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TUCoPS :: Radio :: worldtv.txt

Extensive notes on international video conversion problems




             EXCHANGING VHS CASSETTES WITH FOREIGN VIEWERS AND
                        USING VHS RECORDERS ABROAD


INTRODUCTION

Exchanging any video program with someone living abroad is complicated by
the fact that most of the world does not use the American TV system.
Regardless of the tape format used (i.e., VHS, SVHS, Beta, 8 mm, etc.)
foreign video recordings cannot be played on an incompatible player, or
displayed on an incompatible TV receiver.

I will try to describe here some "tips and traps" of exchanging video
recordings with foreign viewers and on using your NTSC camcoder in foreign
countries.  Since the VHS home recording system predominates at-present, I
will describe here only the specific problems that relate to VHS.
Since the SVHS format differs only in the way in which the luminance
information is separated and recorded, all of the information below applies
equally to SVHS.  The details regarding the TV standards themselves are
applicable to all recording formats.


THE WORLD'S TV STANDARDS

The color television system in use in the United States was adopted in
1953, and because the United States was the first to widely implement color
television, we have the oldest (though not necessarily the best) color
television standard in the world.  Considering the era in which it was
devised, the system represents nothing short of genius on the part of its
designers.  Our TV system acted as the progenitor of all of the other TV
broadcast systems to come.

Our TV system is referred to as "NTSC" (National Television System
Committee), and is used only in the U.S., Canada, Mexico, Central America,
the UAE, Burma, the Pacific coastal countries in South America, and in
parts of the Far East.  When implemented, it represented a comprised effort
to transmit color video within a comparatively narrow bandwidth allocation,
while it maintained compatibility with the 100,000 or so black-and-white
televisions that had already been sold in the U.S.

The European countries began broadcasting color television in the late 50's
and early 60's, and having had the dual advantages of time to improve on
our system, and wider channel bandwidth assignments; adopted either the PAL
(Phase Alternating Line) or SECAM (the French acronym for Sequential Color
with Memory) color TV systems.  Both the PAL and SECAM systems were
intended to alleviated some inherent weaknesses in the early vacuum tube
based NTSC equipment, although today their greatest advantage over NTSC
stems from their wider bandwidth allocations.  With the narrower channel
bandwidths used in the U.S., it would be impossible for us to "switch" to
either the European PAL or SECAM systems.

Besides PAL and SECAM, there also exist two additional color TV standards:
PAL-M, which is used only in Brazil; and PAL-N, which is used in Argentina,
Paraguay, and Uruguay.  PAL-M is a "hybrid" of both the NTSC and European
PAL systems.  It is an attempt to "fit" the PAL system within the same
frequency spectrum that is used by NTSC.  PAL-M uses the same
specifications as NTSC for the black-and-white portion of the program
(referred to in TV parlance as the "luminance" information), but it uses a
modified form of the PAL system for its color (or "chrominance")
information.  Thus, NTSC and Brazilian PAL-M VHS recordings are
interchangeable -- but only for black-and-white playback.  While some PAL-M
VHS machines are capable of playing NTSC, PAL-M televisions cannot
reproduce the color portion of an NTSC program without using a special
device known as a "transcoder."  A transcoder takes the video program and
reduces it to its color components - much like a television receiver does -
and then reassembles these components in the new TV standard.  Transcoding
is a far simpler process than standards conversion, but it can only be used
when the black-and-white standards of the two TV systems are the same.

PAL-N on the other hand, uses the same black-and-white system as PAL and
SECAM, but with a slightly modified PAL system for conveying the color
information within a narrower RF bandwidth.  PAL-N can be transcoded to or
from either PAL or SECAM.


TV STANDARDS CONVERSION

The process of TV standards conversion involves accurately converting video
information to a receiving rate that is different than the rate at which it
is being transmitted.  In NTSC, 30 (actually 29.97) "frames," or individual
pictures, are transmitted each second.  These frames are very similar from
a conceptual standpoint to the individual frames in a motion picture.  Also
in NTSC, each frame is made up of 525 individual scan lines.  PAL on the
other hand has only 25 frames per second (5 fewer per second than NTSC),
and has 625 lines per frame (100 more than NTSC).

     The world today has fortunately settled on only two line and frame
     rate standards:

     NTSC & PAL-M use 30 frames per second and 525 lines per frame.
     PAL, PAL-N, & SECAM use 25 frames per second and 625 lines per frame.

A standards conversion from NTSC to PAL involves discarding 5 frames per
second, while literally inventing 100 lines per frame.  If the extra frames
were simply thrown away, the resulting video would be so full of jerks and
jumps that it would be unviewable, so a good standards converter will
"interpolate" or average the information from one frame to the next.  The
standards converter does this by storing one or more frames in an
electronic memory and then performing a comparison between the stored
frames.  The more memory -- the more accurate is this averaging process.
The extra lines are either invented or discarded by a similar averaging
system.  The inner workings of modern TV standards converters are actually
much more complex than described above: a modern converter uses high speed
real-time computing techniques to detect and differentiate between moving
and stationary objects in every frame of every scene in order to further
reduce the appearance of jerkiness in the converted video.


