Grass Valley Imagestore 750 v.3.0.1 - Manual (Page 183)

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Imagestore 750
User Manual
Mixing generally requires that the input sources to the block be PCM. Exceptions to this are the
‘Audio A/B Mixer’ block, ‘Audio Fade to Silent Data’ block, and ‘Audio AutoMute’ block, which
may be used with data streams.
Audio Delay Blocks
The Imagestore 750 supports 6 delay banks, each of which provides 16 channels of input and
output.
Each delay bank can provide from 1 to 32,767 audio samples of delay, where the audio sample
rate is 48
kHz. This results in over 16 video frames of audio delay for each audio delay block,
although the actual delay in frames depends upon the frame rate for the current video standard
as follows:
50 Hz standards Maximum of 17.06 frames audio delay.
59.94 Hz standards Maximum of 20.45 frames audio delay.
Fig. 8-8: Audio Graph - audio delay bank
See Audio Delay Blocks on page 148 for more information.
Audio fade to silent data Manipulates the audio when the fade-to-silent fader is moved. The block
cuts to silence at the point when the FTS fader is fully off. The cut is per-
formed instantaneously and will result in clicks or squeaks if used with non-
data.
It is intended to be used within data streams that would otherwise be cor-
rupted if a fade were attempted.
Audio AutoMute Mutes the output of the block for a user-specified amount of time when the
“sense” pin changes types (i.e., between PCM, Dolby-E, AC3, or non-audio).
Audio AutoDuck This is a silence detection block used to control an associated voice-over
forcing it to fade up or down according to whether a volume level exceeds a
definable threshold, or is below the threshold, for a definable duration. The
fade in and out rates, and the duck level can be defined. Whether the trig-
gering of a duck is dependent or independent on other channels can be
configured.
Block Type Description
Table 8-3: Audio Graph - Mix blocks