Audio Compression panel
Compression
— VN-Matrix devices support limited compression of audio sources. The
S/PDIF digital data bus can carry two types of data: 2-channel uncompressed audio
and encoded digital data, the latter often in AC-3 (Dolby Digital) format. If the source is
HDMI AC-3, run length encoding (RLE) is applied that results in an output bandwidth of
about 430 kbps. If the source is HDMI PCM, the full set of compression values is used.
The following compression values are supported:
Compression
Stereo Audio Tracks
AC-3 Audio Track
No compression
(~3 Mbps)
24 bit native data (2975 kbps)
24 bit native data (2975 kbps)
24-bit to 16 bit
(~1.5 Mbps)
16 bit data, full sample rate
(1517 kbps)
16 bit data, zeros run length
encoded (430 kbps)
44 kHz to 22 kHz
(~800 kbps)
16 bit data, half sample rate
(784 kbps)
16 bit data, zeros run length
encoded (430 kbps)
44 kHz to 11 kHz
(~400 kbps)
16 bit data, quarter sample rate
(418 kbps)
16 bit data, zeros run length
encoded (430 kbps)
Bitrate panel
)
The
Bitrate
panel sets a specific bandwidth limit for the encoded stream.
Limit Mode
— This drop-down list contains management modes that limit the
instantaneous traffic on the network and drops traffic when the bandwidth rate is
exceeded. This is useful when the network connection between the source and display
has limited bandwidth.
NOTE:
Rapidly changing content may produce instantaneous peaks in bandwidth
rate when using PBR-F management mode.
Six bandwidth management modes are supported.
•
None
— This mode does not use bandwidth management. Only the underlying
compression settings are managed.
•
Manual Frame Drop
— This mode allows the user to specify the precise fraction
of frames to drop. This mode does not manage the bandwidth rate at a fixed level,
but does result in a smoother display update when using rapidly changing video
content types.
•
Shared Flowrate (FD)
— This mode limits the total video network traffic for the
source. Frames are dropped if the
instantaneous
data rate is higher than the
flowrate entered in the
Target
Rate
(Mbps)
field.
•
Peak Flowrate (FD)
— This mode limits the video network traffic for a single
source stream. Frames are dropped if the
instantaneous
data rate is higher than
the flowrate entered in the
Target
Rate
(Mbps)
field. Using
N
output streams
increases the bandwidth
N
times unless the multicast RTP transport protocol is
used.
•
PBR‑F
— This mode dynamically modifies the compression settings to limit the
transmitted bandwidth depending on the specified value entered in the
Target
Rate
(Mbps)
field. The specified
Compression
setting is used as the minimum
compression value. This control mode averages the bit rate over a period of two
frames.
•
PBR‑F (FD)
— This mode is the same as
PBR-F
except frames are dropped when
a larger bandwidth reduction (such as a reduction that cannot be achieved with
compression settings alone) is required.
VNM EC 200 • Device Configuration and Control
76
Summary of Contents for VNM EC 200
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