06-Digital Video

8/4/2019 06-Digital Video

1/35

520251:Multimedia

Systems

[!"#$%&

]

'(!)*+,-&./012"/$3#$4

15 '"5678/ 2554


2/35

Its everywhere!!!

TV

Cinema

MobilePhone

InternetStreamingDVD

VCD VDOChat

...and Many

MORE...

VDO on-demand

e-Learning


3/35

Agenda


4/35

Properties of VDO


5/35

Analog VDO

Motion VDO was originally created andstored in analog form.


6/35

Digital VDO

A means ofreproducing the continuous VDOwaveform as a stream of digital numbers.


7/35

Interlacing

Interlacing was originally conceived as a way toachieve good visual quality within a limitationsof a narrow bandwidth.

odd field even field


8/35

Progressive Scanning

(non-interlaced scanning)

A method of representingmoving images on a display

screen, in which every pixel isrepresented in each frame.

Computer monitors use a progressive scan.

The standard refresh rate for a flicker-freedisplay is a vertical scan rate of 75 Hz or higher.

Its used to project movies in theaters.


9/35

Note

in digital TV terminology:

interlaced scan is denoted

by a lowercase i

progressive scan isdenoted by a lowercase p

frame rate: (60i, 24p)resolution: (1080i, 720p)


10/35

Frame Rate

Frame frequency is a measure of how quicklyan image device can produce unique

consecutive images called frames.(expressed in frames per second - fps)

Typically, the human eye can interpret motion at10 fps, but this rate causes a flicker effect thatsdistract.

Increasing the frame rate reduces flickering.


11/35

Frame Rate

Movies - 14 fps

Television: NTSC - 29.97 fps HDTV - 60 fps

VDO games (frame rate is very important): action-oriented games - 20-30 fps

3D-heavy games - 90-100 fps


12/35

Aspect Ratios

The ratio of the width of the image to itsheight (w:h)

motion-picture - 1.85:1 and 2.35:1 tv screens - 1.33:1 (aka 4:3)

HDTV - 1.78:1 (aka 16:9)

16:9 4:3 letterbox


13/35

Compression

VDO is huge - one sec of analog VDO storedin an uncompressed digital format takes up 1MB of disk space

thus, 5-min VDO ~ 300 MB not practical

VDO compression is a MUST

VDO contains many spatial and temporalredundancies

Codecs are needed for creating and viewing


14/35

VDO Compression

Spatial compression (intra-frame)

Temporal compression (inter-frame) Video compression is a tradeoff between disk

space, video quality, and the cost of hardware

required to decompress the video in areasonable time.
http://en.wikipedia.org/wiki/Hardwarehttp://en.wikipedia.org/wiki/Tradeoffhttp://en.wikipedia.org/wiki/Hardwarehttp://en.wikipedia.org/wiki/Hardwarehttp://en.wikipedia.org/wiki/Computer_diskhttp://en.wikipedia.org/wiki/Computer_diskhttp://en.wikipedia.org/wiki/Tradeoffhttp://en.wikipedia.org/wiki/Tradeoff


15/35

Spatial Compression

Just image compression applied to a sequenceof images.


16/35

Temporal Compression

Make key frames, say every 6 frames and do thespatial compression on these frames. Between key frames, each one of them will be

replaced by a difference frame.


17/35

: http://www.trustedreviews.com/camcorders/review/2007/12/22/The-Codec-Primer-Part-1/p1
http://www.trustedreviews.com/camcorders/review/2007/12/22/The-Codec-Primer-Part-1/p1http://www.trustedreviews.com/camcorders/review/2007/12/22/The-Codec-Primer-Part-1/p1


18/35

Digital VDO File Formats


19/35

AVI

Most common AV data on Windows Can be saved in a variety of compression

schemes - full frames (uncompressed), Radiuss

Cinepak, Intel Video, and Indeo.


20/35

MOV

Quicktime Movie was developed by AppleComputer

MPEG-4 Qt 7 (and later) use H.264


21/35

MPG

The compressed VDO file format for standardDVD using the MPEG-2 encoding standard

A large file can be transferred to MPEG withlittle loss of quality while dropping the bit rate

a great deal


22/35

The MPEG group develops the standards forencoding VDO and audio

MPEG standards:

MPEG-1: used as VCD standard (MP3 is the

popular compression)

MPEG-2: use in many things such as DVD,digital satellite TV and so on

MPEG-4: support 3D content, low bit-rateencoding, support for Digital Right

Management


23/35

WMV a part of Windows Media framework used for streaming VDO over the internet uses MPEG-4 standard

RM

a multimedia container with RealVideo andRealAudio codecs in a single file is used to stream AV over the internet

Others


24/35

VDO Production


25/35

Equipments

Digital tapeless (D)

HDV (D) DV (formerly DVC)

8mm (A)

VHS (A)


26/35

Connecting Recorder toComputer


27/35

Analog Camcorder


28/35

Coaxial

VDO and audio signals are both carries in onecable

Poorest transfer


29/35

A/V

Use RCA connectors Yellow is (composite) video

Red is right audio & White is left audio


30/35

S-Video

Separate video - transmit VDOsignals over a cable by dividing

the VDO info into 2 separatesignals: color (chrominance)and brightness (luminance)

Sharper than composite VDO must be used in conjunctionwith audio cables


31/35

Digital Camcorder


32/35

USB

USB 2.0 are common

480 Mbps


33/35

FireWire

Developed by AppleComputer

IEEE-1394 standard 400 Mbps

higher transfer rates areavailable (800, 1600, andup to 3100 Mbps)


34/35

Transferring from

Recorder to Computer Calculate disk space (uncompressed):

(pixel width) x (pixel height) x (color bitdepth) x (fps) x (duration in secs) / 8,000,000 say, 3-min VDO @ 15 fps, 24-bit depth,

320x240 pixels will take: (320) x (240) x (24) x (15) x (180) /

8,000,000 = 622 MB


35/35

VDO Editing

Editing:

cut and paste sections add special effects

add transitions

add titles

Date post:	07-Apr-2018
Category:	Documents
Upload:	-
View:	221 times
Download:	0 times

06-Digital Video

Documents