Ensemble Designs BrightEye 93 User guide

Ensemble Designs BrightEye 93 User guide
BrightEye 93
HD Cross Converter
User Guide
Revision 2.4 SW v1.2.3
This user guide provides detailed information for using the BrightEye 93
HD cross converter. The information is organized into the following sections:
Product Overview
Functional Description
Rear Connectors
• Front Panel Controls and Indicators
• Using the BrightEye Control Application
Warranty and Factory Service
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BrightEye 93 HD Cross Converter
BrightEye 93 cross converts between a variety of HD standards, whether 720p or
1080i. BrightEye 93 auto-senses the input format and cross converts it, based on
the user’s selection of output format. The user only needs to select the preferred
output format. BrightEye 93 will then accept any video input and perform the
proper video conversion as needed. The built-in frame synchronizer handles any
asynchronous signals fed to the unit.
All vertical interval data and closed captioning is faithfully passed. Up to sixteen
channels of embedded audio are supported. If the incoming video has embedded
audio, the audio will be safely bypassed around the video processing and lipsync
will be preserved.
The rear-panel HDMI output connector is compatible with many LCD monitors
and allows confidence monitoring of signal feeds.
Basic controls are accessed on the front panel. BrightEye PC and BrightEye
Mac Control applications provide access to video processing functions, input and
output, and audio mixer controls that are not available from the front panel.
As shown in the following diagrams, when a high definition serial digital video
input is fed to the BrightEye 93, the signal enters the serial digital receiver and is
frame synchronized to the reference input. Audio is disembedded and passed around
the video processing. The video is cross converted to the selected HD standard.
The video and audio signals are joined in the embedder. This embedded signal
passes through a serializer to a pair of HD SDI outputs. The HDMI output
provides confidence monitoring of the same signal that is on the two HD SDI
output BNCs. A pair of audio channels, selected by the user from the Audio Out
menu, can be monitored on the headphone jack.
BrightEye 93 is powered by a 12 volt DC universal power supply. This power
supply can accept an input voltage between 100 and 230 volts, at 50 or 60 Hertz.
It uses a standard IEC line cord and can be used anywhere in the world. It is
for the converter to be quite warm to the touch when operating.
Tri-Level Ref In
SDI Driver
Video In
Audio Mux
Provides embedded pass through of all 16 audio channels
BrightEye 93 Functional Block Diagram, portrait view
BrightEye 93 - Page 2
Video In
Composite or
Tri-Level Ref In
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Audio Mux
BrightEye 93 Functional Block Diagram, landscape view
Provides embedded pass through of all 16 audio channels
SDI Driver
BrightEye 93
BrightEye 93 HD Cross Converter
When images are converted between different formats, color spaces, and
resolution geometries, the need for accuracy and fidelity are extremely important.
Whether upconverting from standard definition to HD formats, converting
between different HD formats, or downconverting to SD, extra care must be paid
to every aspect of the signal and the content of the images. The BrightEye series
of up, down, and cross converters were designed specifically with this in mind and
provide the highest possible level of signal processing quality.
Key aspects of this design are:
1) The Standard Definition analog inputs and outputs feature 12-bit
quantization, with 4-times oversampling and 4:4:4 internal processing.
This allows for better separation of real image content from artifacts.
2) The RF aspects of the electrical performance of the SDI inputs and outputs
have been carefully optimized for reliable and dependable SDI I/O
performance even under adverse conditions.
3) Input signals are upsampled to 4:4:4 spatial resolution in RGB colorspace
and adaptively de-interlaced. This enables all of the geometrical conversions
of the image to be performed in the Progressive domain. This enhancement
to the temporal resolution of the image is a key contributor to final image
quality, even if the final output is interlaced.
4) The colorspace and geometrical conversions of the signal are performed at
up to 16 bits of resolution.
5) The final output signal is built from this intermediate progressive
workspace, which is the most uncompromised version of the image possible.
It provides the best possible starting point from which to create the final
output signal.
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BrightEye 93
HD Cross Conversion
The BrightEye 93 can perform cross conversion between two different types of HD signals.
As shown here, the 1080i input from an HD network feed is sent to the BrightEye 93
where the format is converted to 720p as required for input to an HD router.
BE 93
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BrightEye 93 HD Cross Converter
All connections to the BrightEye 93 are made on the rear of the unit. Refer to the
photo below.
BrightEye 93 Rear Connectors
Power Connection
Connect a modular power supply to the 12 volt DC power input connection on the
far left of the unit. Use the locking ring to secure it.
USB Connector
Connect a PC or Mac to the USB connector to enable more comprehensive control,
diagnostics, and upgrades to the BrightEye 93. Use the BrightEye PC or Mac
application included on CD-ROM to make adjustments as described in the
OPERATION section of this user guide.
