Specifications

5.1-Channel Production Guidelines Production Techniques
5-7
5.3.4 Downmix - Dolby Surround Compatibility
Always check the downmix for Dolby Surround compatibility. Dolby Surround is
comprised of mono surround information; therefore stereo surround information in
the 5.1-channel mix will be summed and reduced in level to become compatible in
the Dolby Surround downmix. While the LFE channel is used primarily for
supplemental high impact effects (e.g., explosions, crashes, storms, aerial fly-overs,
etc.), delivering crucial low-frequency material exclusively in the LFE channel will
produce a Dolby Surround downmix lacking in low-frequency content.
When the 5.1-channel mix is completed, it is often compared with the Dolby
Surround mix, if one exists. Several audible differences may be noticed.
•
The panning and location of elements within the mix may have changed. Because
the 5.1-channel mix is discrete, positioning of elements is easier than through the
Dolby Surround matrix.
•
Center channel buildup will not be present in the 5.1-channel mix. Mono sounds
in the Left and Right channels will stay there, and not appear in the center.
•
The 5.1-channel mix increases the potential acoustical dynamic range since there
are now five full-range channels instead of two.
•
In the 5.1-channel mix the frequency bandwidth of the Surround channel is now
full-range, not limited as with Dolby Surround. Also, there are now two Surround
channels, not one (stereo, not mono).