SMPTE STANDARD
for Television —
SMPTE 296M-2001
Revision of
ANSI/SMPTE 296M-1997
1280
×
720 Progressive Image Sample
Structure — Analog and Digital
Representation and Analog Interface
Page 1 of 14 pages
Contents
1 Scope
2 Normative references
3 General
4 Timing
5 System colorimetry
6 Raster structure
7 Digital representation
8 Digital timing reference sequences (SAV, EAV)
9 Ancillary data
10 Bit-parallel interface
11 Analog sync
12 Analog interface
Annex A Production aperture
Annex B Pre- and post-filtering characteristics
Annex C Bibliography
1 Scope
1.1
This standard defines a family of progressive
image sample systems for the representation of stationary
or moving two-dimensional images sampled tempo-
rally at a constant frame rate and having an image
format of 1280 pixels by 720 lines and an aspect
ratio of 16:9 as given in table 1. All systems in the
table have the common characteristic that all the
samples gathered within a single temporal unit, a frame,
shall be spatially contiguous and provide a complete
description of that frame (4.2) This standard specifies:
– R′G′B′ color encoding;
– R′G′B′ analog and digital representation;
– Y′P′
B
P′
R
color encoding, analog representation, and
analog interface; and
– Y′C′
B
C′
R
color encoding and digital representation.
Table 1 – Image sampling systems
Luma or R′G′B′
samples per
active line
(S/AL)
1280
1280
1280
1280
1280
1280
1280
1280
Active
lines per
frame
(AL/F)
720
720
720
720
720
720
720
720
Luma or R′G′B′
sampling
frequency
(fs), MHz
74.25
74.25/1.001
74.25
74.25
74.25/1.001
74.25
74.25
74.25/1.001
Luma sample
periods per
total line
(S/TL)
1650
1650
1980
3300
3300
3960
4125
4125
Total
lines
per
frame
750
750
750
750
750
750
750
750
System
nomenclature
1
2
3
4
5
6
7
8
1280
×
720/60
1280
×
720/59.94
1280
×
720/50
1280
×
720/30
1280
×
720/29.97
1280
×
720/25
1280
×
720/24
1280
×
720/23.98
Frame
rate, Hz
60
60/1.001
50
30
30/1.001
25
24
24/1.001
NOTE – For systems 4 through 8, analog video interface is not preferred. See clause 12.
Copyright © 2001 by THE SOCIETY OF
MOTION PICTURE AND TELEVISION ENGINEERS
595 W. Hartsdale Ave., White Plains, NY 10607
(914) 761-1100
Approved
January 4, 2001
SMPTE 296M-2001
Designers should be aware that serial digital inter-
faces for formats other than Y′C′
B
C′
R
have not been
defined.
A bit-parallel digital interface is incorporated by refer-
ence in clause 10.
NOTE – Throughout this standard, references to signals
represented by a single primed letter (e.g., R′, G′, and B′)
are equivalent to the nomenclature in earlier documents of
the form E
R
′,
E
G
′,
and E
B
′,
which in turn refer to signals to
which the transfer characteristics in 5.4 have been applied.
Such signals are commonly described as being gamma
corrected.
ITU-R BT.709-4 (09/00), Parameter Values for the
HDTV Standards for Production and International
Programme Exchange
3 General
3.1
The speci ficat ion of a system cl aiming
compliance with this standard shall state:
– which of the systems of table 1 are imple-
mented;
– which of the analog R′G′B′ or Y′P′
B
P′
R
and/or which
of the digital R′G′B′ or Y′C′
B
C′
R
interfaces are imple-
mented; and
– whether the digital representation employs eight bits
or 10 bits per sample in its uniformly quantized (linear)
PCM coding.
3.2
Digital codeword values in this standard are
expressed as decimal values in the 10-bit repre-
sentation. An eight-bit system shall either round
or truncate to the most significant eight bits as
specified in 7.10.
1.2
This standard specifies multiple system formats
(table 1). It is not necessary for an implementa-
tion to support all formats to be compliant with
this standard. However, an implementation must
state which of the system formats are supported.
2 Normative references
The following standards contain provisions which,
through reference in this text, constitute provisions of
this standard. At the time of publication, the editions
indicated were valid. All standards are subject to
revision, and parties to agreements based on this
standard are encouraged to investigate the possibility
of applying the most recent edition of the standards
listed below.
