Grass Valley Imagestore 750 v.3.0.1 - Manual (Page 147)

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Imagestore 750
User Manual
duction equipment. If the type of A/D converter used is not known, choose the ‘Standard’
setting. Choices include ‘Standard’ and ‘HDCD’.
Features Tab
The parameters of the ‘Features’ tab in the ‘Metadata’ page are described here.
• ‘Low Frequency Effects’
This setting indicates whether the low-frequency effects (LFE) or subwoofer channel is on or
off.
• ‘Copyright’
If you set this attribute, the information in the bitstream is indicated as protected by copy-
right. Otherwise it is not indicated as protected.
• ‘Original Bitstream’
This attribute indicates whether the bitsteam is original or a copy of another bitstream.
• ‘DC High Pass Filter’
This parameter indicates whether the DC blocking 3 Hz high-pass filter is applied to the main
input channels in the Dolby Digital encoder. It is used to remove DC offsets in the program
audio and would only be switched off in exceptional circumstances.
• ‘Bandwidth Low Pass Filter’
This parameter determines whether a low-pass filter is applied to the main input channels of
a Dolby Digital encoder prior to encoding. The filter removes high-frequency signals that are
not encoded. At suitable data rates, this filter operates above 20
kHz. In all cases, it prevents
aliasing on decoding. It is normally switched on. This parameter is not passed to the Dolby
Digital (AC-3) decoder.
• ‘LFE Low Pass Filter’
This parameter determines whether a 120 Hz low-pass filter (used to remove frequencies
above 120 Hz that would cause aliasing when decoded) is applied to the LFE channel input
of a Dolby Digital encoder prior to encoding. It is ignored if the LFE channel is disabled. This
filter should be switched off only if the audio to be encoded is known to have no signal
above 120 Hz. This parameter is not sent to the consumer Dolby Digital (AC-3) decoder.
• ‘Surround 90 Degrees Phase’
This parameter causes the Dolby Digital encoder to apply a 90-degree phase shift to the sur-
round channels. This allows a Dolby Digital decoder to create a Lt/Rt down-mix simply. For
most audio material, the phase shift has a minimal impact when the Dolby Digital program
is decoded to 5.1 channels, but provides a Lt/Rt output that can be Pro Logic®-decoded to L,
C, R, and S, if desired. However, for some phase-critical material (such as music) the phase
shift is audible when one is listening in 5.1 channels. Similarly, some material down-mixes to
a satisfactory Lt/Rt signal without needing this phase shift. It is therefore important to bal-
ance the needs of the 5.1 mix and the Lt/Rt down-mix for each program. This parameter is
not sent to the Dolby Digital (AC-3) decoder.
• ‘Surround Attenuation’
The Surround 3 dB attenuation parameter determines whether the surround channel(s) are
attenuated 3 dB before encoding. It is used to compensate for the level of the surround sig-
nal(s) originating from a theatrical mixing room (dubbing stage) and those originating from
mixing rooms used for television and DVDs. For compatibility with older film formats, theat-