Connect an LCD monitor to this port for confidence monitoring of a video feed.
Audio Monitor
Connect a headset to this 3.5 mm mini jack to monitor the pair of audio channels
selected from the Mon Assign control on the Audio Out menu.
Input/Output BNCs
There are four rear BNC connectors used as inputs and outputs as follows:
This BNC outputs a timed high definition SDI video signal with embedded audio.
This BNC also outputs a timed HD SDI video signal with embedded audio.
This BNC input accepts an HD SDI serial digital video signal with or without
embedded audio.
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Ref In
This BNC accepts an analog composite video signal or Tri-Level Sync reference
which is used as the genlock and timing reference for the internal Frame
Synchronizer. Typically the reference signal is Color Black or Color Bars fed from
a master sync generator (such as the BrightEye 55).
Control and operation of the BrightEye 93 is performed from the front panel or
remotely from a networked PC with the BrightEye PC or BrightEye Mac Control
NOTE: Some control settings are only available with BrightEye PC or Mac. These parameters
cannot be monitored or controlled from the front panel.
Front Panel Controls and Indicators
The front panel of the BrightEye 93, shown below, provides status and control
indicators for the module.
BrightEye 93 Front Panel
Status Indicators
The following status indicators and controls are provided on the front panel:
Embed In
Illuminates green when an embedded audio stream is detected on the HD SDI In
video input BNC.
Mon Vol (Monitor Volume)
Illuminates green when audio monitor volume is set to unity, or red when
set to other than unity. This control affects the audio headset jack output.
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BrightEye 93 HD Cross Converter
Illuminates green when a valid HD video signal is detected on the HD SDI
In video input BNC. Ref (Reference) illuminates when a valid composite or
Tri-Level Sync reference is detected on the Ref input BNC.
Indicates the type of video signal selected on the HD/SD SDI Out BNC.
Choices are 1080i, 720p, 1080p, 1080sF or SD.
Indicates the output aspect ratio of the output signal. Choices are:
• Anamorphic – original material is converted as needed to 4:3.
• Manual – illuminates green when the output aspect ratio has been set
Illuminates green when color bars are selected for the output.
Illuminates green when the on-screen aspect ratio graticule is displayed.
Illuminates green when video gain is set to unity, or red when set to other
than unity.
Pwr (Power)
Illuminates green when power is applied to the unit and the internal
voltage regulator is functioning correctly.
Use the Mode, Right Arrow, and Left Arrow buttons to select and adjust
parameters from the front panel.
Pressing the Mode button activates the front panel for editing and tabs between
each section of editable parameters.
Pressing the Right Arrow or Left Arrow advances the selection within a given
section of parameters, or increases (Right Arrow) or decreases (Left Arrow) the
value of a selected parameter.
NOTE: The LED of an edited parameter will blink for 15 seconds, after which time its value is
stored in memory. If power is interrupted before this 15 second timeout period has
elapsed, the edited state will not be not saved.
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BrightEye 93
The BrightEye PC and BrightEye Mac applications are designed to allow you to
configure and control the BrightEye 93 from a personal computer. BrightEye
PC/Mac Control application software is included on CD that came with your unit,
or the application can be downloaded here:
If the BrightEye 93 is connected to a computer running this software, the
following menus are available for controlling and monitoring the unit.
Video In
Input Pres – indicates the status of the video input (720p/50, 720p/59.94,
720p/60, 1080i/50, 1080i/59.94, 1080i/60, 1080p/25, 1080p/23.98, 1080p/24,
1080sF/25, 1080sF/23.98, 1080sF/24, No Input, or Unknown.).
Captions In – indicates the presence of closed captioned material on the
input signal (None, Line 21, CEA 708). During cross conversion, the
BrightEye 93 carries across closed caption data using the CEA-708
Ref Source – use this control to set the reference input source. Video In
Ref indicates that the SD video output will be locked to the incoming video
signal. Ext Ref indicates that the SD video output will be locked to the
external reference input.
Reference – indicates the status of a reference video presence
(Ref Mismatch, Ref Unlocked, Ref TLS Lock, No Reference, Ref 525
Lock, Ref 625 Lock).
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BrightEye 93 HD Cross Converter
HD Cross – indicates the mode in which the unit is running
(Anamorphic, Manual). The mode is determined by the output selection
made in the Format menu.
Format – use this control to set the desired output format (1080i, 720p,
1080p, 1080sF). Note that closed captions are not supported for 1080p and
1080sF outputs. The unit automatically detects the input standard.
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BrightEye 93
Width – sets the aspect ratio width in percent (range is 30 to 145%,
default is 100%).
