Digital Video Production: A Comprehensive Handbook

Posted on Dec 1, 2024 in Computers

1. Image Digitization

Image Quality

The more samples are taken, the greater the quality of the image. We can take fewer samples of the color signal luminance. Synchronization signal scanning is not required. The sampling frequency is greater than twice the maximum scanning frequency.

CCIR 601 Standard

• Digital active line: 53.33 microseconds; 720 samples
• Sampling Component:
  • Y = 13.5 MHz
  • CR = 6.75 MHz
  • CB = 6.75 MHz

Encodings

• 4:2:2
• 4:1:1
• 4:2:0
• 4:4:4

2. Digital Frame Formation

Color difference samples are transmitted interleaved with the luminance. Transmission period = 37 ns per sample. Data stream (8 bits/sample) = 216 Mbits/s. Data flow (10 bits/sample) = 270 Mbits/s.

Plot Control Signals

• Start of active video (SAV)
• End of active video (EAV)
• Additional data

3. Plot Transmission

Parallel Transmission

• SDI (SMPTE 259M)
  • Video: 10-bit YUV
  • Audio: Multichannel 20-bit
  • Additional data
• SDTI (SMPTE 305M)
  • Compressed video
  • High-speed download
• ILink, Firewire (IEEE 1394)
  • Up to 400 Mbps
  • Local connection

4. Digital Video Quality Measures

Principles of Action

• Measures on the digital frame.
• Measures interpreting the plot.
• Specific digital video measures.

Measures on the Digital Frame

• Measurement of the SDI signal
• Eye chart:
  • Amplitude: 800 mVpp
  • Jitter
  • Signal to Noise
• Visualization Component Y, Pb, Pr:
  • Amplitude levels
  • Synchronization between signals

Specific Digital Video (I)

Gamut measures facilitate exchange between digital formats.

• Divided Diamond
• Errors in the RGB signals
• Arrowhead
• Errors in the luminance and chroma amplitudes.
• Lightning Master: Displays Pr and Pb vectors by the luminance signal.
  • Top half: Y/Pb
  • Lower half: Y/Pr

5. Image Compression Principles

Objective of Image Compression

• Reduce the amount of data to transmit or record.

Any message consists of two components: entropy + redundancy. Redundancy: repetitive or predictable data. Entropy: vital statistics of the message.

Fundamentals of Image Compression

• Type of compression:
  • Lossless
  • Subjectively lossless
  • Subjectively lossy
• Fundamentals of compression:
  • Choice of an appropriate code.
  • Elimination of redundant information.
  • Elimination of less significant information.

Image Compression: MPEG

• MPEG-1:
  • Download: 1.5 Mbps
  • 352 x 288 (VHS)
  • 2 audio channels
• MPEG-2:
  • 4 to 15 Mbps (amps A 80)
  • 720 x 576 (TV)
  • 5 audio channels
• MPEG-3:
  • 1920 x 1080
  • Proposal abandoned
• MPEG-4:
  • 64 Kbps
  • 176 x 144 (basic version)
• Redundancy in a television picture:
  • Spatial redundancy
  • Temporal redundancy

6. Image Compression Systems

• Intra Compression
• Interframe compression: image prediction

Intra Coding (I)

Change of sampling: 4:2:2 (10 bits/sample) to 4:2:0 (8 bits/sample). Division of Image:

• Macroblock (16×16)
• Blocks (8×8)

Blocks of Y, Cr, Cb are obtained, which are compressed separately. Application of the two-dimensional Fourier transform in blocks. Convert image blocks into groups of vertical and horizontal frequency coefficients. This operation is reversible without loss.

Discrete Cosine Transform (DCT)

Image with Low Entropy

If the samples in an image area have similar values, their high-frequency coefficients will have very low values.

Image with High Entropy

When applying DCT to image areas with noise or many details, there are many significant value ratios, and compression will be less effective. Quantifying the DCT coefficients: 8 bits/coefficient. Reading of coefficients in zig-zag. Consolidation in pairs. Huffman code.

