Digital Video At Length

The importance of dependable digital video connectivity continues to grow exponentially as a plethora of consumer and commercial TMDS enabled devices change the nature of installed A/V. With analog infrastructure all but gone, being able to deploy point-to-point connectivity solutions that support TMDS (HDMI) content at critical middle distances is vital. Under 50-feet, AV connections are often best served in a native format. Beyond 350-feet, AVB and IP solutions provide the best technology. But in the important range between 50 and 350 feet, copper structured wiring delivers the greatest efficiency and value. In this presentation participants will explore the characteristics and technology deployed in HDBaseT and Ultra Wideband wired and wireless AV connectivity solutions. This one-hour exploration will focus on operational theory, comparative performance metrics and practical application of the technology to common AV installations.

Transcript

1. PRODUCT LINE Extending Uncompressed Digital Video T0 100 Meters and Beyond! The power of digital is that it either works perfectly or fails utterly – and pushing connectivity beyond 20 meters is an easy way to see the failing part! Here are ideas to avoid that outcome and ensure operability! Digital Video At Length Joseph D. Cornwall, CTS-D
2. PRODUCT LINE Our Learning Objectives Define digital video (DV) and set the expectations of connectivity distance Explore the technical challenges of “long” point-to-point DV connections Dissect and review the components of DV necessary for practical system utility Review DV connectivity options and formats
3. PRODUCT LINE THE LAST 100 METERS “I sense an insatiable demand for connectivity.” − Clifford Stoll
4. PRODUCT LINE Analog Connections Follow Simple Rules • Analog is continuous in nature •Signal is varied continuously with respect to the information • Analog systems have an infinite bandwidth • Primary disadvantages of analog are noise and non-linearity •Additive noise •Generation loss •Intermodulation noise •Harmonic distortion
5. PRODUCT LINE Advantages of Digital Signals •Digital systems use discrete representations of information •Digital systems exhibit a finite resolution •In a binary system, information payloads double with each additional bit •Disturbances in a digital communication do not result in errors unless the disturbance is so large as to result in a symbol being misinterpreted
6. PRODUCT LINE Digital Connections Leverage Analog Signals! •A digital signal is a representation of a series of discrete values •Digital signals in cables leverage analog waveforms •Clock signals used to synchronize digital circuits often act to limit connection length •Synchronous Systems •Asynchronous Systems
7. PRODUCT LINE The Physics Of Wire • Longer wire = greater resistance •Cross-sectional area of the wires •Material composition •Pure resistance causes A frequency independent voltage drop • Capacitance and inductance are proportional to wire length/construction •Impedance is defined as the frequency domain ratio of voltage to current •Capacitance and inductance cause a frequency dependent voltage drop
8. PRODUCT LINE Characteristic Impedance Opposition that a circuit presents to the passage of a current when an AC voltage is applied, expressed in Ohms (Ω) • Determined by the physical material composition and geometry of the cable assembly A precise, constant conductor spacing, is necessary for a cable to function efficiently as a high-frequency transmission line Impedance matching ensures maximum power transfer and minimized reflections in the circuit
9. PRODUCT LINE Skin Effect • Alternating current in a conductor produces an alternating magnetic field. • When the intensity of current in a conductor changes, the magnetic field also changes • The change in the magnetic field creates an electric field which opposes the change in current intensity (counter-EMF). • The counter-EMF is strongest at the center of the conductor and forces the conducting force to the outside of the conductor.