Height – sets the aspect ratio height in percent (range is 30 to 140%,
default is 100%).
Hor Position – sets the horizontal position of the output (range is -100 to
100, default is 0).
Ver Position – sets the vertical position of the output (range is -100 to
100, default is 0).
Make adjustments by clicking and dragging the slider controls, by using the up
and down arrow buttons, or by entering a value directly into the field. Click the
Default buttons to return settings to their default values.
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BrightEye 93 HD Cross Converter
• Noise Reduce – adjusts the amount of noise reduction on the output signal
from Off, Low, Medium, or High. The typical setting for this parameter is
Off or Low.
• Detail – adjusts the amount of picture detail enhancement on the output from
Off, Low, Medium, or High. The typical setting for this parameter is Off
or Low.
• 3:2 Detect – turns the control to detect video that has been converted from film On
or Off. Use this only for film applications. The typical setting for this parameter is Off.
• Cpst Setup – turns Setup on the composite output On or Off (525 only).
Set this to On if your material has Setup on it.
Vert Blanking – sets the blanking mode to Narrow (lines 1-9 are blanked
in NTSC, lines 1-6 in PAL) or Wide (lines 1-20 in NTSC, lines 1-22 in PAL).
Output Muting – set to either Mute On Noise or Off. Mute On Noise
means that the module will mute the video output (output a black signal)
when the module detects that the video quality is unacceptable. Off allows
the video to pass through to the output regardless of video quality.
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BrightEye 93
• Gain – adjusts the percentage of overall gain (luminance and chrominance)
(range is 0 to 150%, default is 100%).
Chroma – adjusts the percentage of chroma amplitude (range is 0 to 150%,
default is 100%).
Pedestal – adjusts the pedestal (black) level of the signal in IRE (range is
-30 to 30 IRE, default is 0 IRE).
Hue – adjusts the hue of the signal in degrees (range is ±180 degrees,
default is 0 degrees).
Make adjustments by clicking and dragging the slider controls, by using the up
and down arrow buttons, or by entering a value directly into the field. Click the
Default buttons to return settings to their default values.
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BrightEye 93 HD Cross Converter
Video Out
Hor Timing – use this control to adjust the horizontal timing of the output
signal to place the leading edge of sync coincident with other sources (range
is -2000 to 2000 clocks, default is 0 clocks).
Vert Timing – sets the vertical timing to a typical setting of 0 lines (range
is -1000 to 1000 lines, default is 0 lines).
Test Pattern – select On or Off. On enables the test pattern to be sent to
the video output. Off disables the test pattern from being sent to the video
HDMI Status – reports the status of a monitor or a display connected to
the HDMI output (No Display, DVI Display, Unknown HDMI,
HDMI Non-Compat, HDMI Native, HDMI Compatible). Status information
comes from the display itself. Some displays may not work with the
BrightEye 93, depending on the formats that the display supports. For best
results, use a display that is HDMI Native.
Captions Out – use this control to enable or disable closed captioning (if
present on the input source material). On enables closed captioning by continuously transmitting captions (including any null or empty caption
packets). Off disables closed captioning by stripping captions from the
source material. The BrightEye 93 translates between CEA-608 and
CEA-708 standards for closed captioning as needed. Note that closed
captions are not supported for 1080p and 1080sF outputs.
Graticule – use this control to display on-screen graticule lines. These
alignment markers facilitate film transfer, post production and quality
control measurements relating to picture location for both the 4:3 and 16:9
aspect ratios. Safe Title displays the safe title boxes. SD Protect Only
displays only the SD Protect area without displaying the safe title boxes.
Off disables graticules.
Target – use this control to select the monitor on which graticule lines are
displayed. Choices are All Outputs, Main Only (the unit’s output BNCs),
or HDMI Only.
Hor Flip – Horizontal Flip is a special Mirror Output Mode that is useful
for flipping the image left-to-right for use with on-screen talent or with
prism lens cameras. Select On to flip the output image left to right. Select
Off (after Reset) to turn Mirror Output Mode off. Power down the module
and turn it back on for the Off selection to take effect.
Color – use this control to set the color of the graticule lines. Choices are:
White, Gray, Black, Red, Blue and Green.
Transparency – use this control to adjust the transparency of the graticule
lines from 0 (completely transparent) to 100 (no transparency).
NOTE: See Video Out diagram on next page
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BrightEye 93
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BrightEye 93 HD Cross Converter
Audio Out
Mon Assign – choose the audio pair that you want to send to the Audio
Monitor headphone jack. Choices are: Chan 1/2, Chan 3/4, Chan 5/6, Chan
7/8, Chan 9/10, Chan 11/12, Chan 13/14, Chan 15/16.
