This document discusses video codecs and file formats. It explains that codecs are needed to compress video files for distribution and playback, as uncompressed video takes up significant storage space. However, there are many different codec options, creating compatibility issues. Common codecs include H.264, MPEG-4, and QuickTime. The document outlines key concepts like interlaced vs progressive formats, and container formats like AVI and QuickTime that combine video and audio into single files using codecs.

2.  Why will your PC play some video files and not
others? It’s all down to codecs.
 So why do we need codecs?

3.  Video uses a lot of storage space on your
PC/Mac.
 For instance 5 minutes of captured camcorder
footage uses about 1gb of storage.
 On the plus side, storage is now cheap.

4.  The trouble really comes when trying to distribute
the footage.
 People don’t want to be given hard drives to plug
in to their computer. They want DVDs, iPod
videos, Sky & Freeview.
 So the files need compressing to fit these media

5. ...the trouble is that there are hundreds
(thousands?) of compression options!
 So let’s start at the top...

6.  Way back in the 1950s three main broadcast
standards were established by various countries:
 PAL (in the UK)
 NTSC (in the USA)
 SECAM (in France)

7.  ...and they all worked quite happily for the next
thirty years!
 This was mainly because video production was
expensive and made by a small number of
companies. Thus easily regulated.
 Then came digital!

8.  The Digital Revolution of the 1990s made video
production cheap and available to the masses.
 This made it difficult (impossible?) to regulate.
 New digital ‘standards’ were required, and lots of
options competed...

9.  Instead of being imposed like the 1950 standards,
the new standards were placed in competition with
each other.
 The theory was that the best standard would
become dominant.
 The actual result was a minefield of formats,
containers and codecs...

10.  Codec stands for Code / Decode
 It is basically a computer program that en-codes
video to a specified format
 From this point on the same codec is needed to
play (decode) the video

12.  The trouble comes when you move your video to
another computer...
 ...if that PC/Mac hasn’t got the required codec
installed (to decode the video) then your video
won’t play.
Tip: PC users can try ‘G-Spot’ (freeware) to
identify the codecs used by a video

13.  Sorenson
 Indeo
 Cinepak
 Oh, and there’s an another pile of codecs for
encoding audio files!
...eh, what about Quicktime and AVI?

14.  Here’s the big confusion: Quicktime, AVI and
Real are not codecs!
 These are ‘container’ formats.
 This basically means that they contain codec
compressed video and audio in one easy to play
file.

16. Video codecs can be broadly split into two types:
 frame-based codecs
 temporal (or field-based) codecs.
 Say What!?!

17.  Well known examples are Cinepak
and Motion-JPEG
 They work by examining and compressing each
frame of video individually.
They have two main disadvantages:
 they can be slow to encode
 file sizes can be quite large

18. =
Time

19.  The best known is MPEG-2 (used for Digital TV &
DVDs)
 They watch how much a video clip changes from
frame to frame then compress only the changes
between the first full frame (a keyframe) and the
next.
 Thus keeping file sizes down!

20. =
+
+
+
Keyframe

21. =
+
+
+
Copies unchanged
parts of the keyframe

22.  The quick answer to this question is to use the
relevant presets within your editing software:
Codecs made Simple in iMovie

23.  But it’s always worth checking with your client
about their requirements.
Especially if they’re planning on showing the video
overseas.
 This is where programs like Apple’s Compressor
come into play (but that’s another presentation for
another day!)

24. Interlaced Progressive

26.  The ‘i’ and ‘p’ make all the difference!
 In terms of picture quality there is very little
between 1080i and 720p:
 1080i has a slightly higher resolution but it’s not
very sharp with fast moving action...
 ...so 720p is favoured by sports networks

27.  1080p is the ideal format but broadcasters are not
yet equipping themselves to transmit in this format
(it takes up too much bandwidth!)
 Also known as ‘Full/True High Definition’ or ‘24p’
 So it is currently being used as an alternative to
expensive film-stock when actually shooting a TV or
movie film production

29.  These are rival disc formats – they are like super
large DVD discs (holding up to 50gb)
 ...this means that a HD movie (which obviously
has a larger file size) could fit on one of these
discs rather than span across five DVDs
 They are nothing (directly) to do with video
formats

30.  Blu-Ray is supported by Sony,
Panasonic & Apple
 HD DVD is supported by Toshiba,
Microsoft & Intel
 This could be the next ‘VHS vs
Betamax’

31.  At the other end of the resolution spectrum is the
booming mobile video market
 This is more concerned with getting files smaller
to fit on the tiny screen on your phone or iPod
 Typical Screen Res is a tiny 176 x 144

32.  You can’t!
 Things are moving too fast, the best you can do
is be aware of the issues and make sure you
know the most common settings you work with
 And always keep a copy of your finished video
at the highest quality it was produced at!

33. ---End---