Join Date: Feb 2001
Location: San Francisco,CA USA
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Hello DTV pals.
You're right that Dolby Digital is the accepted standard for ATSC transmission, but you're also correct that the satellite providers could go their own way and broadcast DTS format audio if they chose to. They don't do this for a number of reasons, among them the lack of DTS broadcast equipment.
The main issue with the DTS algorithm in a broadcast environment is that the DTS data stream does not offer the flexibility of Dolby Digital. On the hardware side, DTS does not manufacture broadcast equipment, or much of anything else either. Most of DTS efforts focus on their licensing business in order to incorporate their technology into consumer equipment, thus achieving a revenue stream (as does Dolby) from each unit sold that incorporates their technology.
Dolby Digital was chosen, and is used as the broadcast standard for terrestrial, cable and satellite transmission of DTV because of three key features:
1. It provides high quality audio performance.
2. As a more efficient coding algorithm it offers substantial bandwidth savings over either baseband PCM digital audio or DTS.
3. It is scalable both in data rate and number of channels encoded, from a single mono signal up to a full 5.1 home theatre presentation.
Additionally, Dolby Digital offers a function called "downmixing" for those folks who do not own a full-blown home theatre (also for use in in-flight entertainment applications) but still want to enjoy a DVD or digital television broadcast over fewer speakers than was optimally intended. To listen to a DTS track, a full-blown home theatre system is required.
So, if a satellite provider chose to broadcast a DTS program (disregarding the fact that the equipment does not exist to multiplex the DTS stream into their ATSC broadcast encoder or to demux the stream at the receiving end), this program would be exclusive to only those folks who owned a full-blown home theatre, and everyone else would be left out.
These issues were also considered when the DVD-V standard was adopted, making Dolby Digital a mandatory audio track on all DVD-Vs, even those carrying a DTS track! However, since DTS takes up much more room on the DVD than Dolby Digital, a DD track on a DTS disk is often a stereo representation of the same multichannel DTS track, and thus it is seldom possible to compare the two tracks on the same disk.
Of course these issues are independent of any perceived difference in quality between the two coding algorithms. That issue is somewhat controversial and subject to personal preference.
You are welcome to contact me directly if you have any further questions or comments.