TV STANDARDS IN USE

The following is a list of TV broadcast standards in use.  This information
is based on the XVIth Plenary Assembly of the Consultative Committee
International Radio (CCIR), Dubrovnik, 1986.

                              NTSC COUNTRIES:

                         Bermudas
                         Bolivia
                         British Virgin Islands
                         Burma

                         Canada
                         Chile
                         Colombia
                         Costa Rica
                         Cuba

                         Dominican Republic

                         Ecuador

                         Guatemala

                         Haiti
                         Honduras

                         Jamaica
                         Japan

                         Korea (South)

                         Mexico
                         Montserrat

                         Netherland Antilles
                         Nicaragua

                         Panama
                         Peru
                         Philippines

                         Saint Christ. and Nevis
                         Surinam

                         United Arab Emirates
                         United States

                         Venezuela


                              PAL COUNTRIES:
                    *PAL-N Standard    **PAL-M Standard

                         Albania
                         Algeria
                         Angola
                         Argentina*
                         Australia

                         Bahrain
                         Bangladesh
                         Belgium
                         Botswana
                         Brazil**
                         Brunei

                         Cameroon
                         China (People's Republic)

                         Denmark,
                         with Greenland and Faroes

                         Equatorial Guinea
                         Ethiopia

                         Finland

                         Germany (Unified) (SECAM is currently being
                                 simulcast in what was formerly "East"     
                                 Germany)
                         Ghana
                         Gibraltar
                         Great Britain (England, Scotland, & Wales)

                         Hong kong

                         Iceland
                         India
                         Indonesia
                         Ireland (Northern & Rep. of)
                         Israel
                         Italy

                         Jordan

                         Kenya
                         Korea (North)
                         Kuwait

                         Lesotho
                         Liberia
                         Luxembourg

                         Malawi
                         Malaysia
                         Maldives
                         Malta
                         Monaco
                         Mozambique

                         Netherlands
                         New Guinea
                         New Zealand
                         Nigeria
                         Norway

                         Oman

                         Pakistan
                         Paraguay*
                         Portugal

                         Qatar

                         Romania

                         Sierra Leone
                         Singapore
                         South Africa
                         Spain
                         Sri Lanka
                         Sudan
                         Sweden
                         Switzerland
                         Syria

                         Tanzania
                         Thailand
                         Tunisia
                         Turkey
                         Uganda
                         Uruguay*

                         Yemen (North & South)
                         Yugoslavia

                         Zambia
                         Zimbabwe


                             SECAM COUNTRIES:
    (Note: Except for France, either the MESECAM or PAL systems are the
      preferred standards for VHS interchange - refer to text below)

                         Afghanistan

                         Benin
                         Bulgaria
                         Burkina Faso
                         Burundi

                         Central African Rep.
                         Chad
                         Congo
                         Cyprus
                         Czechoslovakia

                         Djibouti

                         Egypt

                         France

                         Gabon
                         Greece
                         Guinea

                         Hungary

                         Iran
                         Iraq
                         Ivory Coast

                         Lebanon
                         Libya

                         Madagascar
                         Mali
                         Mauritania
                         Mongolia
                         Morocco

                         Niger

                         Poland

                         Rwanda

                         Saudi Arabia
                         Senegal

                         Togo

                         USSR

                         Vietnam

                         Zaire


Occasionally you may encounter suffix letters after the TV standard
specification, i.e., "PAL-B, PAL-I, SECAM D/K", etc.  These suffixes refer
to internationally agreed upon TRANSMISSION standards (promulgated by the
CCIR), and are important only for TV receivers/tuners and transmitters/RF
converters.  Except for the two unusual standards of PAL-M and PAL-N, which
are separate TV systems in their own right, these terms are irrelevant for
the exchange of PRERECORDED VHS cassettes.

Finally, there are two methods of recording SECAM on VHS.  The first method
complies with the accepted JVC "standard" for SECAM recording and is
generally referred to as either the "Standard" or "French" SECAM method.
(Because of the prevalence of Standard SECAM machines in France, the
Standard SECAM recording method is often referred to as "French SECAM.")
The second, and most common method, is referred to as "MESECAM," or Middle
East SECAM.  The "Middle East SECAM" method derives its name from the fact
that the Middle East has a checkerboard of PAL and SECAM broadcast
services.  MESECAM was developed to allow a PAL VHS machine to record both
PAL and SECAM broadcasts with only a very slight modification of the PAL
circuitry.  Unfortunately, not only is MESECAM video quality inferior to
"Standard" SECAM VHS, but the method of recording SECAM video on the tape
itself makes the recording incompatible with a "Standard" or "French" SECAM
VHS machine -- SECAM recordings that are interchanged between MESECAM and
Standard SECAM VHS machines will play back in black-and-white only.  (For
those who are interested in the technical reason for this incompatibility:
MESECAM uses a heterodyne method for deriving the color-under subcarrier --
the same method that is used for PAL and NTSC VHS, whereas Standard SECAM
digitally divides the two SECAM FM chrominance subcarriers by 4.  If the
wrong reverse-process is used on playback, it results in the SECAM
subcarriers being at the wrong frequencies, and the sidebands being too
wide or too narrow.)

