ARC130S SECTION
6
ARC130S 060801 Version 1 Issue 1
6.1
Aspect Ratio Technical Codes for Video and
Picture Sources
Proposal Version 3.1 -
see end of document for changes from previous versions 2.1 &3.0
These codes can used to describe the aspect ratios used when graphics or video sources are composed or
generated. They describe the image, the raster and conversion protection ratios. They are designed to be
compact yet easy to decode (readable), and are for use in materials requests, recording reports and labelling
including VTR Clocks. They can also be used verbally to overcome some of the terminology confusions that
exist at present.
Code Specification:
Code format is thus:
AABCCD
Where
AA
is the first parameter,
B
is the second etc.
The four parameters of the code must used in the order specified. Not all parameters have to be used if not
appropriate or known, however
B
( The Display Format )
should be present to prevent ambiguity.
AA
Active Image Aspect Ratio -
Number(s)
Aspect Ratio of Active Image Area expressed as a two digit abbreviated numeric value where the
comparison ratio is against a height of 9. Active Image area is the part of the raster / bitmap that
contains picture information. 12 is normally used for 4 by 3 ( 12 by 9 ). Note that areas involved with
code entry into database systems ask that only two digit codes are to be used. Code 99 is used where
ratio is very non-standard and is separately documented.
ie.
Two digit number giving the aspect ratio of the picture area that viewers are interested in, that is
neglecting any areas of continuous and static black due to letter-boxing or pillar-boxing. Numbers
describing ratios seen in use at present are: 12, 14, 15 ( Super 16 ), 16, 17 (1.85:1), 21 (2.35:1), 24.
Thus 14 : 9 becomes
14
.
B
Display Format -
Letter
The visual effect of the image and display raster aspect ratios combined. Abbreviated as an initial.
P
for pillar-box.
That is full height but with black down the sides.
L
for letter-box.
That is full width with black top and bottom.
F
for full frame.
Display and Image aspect ratios are the same.
M
for mixed, that is variations within the material of
P
,
L
or
F
ie. if it’s purely in letter box presentation put in an
L
etc. e.g.
14
L
12A -
”14 by 9 letterbox for..”. This
letter confirms what the pictures look like and separates the two ratio numbers.
Note: Letter
A
has been proposed for material converted an Anamorphic presentation - that is the
image is designed to be displayed distorted. This can be as a result of stretching a picture to fit a
given display shape whilst avoiding cropping.