10. PRODUCT LINE WHAT IS THE DIGITAL VIDEO PAYLOAD? “For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.” - Richard Feynman
11. PRODUCT LINE The Elements of a Video Signal • RGB additive color model divides a video signal into 3 ”components” ─ RGB or YPbPr (YCbCr) • Bandwidth is directly proportional to visual detail ─ In analog systems, the ability to pass higher frequencies equates to the ability to display finer detail • Amplitude is directly proportional to color saturation a m p l i t u d e time
12. PRODUCT LINE Chroma Subsampling 4:4:4 Each R, G, and B channel, or each Y′, CB, and CR channel, is sampled at the same rate. Maximum color detail is maintained. 4:2:2 The color channels are subsampled so that the color resolution is halved. For example, the first pixel in a line contains Y′, CB, and CR samples. The next pixel contains only a Y′ sample. This pattern repeats. Most professional video formats use 4:2:2 color subsampling. 4:1:1 The color is subsampled so that the color resolution is quartered. The first pixel in a line contains Y′, CB, and CR samples. The next three pixels only contain Y′ samples. This pattern repeats. 4:2:0 This ratio indicates that the CB and CR channels are subsampled both horizontally (as in 4:2:2) and vertically. This reduces color resolution in both the horizontal and vertical dimensions compared to 4:2:2, which only reduces horizontal chroma resolution. There are several methods for locating CB and CR samples relative to Y′ samples, yielding several different 4:2:0 formats. Color sample ratio refers to the ratio of luma (Y′) samples to each color difference sample (CB and CR samples, less color detail is recorded and less bandwidth is required for storage and transmission. Because we are less sensitive to color detail than we are to luma detail, subsampling the chroma signal can be considered perceptually lossless.
13. PRODUCT LINE Chroma Subsampling And The DV Payload Detail D2K = 2M Pixel D4K = 8M Pixel Chroma Subsampling Up To 16-Bits Per sRGB Component 4:2:2 YCbCr 4:4:4 “Deep Color” DV Bandwidth Data rate * chrominance decimation Data rate = color depths * vertical resolution * horizontal resolution * refresh frequency
14. PRODUCT LINE Digital Audio • Digital audio is not a discrete element of the DV package •Bits are “fungible” •Digital audio is embedded into the horizontal ancillary data space (HANC) of the •Audio travels with video A sound wave, in red, represented digitally, in blue (after sampling and 4-bit quantization).
15. PRODUCT LINE Digital Rights Protection - HDCP •High Bandwidth Digital Content Protection (HDCP) is a technology designed to allow digital rights management implementation of AV content •Leverages Blom’s Scheme •Converting digital video w/ HDCP is forbidden unless the output supports the HDCP protection
16. PRODUCT LINE System Control •RS232 •CEC is an HDMI feature designed to allow the user to control enabled devices •Allows for individual CEC-enabled devices to command and control each other without user intervention • Infra Red • USB •If “Interactive” is involved, so is USB!
17. PRODUCT LINE DDC, EDID and DisplayID • Display Data Channel • Extended Display Identification Data (EDID) • Enables the display (sink) to communicate supported display modes to the source via a compact binary file format that describes the monitor's capabilities and supported graphics modes • Stored in a read-only memory chip programmed by the manufacturer of the monitor
18. PRODUCT LINE CONNECTION TYPES “Given a choice between two theories, take the one which is funnier.” − Blore's Razor
19. PRODUCT LINE Coaxial • Coaxial connectors are designed to maintain a coaxial form across the connection and have the same impedance as the attached cable. • The characteristic impedance of coax is set by the physical relationship of conductor diameter to dielectric diameter
20. PRODUCT LINE Optical Fiber • Multi-Mode Fiber • Supports many propagation paths within the fiber • Used for shorter connections with emphasis on power • Single-Mode Fiber • Supports only a single transmission path within the fiber • Used for the longest connections