With the exception of France, MESECAM is by far the most common VHS system
used in SECAM broadcast countries.  This is partly a matter of
supply/demand economics, and partly because many of the countries that are
broadcasting SECAM have had closed socialist economies in the past.  As a
result of these closed systems, most of the video software that has been
obtainable has had to be smuggled in from the West -- and was recorded in
PAL.  Everyone who has a MESECAM VHS machine also has the ability to play
PAL recordings, and with the addition of a simple transcoder, a SECAM TV
receiver can display PAL recordings in color.  If the intended recipient of
a VHS cassette has the ability to play PAL recordings I suggest that you
send recordings in PAL rather than MESECAM due to the differences in
recording quality.


BLANK VHS CASSETTES

As described above, there are 5 color television standards in use
throughout the world, and 6 ways of recording video on VHS.  Without
"standards conversion," the only foreign standard that can be played at all
on an American VHS machine is PAL-M (the Brazilian standard), and then only
in black-and-white.

Fortunately, the situation is far less complicated with regard to BLANK VHS
cassettes.  VHS cassettes are mechanically identical in all TV standards.
The only difference is that the tape SPEED is higher in NTSC (and PAL-M),
and therefore, the recording time in NTSC is shorter for a given amount of
tape.

NTSC consumes tape at a rate of 2.0 meters per minute in standard play (SP)
mode, and both PAL and SECAM consume tape at a rate of 1.42 meters per
minute.  Although it isn't necessary to take blank VHS cassettes along with
you on a trip to Europe, you will need to do a little math to determine the
recording time allowed on a blank European VHS cassette.  The tape
manufacturers generally make this easier for you by showing both the length
(in meters) of the blank tape, and by designating the labelled European or
American length with a code letter.  American (NTSC) blank cassettes are
marked with the letter "T" preceding the length, e.g., T-120; and European
PAL/SECAM cassettes are marked with the letter "E" before the length, e.g.,
E-180.

An E-180 (180 minutes in PAL/SECAM) cassette will contain approximately 258
meters of blank tape, and on this blank tape you can record: 258 divided by
2 minutes of NTSC video; or 129 minutes of NTSC program.

The following is a conversion table of tape lengths and recording times:

Length code    Blank tape length *  NTSC/PAL-M time  PAL/PAL-N/SECAM time
-----------    -----------------    ---------------  --------------------

     T-20            44 meters          20 minutes      28 minutes
     T-30            64 meters          30 minutes      42 minutes
     T-40            84 meters          40 minutes      56 minutes
     T-45            94 meters          45 minutes      63 minutes
     T-60           125 meters          60 minutes      84 minutes
     T-80           165 meters          80 minutes     112 minutes
     T-90           185 meters          90 minutes     126 minutes
     T-120          246 meters         120 minutes     169 minutes
     T-130          266 meters         130 minutes     183 minutes
     T-160          326 meters         160 Minutes     225 minutes

     E-30            45 meters          22 minutes      30 minutes
     E-60            88 meters          44 minutes      60 minutes
     E-90           130 meters          65 minutes      90 minutes
     E-120          173 meters          86 minutes     120 minutes
     E-150          215 meters         107 minutes     150 minutes
     E-180          258 meters         129 minutes     180 minutes
     E-240          346 meters         173 minutes     240 minutes

* Most tape manufactures add 3 to 6 meters of blank tape to their cassettes
to allow  for tape  threading in  the mechanism  and  for  recording  speed
inaccuracies.


EXCHANGING VHS RECORDINGS BETWEEN TV STANDARDS:

There are  only four  possible methods  of viewing  a VHS  recording  in  a
foreign TV standard:

1) purchase  a multistandard  converting VCR (such as the Panasonic AG-W1),
2) purchase  a  VCR  and  television  (and  usually  a  voltage  conversion
transformer) designed for the foreign standard,
3) "transcode" the video to the viewer's TV standard or,
4) have  the tape  standards converted  to the  viewer's "home"  television
standard.

