much more music to be recorded than possible on the same multi channel audio formats used with CD’s.
   The DVD-Audio specification requires PCM audio while the Dolby Digital, DTS and MPEG audio formats are optional.
   For compatibility with DVD-Video players, DVD-Audio discs can include audio encoded in Dolby Digital and DTS formats that satisfy the DVD-Video specification.
   However, DVD-Audio players automatically default to the highest level of DVD specification. Therefore, a DVD-Audio player will only recognize the PCM DVD-Audio tracks on a DVD-Audio disc and will not recognise Dolby Digital or DTS audio tracks recorded at the DVD-Video specification. Although these Dolby Digital and DTS tracks are playable on a DVD-Video player, they are invisible to a DVD-Audio player. This applies even if the player supports the DVD-Video specification.
   The following table (below) outlines the technical specifications for PCM on DVD-Audio and standard CD’s.
   With PCM, the ability to accurately represent an analog signal in digital form is mainly dependent upon the "Sample Size" and "Sampling Rate". The combination of Sample Size and Rate are commonly represented as two numbers such as 24/96 meaning a 24-bit sample size taken at a rate of 96,000 samples per second.
   Sample Size or "Quantization" is the number of data bits used to represent the analog audio signal each time it is sampled when being converted from an analog signal to a digital form. A larger number of bits allow the amplitude of the audio signal to be represented more accurately.
   Sampling Rate or Sampling Frequency is the number of samples taken per second when converting the analog signal to digital. A higher "sampling rate" allows for higher frequencies to be represented.
   Data rate is the number of bits-per-second that can be processed. A data rate of 9.6Mbps is 9.6 million bits-per-second.
   The greater the number of bits used for Sample Size and the greater the number of Samples per second (Sample Rate) the more accurately the analog signal can be represented in digital form. With a Sample Size of 24 bits and a Sample Rate of 192KHz (24/192), DVD-Audio is capable of recording an audio signal with a frequency range of 0 to 96KHz with a dynamic range of 144dB.
   In multi channel recordings, the DVD-Audio PCM specification allows each track to be recorded with a number of different factors. These include:

   l The sampling rates and sample size can be set individually for each track. For example, you could use 24/96 for the front channels and 16/48 for the rear.
   l A track for a front center channel may be present or a virtual center channel can be reproduced from the two front speakers.
   l Downmixing of multi channel tracks into a 2-channel mix if a separate 2-channel set of tracks is not present. If a set of 2-channel tracks are available they will be automatically used instead of the multi-channel downmix. The downmixing technology is referred to as "System Managed Audio Resource Technique" or SMART.
   l Whether Meridian Lossless Packing (MLP) lossless compression is used or uncompressed PCM.
System Managed Audio Resource Technique (SMART)
   The technology for downmixing multi channel tracks into a stereo presentation. Parameters to control the downmixing are assigned and recorded with each track. Parameters include signal level and panning parameters.
Meridian Lossless Packing (MLP)
   The DVD Forum has selected a "lossless" compression technology to extend to playback time compared to uncompressed PCM. The Meridian Lossless Packing (MLP) coding scheme compresses about 2 to 1 the raw uncom-pressed PCM data to provide approximately double the audio playback time.
 
   MLP is different than perceptual or lossy data coding schemes such as Dolby Digital or DTS. While compressing audio data, both Dolby Digital and DTS remove some audio content that is viewed as "perceptionally" not significant. MLP does not alter the final decoded signal in any way, but merely ‘packs’ the audio data in such a way that a simple decoder can recover the original signal exactly bit-for-bit. An example of a familiar "lossless" compression system for computer data is PKZip, which will compress and fully restore computer data exactly bit-for-bit.
   With MLP, a single-sided DVD-Audio disc can record over two hours of 6-channel 24-bit/96kHz audio or over two hours of 24-bit/192kHz stereo.
  Note: The PCM audio specification for DVD-Video allows for sample sizes up to 24-bits and sample rates up to 96kHz based upon the number of channels. The maximum possible data rate is 6.144Mbps.
Do   DVD-Audio discs include 
“Region Codes” such as used in 
DVD-Video discs?
   DVD-Audio does NOT include Region Codes. Therefore, all DVD-Audio discs will be playable on all DVD-Audio capable players. However, many DVD-Audio discs include DVD-Video components to provide compatibility with DVD-Video players. Those "objects or files" (usually Dolby Digital or DTS audio and short videos) could be restricted by Region Codes and may not be playable on all DVD-Video players. nn