21. PRODUCT LINE Twisted Pair •Category cable can be optimized for specific tasks •Differential (balanced) signaling ensures environmental noise rejection •Differing twist rates (pitch) minimizes crosstalk between pairs •10base-T, 100base-Tx, 1000base-T
22. PRODUCT LINE WHAT DOES “BASE-T” MEAN? “It is difficult to get a man to understand something when his job depends on not understanding it.” - Upton Sinclair
23. PRODUCT LINE Baseband •BASE denotes a baseband transmission •A systems whose range of frequencies is measured from close to 0 Hz to a cut-off frequency, a maximum bandwidth or highest signal frequency •“T” denotes twisted-pair (balanced) transmission
24. PRODUCT LINE Passband •Also known as bandpass, the signal is sent over a limited frequency range that is a subset of the total signal range •Passband signals are typically translated to a higher frequency, often for transmission by frequency division multiplexing. •RF and modulated systems are examples of passband technologies
25. PRODUCT LINE LIFE BEYOND 20 METERS “Luck is the residue of design.” − Branch Rickey
26. PRODUCT LINE SDI - Serial Digital Interface •SDI (1989) •HD SDI (1998) •3G SDI (2006) • 3 Gbit/s and 1080p • 16 Channels of embedded audio • 6G SDI • 6 Gbit/s and 4Kp30 • 12G SDI • 12 Gbit/s and 4Kp60 • 24G SDI • 24Gbit/s and 8Kp60
27. PRODUCT LINE TMDS Over Twisted Pair • Typically Dual UTP Connectivity • TMDS – RGB and Clock • SCL/SCA I2C, Hot Plug, 5V Power, 5V Ground • No Fundamental Changes Are Made To The Signal • Carriage Distance Is Inversely Proportional To Signal Bandwidth • 60 Meters For 720P Content • 25 Meters For 1080p/60 • 20 Meters For 1080p With 10 Or 12 Bit Color Depth Content
28. PRODUCT LINE THE NEWEST IEEE STANDARD! “The nice thing about standards is that there are so many of them to choose from.” − Andrew S. Tanenbaum
29. PRODUCT LINE HDBaseT •HDBaseT Alliance was established in 2010 •LG electronics, Samsung Electronics, Sony Pictures, Valens Semiconductor •Working to create a global standard for advanced digital media distribution •HDBaseT 2.0 standard finalized in August 2013 •HDBaseT standard will support up to 8 “hops” of 100 meters each
30. PRODUCT LINE
31. PRODUCT LINE HDBaseT and 5-Play
32. PRODUCT LINE Pulse Amplitude Modulation 16 0000 : 15 0001 : 13 0011 : 11 0010 : 9 0110 : 7 0111 : 5 0101 : 3 0100 : 1 1100 : -1 1101 : -3 1111 : -5 1110 : -7 1010 : -9 1011 : -11 1001 : -13 1000 : -15 0 0.5 1 1.5 2 2.5 3 3.5 4 -1 -0.5 0 0.5 1 V nS PAM16 TX Eye Pattern One Symbol Period TX Diff Peak 4bits Level HDBaseT uses PAM16 symbols where each symbol is transmitted using one of 16 discrete, differential voltage levels, each representing 4 bits of data
33. PRODUCT LINE MORE EXTENSION METHODS “All truths are easy to understand once they are discovered; the point is to discover them.”- Galileo Galilei
34. PRODUCT LINE Media Conversion •Tx/Rx pair conversion to multimode or single mode •62.5/125 under 500-feet •50/125 for 500-foot plus runs •Tx/Rx pair conversion to a coaxial link •TMDS is converted to Serial for carriage over coax •Integrated media converter over dedicated fiber channels •Native TMDS •4K certified to 300 meters
35. PRODUCT LINE Modulated Passband • Digital television! • Coaxial cable systems using modulated content can deliver dozens of HD streams simultaneously
36. PRODUCT LINE Video Over IP Uses video codec to reduce the program material to a bitstream MPEG transport stream  Uses an Internet Protocol (IP) network to carry that bitstream encapsulated in a stream of IP packets. Variant of the RTP protocol Quality of Service (QoS) places significant demands on system design and implementation
37. PRODUCT LINE IN CONCLUSION… “A conclusion is the place where you got tired of thinking.” − Harold Fricklestein
38. PRODUCT LINE Fascinating… • In digital video applications, considerable thought must be put into runs greater than 15 meters in length • DV content is transmitted via analog carriers working in a defined medium • DV content includes video, audio, content protection (DRM), control, display data channel information, and even power components • SDI systems do not support HDCP • HDBaseT supports 5-Play “Live long and prosper.”
39. PRODUCT LINE Questions?