If the  exchange is  between NTSC and PAL or SECAM countries, the first two
options will  involve an  expense of  around $2,000.    The  third  option,
transcoding, is  inexpensive and  quite popular  in Eastern  Europe  where
there are  very few pre-recorded movies available in SECAM.  (In fact, in a
recent survey  of Leningrad,  USSR - a SECAM country - I was unable to find
any SECAM  recordings at  the video  rental shops - all of their recordings
were in  PAL.   The Soviet  Union now  manufactures color  televisions that
eliminate  the  need  for  a  transcoder  by  automatically  detecting  and
transcoding PAL  programs, such  as the  "Raduga" or  "Rainbow" TV receiver
manufactured by  Elektornika in Leningrad.)  Unfortunately, the transcoding
method can only be used when converting video between two TV standards that
have the  same line  and frame  rate standards  (the  same  black-and-white
system).  Transcoding is not an option when converting between PAL or SECAM
and NTSC.   The  fourth option,  standards conversion,  is an  economically
appropriate method  for an  occasional exchange  of video  programs between
NTSC and  PAL/SECAM countries.  Standards conversion of a VHS cassette will
cost approximately  $20 per  hour of  program,  and  this  service  can  be
provided usually  with a 4 or 5 day turn-around to any location in the U.S.
by firms such as Video Bridge (telephone: 800-877-4015).

When having  a VHS  cassette standards  converted, it  is important to make
sure that  a digital process is being used for the conversion.  The results
of the  older analog standards converters are inferior in all respects, and
most laboratories  today use  digital "8 bit/2 field" - and more recently -
"8 bit/4  field" systems.  The biggest difference between the 2 field and 4
field systems  is in  the accuracy of their motion interpolation.  With the
older 2 field systems, moving objects in the video, particularly background
scenes during a camera pan, will occasionally appear to jump from point-to-
point rather  than moving  smoothly.   Although the  video output  from a 4
field converter  still represents something of a compromise, moving objects
appear much  more natural.   (Since  the typical  cost of  an 8 bit/4 field
converter  is   $90,000,  some  laboratories  have  yet  to  upgrade  their
equipment.)   The most  rudimentary method of standards conversion involves
literally pointing  a TV  camera of one standard at a TV display of another
standard.  This method produces results that are absolutely unacceptable to
most viewers today.

If you are sending a converted VHS cassette to Europe, it is also important
to determine  if the  conversion service is recording audio using the Hi-Fi
(sometimes called "HD") FM recording system.  Hi-Fi audio capability is far
more common  in Europe  than in the U.S., and some conversion services here
in the U.S. try to skimp on this point.

TV standards  conversion today costs only a fraction of what it cost just a
few years  ago, and with the power of real-time computing performing motion
detection, time-base  correction, interpolation,  noise reduction and image
enhancement; the  quality of converted video has improved to the point that
the conversion  process has  not only  become essentially  transparent, but
often the  converted copies are superior to the original.  In fact, most of
the international  programming that  we see  today was  converted using the
same technology  that will  be applied  to your  videos.   If you intend to
exchange video  programs with someone living abroad, you can do so today by
using any of the quality standards conversion services.



The following glossary of terms is intended to assist you
with the specialized terminology used in international
television standards.

          Glossary:
          Glossary:

            Legend:  The following designations have been used to avoid
                     confusion, and to separate the definitions of terms        
                     that have multiple meanings:

                      (Video):  Applies to a video standard.

                        (VHS):  Applies to the method of recording or
                                reproducing video with a VHS machine.

                         (RF):  Applies to radio frequency spectrum
                                allocations, usually embodied in
                                international treaties.  Used to
                                describe the design of television
                                transmitters, receivers, and tuners.

                  (Receivers):  Applies to terms used to describe the
                                design of television receivers.


            CCIR (Video)   The French acronym for International Radio
                           Consultative Committee.  The CCIR has
                           established recommendations for the video and
                           transmission characteristics of all of the
                           world's television systems.  The term "CCIR
                           video" is often encountered and is
                           meaningless unless the television video
                           standard to which this term applies is
                           further specified.  As a colloquialism, the
                           term "CCIR video" is most frequently
                           used in reference to the monochrome
                           standards of 625 lines per frame and 50
                           fields per second; as well as the voltages,
                           aspect ratios, gammas, etc., that both PAL
                           and SECAM have in common.   Since both PAL
                           and SECAM are the same monochrome video
                           standard, what is usually meant by this
                           colloquial usage is simply; "black-and-white
                           PAL/SECAM."   "CCIR video" is often touted by
                           VHS manufacturers as if it were a separate
                           video or VHS standard.  The term "CCIR video"
                           has been used erroneously by at least one VHS
                           manufacturer in reference to MESECAM (VHS).

            EIA (Video)    Electronic Industries Association.  Often
                           used to refer to the original monochrome
                           standard from which NTSC was later
                           developed, i.e., 525 lines per frame and 60
                           fields per second.  The term "EIA video" is
                           sometimes used to refer to "NTSC without
                           color information."  "EIA video" is often
                           touted by VHS manufacturers a separate video
                           standard, when in fact it is merely black-
                           and-white NTSC.

