Introduction

If you have not already done so, you may wish to read the following articles first ...

Codecs, formats and optimising concepts

Optimising video concepts

NOTE: This article concerns itself with "consumer" and semi-professional/broadcast/hi-end "project" video production technologies such as AVCHD, DV and formats for DVD, CDROM and web sites.

There are at present 2 categories of video ...

1. SD (standard definition) - which uses technologies such as Freeview TV broadcast, miniDV camcorders and DVD video discs.
2. HD (high definition) - which uses technologies such as HD satellite and cable broadcast, iTunes, and Blu-Ray discs.

 

Digital video data file formats

There are many many digital video data file formats (codecs) in the consumer and professional worlds. For example, all of the following can record and/or playback some form of digital video ...

• Computer
• DVD video disc
• DVD ROM
• CD ROM
• Cable TV
• Satellite TV
• DV camcorder
• Games console
• Video mobile phone

But they do NOT all use the same data file formats and codecs.

 

Video file formats & codecs

Unlike the world of digital audio, where 2 uncompressed file formats (.wav, .aif ) and 1 compressed file format (MP3) dominate, digital video is a minefield.

NOTE: You may wish to read an explanation of the difference between file formats and codecs before you continue reading.

Here are SOME of the digital video data file and codec formats ...

Data file type	Codec(s)	Filming / Camcorder?	Editing?	Delivery?
Sony Digital Betacam	Uncompressed	Yes	Professional TV editing systems	No, must be compressed first
DV	DV codec	Yes	PC & Mac editing	No, must be converted first
MPEG-1	MPEG-1	No	No	CD ROM & web
MPEG-2 (SD DVD, digital, cable & satellite TV)	MPEG-2	Yes	No	Satellite & cable TV broadcast, HDV and DVD video discs
QuickTime (.mov)	Multiple	Some	Yes	QuickTime Player
-	Sorenson	No	No	CDROM, DVDROM, web
MPEG-4	Includes many codec variants including H.264	Yes	Yes	Everything ... from HD DVD, digital TV to mobile phones, PSP, iPod etc
divX	Appears to use an MPEG-4 variant codec	No	No	CDROM, DVDROM, web
-	xVid	No	No	CDROM, DVDROM, web
-	3GPP	No	No	Mobile phones
Windows Media (.wmv)	Multiple	No	Yes	Windows Media Player
Flash (.swf)	MPEG-4	-	-	Flash player
Hi-def ... at the time of writing (March 2008) professional and consumer hi-def formats are evolving. There are many formats including the excellent AVCHD format. More on hi-def is here.

 

Camcorder types

Click here to compare different camcorder types

 

Uncompressed video formats

There are SOME professional broadcast quality uncompressed digital video formats including Sony DigiBeta but these require specialist hardware and software and cannot be used on Macs and PCs. This format is used for TV programmes such as news, reality TV, soaps and game shows etc. In practice almost all video data is compressed inside a camcorder as soon as the data leaves the CCD (which converts light into data) and before it reaches the storage device.

 

Compressed video formats

Raw video data files are very large. Most file formats use compression software (codecs) to help in transferring and storing. Usually data must be encoded (compressed) before it is ...

• recorded to the video tape in a camcorder
• stored on the hard disc of a computer
• burnt on to DVD
• transferred over the internet
• broadcast via satellite or cable
• transferred to a portable device (eg iPod or mobile phone)

... and then decoded (uncompressed) to be played.

Quality & file size

The more video is compressed ...

• The smaller the file size (easier to store and transfer)
• The lower the data rate (easier to replay and stream)
• The worse the quality

The compression settings you choose when preparing video will depend upon ...

• The CPU power of the target computer (which will need to compress, decompress and display video files).
• The duration of the video
• The capacity of the media it will be stored on (floppy, CDROM, DVDROM etc?).
• The bandwidth of the connection (if on a web site)

 

Video codecs

What is a codec?

If you don't know the answer to this question, click here to read our article on codecs, formats and optimising concepts now.

Where can video codecs be located??

Video codecs may be located in several places ...

• Computer system folders (so called "soft codecs" such as the ones that QuickTime and Windows Media Player provide)
• Browser plug-ins (usually utilise system installed soft codecs
• Video PCI expansion cards often have "hard codec" chips similar to those found in DV camcorders
• DVD players have "hard codec" chips to decompress the MPEG-2 video files that DVD discs carry
• Set top boxes for satellite and cable TV
• DV camcorders also have "hard codec" chips
• Games consoles
• Mobile phones
• iPod's

The DV format

The most popular semi-pro and amateur video production format is DV. Read about the DV format here and by viewing our PDF on DV Signal Flow.

Incidentally, audio CDs do not use codecs because the data size of digital audio files is small enough to fit on a CD without being compressed. MP3 audio however, is highly compressed. Click here for an article on digital audio file formats.

HD (hi-definition) video

High definition video has "splintered" into many differing file formats, such as AVCHD. Most of these formats use an MP4 "variant" codec such as H.264 which has become standard for Blu-Ray DVD and HD TV broadcast. More on hi-def is here.

Current popular codecs

The table above lists many current popular codecs.

 

Computer media player software & video file formats

Click here to read about how computers handle different video formats and codecs.

 

Optimising video files

Click here for an article on video optimising concepts.

Click here for an article on how to prepare video for DVD.

Click here for an article on how to prepare video for web sites & multimedia projects.

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