DekTec DTC-300 StreamXpress - Manual (Page 17)

DTC-300-SP – StreamXpress
USER MANUAL
17
Note on Stream Looping: StreamXpress can improve the looping performance by “tricking” the
receiver that it is receiving a real time continuous stream. However, StreamXpress cannot make a
100% seamless looping and elements such as buffer integrity, GOP boundary etc… will not be
respected at looping point. In order to minimize the visual effect of the looping, it is advised to use a
single program TS file with black video and audio silence at the start and the end of the clip.
#7 Tools/Test-Signal Generator:
StreamXpress offers the capability to playout a PRBS test signal for accurate bit rate measurements.
A PRBS (Pseudo Random Binary Sequence) is a binary PN (Pseudo-Noise) signal. The sequence of
binary 1’s and 0’s exhibits certain randomness and autocorrelation properties.
Bit-sequences like PRBS are used for testing transmission lines and transmission equipment because
of their randomness properties. StreamXpress implements ITU-T standard O.151 ( See Appendix B.
for more information on how the PRBS sequence is generated)
StreamXpress is capable of encapsulating the O.151 PRBS data into an MPEG-2 TS where the user
specifies the PID where the PRBS data will be carried. The user can also specify the total bitrate of
the transport stream. The total PBRS sequence is 64Mbits so the duration of the sequence will
depend on the bitrate played out.
#8 Settings/RF Output Control:
StreamXpress offers the capability to change the RF output level when using an RF modulator with a
variable RF output. The user can choose to adjust the RF output level and also to invert the spectrum.
#9 Settings/Use NIT for Deriving Parameters:
StreamXpress offers the capability to read the NIT if present in the stream and derive the Streaming
parameters. This is relevant for streams with a DVB “Cable Delivery System Descriptor (CDSD)” or
“Terrestrial Delivery System Descriptor (TDSD)”.
If “Deriving parameters from NIT” is set: