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NTSC What is NTSC 4.43 PAL PAL-N PAL-M SECAM What is MESECAM World Standards Lookup Table
3.579545 Subcarrier Explained How a Video Standards Converter Works
What are the PAL-B, G, H, I & D Variations all about ?
There are several different and incompatible video formats in use around the world. Video broadcasts and recorded material in the US will not play on equipment in Europe for example - and vise versa ! We can convert almost any world standard to another !
The following also contains a brief history and description of world video standards, and articles on how a standards converter works.
The NTSC standard was introduced in the US in 1941 as the first
set of standard protocols for television. It is used predominantly throughout
the USA, Canada, & Japan but has also been adopted elsewhere. NTSC has 525
lines displayed at 30 frames per second in a 2:1 interleave. It has a lower
resolution than PAL or SECAM but a faster frame rate, which reduces flicker.
Though color stability is acceptable in a closed system (ie: direct video to
video), broadcast of the composite signal often results in reflections and
multi-path signals being received by the antenna. The result: phase distortion
resulting in varying color. Engineers lovingly defined NTSC as actually
meaning "Never The Same Color".
The first broadcasts were made in 1939, transmitting 340 lines at 30 frames/sec, as demonstrated at the opening of the New York World's Fair. As there were no standards set at that time, there were a mish mash of other systems soon to be adopted - each one incompatible with the other. This was clearly going to be a format disaster if the various manufacturers were left to their own competitive devices. The FCC finally stepped in to the confused mayhem and founded the NTSC who set the standards in use today.
□ Initially adopted in 1941 and modified in 1953 to include the standards for color.
□ Additional stereo specs were adopted in 1986 and the digital standard adopted in 1996.
□ The actual spec in use today is NTSC-M though it's just called NTSC (We have a habit of abbreviating everything)
NTSC countries are: USA, Antigua, Bahamas, Barbados, Belize, Bermuda, Bolivia, Burma, Canada, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Greenland, Guam, Guatemala, Guyana, Honduras, Jamaica, Japan, South Korea, Mexico, Netherlands Antilles, Nicaragua, Panama, Peru, Philippines, Puerto Rico, St. Vincent & the Grenadines, St. Kitts, Saipan, Samoa, Surinam, Taiwan, Tobago, Trinidad, Venezuela, Virgin Islands.
Variations: NTSC 4.43
A variation of NTSC-M where a 525/59.94 NTSC signal is encoded using the PAL subcarrier frequency and chroma modulation. It is NOT PAL, nor is it it encoded as PAL, but rather it is NTSC color just using PAL's subcarrier frequency. Most (but not all) multi-system Vcr's will support this mode, but only multi-standard monitors are capable of reproducing it.
Line Frequency - 15.734 kHzTechnical Specs:
| System |
NTSC M |
| Lines/Field |
525/60 |
| Horizontal Frequency | 15.734 kHz |
| Vertical Frequency | 60 Hz |
| Color Subcarrier Frequency | 3.579545 MHz |
| Video Bandwidth | 4.2 MHz |
| Sound Carrier | 4.5 MHz |
Somehow, no one ever seems to explain these common questions. Numbers and specs are rattled off with little or no understanding of what they mean or how they were arrived at. The explanation of one question raises but yet another, as they are all inter-related.
This is by no means an in depth technical article, but should explain the gist of it !
The NTSC subcarrier frequency is specified as being 3.579545 MHz with a tolerance of only ± 10 cycles/second. Why was such a specific frequency chosen for the standard ? Why not some nice round number like 3.6 MHz ? What is so magical about 3.579545 ?
To answer this question, requires some historical background...
odd multiple of one-half the scan rate, then the visible beating between the audio and color sub carriers would be greatly reduced.When Black & White television was first introduced, the first NTSC standard (introduced in 1941) specified the use of 525 lines/frame, refreshed at 30 frames/second which resulted in a 15,750 lines/second horizontal scan rate (525 x 30). This most basic of specifications was adopted well before color television became a reality. The concept of color broadcasting wasn't even yet a dream. Thus the initial NTSC adopted standard never took into consideration the possibility of color television. By the time color television came into being, there was now a large installed base of monochrome TV's. It was imperative that the new color signals and method for encoding them, be compatible with the installed base. Unless a scheme could be developed that would allow color to be "added" to the NTSC signal, the entire NTSC system would have to be scrapped and a new color standard adopted - turning every existing black and white TV in the country into a collection of useless electronic junk. The political ramifications would be of epic proportions and many a politician or NTSC member would have been tarred and feathered by a well armed angry public, hell bent on revenge. Though the manufacturers would have loved a new standard so the public would be forced to scrap all their current TV's and purchase all new receivers, economic reality & common sense this time prevailed. Apparently self preservation ranked rather high with the politicians & NTSC...