Mon Volume – sets the volume level sent to the headphone jack from 0 to
100% by moving the slider control, using the up down arrows, or entering a
desired level directly in the field and pressing the Enter key on your
computer. Press the Default button to return to the default setting
of 100%.
HDMI Assign – selects the audio pair that is output on the HDMI Out port.
The HDMI port carries both audio and video signals. Choices are: Chan 1/2,
Chan 3/4, Chan 5/6, Chan 7/8, Chan 9/10, Chan 11/12, Chan 13/14,
Chan 15/16.
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BrightEye 93
Ensemble Designs, Inc. warrants this product to be free from defect in material
and workmanship for a period of 5 years from the date of delivery. During this 5
year warranty period, Ensemble Designs, Inc. will repair any defective units at
Ensemble’s expense if the unit should be determined to be defective after consultation with a factory technician.
This warranty is not transferable. Any implied warranties expire at the expiration
date of this warranty.
This warranty does not cover a defect that has resulted from improper or unreasonable
use or maintenance as determined by us. This warranty is void if there is any
attempt to dissemble or adjust factory set presets without factory authorization.
Factory Service
If you require service (under warranty or not), please contact Ensemble Designs
and ask for Customer Service before you return the unit. This will allow the
service technician to provide any other suggestions for identifying the problem
and recommend possible solutions.
You may also refer to the technical support section of the Ensemble web site for
the latest information on your equipment at the URL below:
If you return equipment for repair, please get a Return Material Authorization
Number (RMA) from the factory first.
Ship the product and a written description of the problem to:
Ensemble Designs, Inc.
Attention: Customer Service RMA #####
870 Gold Flat Rd.
Nevada City, CA 95959 USA
(530) 478-1830
Fax: (530) 478-1832
[email protected]
Be sure to put your RMA number on the outside of the box.
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BrightEye 93 HD Cross Converter
Serial Digital Input
Signal Type
Return Loss
Max Cable Length
Automatic Input Cable
HD Serial Digital 1.485 Gb/s SMPTE 274M, 292M, 296M
75 Ω
100 meters for 1.485Gb/s HD
Reference Input
Return Loss
1 V P-P Composite Video
or Tri-Level Sync
75 Ω
>40 dB
Serial Digital Output
Return Loss
Max Cable Length
HD Serial Digital 1.485 Gb/s SMPTE 274M, 292M, 296M
Adjustable from 1 field to 1 frame
12 and 16 bit
75 Ω
>15 dB
100 meters for 1.485Gb/s HD (Belden 1694A)
HD Standards Supported
1080i 50,59.94 or 60 Hz SMPTE 274M -4,5,6
720p 50,59.94 or 60 Hz SMPTE 296M -1,2,3
1080p 23.98,24 or 25 Hz SMPTE 274M -9,10,11
1080sF 23.98,24 or 25 Hz RP211 -14,15,16
Monitor Output
Follows SDI out
Audio Monitoring Output
One (for monitoring a pair of audio channels)
3.5mm stereo mini jack
General Specifications
5.625” W x 1.7” H x 5.5” D (143 mm x 40 mm x 140 mm)
including connectors
1 lb 7 oz
12 volts, 11 watts
(100-230 VAC modular power supply not included)
Temperature Range
0 to 40˚ C ambient
Relative Humidity
0 to 95%, non-condensing
Due to ongoing product development, all specifications subject to change.
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Below is a list of power supplies and optional items that may have come with your
BrightEye Individual Power Supply.
Spider Power Supply. This powers 6 single high BrightEyes or 3 double high
Redundant Power Supply for Spider.
BrightEye Rack Mount. This holds 6 single high BrightEyes or 3 double high
BrightEyes, or a combination.
BrightEye Blank Panel. Single high, for empty slots in Rack Mount.
Analog Audio Breakout Cable.
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BrightEye 93 HD Cross Converter
The digital audio standard defined as a joint effort of the Audio Engineering
Society and the European Broadcast Union. AES/EBU or AES3 describes a serial
bitstream that carries two audio channels, thus an AES stream is a stereo pair.
The AES/EBU standard covers a wide range of sample rates and quantizations
(bit depths). In television systems, these will generally be 48 KHz and either 20
or 24 bits.
Active Format Description is a method to carry information regarding the aspect
ratio of the video content. The specification of AFD was standardized by SMPTE
in 2007 and is now beginning to appear in the marketplace. AFD can be included
in both SD and HD SDI transport systems. There is no legacy analog implementation. (See WSS).
