ETSI ETS 300 731 ed.1 (1997-03)

SLOVENSKI STANDARD
01-december-2003
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Television systems; Enhanced 625-line Phased Alternate Line (PAL) television; PALplus
Ta slovenski standard je istoveten z: ETS 300 731 Edition 1
ICS:
33.160.25 Televizijski sprejemniki Television receivers
33.170 Televizijska in radijska Television and radio
difuzija broadcasting
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 731
TELECOMMUNICATION March 1997
STANDARD
Source: EBU/CENELEC/ETSI JTC Reference: DE/JTC-PALplus
ICS: 33.020
Key words: Broadcasting, analogue, TV, wide screen
Union Européenne de Radio-Télévision
European Broadcasting Union
Television Systems;
Enhanced 625-line Phased Alternate Line (PAL) television;
PALplus
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16
Copyright Notification:
No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997.
© European Broadcasting Union 1997.
All rights reserved.
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ETS 300 731: March 1997
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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Contents
Foreword .7
1 Scope .9
2 Normative references.9
3 Abbreviations.9
4 Basic PALplus system description .10
4.1 Introduction .10
4.2 Normative features of a PALplus transmission.11
5 The PALplus signal .12
5.1 Input picture signal to the PALplus encoder .12
5.2 The encoded composite PALplus signal.12
6 The PALplus encoding processes.15
6.1 Vertical conversion.16
6.1.1 Encoder vertical conversion of luminance.16
6.1.2 Encoder vertical conversion of chrominance .16
6.1.3 430-line letterbox.17
6.2 Vertical helper encoding .20
6.2.1 Helper amplitude .20
6.2.2 Modulation.20
6.2.3 Description of helper processing.21
6.2.4 Baseband helper .25
6.3 Motion Adaptive Colour Plus.25
6.3.1 Pre-processing in the encoder .26
6.3.2 Motion detector operation.29
6.3.3 Non-PALplus use of Motion Adaptive Colour Plus .32
6.4 PAL encoding.32
6.4.1 Luminance.33
6.4.2 Chrominance.33
6.5 Reference signals .33
6.5.1 Helper reference signals with baseband helper .35
6.6 Signalling .35
Annex A (normative): Filter and look-up table coefficients.37
A.1 General rules for filter descriptions .37
A.1.1 General rules for horizontal filters.37
A.1.2 General rules for vertical filters .37
A.2 Vertical conversion.37
A.2.1 ENC_Y_QMF (camera mode) .37
A.2.2 ENC_Y_QMF (film mode).42
A.2.3 ENC_UV_C_VSRC.45
A.2.4 ENC_UV_F_VSRC .47
A.3 Helper encoding .49
A.3.1 ENC_BB_US.49
A.3.2 ENC_BB_PRE_MOD_LPF_SS .49
A.3.3 ENC_BB_POST_MOD_NYQ.50
A.3.4 LUT_BB_ENC (film mode).50
A.3.5 LUT_BB_ENC (camera mode) .51

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A.4 Motion Adaptive Colour Plus . 52
A.4.1 Y_BSPLIT. 52
A.4.2 ENC_Y_IFA. 52
A.4.3 ENC_UV_LPF . 53
A.4.4 VERT_IFA . 54
A.4.5 ENC_MD_UV_LPF. 55
A.4.6 ENC_M_US. 55
A.4.7 LUT_IFD_U_CLIP .56
A.4.8 LUT_IFD_V_CLIP .57
A.4.9 LUT_MD_M. 58
A.4.10 LUT_ENC_MD_YL. 59
A.4.11 LUT_ENC_MD_CS . 59
A.5 PAL encoding . 59
A.5.1 ENC_UV_US. 59
Annex B (informative): Encoder filter plots . 60
Annex C (informative): The PALplus decoder . 65
C.1 General. 65
C.1.1 Composite PALplus input signal. 65
C.1.2 Decoder output signal . 65
C.2 Overview of the PALplus decoding process .66
C.2.1 PAL decoding. 66
C.2.2 MACP post-processing . 67
C.2.2.1 Motion detector operation . 70
C.2.3 Helper processing . 73
C.2.4 Vertical conversion of luminance . 74
C.2.5 Vertical conversion of chrominance . 74
C.2.6 Use of the Line 23/623 reference signals to assist vertical conversion. 77