The scheme for encoding and de-coding the new color information was based on using a color subcarrier frequency which was the only scheme that would allow compatibility with the existing installed base of broadcast equipment and televisions. The hue of the color was determined by comparing the phase of the reference color carrier (the color burst signal ) to the phase of the chroma part of the signal. Put another way, the color is determined by how the chroma frequency part of the picture is delayed from the reference frequency. Clearly, there had to be one agreed on color subcarrier reference frequency for this color system to work. Selecting the proper frequency turned out to be somewhat more complicated than just picking one somewhere in the ballpark and "hoping for the best".... (actually, that was what was originally tried, and it didn't work ! - so much for the easy solution...) To better understand what's involved, we'll have to touch upon some technical issues.
NTSC broadcast standards previously established before the advent of color, called for the audio sound carrier frequency to be 4.5 MHz above the picture carrier. This would insure that the audio and video components of the broadcast signals wouldn't interfere with one another. Somehow a chroma subcarrier frequency had to be chosen that would maintain backward compatibility with the large installed base of monochrome sets, without having to scrap the entire system and starting from scratch. The broadcast bandwidth was fixed and cast in concrete by then, and yet now, even more information had to be crammed into the already narrow bandwidth space available. Early attempts at arbitrarily selecting an appropriate frequency resulted in failure. There was interference between the sidebands of the new chroma subcarrier needed to convey the chroma information and the existing sound carrier frequency. Even keeping the chroma bandwidth to an absolute minimum wasn't quite enough. There was simply too much "stuff" to be crammed into too little "real estate". So, a bunch of clever folks got together and simply found a way to make the chroma subcarrier "just fit" if you will. It entailed the use of a very specific subcarrier, the frequency of which allowed the chroma signal to interleave with the luminance. The following is quite technical but we'll attempt to explain how it was determined as simply as possible.
To keep everything "marching in lockstep", the color subcarrier frequency in the television signal needs to be modulated onto the picture carrier at 455/2 times the horizontal line frequency. Where does the "455" come from you ask ? Experiments conducted by General Electric at the time, concluded that if the difference signal happened to be an
First, keep in mind that the entire video bandwidth of from 0 to 4.2 MHz is allocated to reproducing the luminance information. To get the new color information to fit as closely as possible, a .6MHz chroma bandwidth was the maximum chroma bandwidth permissible. Thus the subcarrier had to be somewhere around 4.2 MHz minus .6Mhz or 3.6Mhz. Thus to achieve a subcarrier around 3.6 MHz that would meet the "odd multiple of one half the scan rate" would mean a subcarrier that was around 455 times the horizontal scan rate/2 or 15,750/2 x 455 = 3.583125 MHz (pretty close to 3.6 MHz). Keep in mind that the sound subcarrier rides 4.5 MHz above the picture carrier. If the audio subcarrier were to interfere with the color subcarrier, then the 916.875kHz difference (4.500000 - 3.583125 MHz) might be visible. The NTSC found that this frequency interference was evident, so it was back to the drawing boards again.