A commonly used transport method for MPEG video streams, ASI or
Asynchronous Serial Interface, operates at the same 270 Mb/s data rate as SD
SDI. This makes it easy to carry an ASI stream through existing digital television
infrastructure. Known more formally as DVB-ASI, this transport mechanism can
be used to carry multiple program channels.
Aspect Ratio
The ratio of the vertical and horizontal measurements of an image. 4:3 is the
aspect ratio for standard definition video formats and television and 16:9 for high
definition. Converting formats of unequal ratios is done by letterboxing
(horizontal bars) or pillar boxing (vertical pillars) in order to keep the original
format's aspect ratio.
Strictly speaking, this refers to the range of frequencies (i.e. the width of the band
of frequency) used by a signal, or carried by a transmission channel. Generally,
wider bandwidth will carry and reproduce a signal with greater fidelity and
Sony Beta SP video tape machines use an analog component format that is
similar to SMPTE, but differs in the amplitude of the color difference signals. It
may also carry setup on the luminance channel.
A binary digit, or bit, is the smallest amount of information that can be stored or
transmitted digitally by electrical, optical, magnetic, or other means. A single bit
can take on one of two states: On/Off, Low/High, Asserted/ Deasserted, etc. It is
represented numerically by the numerals 1 (one) and 0 (zero). A byte, containing 8
bits, can represent 256 different states. The binary number 11010111, for
example, has the value of 215 in our base 10 numbering system. When a value is
carried digitally, each additional bit of resolution will double the number of
different states that can be represented. Systems that operate with a greater
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number of bits of resolution, or quantization, will be able to capture a signal with
more detail or fidelity. Thus, a video digitizer with 12 bits of resolution will
capture 4 times as much detail as one with 10 bits.
The Horizontal and Vertical blanking intervals of a television signal refer to the
time periods between lines and between fields. No picture information is
transmitted during these times, which are required in CRT displays to allow the
electron beam to be repositioned for the start of the next line or field. They are
also used to carry synchronizing pulses which are used in transmission and
recovery of the image. Although some of these needs are disappearing, the
intervals themselves are retained for compatibility purposes. They have turned
out to be very useful for the transmission of additional content, such as teletext
and embedded audio.
Component Analog Video. This is a convenient shorthand form, but it is subject to
confusion. It is sometimes used to mean ONLY color difference component formats
(SMPTE or Beta), and other times to include RGB format. In any case, a CAV
signal will always require 3 connectors – either Y/R-Y/B-Y, or R/G/B.
A Checkfield signal is a special test signal that stresses particular aspects of
serial digital transmission. The performance of the Phase Locked-Loops (PLLs) in
an SDI receiver must be able to tolerate long runs of 0’s and 1’s. Under normal
conditions, only very short runs of these are produced due to a scrambling
algorithm that is used. The Checkfield, also referred to as the Pathological test
signal, will “undo” the scrambling and cause extremely long runs to occur. This
test signal is very useful for testing transmission paths.
The color or chroma content of a signal, consisting of the hue and saturation of
the image. See also Color Difference.
In a component video system, the totality of the image is carried by three separate
but related components. This method provides the best image fidelity with the
fewest artifacts, but it requires three independent transmission paths (cables).
The commonly used component formats are Luminance and Color Difference
(Y/Pr/Pb), and RGB. It was far too unwieldy in the early days of color television to
even consider component transmission.
Composite television dates back to the early days of color transmission. This
scheme encodes the color difference information onto a color subcarrier. The
instantaneous phase of the subcarrier is the color’s hue, and the amplitude is the
color’s saturation or intensity. This subcarrier is then added onto the existing
luminance video signal. This trick works because the subcarrier is set at a high
enough frequency to leave spectrum for the luminance information. But it is not a
seamless matter to pull the signal apart again at the destination in order to
display it or process it. The resultant artifacts of dot crawl (also referred to as
chroma crawl) are only the most obvious result. Composite television is the most
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BrightEye 93 HD Cross Converter
commonly used format throughout the world, either as PAL or NTSC. It is also
referred to as Encoded video.
Color Difference
Color Difference systems take advantage of the details of human vision. We have
more acuity in our black and white vision than we do in color. This means that we
need only the luminance information to be carried at full bandwidth, we can
scrimp on the color channels. In order to do this, RGB information is converted to
carry all of the luminance (Y is the black and white of the scene) in a single
channel. The other two channels are used to carry the “color difference”. Noted as
B-Y and R-Y, these two signals describe how a particular pixel “differs” from being
purely black and white. These channels typically have only half the bandwidth of
the luminance.
