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---