More experimentation revealed that if the frame rate was dropped just 0.10001 % down to 29.97 frames/second then the resulting horizontal scanning frequency would be 15.734264 kHz (29.97 x 525), and the chrominance subcarrier would be 3.579545 MHz (455/2 * 15734264). Thus the audio/color subcarrier difference would be 920.455 kHz (4.5mHz - 3.579545 MHz). Turns out this is very close to being an odd multiple of one-half the scan rate. (15734.264 / 2 = 7867.132 * 117 = 920.4544 (almost an exact odd multiple - the 117th multiple in fact !) So by dropping the scan rate from 15,750 to 15,734.26573 and selecting the 455th/2 harmonic for the chroma subcarrier, effectively interleaved the chroma with the luminance information, which greatly reducing the visible interference. Turns out that "455" is a "magical" number for other reasons as well. It can be factored as 5x7x13 = 455 making design of a frequency divider a snap !"Thus the 455 and the 3.57954545... MHz are related to each other exactly. The chroma subcarrier frequency is precisely 455 times one half the line frequency. This exact integer relationship is the ONLY reason that the extra chroma information could fit into the existing bandwidth previously used for monochrome. But the surprising reality is that it fits only as far as the human eye is concerned. Electrically, it doesn't fit at all. Instead, the luminance information is severely crosstalked with the chroma information. In the luminance channel, this interference appears as a moving fine "screen wire" interference pattern in colored areas. In the chroma channel, this interference appears as extraneous moving rainbow colors in areas of fine luminance detail.
What that precise integer relation does, is to greatly reduce the VISIBILITY of that severe crosstalk by making the interference patterns move in such a way as to make it hard for the human eye to follow and notice it. This is the heart of the ground breaking innovation from RCA, without which compatible color would not have been practical. (The second NTSC later added the important final touches, but without this crucial RCA innovation, there would have been no second NTSC.) Although this technique greatly reduces the visibility of the crosstalk interference between chroma and luminance, that visibility is not entirely eliminated. On strong color edges the crosstalk interference is still mildly visible as "dot crawl". The dots are the interference that appears in the luminance channel, and the crawl is due to the motion given to the dots by that exact integer relationship between the line frequency and the chroma subcarrier frequency. Also, in areas of fine luminance detail, if someone is wearing a fine patterned suit for example, you will sometimes see moving rainbow colors that are obviously accidental and not supposed to be part of the picture." 1
It turns out that 15.734 KHz was close enough to the original 15,750 KHz scan rate so that no compatibility issue would be raised and current b/w TV's would still be able to work with a color picture. Thus the frame rate for NTSC was dropped to (15734.26573 / 15750) * 30 fps or 29.97 frames/second when color was introduced. Thus 3.57954545 is a magic number that keeps the chroma subcarrier from visibly interfering with the audio carrier when broadcast. It allows a lot of additional color information to be crammed into a narrow bandwidth never designed for it in the first place... Pretty clever, huh ? Now you know where the 3.57954545 MHz comes from !Equipment manufacturers weren't all that happy in reducing the frame rate from 30 fps to 29.97 fps. It meant that simple locking of the vertical sync to the the AC line could no longer be done and that more expensive techniques were now required.
Other than these considerations, the specific 3.57954545 MHz frequency is nothing really special. It is merely the color reference to which the color phase of the recorded signal is compared - the phase determining the hue, and the amplitude determining the saturation if you will..
The PAL subcarrier frequency was chosen using similar logic. The PAL chroma subcarrier is 4.43361875 MHz and was arrived at in much the same manner with only some other minor considerations.
Turns out, almost any subcarrier frequency within reason would work fine for NTSC if you didn't actually have to broadcast it..
1 Special
Thanks to Richard Emery for his highlighted additional explanation on the
relationship.
What is NTSC 4.43 ? - NTSC 4.43 Explained
What is NTSC 4.43 and why does it exist....
If NTSC didn't actually have to be broadcast, then the color subcarrier could almost be anything within reason
. NTSC would not be locked in to using the 3.579545 subcarrier. If the video need not ever be broadcast (for recording purposes only) then the NTSC composite signal could just as effectively use PAL's higher subcarrier. Using PAL's higher subcarrier would allow the chroma bandwidth to be increased, thus yielding superior chroma detail.The other reason is that some European TV's support NTSC 4.43 but NOT NTSC-M, since it required little additional circuitry to support NTSC 4.43. Tapes recorded in NTSC 4.43 will happily display on these TV monitors without needing to be converted. (assuming they have an NTSC 4.43 compatible player).
Note that although NTSC 4.43 uses PAL's color subcarrier frequency of 4.433618 mHz, the chroma is still encoded as an NTSC signal. Thus although it uses PAL's subcarrier, tapes recorded in NTSC 4.43 will not display on a standard PAL monitor or play in a standard PAL VCR.
Most newer European PAL TV sets support 60 cycle frame rates. PAL-M is often referred referred to as being 60 cycle PAL. However, PAL-M is not the same as NTSC 4.43 !