          THE NTSC SYSTEMS:

            EIA 4.43 MHz   A colloquial misnomer.  See N443 (Video/VHS).
            (Video/VHS)

            N443, or       An unofficial television video standard.
            NTSC 4.43      With NTSC 4.43 (or N443), a recording is made
            (Video/VHS)    in normal NTSC.  The recorded tape may then
                           be viewed on a compatible PAL monitor that is
                           capable of "locking" its deflection circuitry
                           onto the NTSC line and field rates.  During
                           playback, the down-converted chrominance
                           sidebands that are centered around 629 kHz
                           on the tape, are up-converted to be centered
                           around 4.43 MHz. Since the video was recorded
                           with the NTSC color system, a compatible PAL
                           monitor will detect a 59.94 Hz field rate
                           (NTSC) and will disable its PAL "switching"
                           circuitry and thus reproduce color NTSC
                           pictures (but without the advantages of the
                           PAL color "system," i.e., the phase of the R-
                           Y component will not be reversed on alternate
                           lines). This allows the playing of NTSC tapes
                           in PAL countries on compatible tape machines,
                           without the use of an expensive standards
                           converter.  Unfortunately, comparatively few
                           multistandard VHS machines and monitors
                           exist.  Therefore, this "standard" is of
                           little significance for exchanging VHS programs.

            NTSC 3.58      Ordinary NTSC color video.  This term is used
            (Video/VHS)    on some multistandard VHS machines and
                           receivers/monitors to distinguish normal NTSC
                           from the NTSC 4.43 "standard."

            NTSC           National Television System Committee.  The
            (Video/VHS)    color television video standard used
                           throughout North America, in much of
                           Central and South America, and in much of
                           East Asia.  Implemented in 1953, it was the
                           first form of monochrome-compatible color
                           television, and uses a slightly modified
                           version of the original 525 lines per
                           frame/60 fields per second monochrome system.
                           NTSC employs suppressed-carrier
                           quadrature amplitude modulation for
                           transmitting two color difference signals
                           (I and Q) on a 3.58 MHz suppressed
                           subcarrier.  There is no interchangeability
                           of recorded material between non-
                           multistandard PAL-N/PAL/SECAM (625 line/50
                           field) and NTSC/PAL-M (525 line/60 field) VHS
                           machines.  NTSC may be transcoded to PAL-M.

            SuperNTSC *    A proprietary NTSC-compatible "line doubling"
            (Receivers/    technique developed by Faroudja Laboratories
            Video)         that provides enhanced definition video.
                           Although full implementation of the system
                           requires a decoder and line-doubler at the
                           receiver end, receivers without decoders are
                           claimed to benefit from the removal of NTSC
                           "artifacts."

            M/NTSC (RF)    Also called NTSC-M.  The "M" designation is
                           of no interest in VHS duplication.  M/NTSC is
                           the transmission/video standard that is used
                           in the United States and in all other NTSC
                           countries except Jamaica.

           THE PAL SYSTEMS:

            PAL            Phase Alternating Line. An improvement of
            (Video/VHS)    NTSC video.  Since PAL was implemented
                           mostly in countries using 50 hertz mains
                           supply power and the early scanners (Nipkow
                           disc, Weiller wheel, and film scanners) made
                           use of AC supplied synchronous motors, a
                           field frequency of 50 fields per second was
                           chosen.  PAL uses 625 lines per frame.  In
                           the PAL video standard, the phase of the R-Y
                           (or "V") component is reversed on alternate
                           lines, and thus any phase distortion that
                           occurs in transmission can be "averaged out"
                           at the receiver by use of a delay line.
                           Unlike NTSC, in the PAL system differential
                           phase errors do not appear as objectionable
                           hue errors in the displayed video (the colors
                           become desaturated instead).  The PAL system
                           does not eliminate the distortions in color
                           saturation that are caused by either
                           differential gain errors or as a by-product
                           of differential phase errors.  Like NTSC, PAL
                           employs a similar method of suppressed-
                           carrier quadrature amplitude modulation for
                           transmitting two color difference signals
                           (designated "U" and "V"); but on a subcarrier
                           frequency of 4.43 MHz.  There is no
                           interchangeability of recorded material
                           between non-multistandard PAL and NTSC VHS
                           machines.  PAL VHS recordings are
                           interchangeable with SECAM (VHS) and MESECAM
                           (VHS), but only for monochrome playback.  PAL
                           can be transcoded to SECAM and PAL-N.

            PAL B          Refers to the modern form of the PAL video
                           standard.  This term is rarely encountered.
                           This term should not be confused with PAL
                           video that is transmitted within the
                           bandwidth limits and on the channel spacings
                           that carry a CCIR "B" designation {see also
                           B/PAL (RF)}.

