DVD-Audio

DVD-Audio is a digital audio application format developed by the DVD Forum and based on the DVD physical medium.

The Forum approved the Version 1.0 specification in February 1999; however, due to content protection schemes and product development schedules, commercial recordings and playback devices did not begin appearing on the market until 2000. DVD-Audio is designed for stereo and multichannel music, but can also include menus, still images, text, and limited video content.

It uses the same disc capacity classes as DVD-Video but employs a different logical structure and playback requirements. DVD-Audio The main program is located in the AUDIO_TS directory, and media data is typically encapsulated in AOB files; associated IFO files record track groups, playback order, audio attributes, and navigation information, while BUP files store backups of key control data. Standard DVD-Video players can recognize the disc’s basic file system but may not be able to parse the AUDIO_TS directory or decode the high-fidelity audio it contains.

DVD-Audio is based on linear PCM and supports six sampling rates—44.1, 48, 88.2, 96, 176.4, and 192 kHz, as well as 16-, 20-, and 24-bit quantization. The maximum specifications are mutually dependent on the number of channels: stereo programs can reach 192 kHz, 24-bit, while multichannel programs are limited to a maximum of six channels, with a common upper limit of 96 kHz, 24-bit. The total audio bitrate must not exceed 9.6 Mbit/s; therefore, not all combinations of sampling rates, bit depths, and channel counts can be used in uncompressed form. A single disc can contain multiple title groups or program versions, such as simultaneously including a high-sampling-rate stereo mix and a 5.1-channel mix. The specification also allows multichannel audio to be divided into two channel groups, with different sampling rates or bit depths assigned to each group to prioritize the precision of the front channels within the bitrate limit; this asymmetric configuration is rarely seen in commercial releases. A downmix factor can be written into the program by the producer to ensure that multichannel content is played back on a stereo system at a predetermined ratio.

DVD-Audio can store uncompressed LPCM directly or use MLP (Meridian Lossless Packing) lossless compression. All compliant players must support both PCM and MLP decoding; the disc can select one of these per track. The raw data rate for six-channel 96 kHz, 24-bit PCM is 13.824 Mbit/s, which exceeds the format’s upper limit; the bitrate must be reduced using MLP to comply with the specification. MLP decoding restores the pre-encoded PCM samples; it is not a lossy codec like Dolby Digital or DTS.

MLP later became the technical foundation for Dolby TrueHD, but the two operate within different bitrate and disc application frameworks. The MLP data in DVD-Audio is encapsulated within AOBs and the corresponding navigation structure, whereas Dolby TrueHD on Blu-ray follows its own substreams, metadata, and transmission rules; sharing a common technical origin does not imply that bitstreams are directly interchangeable.

DVD-Audio can display lyrics, album art, sheet music, or other still images during audio playback, and can also create on-screen menus and links. The specification allows for limited video content, but full-length video is typically provided via the DVD-Video section of the disc. Visual material, text, and navigation are part of the application layer data and do not alter the encoding properties of the main audio, whether it uses PCM or MLP.

Some discs also include a VIDEO_TS-compatible zone containing LPCM, Dolby Digital, or DTS audio tracks that can be played on standard DVD-Video players. The compatible section is not an automatically downconverted output of the main AUDIO_TS program, but rather a set of independently mastered data that may feature different audio channels, sample rates, mixes, and track arrangements. A DVD-Audio disc without a VIDEO_TS compatibility zone may only display an error message on a standard DVD-Video player, or may be completely unplayable.

Commercial DVD-Audio discs use CPPM (Content Protection for Prerecorded Media) to manage encryption and playback authorization. Early players often restricted the output of high-quality audio through unprotected digital interfaces; complete multichannel programs were typically transmitted via analog terminals or controlled links such as IEEE 1394; HDMI 1.1 and later versions provide a path for compatible devices to transmit DVD-Audio multichannel PCM. The connector version alone does not guarantee that a player has the DVD-Audio authorization and decoding capabilities.

“Audio DVDs,” “Music DVDs,” or DVD-Video discs produced with still images accompanied by high-bitrate audio tracks are not equivalent to DVD-Audio. To determine the format, one must examine the DVD-Audio flag, the AUDIO_TS structure, and the player’s recognition; one cannot rely solely on the simultaneous presence of “DVD” and “Audio” in the product name. DVD-Audio and SACD, which were introduced around the same time, are based on multi-bit PCM/MLP and DSD, respectively; their disc structures and decoding systems are incompatible.