The more widespread availability today of multi-standard VCR's and monitors, have made NTSC 4.43 somewhat obsolete.
Here is another technical subject that we'll try and explain as simply as possible.
The color subcarrier reference frequency must be absolutely stable, as any variation in frequency or phase will result in a color shift. The subcarrier frequency of 3.57954545 is not directly recorded on a videotape for example, or even fully broadcast for that matter. Instead only just 9 cycles (a very tiny sample) is included at the start of each horizontal line of the composite video signal. The 9 cycles of subcarrier reference is called appropriately the Color Burst. It re-syncs and keeps accurate the TV's or VCR's internal subcarrier frequency phase lock loop reference oscillator that must always be locked accurately to the source, be it broadcast or from videotape. Put another way, it re-calibrates the subcarrier reference at the beginning of every horizontal line. Consider that every second there are nearly 15,734 re-calibrations ! (525 lines x 29.97 frames/sec).
It sounds like this should be more than enough to keep the reference tightly locked, but alas, sometimes even this is not quite enough. Broadcast signals are subject to multi-path distortions (the signal arriving at the antenna at slightly different times due to parts of it being reflected off interfering objects). As the frequency is only re-calibrated at the start of each line, multi-path reflections can knock it out of phase by the time the scanning beam reaches the end of the line. The result: a changing color hue from the left side of the picture to the right...... Better tuners and directional antennas greatly reduce the effects, but ultimately, there's no way around it - NTSC shall be forever plagued with the problem. It's designed into the system and too late to change. PAL however, came along later and doesn't have these troubles...
Thus, folks in the States may notice the slight
flicker of a PAL video, having become used to the higher frame rate of
NTSC. However PAL offers noticeably improved resolution and color
stability. After several minutes of viewing a PAL video, our brains compensate,
and the flicker becomes un-noticeable.
PAL countries include: Afghanistan, Algeria, Argentina (PAL-N), Australia, Austria, Bahrain, Bangladesh, Belgium, Brunei, Cameroon, Canary Islands, China, Cyprus, Denmark, Finland, Germany, Ghana, Gibraltar, Greece (also Secam), Hong Kong, Iceland, India, Indonesia, Ireland, Israel, Italy, Jordan, Kenya, North Korea, Kuwait, Liberia, Luxembourg (also Secam), Madeira, New Zealand, Nigeria, Norway, Oman, Pakistan, Paraguay (PAL-N), Portugal, Qatar, Saudi Arabia (also Secam), Sierra Leone, Singapore, South Africa, Spain, Sri Lanka, Sudan, Swaziland, Tanzania, Thailand, Turkey, Uganda, United Arab Emirates, United Kingdom, Uruguay (PAL-N), Yemen (the former Yemen Arab Republic was PAL, and the former People's Democratic Republic of Yemen was NTSC, Yugoslavia, Zambia, Zimbabwe.
Technical Specs:
Line Frequency 15.625 kHz (PAL-M is 15.750)
Scanning Lines - 625 (PAL-M is 525)
Field Frequency - 50 Hz (PAL-M is 60 Hz)
Color Signal Modulation System: Suppressed Quadrature Modulation System
Color Signal Frequency - 4.433618.75 MHz
Burst Signal Inversion by 1H
Video bandwidth - PAL-B, G, H: 5.0 MHz; I: 5.5; D: 6.0; N, M: 4.2
Sound Carrier - PAL-B, G, H: 5.5 MHz; I: 6.0; D: 6.6; N, M: 4.5
Variations:
There are two variations that have been developed: PAL-M and PAL-N. The main differences between PAL and PAL-M is a lower resolution (525 lines instead of 625) and a higher frame count (30 frames per second at 60Hz versus 25 frames per second at 50Hz). PAL-M grew out of NTSC as an attempt to correct the inherent color problems of NTSC. PAL-M is essentially PAL at NTSC line and frame rates. The only major difference is how the color is processed. ie: the sub-carrier frequency.