Decibel (dB)
The decibel is a unit of measure used to express the ratio in the amplitude or
power of two signals. A difference of 20 dB corresponds to a 10:1 ratio between
two signals, 6 dB is approximately a 2:1 ration. Decibels add while the ratios
multiply, so 26 dB is a 20:1 ratio, and 14 dB is a 5:1 ratio. There are several
special cases of the dB scale, where the reference is implied. Thus, dBm refers to
power relative to 1 milliwatt, and dBu refers to voltage relative to .775V RMS.
The original unit of measure was the Bel (10 times bigger), named after
Alexander Graham Bell.
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.
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.
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 bitstream 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
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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.
Eye Pattern
To analyze a digital bitstream, the signal can be displayed visually on an
oscilloscope by triggering the horizontal timebase with a clock extracted from the
stream. Since the bit positions in the stream form a very regular cadence, the
resulting display will look like an eye – an oval with slightly pointed left and right
ends. It is easy to see from this display if the eye is "open", with a large central
area that is free of negative or positive transitions, or "closed" where those transitions are encroaching toward the center. In the first case, the open eye indicates
that recovery of data from the stream can be made reliably and with few errors.
But in the closed case data will be difficult to extract and bit errors will occur.
Generally it is jitter in the signal that is the enemy of the eye.
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
switch glitch-free 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.
The latest salvo in the compression wars is H.264 which is also known as MPEG4 Part 10. MPEG-4 promises good results at just half the bit rate required by
High Definition. This two letter acronym has certainly become very popular. Here
we thought it was all about the pictures – and the radio industry stole it.
The High Definition Multimedia Interface comes to us from the consumer
marketplace where it is becoming the de facto standard for the digital
interconnect of display devices to audio and video sources. It is an uncompressed,
all-digital interface that transmits digital video and eight channels of digital
audio. HDMI is a bit serial interface that carries the video content in digital
component form over multiple twisted-pairs. HDMI is closely related to the DVI
interface for desktop computers and their displays.
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The International Electrotechnical Commission provides a wide range of
worldwide standards. They have provided standardization of the AC power
connection to products by means of an IEC line cord. The connection point uses
three flat contact blades in a triangular arrangement, set in a rectangular
connector. The IEC specification does not dictate line voltage or frequency.
Therefore, the user must take care to verify that a device either has a universal
input (capable of 90 to 230 volts, either 50 or 60 Hz), or that a line voltage switch,
if present, is set correctly.
Human vision can be fooled to see motion by presenting a series of images, each
with a small change relative to the previous image. In order to eliminate the
flicker, our eyes need to see more than 30 images per second. This is
accomplished in television systems by dividing the lines that make up each video
frame (which run at 25 or 30 frames per second) into two fields. All of the oddnumbered lines are transmitted in the first field, the even-numbered lines are in
the second field. In this way, the repetition rate is 50 or 60 Hz, without using
more bandwidth. This trick has worked well for years, but it introduces other
temporal artifacts. Motion pictures use a slightly different technique to raise the
repetition rate from the original 24 frames that make up each second of film—
they just project each one twice.
Video level is measured on the IRE scale, where 0 IRE is black, and 100 IRE is
full white. The actual voltages that these levels correspond to can vary between
ITU-R 601
This is the principal standard for standard definition component digital video. It
defines the luminance and color difference coding system that is also referred to
as 4:2:2. The standard applies to both PAL and NTSC derived signals. They both
will result in an image that contains 720 pixels horizontally, with 486 vertical
pixels in NTSC, and 576 vertically in PAL. Both systems use a sample clock rate
of 27 Mhz, and are serialized at 270 Mb/s.
Serial digital signals (either video or audio) are subject to the effects of jitter. This
refers to the instantaneous error that can occur from one bit to the next in the
exact position of each digital transition. Although the signal may be at the correct
frequency on average, in the interim it varies. Some bits come slightly early,
others come slightly late. The measurement of this jitter is given either as the
amount of time uncertainty or as the fraction of a bit width. For 270 Mb/s SD
video, the allowable jitter is 740 picoseconds, or 0.2 UI (Unit Interval – one bit
width). For 1.485 Gb/s HD, the same 0.2UI spec corresponds to just 135 pico
The “black & white” content of the image. Human vision had more acuity in
luminance, so television systems generally devote more bandwidth to the
luminance content. In component systems, the luminance is referred to as Y.
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The Moving Picture Experts Group is an industry group that develops standards
for the compression of moving pictures for television. Their work is an on-going
effort. The understanding of image processing and information theory is
constantly expanding. And the raw bandwidth of both the hardware and software
used for this work is ever increasing. Accordingly, the compression methods
available today are far superior to the algorithms that originally made the realtime compression and decompression of television possible. Today, there are many
variations of these techniques, and the term MPEG has to some extent become a
broad generic label.