Annex D (informative): Reference PALplus decoder: filter and look-up-table coefficients . 78
D.1 General rules for filter descriptions. 78
D.1.1 General rules for horizontal filters . 78
D.1.2 General rules for vertical filters .78
D.2 Vertical conversion . 78
D.2.1 DEC_Y_QMF (camera mode). 78
D.2.2 DEC_Y_QMF (film mode) . 81
D.2.3 DEC_UV_VSRC.83
D.2.4 DEC_UV_VSRC_NDL. 85
D.3 Helper decoding. 88
D.3.1 DEC_BB_PRE_MOD . 88
D.3.2 DEC_BB_POST_MOD_LPF_ISS . 88
D.3.3 LUT_BB_DEC (film mode). 89
D.3.4 LUT_BB_DEC (camera mode) . 90
D.4 Motion Adaptive Colour Plus, decoder . 91
D.4.1 Y_BSPLIT. 91
D.4.2 DEC_Y_VAA . 91
D.4.3 DEC_UV_LPF . 92
D.4.4 VERT_IFA . 93
D.4.5 DEC_MD_UV_LPF. 94
D.4.6 DEC_M_US. 94
D.4.7 LUT_IFD_U_CLIP .95
D.4.8 LUT_IFD_V_CLIP .96
D.4.9 LUT_MD_M. 97
D.4.10 LUT_DEC_MD_YL. 98
D.4.11 LUT_DEC_MD_CS . 98

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D.5 PAL decoding .98
D.5.1 DEC_UV_DS_LPF.98
D.5.2 DEC_CHROM_BPF.98
Annex E (informative): Decoder filter plots.99
Annex F (informative): Receivers for the PALplus system .103
F.1 General.103
F.2 Receiver IF characteristics.103
F.3 Features included in a PALplus receiver.103
F.4 Receiver switching time in response to changes signalled by the WSS.104
F.5 Use of Wide Screen Signalling (WSS).104
F.5.1 PALplus.104
F.5.2 Non-PALplus Motion Adaptive Colour Plus .105
F.5.3 Conventional PAL .105
F.5.4 Conventional PAL with helper.105
F.5.5 Transmissions transcoded into SECAM .105
Annex G (informative): Application of ghost cancellation .106
Annex H (informative): Studio production requirements .107
H.1 General.107
H.2 Limitations of the composite PALplus signal.107
H.3 Camera mode and film mode.108
H.4 Programme junctions between transmissions in PALplus and PAL .108
H.5 Open subtitles and logos.109
H.6 Non-PALplus use of Motion Adaptive Colour Plus.109
History.110

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Joint Technical Committee
(JTC) of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique
(CENELEC) and the European Telecommunications Standards Institute (ETSI).
NOTE: The EBU/ETSI JTC was established in 1990 to co-ordinate the drafting of ETSs in the
specific field of broadcasting and related fields. Since 1995 the JTC became a tripartite
body by including in the Memorandum of Understanding also CENELEC, which is
responsible for the standardization of radio and television receivers. The EBU is a
professional association of broadcasting organizations whose work includes the co-
ordination of its Members' activities in the technical, legal, programme-making and
programme-exchange domains. The EBU has Active Members in about 60 countries
in the European Broadcasting Area; its headquarters is in Geneva *.
* European Broadcasting Union
Case Postale 67
CH-1218 GRAND SACONNEX (Geneva)
Switzerland
Tel: +41 22 717 21 11
Fax: +41 22 717 24 81
Transposition dates
Date of adoption: 28 February 1997
Date of latest announcement of this ETS (doa): 31 May 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 November 1997
Date of withdrawal of any conflicting National Standard (dow): 30 November 1997

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1 Scope
This European Telecommunication Standard (ETS) is applicable to 625-line PAL systems B, G, H, I, D
and K.
It specifies an enhanced transmission system which allows PAL broadcasters to offer wide-screen
pictures in the 16:9 aspect ratio format, maintaining compatibility with existing PAL receivers.
