Metadata delays, Audio delay blocks, Metadata delays audio delay blocks – Grass Valley Imagestore 750 v.3.0.1 User Manual
Page 164
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Advanced Audio
Audio Delays
See
on page 18 for additional information.
Note: In rows 1, 3, and 4 of the preceding table, the video delay for in-stream branding exceeds
the audio delay for Dolby processing. Additional PCM audio delays must therefore be added so
lip sync is maintained.
Metadata Delays
Dolby metadata normally corresponds to one of the following use-cases:
Pass-through
Metadata from the video source(s) is passed through decoder(s) and
encoder(s).
Insert at output
Metadata stream is fed to the Dolby encoder.
Dolby metadata that passes through decoders and encoders automatically incur the same delay
as audio. (See
on page 146.) Any meta-
data that bypasses decoders must be set up to match the audio delay.
Note: Dolby metadata processors incur a minimum 2 frame delay when set in modification
mode.
Audio Delay Blocks
The audio engine has up to 6 audio delay banks available for use in the ‘Audio Graph’ of the
Imagestore 750 Configurator. Each audio delay bank is 16 audio channels wide. Each banks’s
delay value is configurable in the Imagestore 750 Configurator ‘Audio Graph’ or in the front
panel using ‘Setup > Audio Setup > Delays’. (See
Each delay bank can provide from 1 to 32,767 audio samples of delay, where the audio sample
rate is 48
kHz. This provides 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.
You can use audio delay banks and video frame delays in conjunction to ensure that the audio
and video are kept in sync when processing in-stream branding insertion, DVE, Dolby E, Dolby
Digital encoding or decoding, stereo to 5.1, or up-mix.
Dolby E
Dolby E
2
4
6
0
Dolby E
Dolby Digital
7
—
6
1
Decode
Encode
PGM Audio Delay
PGM Video Delay—In-
Stream Branding
Dolby
PCM
Post A/B-Mix Output
Table 6-12: PGM delays for Dolby cases, in-stream branding