This word comes from the Greek, meta means 'beyond' or 'after'. When used as a
prefix to 'data', it can be thought of as 'data about the data'. In other words, the
metadata in a data stream tells you about that data – but it is not the data itself.
In the television industry, this word is sometimes used correctly when, for
example, we label as metadata the timecode which accompanies a video signal.
That timecode tells you something about the video, i.e. when it was shot, but the
timecode in and of itself is of no interest. But in our industry's usual slovenly way
in matters linguistic, the term metadata has also come to be used to describe data
that is associated with the primary video in a datastream. So embedded audio
will (incorrectly) be called metadata when it tells us nothing at all about the
pictures. Oh well.
Multi-mode fibers have a larger diameter core than single mode fibers (either 50
or 62.5 microns compared to 9 microns), and a correspondingly larger aperture.
It is much easier to couple light energy into a multi-mode fiber, but internal
reflections will cause multiple “modes” of the signal to propagate down the fiber.
This will degrade the ability of the fiber to be used over long distances. See also
Single Mode.
The color television encoding system used in North America was originally
defined by the National Television Standards Committee. This American standard
has also been adopted by Canada, Mexico, Japan, Korea, and Taiwan. (This
standard is referred to disparagingly as Never Twice Same Color.)
An optical interface between two devices carries data by modulating a light
source. This light source is typically a laser or laser diode (similar to an LED)
which is turned on and off at the bitrate of the datastream. The light is carried
from one device to another through a glass fiber. The fiber’s core acts as a
waveguide or lightpipe to carry the light energy from one end to another. Optical
transmission has two very significant advantages over metallic copper cables.
Firstly, it does not require that the two endpoint devices have any electrical
connection to each other. This can be very advantageous in large facilities where
problems with ground loops appear. And secondly, and most importantly, an
optical interface can carry a signal for many kilometers or miles without any
degradation or loss in the recovered signal. Copper is barely useful at distances of
just 1000 feet.
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A technique to perform digital sampling at a multiple of the required sample rate.
This has the advantage of raising the Nyquist Rate (the maximum frequency
which can be reproduced by a given sample rate) much higher than the desired
passband. This allows more easily realized anti-aliasing filters.
During the early days of color television in North America, European
broadcasters developed a competing system called Phase Alternation by Line.
This slightly more complex system is better able to withstand the differential gain
and phase errors that appear in amplifiers and transmission systems. Engineers
at the BBC claim that it stands for Perfection At Last.
Pathological Test Pattern – see Checkfield
An image scanning technique which progresses through all of the lines in a frame
in a single pass. Computer monitors all use progressive displays. This contrasts to
the interlace technique common to television systems.
Return Loss
An idealized input or output circuit will exactly match its desired impedance
(generally 75 ohms) as a purely resistive element, with no reactive (capacitive or
inductive) elements. In the real world, we can only approach the ideal. So, our
real inputs and outputs
will have some capacitance and inductance. This will create impedance matching
errors, especially at higher frequencies. The Return Loss of an input or output
measures how much energy is returned (reflected back due to the impedance
mismatch). For digital circuits, a return loss of 15 dB is typical. This means that
the energy returned is 15 dB less than the original signal. In analog circuits, a 40
dB figure is expected.
RGB systems carry the totality of the picture information as independent Red,
Green, and Blue signals. Television is an additive color system, where all three
components add to produce white. Because the luminance (or detail) information
is carried partially in each of the RGB channels, all three must be carried at full
bandwidth in order to faithfully reproduce an image.
ScH Phase
Used in composite systems, ScH Phase measures the relative phase between the
leading edge of sync on line 1 of field 1 and a continuous subcarrier sinewave.
Due to the arithmetic details of both PAL and NTSC, this relationship is not the
same at the beginning of each frame. In PAL, the pattern repeats ever 4 frames (8
fields) which is also known as the Bruch Blanking sequence. In NTSC, the repeat
is every 2 frames (4 fields). This creates enormous headaches in editing systems
and the system timing of analog composite facilities.
Serial Digital Interface. This term refers to inputs and outputs of devices that
support serial digital component
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video. This could refer to standard definition at 270 Mb/s, HD SDI or High
Definition Serial Digital video at 1.485 Gb/s, or to the newer 3G standard of High
Definition video at 2.97 Gb/s.
The Society of Motion Picture and Television Engineers is a professional
organization which has done tremendous work in setting standards for both the
film and television industries. The term “SMPTE’” is also shorthand for one
particular component video format - luminance and color difference.
Single Mode
A Single mode (or mono mode) optical fiber carries an optical signal on a very
small diameter (9 micron) core surrounded with cladding. The small diameter
means that no internally reflected lightwaves will be propagated. Thus only the
original “mode” of the signal passes down the fiber. A single mode fiber used in an
optical SDI system can carry a signal for up to 20 kilometers. Single mode fibers
require particular care in their installation due to the extremely small optical
aperture that they present at splice and connection points.
