Bosch Security Systems | 2008-12
PRS-1AIP1 IP Audio Interface
| Installation and User Instructions | Configuration
en
| 14
Line gain
Default: 0 dB
You can adjust the gain of the line input (0...22.5 dB) to
adapt it to the signal level of the source.
Loop Input to Output
Default: No
You can select Yes to route the Audio Input signal
immediately to the local Audio Output. This is typically
done for testing. Acoustical feedback (howling) may
occur if a microphone and a loudspeaker are connected.
Audio Output
Output level
Default: 0 dB
You can select the output signal level (0...-70 dB) here.
Audio Output 2 may have a fixed level 20kHz pilot tone
signal.
Output delay
Default: 64 ms
The default 64 ms is a practical minimum value. You
can change this audio buffer size setting to adjust the
delay before the received audio stream is played. A too
low value may cause dropouts in the audio signal
depending on the quality of the network connection.
Higher delay values can be used with the purpose of
acoustically aligning loudspeakers connected to different
IP Audio Interfaces, e.g. in tunnel applications.
The maximum delay that can be selected depends on
the chosen audio coding format and whether the audio
stream is full duplex or not. A more efficient coding
scheme, lower sample rate and half duplex mode allows
for a longer delay. For G.711 (u-Law or A-Law) at 8 kHz
sampling rate and half-duplex, the delay can be set up
to approximately 8 s.
Audio format
Encoding
Default: MPEG1-L2/22.05 kHz
You can select the audio encoding format here.
Options are MPEG1/2-layer 2 and -layer 3 (better
known as MP3), G.711 (u-Law, A-Law) or
uncompressed PCM at various sample rates.
MPEG1/2-layer 2 and -layer 3 allow for 2-channel
audio streaming; in that case select
In1 + In2, Line
as
audio input.
G.711 (u-Law and A-Law) and PCM are single channel
modes; use either
In2, Line
or
In1, Microphone
as input.
The bit rate is highest for uncompressed PCM and
lowest for MPEG1/2 formats.
MPEG Encoding Quality
Default: 7 (Highest)
You can select a quality level between 0 (lowest) and
7 (highest) for the encoding quality. This setting is only
valid for MPEG1/2-layer 2/3 (MP3). Higher quality
settings use a higher bit rate and take up more network
bandwidth. Also a higher sample rate for the same
quality level increases the bit rate. If the required
network bandwidth is not available (continuously) then
audio dropouts may occur, especially for low delay
settings.
The bit rate varies between approximately 30 kbps
(quality level 0, sample rate 16 kHz) and 190 kbps
(quality level 7, sample rate 48 kHz) for 2 channels.
Audio Coding
Default: Full Duplex
Full Duplex
is only available for the G.711 (u-Law,
A-Law) and PCM formats. This means the device can
simultaneously transmit an audio stream and receive an
audio stream. In
Half Duplex
mode the device only
receives audio streams or transmits audio streams.
If MPEG1/2 is chosen, the device can only operate as
audio stream receiver or as audio stream transmitter,
but not simultaneously. This is
Half Duplex
(or Simplex)
mode.
Submit / Cancel button
Submit saves the set values, restarts the device and
returns back to the last screen. Cancel restores the last
submitted values.
