Digital Video Creation

Author: Paul Browne , 2004 - 1 # 31 -

Digital Video Creation

Paul Browne


Contents

• Introduction • Digital Video Formats• Capturing• Digital Video Editing• Streaming• DVD-Video Creation


Introduction

• Video contains:– Frames

– Audio

• Video can be stored in Analog or Digital formats• VHS Video is stored in Analog format• DVD Video is stored in Digital format

• Frame rate – Number of frames/ images shown per second (fps)– Low frame rate will have unnatural motion like early cinema– Natural motion needs to be 20 fps or more – Cinema Film = 24 fps, TV PAL = 25fps, TV NTSC = 30fps (USA, Japan)

• Video can have large space requirements so compression is essential


Introduction

• Video and Audio Compression/ decompression methods are called CODECS

• The Audio and Visual information is handled by a separate audio and video codec

• These codecs need to be installed any computer that will view the video– Many are installed by default or with media player

but some might need be installed separately.

• Many video formats are actually wrappers that handle the synching of audio and video – They offer the facility to use numerous codecs for

audio and visual for compression/ decompression . – .AVI and .MOV files are good examples of this.


File Sizes

• File Sizes– 1 bit = 0 or 1 (Binary)– 1 byte = 8 bits (00100110)– 1 Kilobyte = 1024 bytes– 1 Megabyte = 1024 kilobytes– 1 Gigabyte = 1024 Megabytes– 1 Terabyte = 1024 Gigabytes

• Typical Bitrates– CD Audio : 1.3 Mbps– mp3 audio (CD quality) : 96-320 Kbps– Compressed Video : 150 Kbps - 6 Mbps

Uncompressed Video : 31 Mbps – Digital Photo (4 Megapixel quality) : 1 Megabyte

Kbps: kilobits per second

Mbps: Megabits per second

Capacities Floppy Disk: 1.4 Megabytes

CD-ROM: 650 Megabytes

DVD: 4.5 Gigabytes

Typical Hard Drive:

80-250 Gigabytes


Bandwidth

• Bandwidth is the amount of data that can be sent/received per second – This is important for streaming digital audio/video as they will

be encoded at a specific bitrate per second. – Higher quality Digital Video (high bitrate) needs higher

bandwidth • Compressed Video at 250 Kbps needs a bandwidth of at least 250

Kbps. In practice it will need to be more to cover network traffic.

• Common bandwidth restrictions – Mobile Phone (GPRS Date) 26.8 kbps– Mobile Phone (Voice) 9.6 kbps– Computer Modem 56 kbps– ADSL (Broadband) 256+ kbps– Ethernet Network 100+ Mbps


Digital Video Formats


MPEG Digital Video Formats

• MPEG (Motion Picture Experts Group)– Formed to create an interoperable standard for

digital video. Lots of different companies and research groups participate.

– The results from MPEG work can be found in DVD’s and Digital Satellite television.

• MPEG-1: Allows VHS quality digital video (VCD)• MPEG-2: Digital TV and DVD • MPEG-4: Digital Video over the Internet and

Networks• MPEG-7: Video Content descriptor layer only


Popular Digital Video Formats

• Microsoft – .AVI (interoperable standard), WMV

• Apple– .MOV (interoperable standard), .QT (QuickTime)

• RealNetworks– .ra , .rm , .ram

• DivX– Based on advanced MPEG-4 compression – Audio requires a separate codec (typically mp3)– Has .avi compatible format

• MiniDV– Compression used in MiniDV camcorders (bitrate 31.2 Mbps)– 1 minute = 219 Meg


Capturing & Recording Digital Video


Capturing

• Digital Video Digitization Procedures

– 1. Select Connection method

– 2. Choose input method

– 3. Select bitrate quality

– 4. Record content

• Common methods of video connection

– DV capture (digital) Firewire/ USB-2

– TV/ Video capture (low quality Analog) Composite

– TV/ Video capture (higher quality Analog) S-Video


Connecting To The Computer


Capturing: Connection Types

• Firewire: For Apple machines and Laptops this is standard but most PC’s desktops need a card installed. Bandwidth 400 Mbps

– Suitable for uncompressed digital video capture off a mini-dv camcorder

• USB 1.2: This is available on most computers at this stage. Bandwidth is poor at 1.2 Mbps (so not suitable for quality digital video)

• USB 2.0: Available as default on Pentium 4 machines. Connections look the same as USB 1.2 but with higher bandwidth capability: 440 Mbps. Future DV Capture will use this also but currently firewire is king


Capturing: Connection Approaches

• Connecting a camcorder to computer using analog connection for digitization– Typical computer will not have analog input. Requires an ATI All

in one wonder or WinTV PDR cards

1: Connect to

camcorder

2: Connect white and red (audio) cables to phono connection

3: Connect yellow (video) cable to composite-in, phono connection placed into line-in.

composite-in line-in



• Connecting camcorder to computer using Digital Firewire connection.