See also Multi-mode.
A Time Base Corrector is a system to reduce the Time Base Error in a signal to
acceptable levels. It accomplishes this by using a FIFO (First In, First Out)
memory. The incoming video is written into the memory using its own jittery
timing. This operation is closely associated with the actual digitization of the
analog signal because the varying position of the sync timing must be mimicked
by the sampling function of the analog to digital converter. A second timing
system, genlocked to a stable reference, is used to read the video back out of the
memory. The memory acts as a dynamically adjusting delay to smooth out the
imperfections in the original signal’s timing. Very often a TBC will also function
as a Frame Synchronizer. See also Frame Sync.
Time Base Error
Time base error is present when there is excessive jitter or uncertainty in the line
to line output timing of a video signal. This is commonly associated with playback
from video tape recorders, and is particularly severe with consumer type
heterodyne systems like VHS. Time base error will render a signal unusable for
broadcast or editing purposes.
Timecode, a method to uniquely identify and label every frame in a video stream,
has become one of the most recognized standards ever developed by SMPTE. It
uses a 24 hour clock, consisting of hours, minutes, seconds, and television frames.
Originally recorded on a spare audio track, this 2400 baud signal was a
significant contributor to the development of video tape editing. We now refer to
this as LTC or Longitudinal Time Code because it was carried along the edge of
the tape. This allowed it to be recovered in rewind and fast forward when the
picture itself could not. Timecode continues to be useful today and is carried in
the vertical interval as VITC, and as a digital packet as DVITC. Timecode is the
true metadata.
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Tri-Level Sync
For many, many years, television systems used composite black as a genlock
reference source. This was a natural evolution from analog systems to digital
implementations. With the advent of High Definition television, with even higher
data rates and tighter jitter requirements, problems with this legacy genlock
signal surfaced. Further, a reference signal with a 50 or 60 Hz frame rate was
useless with 24 Hz HD systems running at film rates. Today we can think of
composite black as a bi-level sync signal – it has two levels, one at sync tip and
one at blanking. For HD systems, Tri-Level Sync, which has the same blanking
level (at ground) of bi-level sync, but the sync pulse now has both a negative and
a positive element. This keeps the signal symmetrically balanced so that its DC
content is zero. And it also means that the timing pickoff point is now at the point
where the signal crosses blanking and is no longer subject to variation with
amplitude. This makes Tri-Level Sync a much more robust signal and one which
can be delivered with less jitter.
The Universal Serial Bus, developed in the computer industry to replace the
previously ubiquitous RS-232 serial interface, now appears in many different
forms and with many different uses. It actually forms a small local area network,
allowing multiple devices to coexist on a single bus where they can be
individually addressed and accessed.
Video Graphics Array. Traditional 15-pin, analog interface between a PC and
Word Clock
Use of Word Clock to genlock digital audio devices developed in the audio
recording industry. Early digital audio products were interconnected with a
massive parallel connector carrying a twisted pair for every bit in the digital
audio word. A clock signal, which is a square wave at the audio sampling
frequency, is carried on a 75 ohm coaxial cable. Early systems would daisychain
this 44.1 or 48 kilohertz clock from one device to another with coax cable and Tee
connectors. On the rising edge of this Work Clock these twisted pairs would carry
the left channel, while on the falling edge, they would carry the right channel. In
most television systems using digital audio, the audio sample clock frequency
(and hence the 'genlock' between the audio and video worlds) is derived from the
video genlock signal. But products that are purely audio, with no video reference
capability, may still require Word Clock.
Wide Screen Signaling is used in the PAL/625 video standards, both in analog and
digital form, to convey information about the aspect ratio and format of the
transmitted signal. Carried in the vertical interval, much like closed captioning, it
can be used to signal a television receiver to adjust its vertical or horizontal sizing
to reflect incoming material. Although an NTSC specification for WSS exists, it
never achieved any traction in the marketplace.
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Strictly speaking, YUV does not apply to component video. The letters refer to the
Luminance (Y), and the U and V encoding axes using in the PAL composite
system. Since the U axis is very close to the B-Y axis, and the V axis is very close
to the R-Y axis, YUV is often used as a sort of shorthand for the more longwinded “Y/R-Y/B-Y”.
In digital component video, the luminance component is Y, and the two color
difference signals are Cr (R-Y) and Cb (B-Y).
In analog component video, the image is carried in three components. The
luminance is Y, the R-Y color difference signal is Pr, and the B-Y color difference
signal is Pb.
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