This ETS specifies the transmitted signal. It specifies the method of coding for accommodating wide
aspect ratio signals, and the method of coding for reducing conventional PAL cross-effects and for making
optimal use of the video signal spectrum. The method for reduction of PAL artefacts may also be used for
studio contribution or distribution purposes. Annex C provides details of a reference PALplus decoder that
makes full use of the picture enhancements offered by PALplus. Annex F gives rules of operation for the
minimum requirements for a PALplus receiver.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ITU-R Recommendation BT.601-5: "Studio Encoding Parameters of Digital
Television for Standard 4:3 and Wide-screen 16:9 Aspect Ratio".
[2] ITU-R Recommendation BT.470-4: "Television Systems".
[3] EBU Technical Recommendation R62: "Recommended dominant field for
625-line 50-Hz video processing".
[4] ETS 300 294: "Television Systems; 625-Line television Wide Screen Signalling
(WSS)".
3 Abbreviations
For the purpose of this ETS, the following abbreviations apply in the construction of system coefficient
names:
BB Black Bands
BPF Band-Pass Filter
BSPLIT Band-SPLITing filter
C Camera mode
CHROM Modulated PAL CHROMinance
CLIP CLIPping
CS motion detector Chrominance Switching control
CVBS Composite Video, Blanking and Sync
DEC DECoder
DS Down-Sampling
ENC ENCoder
F Film mode
HDTV High-Definition TeleVision
IFA Intra-Frame Averaging
IFD Inter-Frame Difference
ISS Inverse Spectrum Shaping
L motion detector Luminance level control signal
LPF Low-Pass Filter
LUT Look-Up Table
M Motion detector chain chrominance motion signal
MAC Multiplexed Analogue Components
MACP Motion Adaptive Colour Plus
MD Motion Detector chain
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NDL Not incorporating PAL Delay Line function
NYQ NYQuist
PAL Phased Alternate Line
POST_MOD POST-(de)MODulation
PRE_MOD PRE-(de)MODulation
QMF Quadrature Mirror Filter
S motion detector chrominance Switching control signal
SS Spectrum Shaping
U present in C path
B
US Up-Sampling
UV present in both colour-difference signal (C and C ) paths
B R
V present in C path
R
VAA Vertical Anti-Aliasing
VERT VERTical
VSRC Vertical Sample-Rate Conversion
Y luminance signal
YL motion detector luminance Level control
4 Basic PALplus system description
4.1 Introduction
PALplus is an enhanced transmission system which has been designed to allow PAL broadcasters to offer
wide-screen pictures with greatly reduced levels of conventional PAL artefacts, whilst retaining a high level of
compatibility with the PAL transmission infrastructure and with existing PAL receivers. The system is
intended to co-exist with both MAC and digital television services in a complementary fashion, enabling
viewers to receive enhanced quality wide-screen pictures originated in component form. The objective of the
PALplus project has not been to design an HDTV system. The expected cost of PALplus receivers is
therefore lower than that of HDTV receivers.
The format of the primary input and output signals for PALplus shall be 625/50/2:1, with 16:9 aspect ratio.
HDTV 1250/50/2:1 sources can be used after down-conversion to 625/50/2:1.
The wide-screen picture shall be transmitted in letterbox format to achieve compatibility with existing 4:3
receivers. Loss of vertical resolution (as compared to the 576 active line source picture) is minimized in the
PALplus receiver by making use of a vertical helper signal transmitted in the black bands above and below
the letterbox picture.
The PALplus system has two modes of operation. These are called "film mode", which should be used only
with film sources, and "camera mode" which should be used with normal 50 Hz video sources. Both the
vertical conversion (to the letterbox picture) and the Motion Adaptive Colour Plus (MACP) method of
improved chrominance/luminance separation make use of a camera mode and a film mode to give optimum
system performance.
Starting from a 625/50/2:1 4:2:2 digital component input signal (in accordance with ITU-R Recommendation
BT.601-5 [1], based on 13,5 MHz sampling) with 576 active lines per frame and an aspect ratio of 16:9, a
conversion to 430 active picture lines shall be first carried out.