1: Connect to

camcorder

2: Connect to

firewire port on PC



• Connecting Camcorder to TV / Video

1: Connect to

camcorder

2: connect the three wires to scart adapter

3: Connect scart to TV /Video

S-Video Composite StereoAudio


Capturing: Digitisation

Firewire/ Mini DV Capture program

Digital Source

Video Capture

Analog/ TV Capture Board

•Example Digitisation Programs


Capturing: Digitisation

• Select bitrate quality – 1 minute MPEG-1 at 1 Mbps = 7 MB

– 1 minute MPEG-2 at 6 Mbps = 48 MB

– 1 minute DV capture at 31.2 mbps = 219 MB

• The Captured Digital Video can be further compressed at a later stage– QuickTime Pro, Helix Producer, TMPGenc or

FlaskMPEG can reduce the bitrate further

• Digital video editing is generally done on higher quality video before being further compressed for e-mail or the internet


Now that the digital videohas been recorded we can edit it


Digital Video Editing

• Digital Video Editing can involve simple operations like removing and/or joining sections of video content. – This can be quick for the computer to complete as it

does not require any re-encoding of the video.

• More complex Digital Video Editing is the addition of titles, visual transition effects like swirls and the mixing of different audio and video sources.– This is usually slower for the computer to complete– generally a number of times the duration of the

content.



• Semi-Professional (complex editing): Avid Express,Adobe Premiere

Current Project:Videos, audio andimages for edit

Output Timelineshowing durationand audio+videotransitions andeffects

Visual Output Transitions andeffects



• Microsoft Movie Maker 2: Designed for home users: Allows Simple and Semi-complex Editing

Output Timeline



• TMPGenc: Create MPEG-1 & 2 and allows simple Editing and Re-compression at modified bitrates

Simple Edit Remove sectionof video


Now That the video is ready it can beviewed on computer or over the internet


Streaming Digital Video

• Streaming Video– Allows the video to be played over the internet

without having to be downloaded to the computer beforehand

– The video is sent in a number of segments to peoples computers

– The video can be streamed at different bandwidths• The bandwidth of the persons connection to the internet

needs to be higher than the video’s bitrate

– The streamed video is not saved onto the client machine and therefore cannot be copied


Streaming Digital Video

• Streaming video can be expensive requiring a fast computer and expensive streaming software

• Edited digital video needs to re-compressed (re-encoded at a lower bitrate as people’s internet bandwidth might be low.– 48 Kbps for a 56K modem– 200 Kbps for broadband

• Two Free streaming packages are available – Apple’s Darwin Streaming Server

• http://developer.apple.com/darwin/projects/streaming

– RealNetworks• www.realnetworks.com/products/server/


Creation of DVD-Video disks from thesource video is also possible


DVD-Video Creation

• DVD-Video Creation Procedures– Obtain your Digital Video source

• MPEG-1, MPEG-2 or AVI (Mini DV format)

– Create a DVD Menu Structure with your source video as input (See Slide 29)

– Output your created DVD to computer hard disk – Place a blank DVD-R (recordable) into the DVD

recorder drive on your computer

– Use DVD burning software like Nero 6 Ultra-edition to write the DVD-Video files on the harddisk to your DVD-R (See Slide 30)

• Note: Not All burning software will write a DVD compliant DVD-Video


DVD-Video Creation

• Screenshot from TMPGENC DVD Author

DVD ChapterLayout

BackgroundLayout Design

Video SourceFiles

DVD RecordableCapacity


DVD-Video Creation

• Screenshot from Nero 6 Burning Software

DVD-Video Project

DVD Video Source Fileson Computer

DVD Video to Create


The End

Digital Video Creation

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