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           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
/data/webs/external/dokuwiki/data/pages/archive/fun/worldtv.txt · Last modified: 1999/08/01 17:07 by 127.0.0.1

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