NOTE: All references to ITU-R Recommendation BT.601-5 [1] refer to the 13,5 MHz sampling
rate variant specified in part A thereof.
In "camera mode" (when the source provides 50 Hz motion), this conversion shall be performed intra-field
in order to avoid motion artefacts but, in "film mode" (when the source is known to have only 25 Hz
motion), then an intra-frame conversion shall be used. The letterbox picture signal used for transmission
has only three quarters of the number of active picture lines as the source; in order to minimize loss of
vertical resolution in the PALplus display, the black bands shall be used to transmit a vertical helper signal.
An enhanced PAL encoding and decoding technique known as "Motion Adaptive Colour Plus" shall be
used to reduce PAL luminance/chrominance cross-talk artefacts and to maximize horizontal resolution. In
film mode, the system takes advantage of the known temporal redundancy of the signal and uses an
intra-frame PAL encoding technique ("fixed" Colour Plus). In camera mode, the same technique shall be
applied to appropriate areas of each picture frame. However, in areas containing moving saturated colour
(usually representing only small parts of typical pictures), there is likely to be a significant amount of

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movement between the adjacent fields of a source picture frame, which could lead to occasionally visible
colour judder if fixed Colour Plus processing were applied. To minimize this problem, in such areas of the
picture the system shall revert adaptively to a simpler form of PAL encoding, making use of motion
detectors in both the encoder and decoder to identify areas of fast colour motion between adjacent
frames.
Ghost cancellation is an optional enhancement. The parameters of the ghost cancellation reference signal
are given in ITU-R Recommendation BT.1 124, annex 1, section 1.3.
4.2 Normative features of a PALplus transmission
A PALplus signal shall be derived according to the processes illustrated in figure 1. These are summarized
below and detailed descriptions of each process are given in clause 6. The signal at the output of the
encoder shall be described as "PALplus" only when all of the following processes are implemented:
a) Vertical conversion (QMF process) to 430-line letterbox;
- this is the conversion of the 16:9 aspect ratio source picture with 576 active lines to a 16:9
aspect ratio letterbox picture with 430 active lines. The QMF (Quadrature Mirror Filter) format
conversion process also yields vertical luminance resolution information that shall be
encoded and transmitted in the black bands.
b) Vertical helper encoding;
- this is the method of processing and modulating the vertical luminance information derived
from the QMF format conversion process, resulting in the "vertical helper" signal that shall be
transmitted in the black bands above and below the active letterbox picture.
c) Motion Adaptive Colour Plus (MACP);
- this is the encoding technique that makes possible improved separation of chrominance and
luminance in the PALplus receiver.
d) Wide Screen Signalling (WSS);
- this shall be used to convey essential information about the content of the transmitted signal
to the decoder. The system used is defined in ETS 300 294 [4].
e) Reference signals;
- the transmission shall contain reference signals in lines 23 and 623 that may be used by the
PALplus receiver for the accurate setting of the levels of the incoming luminance and vertical
helper signals. Details are given in subclause 6.5.
The PALplus signal at the output of the encoder shall consist of the combination of the PAL-encoded MACP
pre-processed letterbox picture, the modulated helper signal resulting from the QMF conversion process, the
reference signals, and the signalling bits, as shown in figure 1.
The features of a PALplus transmission are summarized in table 1. Compensating delays should be included
in associated audio paths prior to transmission, so as to match the vision processing time in the PALplus
encoder.
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Table 1: The enhancement features incorporated in a PALplus transmission
Enhancement Normative for PALplus?
Format conversion (QMF) from ITU-R YES
Recommendation BT.601-5 [1] source with 16:9
aspect ratio to central 430-line letterbox
Vertical helper encoding YES
Motion Adaptive Colour Plus YES
Reference signals (lines 23/623) YES
Wide Screen Signalling (ETS 300 294 [4]) YES
Ghost cancellation reference signal OPTIONAL
NOTE: Helper not used with non-PALplus MACP.
Figure 1: Outline of PALplus encoding process
5 The PALplus signal
Figure 1 gives a top-level block diagram of the encoding process. All operations are carried out in the digital
domain, using line-locked sampling rates of 13,5 MHz, 27 MHz, and 6,75 MHz.