PAL-N is effectively PAL (identical frame/scan rate), but uses a 3.582056 MHz chroma subcarrier. PAL-N in engineering circles is known as "Chrominance Lock Technique". Without going into a long technical dissertation on PAL subcarrier like we did with NTSC, PAL-N was simply a more sophisticated delay-line technique which could better track and cancel differential phase distortions especially encountered in remote/mountainous areas. With subsequent improvements in tuners and filtering techniques, the reality was, that it didn't "buy" much and was never widely adopted. The only countries employing PAL-N are Argentina, Paraguay & Uruguay. Note that attempting to display a PAL signal on a PAL-N monitor will result in only a monochrome image.
| SYSTEM |
PAL B, G, H |
PAL I | PAL D | PAL N | PAL M |
| Line/Field | 625/50 | 625/50 | 625/50 | 625/50 | 525/60 |
| Horizontal Frequency | 15.625 kHz | 15.625 kHz | 15.625 kHz | 15.625 kHz | 15.750 kHz |
| Vertical Frequency | 50 Hz | 50 Hz | 50 Hz | 50 Hz | 60 Hz |
| Color Sub Carrier Frequency | 4.433618 MHz | 4.433618 MHz | 4.433618 MHz | 3.582056 MHz | 3.575611 MHz |
| Video Bandwidth | 5.0 MHz | 5.5 MHz | 6.0 MHz | 4.2 MHz | 4.2 MHz |
| Sound Carrier | 5.5 MHz | 6.0 MHz | 6.5 MHz | 4.5 MHz | 4.5 MHz |
What are the PAL-B, G, H, I & D Variations all about ?
Here's another question we're constantly asked..
Pal-B, G, H, I and D as far as the actual video is concerned, are all the same format. That is: they are all PAL. There is no difference. All use the 625/50 line/field rate..... scan at 15,625 h-lines/sec and use a 4.433618 color subcarrier frequency. The only difference is in how the signal is modulated for broadcast. Thus the B, G, H, I & D designate broadcast variations as opposed to any variation of the video format. PAL-I for example, has been allocated a wider bandwidth than PAL-B, necessitating that the sound carrier is placed 6Mhz above the picture instead of 5.5 MHz above the picture carrier. Thus a PAL-I TV (the United Kingdom for example) will get no sound if taken to the Netherlands for example (PAL-B) if all the TV's tuner is able to decode is PAL-I. (Fortunately, most European tuners support most of the broadcast variations ).This is why for example, you won't find a standards converter that will convert a video from PAL-B to PAL-I. There's simply nothing to convert.....They are already the same PAL format. There are major differences between PAL-M and PAL-N however, that would require conversion, as the line/field rate and color subcarrier frequencies are different from standard PAL.
Why is PAL so stable when it comes to Color Stability ?
PAL in part, came about as a result of NTSC's weakness in the area of color stability. It circumvented NTSC's inherent problems by inverting the color phase by 180 degrees on every other line. If the color drifted off by Plus 5 degrees on line 100 for example, then on line 101 the color drifted back minus 5 deg. since the color phase reference was inverted every other line. True, the color errors were still there, but the human eye and brain are wonderfully marvelous devices.... the image processing center of our brains integrate the interleaving lines smoothly all into one coherent corrected image. The effect is that phase shifts are effectively cancelled out using our human brain as a super high speed image integrating processor.
This very trait is where PAL got it's
name---- Phase Alternation by Line.... which leads us to the next
world standard.
SECAM uses an FM color subcarrier that carries the color difference signals somewhat similar to PAL. But instead of all the color difference information being transmitted all at once, in SECAM the color difference signals are transmitted sequentially ...... that is: R-Y on one line and B-Y on the next. A delay line in the receiver provides the necessary time delay for making R-Y and B-Y available for display at the same time and thus the term "Memoire" as part of the standard's name.
SECAM was not developed for any technical reason of merit (as was PAL) but was mainly invoked as a political statement, as well as to protect the French manufacturers from stiff foreign competition. In that regard, they were highly successful !.....
Reminds one of the classic lines from Star Wars - The Empire Strikes Back.... Where Hans Solo is about to deliberately fly into an asteroid field to avoid the Empire's perusing Tie Fighters.......
Princess Leia: You're not actually going IN to an asteroid field ?
Han Solo: They'd be crazy to follow us, wouldn't they ?Likewise, no other foreign manufacturer in their right mind had any burning desire to commit economic suicide by having to deal with and support such a limited market that was incompatible with everything else on the planet.