SMPTE 274M-1998, Television — 1920
×
1080 Scan-
ning and Analog and Parallel Digital Interfaces for
Multiple Picture Rates
SMPTE 291M-1998, Television — Ancillary Data
Packet and Space Formatting
SMPTE RP 160-1997, Three-Channel Parallel Analog
Component High-Definition Video lnterface
SMPTE RP 177-1993 (R1997), Derivation of Basic
Television Color Equations
CIE Publication 15.2 (1986), Colorimetry, Second
Edition
IEC 60169-8 (1978-01), Radio Frequency Connectors,
Part 8: R.F. Coaxial Connectors with Inner Diameter
of Outer Conductor 6.5 mm (0.256 in) with Bayonet
Lock — Characteristic Impedance 50 Ohms (Type
BNC) plus amendments IEC 60169-8-am1 (1996-03)
and IEC 60169-8-am2 (1997-11)
4 Timing
4.1
Timing shall be based on a reference clock of
the sampling frequency indicated in table 1, which
shall be maintained to a tolerance of
±
10 ppm.
4.2
A frame shall comprise the indicated total
lines per frame, each line of equal duration as
determined by the sampling frequency (fs) and the
samples per total line (S/TL). Samples may be
obtained in an optoelectronic conversion process
sequentially, simultaneously, or via a combination
of both, provided all samples in the frame are
contiguous in the image and obtained within the
same temporal frame period. The samples within
each line shall be uniformly delivered to and col-
lected from the interface in a spatially left-to-right
sequence; lines in a frame shall be uniformly
delivered to and collected from the interface in
a spatially top-to-bottom sequence. Lines are
numbered in time sequence according to the raster
structure described in clause 6.
4.3
Timing instants in each line shall be defined with
respect to a horizontal datum denoted by 0
H
which
is established by horizontal synchronizing (sync)
information in clauses 8 and 11. Each line shall be
Page 2 of 14 pages
SMPTE 296M-2001
divided into a number of reference clock intervals,
of equal duration, as specified by the column S/TL
in table 1. The time between any two adjacent sam-
ple instants is called the reference clock interval T.
T = 1/fs.
5 System colorimetry
5.1
Equipment shall be designed in accordance
with the colorimetric analysis and optoelectronic
transfer function defined in this clause. This cor-
responds to ITU-R BT.709.
5.2
Picture information shall be linearly repre-
sented by red, green, and blue tristimulus values
(RGB), lying in the range 0 (reference black) to 1
(reference white), whose colorimetric attributes are
based upon reference primaries with the follow-
ing chromaticity coordinates, in conformance
with ITU-R BT.709, and whose white reference
conforms to CIE D
65
as defined by CIE 15.2:
CIE
x
Red primary
Green primary
Blue primary
Reference white
0.640
0.300
0.150
0.3127
CIE
y
0.330
0.600
0.060
0.3290
NOTE – Because the Y′ component is computed from
nonlinear R′G′B′ primary components rather than from the
linear tristimulus RGB values, it does not represent the true
luminance value of the signal, but only an approximation.
To distinguish it from luminance, the term luma is used for
the Y′ signal. For more information, see e.g. Poynton,
A
Technical Introduction to Digital Video.
5.6
Color-difference component signals P′
B
and
P′
R
, having the same excursion as the Y′ com-
ponent, shall be computed as follows:
P
′
B
=
P
′
R
=
0.5
(
B
′
–Y
′)
1 – 0.0722
0.5
(
R
′
–Y
′)
1 – 0.2126
P′
B
and P′
R
are filtered and may be coded as C′
B
and
C′
R
components for digital transmission. Example
filter templates are given in figure B.2.
6 Raster structure
6.1
For details of vertical timing, see figures 1
and 2.
6.2
In a system according to this standard, each
frame shall comprise 750 lines including:
– Vertical blanking: lines 1 through 25 inclusive
(including vertical sync, lines 1 through 5 inclusive)
and lines 746 through 750 inclusive; and
– Picture: 720 lines, lines 26 through 745 inclusive.
6.3
Ancillary signals, as distinct from ancillary
data, may be conveyed during vertical blanking,
lines 7 through 25 inclusive. The portion within
each of these lines that may be used for ancillary
data is defined in 9.3. Ancillary signals shall not
convey picture information although they may be
employed to convey other related or unrelated
signals, coded similarly to picture information.
Further specification of ancillary signals is out-
side the scope of this standard.
6.4
During time intervals not otherwise used, the
R′, G′, B′ or Y′, P′
B
, C′
B,
P′
R
, and C′
R
components
shall have a blanking level corresponding to zero.