Image Type I

• 5400 Y blocks
• 1350 Cr blocks
• 1350 Cb blocks
• Moderate Compression

Intra Coding (II) – P Image Coding

Image Prediction

• Areas of analysis: 64×48
• Identification of equal macroblocks
• Motion Vectors
• New information
• Consolidation

B Image Coding

Bidirectional Prediction

• Use I or P pictures transmitted before and after as reference.
• Only new information is transmitted.

Group Pictures

• Only I images
• I and P images
• I, P, and B images

Hierarchy of Video Data

• Sequence
• Group of Pictures
• Portion
• Macroblock
• Block

Plot Formation

Program Flow: Video, audio, and data information from the same service. Transport stream: Contains various multiplexed services. Error Correction:

• Reed-Solomon
• Viterbi

Multiplex Frame

7. Levels, Profiles, and Scales

ENG Cameras

• Camera with built-in VCR
• Visor
• Wireless Microphone Receiver
• Battery
• Focus Notebook

Studio Cameras

• Tripod or pedestal
• Dolly (base stock)
• Intercom
• Optical control
• Camera monitor
• Interconnection:
  • Triaxial line
  • Multicore line

Virtual Sets

• Predefined plans
• Detection of camera axes
• Image detection array
• Position detection sensors

3. Production Control

• Technical control
• Implementation
• Sound Control
• Computer Room

Equipment Room

• Sync generator
• Test signal generator (VITS)
• Distributors
• Interconnection Panels
• Tally drivers
• Mainframe video mixer
• Switching matrix central unit
• Intercom central unit
• Video servers

Production Control (Audio) – Sound Control

• Patch panels
• Audio cameras
• VTR’s Audio
• Other audio sources:
  • Minidisc
  • CD
  • Cassette
  • Telephone hybrid
  • Sound Library
• Audio Mixer
• Distributors
• Monitoring:
  • Sound Control
  • Realization
  • Technical
• Processors:
  • Compressors
  • Noise gates
  • Effects Processors

Intercom Systems

• Two-wire Intercom
• Four-wire Intercom

4. Post-Production

• Recording Studio
  • Insertion of comments or dubbing.
• Graphics
  • Computer graphics and photo retouching.
  • Creating program headers.
  • Qualifications and specific graphics.
• Editing
  • Assembly of the audiovisual document.
  • Insert effects.

Post-Production Unit

• Monitors
• Intercom
• Video mixer
• Edit controller
• Audio Mixer

NLE Network – Room Size Change

17

5. Central Technical Control

Basic Functions

• Provision of signals to the studios
• Technical supervision of the signals
• Link to external sites
• Generation of sync pattern

Central Technical Control – Structure

18

• External Receivers
• Matrix Switcher
• Synchronization
• Sync pattern generator
• Technical monitoring
• Monitoring of sources
• Interconnection Panels
• Character generator adjustment
• Distributors

Continuity Control

Basic Functions

• Composition of the broadcasting program
  • Managing the issue rundown
• Archival recording of programs
• Issuance of advertising
• Issuance of prerecorded programs
• Coordination of disconnections

Transmission Room and Links

Basic Functions

• Disseminate the program signal:
  • To the end user
  • To the distribution network
• Serve signals to other locations (input)
• Receive external signals

Computerized Television Systems

• Intake
• Shared Storage
• Post-production
• Quick Edit
• Production
• Broadcast
• Cataloging and archiving

10. Quality Measures

• VITS (Vertical Interval Test Signal)
• First field:
  • Line 17
  • Line 18
• Second field:
  • Line 330
  • Line 331

Quality Measures II

• Insertion Gain:
  • White level bar
• Chrominance range:
  • Burst level
• Frequency Response:
  • Multiburst signal
• Distortion:
  • K factor (bar and pulse-bar)
• Luminance-chrominance value:
  • 20T pulse
• Distortion:
  • Step level