History of Film

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History of Film

• Week 9

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Lecture Outcomes

• Global TV standards and TV frame sizes
• How TVs draw pictures
• Interlaced and progressive scan
• What video tape and camera formats are available?
• Connecting devices
• Digital Technology Explained
• Sampling
• Hollyoaks

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GLOBAL TV STANDARDS
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Global TV Standards NTSC(Never twice the same
colour)

• NTSC TV
• National Television Standards Committee
• Used in North and Central America and Japan
• 525 lines of horizontal resolution
• Runs at 60Hz of vertical frequency (60 cycles per
  sec) at 110 volts of AC

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Global TV Standards - SECAM

• SECAM
• Sequential Couleur Avec Memoireor Sequential
  Colour with Memory
• Used in France, Iran and Iraq to name a few
• 625 lines of horizontal resolution
• Runs at 50Hz of vertical frequency (50 cycles per
  sec) at 220 volts of AC
• Adopted in 1967

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Global TV Standards - PAL

• PAL TV
• Phase Alternative Line
• A German invented system
• Used in most of Europe, Africa, Australia, and
  South America
• 625 lines of horizontal resolution
• Runs at 50Hz of vertical frequency (50 cycles per
  sec) at 220 volts of AC

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3 Global TV Standards exist at standard
definition

• PAL 625 vertical lines at 50Hz
• NTSC 525 vertical lines at 60Hz
• SECAM 625 vertical lines at 50Hz
• Compatibility??

No they are not compatible
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Drawing a TV picture Interlacing and Progressive
Scanningexplained
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TV Scan lines
A TV picture is made up of either 525 or 625
individually painted horizontal lines called scan
lines or rasters.
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Interlaced Scanning

• Half of the 625 lines are drawn first. This is
  called field 1.
• The first field draws is called the odd field as
  it draws the odd numbers 1,3,5,7, etc
• The second half of the lines are called field 2
  and this draws the even numbered lines 2,4,6,8
  etc
• This is also called 50i recording, for 50
  interlaced images per second.
• Field 1 and Field 2 1 Frame

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Interlaced TV Image
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Progressive Scan

• A progressive scan draws each of the scan lines
  one after another in numerical order e.g.
  1,2,3.625
• This gives a sharper image that an interlaced
  image.
• This is called 25p recording.
• There are no fields in a progressive scan just a
  single frame.

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Progressive Scan (De-interlaced image a field
removed)
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How a Camera deals with light

• RGB is split via a prism onto its corresponding
  CCD
• The data sent to a colour matrix where it is
  converted into luminance and chrominance.

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What is Luminance and Chrominance

• Luminance is the brightness or blakc and white
  information.
• Chrominance is the colour information.

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Why split light into luminance (Y) and
chrominance (C)?

• The Human eye might work with RGB but its not
  easy to image process.
• We convert into YC to allow brightness level and
  colour levels to be adjusted easier.
• This would be difficult if the image was in RGB
  as RGB mixed in 29/60/11 ratios white.
• Equal levels grey.
• Grey gives us shadows and depth.

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Video Connections and Types
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Analogue Video Signals Connector Plugs
Composite (YC combined)
S-Video (Y/C separate)
Component (Y U V signals kept separate)
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Video Types Explained

• Composite - Video information is carried in a
  single signal combining colour and brightness
  information into the one signal.
• S-Video Separates the colour and brightness
  information into two separate signals. S-Video
  (also known as Y/C-Video) transfers chrominance
  (colour portion of video signal denoted C) and
  luminance (brightness portion of the video signal
  denoted Y)
• Component video - separates the colour from the
  black-and-white portions of the picture by
  further splitting the colour information into two
  colour-difference signals (red and blue). This is
  represented by Y, r-y and b-y.

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Digital Video Signals

• DV IEEE1394 Firewire
• Digital component (Digital YUV or commonly called
  YCC)

6 pin 4 pin
Uses 420 compression at 8 bit Uses 4MB/s video
e.g Avid, Premiere and Final Cut
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Digital Video Signals

• SDI Serial Digital Interface

Digital component all signals (0s and 1s)
multiplexed together into one cable. Generally
uses 422 10bit compression The standard based
on a 277 Mbps transfer rate. Its can transmit
the signal over 600 feet (200meters) depending on
cable type.
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What type are the outputs on the following pieces
of equipment?

• A VHS player
• A standard DVD player
• A Canon XL1
• A Panasonic DV Deck
• A Media 100
• VHS RF (TV output) and scart analogue
  composite
• DVD Analogue composite
• Canon Analogue composite and a digital Firewire
  connection
• Panasonic Analogue composite, analogue S-video
  and a digital connection.
• Media 100 Firewire, composite and component and
  SDI (our systems do composite output to the TV
  and Firewire to the DV decks. SDI and component
  are disconnected)

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What type are the inputs on the following pieces
of equipment?

• A VHS player
• A standard DVD player
• A Canon XL1
• A Panasonic DV Deck
• A Media 100
• VHS RF and scart analogue composite
• DVD Digital disc only
• Canon Analogue composite and a digital Firewire
  connection
• Panasonic Analogue composite, analogue S-video
  and a digital connection.
• Media 100 Firewire, composite and component and
  SDI (our systems do composite for inputting
  VHS/DVD footage and Firewire to the DV decks. SDI
  and component are disconnected)

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How can you link a VHS or DVD player to a Media
100?

