User's Manual

15
PROGRAMMING
Audio Encoder
Audio encoder selects quantity of active audio channels (2 maximum), sampling rate (8, 16
or 32 kHz) which determines upper frequency response, and sampling bits (8 or 12) which
determines audio signal to noise. (Options are listed on right.)
NOTE: The higher the sampling rate, the more bandwidth required, which can
increase video latency.
Audio Source
If the SDI option has been purchased for the unit, the audio can be sourced from either the
microphone inputs (Analog) or embedded audio present in an SDI input stream. Note that
if an SDI video input has been selected the microphone input can still be used as the audio
source if desired. If Embedded Audio is selected, the Audio Encoder must be set to one of the
48kHz MPEG options.
Audio Input Level
Audio input level selects the audio preamp gain level. Options are:
0 dB, 12 dB, 24 dB, 36 dB, 48 dB. Use 24 dB for DTC supplied microphones. Note: 3.5 VDC
phantom power is at the microphone input for powering electret condenser microphones.
MPEG Layer Audio (kbps)
The user can select the MPEG audio bit rate.
Higher bit rates result in better audio quality at the receiver. For narrowband modulations,
note that selecting higher bit rates will result in restricted data capacity for the video link and
will require slow frame rates.
MPEG Audio Offset
MPEG Audio Offset is a tool to manually synchronize audio to the video, should it be
necessary. The user enters an integer value that offsets the PTS (Presentation Time Stamp) in
the MPEG-2 transport stream.
Audio DID (SDI data ID)
SD-SDI (Standard Definition) can carry up to 16 embedded stereo audio streams, The VMD
can extract one of these streams for transmission with video. If SDI embedded audio is
selected as the audio source, the hexadecimal DID (Data Identifier) identifies the stream
number.
Audio Encoder Options are:
• Off
• 8 kHz 8 bit mono
• 8 kHz 8 bit stereo
• 16 kHz 8 bit mono
• 16 kHz 8 bit stereo
• 32 kHz 8 bit mono
• 32 kHz 8 bit stereo
• 32 kHz 12 bit mono
• 32 kHz 12 bit stereo
• 32 kHz MPEG L1 stereo
• 32 kHz MPEG L1 mono
• 48 kHz MPEG L1 stereo
• 48 kHz MPEG L1 mono
• 32 kHz MPEG L2 stereo
• 32 kHz MPEG L2 mono
• 48 kHz MPEG L2 stereo
• 48 kHz MPEG L2 mono