5.1 Input picture signal to the PALplus encoder
The input to the PALplus encoder shall be a component digital 625-line, 50 field/s interlaced 4:2:2 YC C
B R
signal (according to ITU-R Recommendation BT.601-5 [1], minimum 8-bit resolution), with 576 (nominal)
active picture lines and an aspect ratio of 16:9. Field 1 shall be the dominant field (see EBU Technical
Recommendation R62 [3]) at all times in the case of material to be PALplus encoded in film mode.
5.2 The encoded composite PALplus signal
The output of the PALplus encoder shall be a standard analogue PAL composite signal containing 430 active
picture lines in letterbox format, together with helper information contained in the black bands above and
below the visible letterbox picture area (see figures 2 and 3). In addition, signalling bits are contained in the
first half of Line 23 (see subclause 6.6), and reference signals for use by the PALplus decoder are inserted

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into the second half of Line 23 and the first half of Line 623 (see subclause 6.5 and figures 17 and 18). The
structure of the PALplus frame is illustrated in figure 3.
All general characteristics of the encoded PALplus signal shall conform to the parameters listed in
ITU-R Recommendation BT.470-4 [2]. These include all aspects of the standard PAL colour burst, which
shall be retained on the same lines as for a standard PAL signal.
NOTE 1: Standard PAL horizontal blanking shall be applied in lines carrying the vertical helper signal.
NOTE 2: Burst blanking shall be identical to that of a standard PAL signal.
Figure 2: Waveforms showing typical lines of PALplus letterbox and vertical helper signals
All operations in the encoder are performed in digital form. Prior to digital-to-analogue conversion at the
output of the encoder, the encoded PALplus signal shall have the following characteristics:
- sampling rate: 13,5 MHz (or multiple thereof), quantizing range: 0,00 to 25255,755 (unsigned),
10 10
10-bit resolution. Black level = 64,00 , peak-white level = 192,00 ;
10 10
- the quantizing range is illustrated in figure 4. The use of 10-bit resolution within this range reduces
the effects of quantizing errors in critical areas of processing;
- permitted signal data levels for this 10-bit signal shall be in the range 1,00 to 254,75 for
10 10
compatibility with the signal data levels of ITU-R Recommendation BT.601-5 [1]. (All vision signals
lie within this range);
- using the above quantizing scale, the maximum peak-to-peak amplitudes of the modulated
chrominance signals shall be: U = 112,00 , V = 157,50 .
10 10
NOTE 1: Within this ETS, the contents of digital words are expressed in decimal form. To avoid
confusion between 8-bit and 10-bit unsigned representations, the eight most significant
bits are considered to be an integer part while the two additional bits, if present, are
considered to be fractional parts. (For example, the bit pattern 10 010 001 would be
expressed as 145 , and 1 001 000 101 as 145,25 ). Where no fractional part is
10 10
shown, it is to be assumed to have binary value 00.
Each active line of letterbox picture and of helper shall be formed from 702 digital active samples, and the
structure of the PALplus frame shall be as shown in figure 3.
NOTE 2: For convenience, the sampling clock period numbers are indicated in this ETS as
being in the range 1 to 864, where clock period 1 represents the leading edge of line
syncs, half amplitude reference (see figure 3). Sampling clock period 1 therefore
corresponds to ITU-R Recommendation BT.601-5 [1] luminance sample number 732.
The first active sample of each line shall be in clock period 143, which corresponds to
the 11th sample of the digital active luminance line of ITU-R Recommendation
BT.601-5 [1] (luminance sample number 10).
The frequency spectrum occupied by the chrominance signal shall be 4,43 MHz ± 1,3 MHz at -3 dB.

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NOTE 1: Sampling clock periods correspond to those of ITU-R Recommendation BT.601-5 [1] (sampling
frequency: 13,5 MHz) as indicated above.
NOTE 2: Active lines contain 702 samples for letterbox picture or helper.
