct" by 2007.〔Jack Schofield: (No taste for high-quality audio ). The Guardian, 1 August 2007〕 ==Audio specifications== 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: *Considerably more music (with respect to total running time and quantity of songs) or *Encoding at higher linear sampling rates and more bits-per-sample, and/or *Additional channels for spatial sound reproduction. Audio on a DVD-Audio disc can be stored in many different bit depth/sampling rate/channel combinations: Different bit depth/sampling rate/channel combinations can be used on a single disc. For instance, a DVD-Audio disc may contain a 96 kHz/24-bit 5.1-channel audio track as well as a 192 kHz/24-bit stereo audio track. Also, the channels of a track can be split into two groups stored at different resolutions. For example, the front speakers could be 96/24, while the surrounds are 48/20. Audio is stored on the disc in Linear PCM format, which is either uncompressed or losslessly compressed with MLP (Meridian Lossless Packing).〔 The maximum permissible total bit rate is 9.6 Megabits per second. Channel/resolution combinations that would exceed this need to be compressed. In uncompressed modes, it is possible to get up to 96/16 or 48/24 in 5.1, and 192/24 in stereo. To store 5.1 tracks in 88.2/20, 88.2/24, 96/20 or 96/24 MLP encoding is mandatory. If no native stereo audio exists on the disc, the DVD-Audio player may be able to downmix the 5.1-channel audio to two-channel stereo audio if the listener does not have a surround sound setup (provided that the coefficients were set in the stream at authoring). Downmixing can only be done to two-channel stereo, not to other configurations, such as 4.0 quad. DVD-Audio may also feature menus, text subtitles, still images and video, plus in high end authoring systems it is also possible to link directly into a Video_TS directory that might contain video tracks, as well as PCM stereo and other "bonus" features. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DVD-Audio」の詳細全文を読む スポンサード リンク
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