Is SACD supported by HDMI?

Is SACD supported by HDMI?

Is SACD supported by HDMI? SACD stands for Super Audio CD. This is an optical audio disc format that is read-only and is aimed at giving much higher fidelity digital audio reproduction than compact disc. SACD was introduced in 2000 and was developed by Sony and Philips Electronics, the companies that created the CD. SACD is currently in a format war with DVD-Audio. Although neither side has made significant progress toward acquiring consumer acceptance, SACDs have an extra advantage over DVD-Audio because most discs are hybrids compatible with existing CD players.

SACD uses a very different technology from that used in DVD-Audio and CD to encode the audio data, a 1-bit delta-sigma modulation process that is known as Direct Stream Digital at the very high sampling rate of 2.8224MHz. The typical sampling rate present on audio CDs is currently 44.1kHz at a resolution of 16 bit. SACD authoring guidelines suggest that an SACD should always contain a 2-channel stereo mix although not all SACD contain it. An SACD may optionally contain a surround mix with either a 5.0 or a 5.1 layout. The correct designation for the surround part of a SACD is "multi-channel", and usually has either the label "SACD Surround" or its own "Multi-Ch" logo on the back cover.

There are three types of SACDs. The first type is a hybrid. This is the most popular of the three types. Hybrid discs include an audio CD "Red Book" layer that is compatible with Compact Disc players, called the "CD layer," and a 4.7 GB SACD layer, called the "HD layer." The second type of SACD is a single layer. This is physically a DVD-5 DVD, a single-layer SACD includes a 4.7 GB HD layer with no CD layer. The third type of SACD is called a dual layer. This is physically a DVD-9 DVD, a dual-layer SACD which includes two HD layers that total 8.5 GB, with no CD layer. This type of SACD is rarely used. It allows nearly twice as much data to be stored, but eliminates the CD player compatibility.

SACD has several copy prevention features in play at the physical level which, for right now, appears to be able to make SACD discs impossible to copy without using the analog hole. These copy prevention features include physical pit modulation and 80 bit encryption of the audio data, with a key encoded on a special area of the disk that can only be read by a licensed SACD device. The HD layer on an SACD disc cannot be played back on a computer CD/DVD drive, nor can any SACDs be created except in the licensed disc replication facilities for SACDin Shizuoka and Salzburg, Germany.

The only way to capture the DSD digital audio signal is after the decryption stage, right before the digital to analog converters of an SACD player, but since there is no possible way for the public to create their own SACD discs, this option poses no major threat. Several of the newer SACD players have encrypted IEEE 1394, also called FireWire or i. Link, digital outputs that carry DSD data, and it could be possible for someone to get the raw DSD data from these links. The protection mechanism that is used is called Digital Transmission Content Protection, or DTCP, which may be used in the "Copy Once" or the "Copy Never" modes. However, it is not likely that the SACD license agreement rules give permission for anything but the "Copy Never" mode to be used.

There have been over 4,000 SACD releases, as of January 2007, but a little over half that number appear to be classical. The next biggest number of SACD releases are jazz. Popular music, mainly remastered previously released albums, seems to have an even fewer number of releases than Jazz. Most SACDs today are now issued only in a hybrid format, like the remastered Bob Dylan and Rolling Stones albums that were released in 2002, and because of this, a lot of music buyers are building an SACD collection, even if they do not have SACD playback equipment, and they are not specifically inclined to purchase SACDs. This could give the SACD format a distinct advantage over DVD-Audio, because the hybrid discs are created to play on any standard Red Book CD player.

The One Bit Audio format, like SuperAudio CD's Direct Stream Digital, has been supported by HDMI since version 1.2 of the specifications, which was released in August of 2005. Any consumer who is interested in an SACD feature should verify that their device supports it.