Ensemble Designs BrightEye 71 HD/SD 8 Channel Analog Audio Embedder/Disembedder - Manual (Page 23)

www.ensembledesigns.com BrightEye 71 and 71-F - Page 23
HD/SD 8 Channel Analog Audio Embedder/Disembedder User Guide TM BrightEye 71 and 71-F
dBFS
In Digital Audio systems, the largest numerical value that can be represented is referred to as Full
Scale. No values or audio levels greater than FS can be reproduced because they would be clipped.
The nominal operating point (roughly corresponding to 0 VU) must be set below FS in order to have
headroom for audio peaks. This operating point is described relative to FS, so a digital reference level
of -20 dBFS has 20 dB of headroom before hitting the FS clipping point.
DVI
Digital Visual Interface. DVI-I (integrated) provides both digital and analog connectivity. The larger
group of pins on the connector are digital while the four pins on the right are analog.
EDH
Error Detection and Handling is a method to verify proper reception of an SDI or HD SDI signal at the
destination. The originating device inserts a data packet in the vertical interval of the SDI signal and
every line of the HD signal which contains a checksum of the entire video frame. This checksum is
formed by adding up the numerical values of all of the samples in the frame, using a complex formula.
At the destination this same formula is applied to the incoming video and the resulting value is
compared to the one included in the transmission. If they match, then the content has all arrived with
no errors. If they don’t, then an error has occurred.
Embedded Audio
Digital Audio can be carried along in the same bit stream as an SDI or HD SDI signal by taking
advantage of the gaps in the transmission which correspond to the horizontal and vertical intervals
of the television waveform. This technique can be very cost effective in transmission and routing, but
can also add complexity to signal handling issues because the audio content can no longer be treated
independently of the video.
Frame Sync
A Frame Synchronizer is used to synchronize the timing of a video signal to coincide with a timing
reference (usually a color black signal that is distributed throughout a facility). The synchronizer
accomplishes this by writing the incoming video into a frame buffer memory under the timing
direction of the sync information contained in that video. Simultaneously the memory is being read
back by a timing system that is genlocked to a house reference. As a result, the timing or alignment of
the video frame can be adjusted so that the scan of the upper left corner of the image is happening
simultaneously on all sources. This is a requirement for both analog and digital systems in order to
perform video effects or glitch-free switches in a router. Frame synchronization can only be performed
within a single television line standard. A synchronizer will not convert an NTSC signal to a PAL signal;
it takes a standards converter to do that.
Frequency Response
A measurement of the accuracy of a system to carry or reproduce a range of signal frequencies. Similar
to Bandwidth.