Figure 3: Structure of the PALplus frame
The amplitude/frequency characteristic of the luminance signal shall be substantially uniform from 0 to
5,5 MHz. The horizontal bandwidth of the luminance signal shall be limited principally by the use of digital
processing with 13,5 MHz sampling according to ITU-R Recommendation BT.601-5 [1] and, unlike standard
PAL encoding, may not be modified by the use of a notch filter in the region embracing the subcarrier
frequency.
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The transmitted luminance and chrominance bandwidths may be restricted by the characteristics of the
transmission system; for example, the luminance bandwidth will be limited to 5 MHz in the case of System
B/G, and to 5,5 MHz in System I (see ITU-R Recommendation BT.470-4 [2]).
The total delay in the encoding process shall preferably be the same in both camera mode and in film
mode. The exact delay will depend on the encoder implementation, but might in practice be expected to
be of the order of 30 ms. An equivalent compensating delay should be applied to associated audio paths
prior to transmission.
NOTE: Time delay in encoder: the modular description of the encoding processes will result in
a longer time delay than this. Although it is possible to combine some elements so as
to reduce the time delay, a fully modular approach to the description of the formation of
a PALplus signal has been adopted for reasons of clarity.
NOTE: Nominal values are shown for the line waveform for 100 % amplitude, 100 % saturation colour
bars. The signal shall be coded with 10-bit resolution.
Figure 4: Digital representation of the PALplus signal, showing the quantization ranges
6 The PALplus encoding processes
This clause describes in greater detail the operation of each of the processing blocks in the encoder (see
figure 1). Filter and look-up table coefficients shall be as specified in annex A.
Starting at the input of the PALplus encoder, the Vertical Conversion processing block (see figure 5 for the
case of camera mode, and figure 6 for film mode) produces a YC C signal with 430 active picture lines,
B R
together with a helper signal representing additional vertical resolution contained in the 576-active line source
picture.
The Helper Encoding block (see figure 9) processes the vertical helper signal, modulating it onto a carrier of
PAL colour subcarrier frequency, for insertion into the black bands above and below the letterbox picture.
A delay precedes this block (or may be incorporated within it) to compensate for the delay within the Motion
Adaptive Colour Plus process.
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ETS 300 731: March 1997
The Motion Adaptive Colour Plus block (see figure 11) carries out pre-processing to enable subsequent
separation of luminance and chrominance with greatly reduced levels of conventional PAL artefacts
(cross-colour and cross-luminance) with appropriate post-processing in the decoder. The pre-processing in
the encoder shall be performed on the 430-active line YC C signal supplied by the Vertical Conversion
B R
process.
The Motion Adaptive Colour Plus pre-processed 430-active line YC C signal shall be then PAL encoded
B R
(see figure 16).
The PALplus signal at the output of the encoder consists of the combination of the PAL-encoded MACP pre-
processed letterbox picture, the modulated helper signal resulting from the QMF conversion process,
reference signals in lines 23 and 623, and the Line 23 Wide Screen Signalling information, as shown in
figure 1.
6.1 Vertical conversion
The incoming 576-active line YC C signals shall be converted to a central 430-line letterbox picture,
B R
together with 144 lines of a vertical helper signal representing luminance vertical information. The conversion
shall be carried out intra-frame in film mode, and shall be carried out intra-field in camera mode, as specified
in annex A, clause A.2.
The entire contents of lines 23 and 623 of the input signals to the encoder shall be set to black, overwriting
any active video in the half-lines, before entering the encoder luminance QMF and chrominance vertical
sample rate conversion blocks. (Y shall be set to 16 , and C /C to 128 ).
10 B R 10
In film mode, field memories M4A (luminance) and M5A (C ,C ) together with the associated line memories
B R
(M4B for luminance, M5B for C ,C ) and switches perform field insertion during the second input field (see
B R
figure 6). This results in a sequential frame for processing at the rate of 27 MHz for luminance, and 13,5 MHz
for each of C and C .
B R
6.1.1 Encoder vertical conversion of luminance
For luminance, a special Quadrature Mirror Filter (QMF) technique shall be used to generate two sub-bands:
the 430-line letterbox luminance, and 144 lines representing the vertical detail information that would
otherwise be lost by the vertical filtering to 430 lines (see figure 7). The QMF technique used shall be
essentially loss-free, and has the advantage that in the decoder there will be cancellation of alias
components in the main and helper signals.
