All modern DVD players can decode DTS internally, or pass it on to an external decoder through a digital link of some kind, but it is often reduced to a bit rate of 768 kbps. The original 1997 DVD specification did not mention DTS, so older DVD players do not recognize DTS audio tracks. Dolby Digital is also a constant bitrate (CBR) encoding, which means it operates at the same bitrate at all times, regardless of the compressed audio material it is handling at any given moment. According to some sources, Dolby Digital can achieve compression ratios as high as 12:1, though ratios in a range 4:1 to 6:1 are more common. In the simplest of terms this means that audio information gets lost, and some sound fidely compromised (as compared to the original studio master recording) during the process of performing the data manipulations and reductions necessary to squeeze these types of audio tracks into their recorded forms. Both Dolby Digital and DTS (covered in the next section) use whatвЂ™s called вЂњlossy compressionвЂќ to create audio tracks.

See Table 1 for information about sound schemes, SPDIF, and HDMI handling for Dolby Digital. 448 kbps is the maximum bit rate for conventional DVDs. Audio Bit Rate values are usually 640 kbps (most 5.1 discs), but may be either 192 kbps (1.0) to 448 kbps (2.0 and some 5.1).Audio Fidelity data does not appear for this encoding, but the Dolby Digital specification indicates that it is always 16 bits, and can be 32 kHz, 44.1 kHz (the typical audio CD frequency), or 48 kHz (typical for DVDs and Blu-ray discs).The Audio Channels (sound scheme) can appear as 1.0 (rare, only for older movies), 2.0 (likewise, though not as old), or 5.1 (most typical).