3-6
OPERATION
ORBAN MODEL 1101
Speech/Music Detector
The Speech/Music Detector allows OPTIMOD-PC to change its processing parameters
depending on whether the input program material is speech or other material (usu-
ally music).
The algorithm is straightforward: Speech is detected if (1) the input is mono, and (2)
there are syllabic pauses at least once every 1.5 seconds. Speech with a stereo music
background will usually be detected as “music,” or the detector may switch back
and forth randomly if the stereo content is very close to the stereo / mono detector’s
threshold. Mono music with a “speech-like” envelope may be incorrectly detected as
“speech.” Music incorrectly detected as “speech” can exhibit a slight loss of loudness
and punch, but misdetection will never cause objectionable distortion on music.
Speech that is not located in the center of the stereo sound field will always be de-
tected as “music” because the detector always identifies stereo material as “music.”
Processing for Audio Codecs
V2 software employs Orban’s PreCode™ technology to minimize codec artifacts,
particularly when the codec bitrate is lower than 128 kbps. To exploit PreCode tech-
nology fully, do not set up OPTIMOD-PC for very bright sound (with large amounts
of high frequency energy) because this is likely to exacerbate codec artifacts. Some
appropriate presets include
J
AZZ
,
S
MOOTH
J
AZZ
,
G
OLD
,
R
OCK
S
OFT
, and the
C
LASSICAL
presets. Avoid presets like
C
RISP
and
E
DGE
; these are very bright-sounding presets
and are more appropriate for uncompressed channels or compressed channels with
relatively high bitrates.
OPTIMOD-PC has several controls whose settings determine brightness. To control
excessive brightness when using the Five-band structure:
•
Use little or no high frequency boost in the equalization section.
•
Set Band 4>5 coupling to 100%.
•
Set the band 5 compression threshold to match the codec. Adjust the threshold
until you find a good compromise between presence and high frequency codec
artifacts. We find the range from –6.0 to +6.0 dB to be useful.
•
Use a moderate Band 5 attack time. 25 ms works well.
•
If necessary, lower the Band 4 compression threshold.
In addition, it is unwise to use stereo enhancement with low bitrate codecs. At low
bitrates, codecs use various parametric techniques for encoding the spatial attributes
of the sound field. Stereo enhancement can unnecessarily stress this encoding proc-
ess.
Starting with one of our suggested presets will help keep you out of trouble when
you edit them to create user presets.
Summary of Contents for Optimod-PC 1101
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