6.5
The production aperture defines a region
1280 samples by 720 lines. The horizontal ex-
tent of the production aperture shall have the
5.3
From the red, green, and blue tristimulus
values, three nonlinear primary components,
R′, G′, and B′, shall be computed according to
the optoelectronic transfer function of ITU-R
BT.709, where L denotes a tristimulus value and
V′ denotes a nonlinear primary signal:
4.5L,
V
′ =
0.45
– 0.099,
1.099L
0
≤
L< 0.018
0.018
≤
L
≤
1.0
5.4
To ensure the proper interchange of picture
information between analog and digital repre-
sentations, signal levels shall be completely
contained in the range specified between refer-
ence black and reference white specified in 7.6
and 12.4, except for overshoots and under-
shoots due to processing.
5.5
The Y′ component shall be computed as a
weighted sum of nonlinear R′G′B′ primary compo-
nents, using coefficients calculated from the reference
primaries according to the method of SMPTE RP 177:
Y′ = 0.2126R′ + 0.7152G′ + 0.0722B′
Page 3 of 14 pages
SMPTE 296M-2001
0
FRAME
27
Picture
Picture
Picture
Figure 1 – Vertical timing (analog representation)
FRAME
Picture
Picture
Picture
Figure 2 – Vertical timing (digital representation)
50% point of its leading transition at reference
luma sample 0 and the 50% point of its trailing
transition at luma sample 1279. The production
aperture defines the maximum extent of picture
information. For further information, consult annex
A.
6.6
The aspect ratio of the image represented by
the production aperture shall be 16:9. The sample
aspect ratio is 1:1 (square pixels).
7 Digital representation
7.1
Digital representation shall employ either
R′G′B′ or Y′C′
B
C′
R
components, as defined in
clause 5 or clause 6, uniformly sampled.
NOTE – Each component is prepared as an individual
channel. Combinations of channels may be presented to an
appropriate interface for signal interchange. For example,
the Y′ channel and the multiplexed C′
B
/C′
R
channel data
together comprise a source format for the serial interface
specified in SMPTE 292M.
6.7
The center of the picture shall be located at
the center of the production aperture, midway
between samples 639 and 640, and midway
between lines 385 and 386.
7.2
The digital signals described here are
assumed to have been filtered to reduce or pre-
vent aliasing upon sampling. For information
regarding filtering, consult annex B.
7.3
The characteristics of the digital signals are
based on the assumption that the location of any
required sin (x)/x correction is at the point where
the signal is converted to an analog format.
6.8
Each edge of the picture width, measured
at the 50% amplitude point, shall lie within six
reference clock intervals of the production aperture.
Page 4 of 14 pages
SMPTE 296M-2001
7.4
R′G′B′ signals and the Y′ signal of the
Y′C′
B
C′
R
int erf ace shall be sampled ortho-
gonally, line- and picture-repetitive, at the sam-
pling frequency, f
s
. The period of the sampling
clock shall be denoted T. R′G′B′ samples shall
be cosited with each other.
7.5
A luma sampling number in a line is denoted in
this standard by a number from 0 through one
less than the total number of samples in a line.
Luma sample number zero shall correspond to the
first active video sample. The luma sample num-
bering is shown in figure 3. Note that the distance
between 0
H
and the start of SAV is 256 samples.
NOTE – The active video digital representation is 1280 clock
periods (0-1279) in length.
7.6
Digital R′, G′, B′, and Y′ components shall
be computed as follows:
L′
D
= Floor (219DL′+ 16D + 0.5); D = 2
n-8
where L′ is the component value in abstract terms
from zero to unity, n takes the value 8 or 10 corre-
sponding to the number of bits to be represented, and
L′
D
is the resulting digital code. The unary function
Floor yields the largest integer not greater than its
argument.
NOTE – This scaling places the extrema of R′, G′, B′, and
Y′ components at codewords 64 and 940 in a 10-bit repre-
sentation or codewords 16 and 235 in an eight-bit repre-
sentation.
0
H
Analog
Waveform
(Y’R’G’B’)
256T
Durations in
References
Clock Periods
(T)
Luma
Sample
Numbering
Digital
Data
Stream
A.T
B.T
4T
40T
40T
C.T
4T
1280T
pa bc d e
4T
f
ghi
BT
j
k l mno
4T
1280T
pa bc d
Duration in
ref. Clock
periods
EAV
BLANKING CODEWORDS
ANCILLARY DATA or
SAV
VIDEO DATA
(EAV)
NOTES
1 Horizontal axis not to scale.
2 0
H
is the analog horizontal timing reference point, and in the analog domain, is regarded as the start of the line.
3 A line of digital video extends from the first word of EAV to the last word of video data.
Figure 3 – Analog and digital timing relationships
Page 5 of 14 pages
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