The luminance QMF (ENC_Y_QMF) operates at 13,5 MHz in camera mode, and at 27 MHz in film mode
(during the period of one field only), while for chrominance the sample rate conversion takes place at
6,75 MHz in camera mode and 13,5 MHz in film mode. In film mode, memories M1, M2, M3, M4 and M5 are
used to change sample rates from the input/output rates to the double speed used in the luminance QMF
and chrominance vertical sample rate conversion processes.
Following the QMF, some further memories and field-rate switches are required. This is because although
the filters and the QMF have produced the correct number of lines for the letterbox signal, these lines are in
the form of a multiplex of letterbox picture and helper lines (three lines of letterbox picture followed by one
line of helper) spread out across the period of the input field (camera mode) or frame (film mode). Referring
to figures 5 and 6, M2A and M2B store the two fields of each letterbox luminance frame. M3A and M3B hold
the first and second fields of the colour-difference signals. M1A and M1B perform a similar function for the
helper lines, storing them as they are output from the QMF. The frame memory sizes shown in figure 5 for
M1A, M2A and M3A ensure that the camera mode processing time delay is identical to that of film mode.
6.1.2 Encoder vertical conversion of chrominance
The colour-difference signals undergo vertical sample rate conversion to produce a 430-line picture signal,
carried out intra-field in camera mode, and intra-frame in film mode, by a bank of filters operating in parallel.
In film mode, vertical filter ENC_UV_F_VSRC generates 215 lines of intra-frame averaged colour difference
signal by a single intra-frame down-conversion operation. The output from the vertical filter
ENC_UV_F_VSRC shall be a single field of film mode colour-difference signal. In field memories M3A and
M3B, the colour difference signal shall be stored with 64μs output lines in the two successive fields of the
output frame. This ensures that the colour-difference signal in the two fields is identical.

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Camera mode colour-difference signals are converted by vertical filter ENC_UV_C_VSRC. The coefficients
are arranged to provide separate conversion of each field.
There is no attempt to convey additional vertical chrominance resolution to the receiver as there is in the
case of luminance (representing the lost vertical resolution arising from the format conversion to 430 lines).
Even without such a helper signal, the colour vertical resolution is already much higher than the colour
horizontal resolution.
6.1.3 430-line letterbox
A complication arises because in PAL the transmitted 625-line signal does not contain 576 complete active
lines. There are only 574 full active lines, with lines 23 and 623 containing only half lines. Application of the
Motion Adaptive Colour Plus encoding technique requires averaging of picture information between pairs of
adjacent lines within the frame. There are no corresponding "partner" picture lines for half-lines at the start
and end of a frame, and it would be pointless to generate half-lines of letterbox picture in the vertical
conversion process.
The entire contents of lines 23 and 623 of the input signals to the encoder are therefore set to black,
overwriting any active video in the half-lines, before entering the encoder luminance QMF and chrominance
vertical sample rate conversion blocks. (Y shall be set to 16 , and C /C to 128 ).
10 B R 10
The encoder luminance QMF and chrominance vertical sample rate conversion processes can give outputs
with 216 picture lines per field. However, the first resulting picture line of the odd field and the last line of the
even field would not contain useful picture information, so if produced these should not be stored in the
subsequent letterbox picture memories (M2 and M3), each of which holds only 215 lines per field.
The result of the vertical conversion process shall be a letterbox picture with 430 full picture lines per frame,
suitable for subsequent Motion Adaptive Colour Plus encoding and decoding.

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ETS 300 731: March 1997
Figure 5: Encoder vertical conversion (camera mode)

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ETS 300 731: March 1997
Figure 6: Encoder vertical conversion (film mode)

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ETS 300 731: March 1997
NOTE: Output lines have mid-grey set-up of 128 .
Figure 7: Encoder QMF (ENC_Y_QMF)
6.2 Vertical helper encoding
The vertical helper signal in the black bands shall be transmitted symmetrically around black level, with a
maximum amplitude of 300 mV peak-to-peak, the same as that of the colour subcarrier burst. The vertical
helper shall
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