Specifications

5.1-Channel Production Guidelines Production Techniques
5-12
Other Formats
Dolby analog, or Dolby Stereo matrix-encoded film soundtracks were originally
produced from discrete four-track master tapes. While the four tracks on these
masters corresponded to L, C, R, and S, during the matrix-encoding process the
results were monitored through a matrix decoder (4:2:4 monitoring) to anticipate
what would actually be heard in the cinema. The final sound heard in the cinema,
therefore, can be quite different from that of the four channels played discretely, due
to the matrix encoding and decoding. It is therefore a good idea to compare the
discrete four-track mix to the decoded Lt/Rt mix, and adjust accordingly.
Alternatively, you may simply use a Dolby Surround matrix encoder to create a
surround-encoded two-channel mix for DTV or DVD from the four-channel master,
and flag the bitstream as matrix surround-encoded.
A few films were released in a six-track format based on magnetic tracks recorded on
70 mm film. These masters require special consideration; for example, there were two
different channel configurations available to filmmakers. They first used the
conventional LCRS channels and added both Left-Extra and Right-Extra channels to
convey extra low-frequency information. The other format had a channel
identification similar to the 5.1 seen today.
5.3.7 Translation to Consumer Systems
One of the most important considerations when dealing with multichannel audio is
the translation to the final listening environment. Everyone is familiar with the