            PAL D          PAL Deluxe.  Referred to occasionally as
            (Receivers)    "D.L. PAL."  This is a receiver/monitor
                           specification, and the term has no
                           application to VHS or to the PAL video
                           standard.  In PAL D, a delay line is used in
                           the receiver or monitor to average the
                           chrominance on alternating lines.   Many
                           studio monitors allow this delay line to be
                           switched off, yielding "simple PAL."  Due to
                           the averaging of the chrominance information,
                           use of a delay line results in an inherent
                           reduction in vertical chrominance resolution,
                           but alleviates an effect in PAL known as
                           "Hanover bars," which occur in the presence
                           of moderate differential phase distortion.
                           This term should not be confused with PAL
                           video that is transmitted within the
                           bandwidth limits and on the channel spacings
                           that carry a CCIR "D" designation {see also
                           D/PAL (RF)}.

            Simple PAL     See PAL D (Receivers).
            (Receivers)

            PAL-M          A television video standard used only
            (Video/VHS/RF) in Brazil.  PAL-M uses the same 525 line 60
                           field system as NTSC for monochrome video
                           (RF bandwidth, field/line rates, gamma,
                           etc.), but it uses the PAL system (with a
                           modified subcarrier frequency) for its color
                           information.  Since PAL-M has the same line
                           and field rates as NTSC, PAL-M can be
                           transcoded to and from NTSC.

            PAL-N          A television video standard used principally
            (Video/RF)     in Argentina.  PAL-N uses the same color
                           system and line/field rates as PAL, but with
                           a lower subcarrier frequency to accommodate
                           restricted RF bandwidth allocations for
                           broadcasting.  Most PAL-N VHS machines are capable
                           of playing (standard) PAL recordings.  PAL-N
                           can be transcoded to PAL and SECAM.

            B/PAL (RF)     A transmission standard that specifies
                           channel spacings and bandwidths for
                           transmitters and tuners.  Does not relate
                           directly to VHS recordings.  The "B"
                           designation is of no interest in VHS
                           duplication.  B/PAL channel assignments are
                           used by the majority of PAL countries, with
                           the notable exception of the United Kingdom.

            D,G,H,/PAL     A transmission standard that specifies
            (RF)           channel spacings and bandwidths for
                           transmitters and tuners.  Does not relate
                           directly to VHS recordings.  The "D,G,or H"
                           designation is of no interest in VHS
                           duplication.  The CCIR designation "D/PAL"
                           should not be confused with the PAL D receiver
                           specification {see also PAL D (Receivers)}.

            I/PAL (RF)     A transmission standard that specifies
                           channel spacings and bandwidths for
                           transmitters and tuners.  Does not relate
                           directly to VHS recordings.  The "I"
                           designation is of no interest in VHS
                           duplication.
      THE SECAM SYSTEMS:

            SECAM (Video)  Sequence Couleur a Memoire, or Sequential
                           Color with Memory.  A monochrome-compatible
                           color television video standard proposed in
                           1959/1960, and intended to reduce the
                           problems of crosstalk between the two color
                           difference signals and the problems of
                           differential gain that are inherent in both
                           the PAL and NTSC video standards.  SECAM
                           circumvents these problems by using two FM
                           carriers to convey the color information.
                           SECAM uses the same set of specifications as
                           PAL for its luminance information, and is
                           therefore the same monochrome video standard
                           as PAL.  SECAM differs from PAL only in the
                           way that its chrominance information is
                           conveyed.  The CCIR recommends a single
                           standard for SECAM video, and only slight and
                           generally irrelevant dissimilarities exist in
                           SECAM video in the countries in which it is
                           used; the most notable difference being the
                           deletion of vertical-interval "bottles" in
                           some countries {see SECAM Bottles (Video)}.
                           There are two incompatible methods of recording
                           SECAM on VHS {see also SECAM (VHS) and MESECAM
                           (VHS)}.  SECAM can be transcoded to PAL and PAL-N.

            SECAM Bottles  The subject of SECAM "bottles" has been the
            (Video)        source of considerable confusion with regard
                           to VHS duplication.  The failure of color
                           playback of SECAM VHS recordings has often
                           been blamed on the absence or presence of
                           recorded "bottles" in the SECAM video; when
                           in fact the compatibility problems are usually
                           the result of an interchange of tapes between
                           Standard or "French" SECAM and MESECAM
                           machines.  The inclusion or deletion of
                           "bottles" in recorded SECAM video is not a
                           compatibility issue with regard to the
                           operation of VHS machines; since SECAM and
                           MESECAM VHS machines never demodulate the
                           SECAM chrominance information, and therefore
                           never make any use of the "bottles."  Both
                           SECAM and MESECAM VHS machines will record
                           and play back SECAM "bottles."  With regard
                           to VHS duplication, the need for recorded
                           "bottles" is dictated only by the design of
                           the viewers' television receivers.  Most SECAM
                           countries, including France, have dropped the
                           requirement for vertical interval "bottles"
                           in their broadcast video {CCIR report 624-3}.
                           Unless a conflict exists that requires the
                           use of the horizontal lines that are normally
                           occupied by the "bottles" for recording

                           information such as teletext or other
                           vertical interval signals on VHS; including
                           the "bottles" signal in VHS duplicates will
                           do absolutely no harm and will assure
                           compatibility with the few receivers that make
                           use of this signal.

