Thompson ViBE EM4000, Руководство пользователя

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Appendix A ’Technical Specifications’ — Features
178 ViBE EM4000 — Release 1.10
User Manual — 46073586AB02
synchronous with the video and are sent unchanged. This type of
encoding is used to transparently transport audio samples encoded in
Dolby
®
Digital (2.0 or 5.1).
The error masking (error detection and last frame repetition) feature is
implemented.
Audio description encoding
Audio descriptions can be encoded in MPEG-1 Layer II or HE-AAC if the
associated options are available.
The Audio Description feature, is used to send an audio commentary
channel and associated data (
fade and pan values) in addition to its
normal stereo sound. This channel is designed for the visually impaired
and is used to send a verbal description of the visual scene on the screen,
subject to decoder compatibility. The data associated with the
commentary is used to define the mix (adjust right / left levels) for the
pan values and the commentary level in relation to the normal sound for
the fade values.
Figure A-3. Principle of the fade command during the verbal description
If a Dolby Digital Transport component has been instantiated and the
input is a Dolby Digital Plus stream, then the Dolby Digital Plus
stream is passed-through, and an alarm is raised.
If a Dolby Digital Plus Transport component has been instantiated
and the input is a Dolby Digital stream, then the Dolby Digital stream
is passed-through, and an alarm is raised.
Table A-14. Dolby® Digital (AC3) / Dolby® Digital Plus (E-AC3) Transport audio bitrates
Mode Bitrates (kbit/s)
Dolby® Digital (AC3) Transport 96, 128, 192, 224, 256, 320, 384, 448, 512,
576, 640
Dolby® Digital Plus (E-AC3) Transport 96, 128, 192, 224, 256, 320, 384, 448, 512,
576, 640
Description
Normal sound after fade
Normal sound before fade
fade