• Attach the scart output to a Media 100 composite
  input cables (same as the cables that link the
  Media 100 to the TV but they are inputs not
  ouputs)
• Remember the direction of the signals is the
  signal going in or out of a piece of equipment.
• Setup up the Media 100 hardware settings to
  composite and turn off the machine control.

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Lines of vertical resolution of Video Cameras

• VHS 240 lines
• SVHS 300 lines
• Sony handcam using Digital 8 (Sony invented it as
  consumer format) 500 (using s-video)
• Canon XL1 625 (using IEEE1394)
• JVC DV700WE (Pro ENG Camera, Mini DV format )
  750
• Sony Digital Betacam 800 depends on the camera
  recording it up to about 950

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Video Formats and their Resolution
Quality
lowest

• VHS (analogue composite)
• SVHS (analogue composite)
• Digital 8 (analogue composite)
• Betacam SP (analogue component)
• Mini DV (digital component - firewire)
• DVCAM (digital component - firewire)
• DVCPro25 (digital component firewire)
• IMPEG IMX (SDI serial digital interface)
• DVCPro50 (SDI)
• Digital Betacam (SDI)
• DVCPro HD (HD-SDI)
• HDCAM (HD-SDI)

highest
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Sony Tape Formats
Betacam SX for use in Sony SX cameras. Digital
SDI News gathering equipment
Betacam SP Analogue component HQ video used by
news gathering camera person in late 1990s
Digital Betacam Very HQ Digital component
video. Used to film all major dramas such as
Jack Frost.
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DV Tape Formats
SONY DVCAM Sonys answer to pro/consumer DV.
DVCPRO (D-7) JVCs HQ format. Uses SDI
Mini DV
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Video Recorders how do they work?
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Digital Tape Recoding
Digital tape can record audio either linearly
along the audio tracks the same as analogue tape
or the audio can be multiplexed together with the
video fields on the video track (noted as
pcm-pulse coded modulation)
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Helical Recording
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Helical Recording
The green object is the recording drum and it
mounted at an angle inside all VCR/VTR
player/recorders.
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Quick RefresherStandard Definition TV Frame Sizes

• What frame size is an analogue PAL TV image?

768 x 576
What frame size is a digital PAL TV image?
720 x 576
A Pal TV runs at how many individual images per
second?
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A NTSC TV runs at how many images per second?
29.97 its common to round it up to 30fps
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Question

• How do you record light and sound?
• With audio pickup devices and a light sensitive
  material
• E.g. a microphone and a camera

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How do we record analogue signals digitally?
A process called Sampling is used
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Sampling Signals

• In 1927 Nyquist and fellow scientists determined
  that an analog signal should be sampled at
  regular intervals over time and at twice the
  frequency of its highest-frequency component in
  order to be converted into an adequate
  representation of the signal in digital form.
• This theory is actually called the
  Whittaker-Nyquist-Kotelnikov-Shannon sampling
  theorem but generally it is shortened to the
  Nyquist theory

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Recording Signals through Sampling

• How does sampling a signal actually work?
• Sampling is the process used to convert an
  analogue signal (such as sound and light) into
  its electrical equivalent.
• Recording devices translate sound or light into a
  voltage.
• The decimal number recorded is then converted
  into its binary (0 and 1s) equivalent. This is
  called analogue to digital conversion.

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What is binary?

• The base 10 number system, the decimal system, is
  based on ten numbers 0, 1, 2, 3, 4, 5, 6, 7, 8,
  and 9.
• In mathematics and computer science, the binary
  (base-two) numeral system is a representation for
  numbers that uses only zeros and ones as digits.
  
• All decimal numbers can be converted into binary.
  
• How do we convert them?

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The easy way!!

• Use the Windows calculator (start
  programmesgtaccessoriesgtcalculator)
• Click the view tab and click scientific.
• Ensure the dec button is selected. Enter the
  decimal number.
• The click bin button and it will display the
  binary equivalent.
• Decimal 32 Binary 100000 or 0010 0000

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Converting decimal into binary
This table shows the binary number and the
decimal equivalent.
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Each binary number represents a decimal
equivalent as shown here to the right. The
pattern of binary against decimal is fairly
straight forward to understand.
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All computers run using binary. Everything is
converted into zeros and ones. There is an
easier way to work this out. Use a calculator!!!!
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How does sampling signals work?
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Sampling Made Simple

• To reproduce this signal we have sampled it at 4
  sample points.
• We have a 1 signal split into 8 possible voltage
  points (the quantization level).
• Whats the bit depth of this scale?
• 238
• We amount of times per second we sample is called
  the frequency. In this case its 4 or correctly
  termed 4Hz

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Sample Plot Table
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What happens when we reproduce this waveform from
the sampled points?
As you can see with such a low sampling frequency
the waveform cannot be accurately reproduced.
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How could we reproduce the signal accurately?

• Increase bit depth and increase the sampling
  frequency
• CD quality audio is sampled at 44100 times per
  second at a bit depth of 16bit (65536 levels to
  break up the 1 voltage)
• This means a very accurate signal can be
  reproduced.
• The voltages recorded at then converted into
  digital numbers (binary 0s and 1s) and stored.

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What Colour Systems do Cameras and TVs use?

• Standard televisions use 8bit RGB colour
• A low to mid range video camera uses 8bit RGB
  too.
• A top end camera uses 10bit RGB (like our studio
  cameras and digital betacam)

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Lighting Review
Hollyoaks!!