            SECAM (VHS)    Also called "French SECAM" or "Standard
                           SECAM."  Only relates to VHS recordings.
                           A method of producing the color-under
                           chrominance information for recording and
                           playing back SECAM video on VHS by dividing
                           the two SECAM FM chrominance subcarriers by 4
                           during recording, and multiplying these
                           subcarriers by 4 during playback.  Because
                           this method uses a completely different
                           scheme than that used in PAL VHS machines for
                           recording the chrominance information, this
                           method of recording SECAM video is most
                           commonly found on single-standard SECAM-only
                           VHS machines.  Because of the availability of
                           pre-recorded VHS program material in France,
                           the consumer-base in France has not been
                           forced to resort to using PAL VHS machines to
                           view pre-recorded programs.  Therefore,
                           SECAM-only (standard) VHS machines are
                           predominant in France.  This is the basis for
                           the term "French SECAM" when used in
                           reference to VHS recording methods.  Although
                           both SECAM (VHS) and MESECAM (VHS) machines
                           will record and play back SECAM color video,
                           there is no interchangeability of recorded
                           material for color playback between MESECAM
                           (VHS) and SECAM (VHS) machines.  Color video
                           recordings that are interchanged between
                           MESECAM (VHS) and SECAM (VHS) machines will
                           play back in monochrome.  PAL VHS recordings
                           are interchangeable with SECAM (VHS)
                           machines, but also for monochrome-only
                           playback.  {See also MESECAM (VHS), SECAM
                           Bottles (Video)}.

            SECAM-East     See MESECAM (VHS).  Relates only to VHS
            (VHS)          recordings.

            French SECAM   A colloquialism.  This term is generally used
            (Video/VHS)    in the vernacular only in reference to VHS;
                           and in this instance, see SECAM (VHS).  When
                           used in reference to receivers and tuners,
                           see L/SECAM (RF).  When used in reference to
                           video, see SECAM (Video).  "French SECAM" is
                           often referred to incorrectly as if it were
                           a completely unique video or VHS standard.
                           SECAM in France is unique only in the way in
                           which it is broadcast {see L/SECAM (RF)}.
                           The confusion regarding the term "French
                           SECAM" is exacerbated by the fact that France
                           uses a unique method for broadcasting both
                           video and audio; and thus, the tuners and RF
                           modulators in French VHS machines must follow
                           a slightly different design.  However, the
                           SECAM video signals that are applied to
                           transmitters in France, and the demodulated
                           video that is  produced by VHS machines in
                           France; conform to the single CCIR standard
                           that is used in all SECAM countries.

            MESECAM (VHS)  Middle-East SECAM.  Also called "SECAM-East"
                           or "Pseudo SECAM."  "MESECAM" relates only VHS
                           recordings, and does not relate to the SECAM
                           video standard itself.  MESECAM derives its
                           name from the fact that the Middle-East has
                           many overlapping areas of both PAL and SECAM
                           broadcast coverage.  MESECAM provides an
                           economical method of using the PAL circuitry
                           in a PAL/MESECAM VHS machine for recording
                           and playing back SECAM video.  These machines
                           accomplish this by using the same
                           mixer/heterodyne circuitry that is used for
                           recording and playing back PAL video.  This
                           method requires only slight modification of a
                           PAL recorder/reproducer, and thus it is the
                           most common and economical method of
                           recording and playing back both SECAM and PAL
                           video on these dual standard VHS machines.
                           Although both (standard or "French") SECAM
                           (VHS) and MESECAM (VHS) machines will record
                           and play back SECAM video in color, there is
                           no color interchangeability of recorded tapes
                           between standard SECAM VHS and MESECAM VHS
                           machines.  The video quality of MESECAM (VHS)
                           is generally inferior to that of SECAM (VHS).
                           In countries where MESECAM (VHS) predominates
                           (such as in the USSR), you should
                           consider duplicating in PAL (VHS) since all
                           MESECAM (VHS) machines possess PAL playback
                           capability.  {See also SECAM (VHS), SECAM
                           "Bottles"}.

            Pseudo SECAM   See MESECAM (VHS).  Relates only to VHS
            (VHS)          recordings.

            B,G/SECAM      A transmission standard that specifies
            (RF)           channel spacings and bandwidths for
                           transmitters and tuners.  Does not relate
                           directly to VHS recordings.  The "B,G"
                           designation is of no interest in VHS
                           duplication.  B,G SECAM transmission
                           assignments have been assigned to countries
                           in the Middle-East, Northern Africa, and at
                           the time of this writing to "East" Germany.
                           ME-SECAM (VHS) is predominate in these markets.
                         
            D,K/SECAM      A transmission standard that specifies
            (RF)           channel spacings and bandwidths for
                           transmitters and tuners.  Does not relate
                           directly to VHS recordings.  The "D,K"
                           designation is of no interest in VHS
                           duplication.  D,K/SECAM relates only to
                           spectrum and channel assignments for
                           broadcasting.   D,K/SECAM is used in
                           Bulgaria, Czechoslovakia, Hungary, Poland,
                           and the USSR.  A SECAM television
                           receiver purchased in Poland, for example,
                           will not receive television broadcasts in
                           France -- although the SECAM video in
                           both countries is exactly the same.
                           ME-SECAM (VHS) is predominate in these markets.

            H,K1/SECAM     A transmission standard that specifies
            (RF)           channel spacings and bandwidths for
                           transmitters and tuners.  Does not relate
                           directly to VHS recordings.  The "H or K1"
                           designation is of no interest in VHS duplication.
                           ME-SECAM (VHS) is predominate in these markets.
                         
            L/SECAM (RF)   A transmission standard that specifies
                           channel spacings, visual modulation polarity,
                           and bandwidths for transmitters and tuners.
                           The "L" designation is of no interest in VHS
                           duplication.  L/SECAM is used in France.
                           L/SECAM is unique in the way that it is
                           transmitted.  Although the video is the same
                           as in all other SECAM countries, L/SECAM is
                           transmitted with the opposite video RF
                           modulation polarity (positive) from all other
                           systems, and the audio is transmitted using
                           AM rather than FM modulation.  You
                           should use standard (frequency division) SECAM
                           VHS for this market.

            Russian SECAM  A colloquialism.  Used in the vernacular only
            (VHS)          in reference to VHS.  See MESECAM (VHS). (The
                           SECAM video that is broadcast in the USSR is
                           not unique and conforms to the single CCIR
                           standard.)

            SECAM I,II,    Early phases of development of the television
            or III         video standard that is now known simply as
            (Video)        "SECAM."  Since the final form of modern
                           "SECAM" resulted from the optimization of the
                           model called "SECAM III," modern SECAM will
                           still occasionally be referred to as "SECAM
                           III."

            SECAM IV       A variant of early SECAM that was never
            (Video)        considered or implemented.

            Soviet SECAM   A colloquialism.  Used in the vernacular only
            (VHS)          in reference to VHS.  See MESECAM (VHS). (The
                           SECAM video that is broadcast in the USSR is
                           not unique and conforms to the single CCIR
                           standard.)

            Standard       See SECAM (VHS).
            SECAM (VHS)

            VHS            Video Home System.  Developed by Japan Victor
                           Company (JVC).  A 1/2 inch helical scan video
                           cassette format where the luminance
                           information is recorded by FM means, and the
                           chrominance sideband information is converted
                           by either heterodyne or frequency division
                           methods to a lower frequency for direct
                           recording.

            VHS SP         VHS Standard Play.  Refers to the linear
                           velocity of the video tape as it passes
                           through the transport.  The "standard play"
                           speed for NTSC/PAL-M (525 line standards) is
                           33.35 millimeters per second, and for PAL/
                           PAL-N/SECAM/ME-SECAM (625 line standards) is
                           23.39 millimeters per second.  Since the
                           amount of tape that is commonly loaded onto a
                           NTSC VHS cassette allows for 2 hours of recording
                           time in VHS SP mode, this speed is often
                           referred to as the "2 hour" mode.

            VHS LP         VHS Long Play.  Refers to the linear velocity
                           of the video tape as it passes through the
                           transport.  The "long play" speed for NTSC
                           is 16.67 millimeters per second, and for PAL/PAL-N
                           SECAM/ME-SECAM is 11.69 millimeters per second.
                           VHS LP speed is one-half (50%) that of VHS SP
                           speed.  VHS LP is not commonly found in NTSC
                           countries outside of North America.  Since the
                           amount of tape that is commonly loaded onto a NTSC
                           VHS cassette allows for 2 hours of recording time
                           in VHS SP mode, this speed is often referred
                           to as the "4 hour" mode.  Because the LP speed
                           in PAL/SECAM is only slightly faster than EP
                           speed in NTSC, and because of the inherent
                           difficulties of recording in VHS PAL/SECAM;
                           the quality of PAL/SECAM VHS LP recordings is
                           generally unacceptable.  You should
                           avoid the use of LP in PAL/SECAM.

            VHS EP/SLP     VHS Extended Play.  Also called "SLP" for
                           Super Long Play.  "EP" or "SLP" speed
                           does not exist in PAL/SECAM VHS.
                           The recording speed of VHS EP is one-third that
                           of the SP speed.  Since the amount of tape that
                           is commonly loaded onto a NTSC VHS cassette allows
                           for 2 hours of recording time in VHS SP mode,
                           this speed is often referred to as the "6 hour"
                           mode.

            * SuperNTSC is a trademark of Faroudja Laboratories


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