The Eastern Block countries during the cold war adopted variations of SECAM simply because it WAS incompatible with everything else !
Countries include: Albania, Benin, Bulgaria, Congo, former Czechoslovakia, Djibouti, Egypt, France, French Guiana, Gabon, Greece (also PAL), Guadeloupe, Haiti, Hungary, Iran, Iraq, Ivory Coast, Lebanon, Libya, Luxembourg (also PAL), Madagascar, Martinique, Mauritius, Monaco (also PAL), Mongolia, Morocco, New Caledonia, Niger, Poland, Reunion, Romania, Saudi Arabia (also PAL), Senegal, Syria, Tahiti, Togo, Tunisia, the former USSR, Viet Nam, & Zaire.
Technical Specs:
Line Frequency - 15.625 kHz
Scanning Lines - 625
Field Frequency - 50 Hz
Color Signal Modulation System FM Conversion System
Color Signal Frequency - 4.40625 MHz/4.250 MHz
Burst Signal Phase settled
Video bandwidth - B, G, H: 5.0 MHz; D,K,K1,L: 6.0 MHz
Sound Carrier - B, G, H: 5.5 MHz; D,K,K1,L: 6.5 MHz
Variations: If that wasn't bad enough, there are other
variations of SECAM: SECAM-L (also known as French SECAM) used in France and
its' now former territories, MESECAM and SECAM-D which is used primarily
in the C.I.S. and the former Eastern Block countries. Naturally, none of the
three variations are compatible with even one another. (By this time, were you
expecting anything less ?).... I'm not certain, but guess they couldn't
even agree on a single incompatible standard even amongst
themselves....
| System | SECAM B, G, H | SECAM D, K, K1, L | MESECAM |
| Line/Field | 625/50 | 625/50 | 625/50 |
| Horizontal Frequency | 15.625 kHz | 15.625 kHz | 15.625 kHz |
| Vertical Frequency | 50 Hz | 50 Hz | 50 Hz |
| Video Bandwidth | 5.0 MHz | 6.0 MHz | 5.0 MHz |
| Audio Carrier | 5.5 MHz | 6.5 MHz | n/a |
| Color Burst | 4.25/4.4 MHz | 4.25/4.4 MHz | 4.40625 MHz (DB) |
(For all it's shortcomings, NTSC is the ultimate in simplicity: ONE standard: NTSC-M with No variations !)
Note that in both SECAM and MESECAM systems, the color signal modulation system differs from NTSC, PAL, PAL-M & PAL-N.
SECAM and MESECAM use FM Modulation while the other systems use what's known as Suppressed Subcarrier Quadrature Modulation.
As in PAL, there are broadcast variations such as B, G, H, K, & K1 that differ in how the audio/video is modulated for broadcast.
WHAT IS MESECAM (Middle East SECAM) - MESECAM Explained
This is a common question we're often asked, so here's the answer....
MESECAM stands for Middle East Systeme Electronique Couleur Avec Memoire.. It is a modified variant of SECAM used for recording SECAM on videotape only. This variation of SECAM is never broadcast but is just a less expensive way to record SECAM on a video tape. Thus, you'll never see MESECAM listed in any of the world standards charts, for as just stated, it is a format which is never broadcast.
So why would anyone in their right mind who is not a glutton for punishment, ever want to create a format
that is never broadcast, you're probably asking ?Well, it all came about owing to the limited number of units of SECAM equipment manufactured. SECAM equipment; televisions in particular, are quite expensive, since the economic efficiencies of high volume mass production and competitive market forces could never be realized. PAL televisions however, are "dirt cheap" by comparison. Europe is swimming in the things ! Short of totally scrapping SECAM, what was needed was a way for SECAM video tapes to be played back on inexpensive PAL televisions. The answer: MESECAM ! ....... (this was perhaps the only logical thing that ever came about in the ever wonderful world of SECAM)
MESECAM allows a standard SECAM signal to be slightly modified and recorded on tape that is close enough to PAL, so that SECAM programs can be played back on a standard PAL television. Thus many so called SECAM recorders aren't true SECAM recorders at all. They internally convert SECAM to MESECAM. MESECAM is the actual format written to tape.
The price that's paid for this "wonderful" cross compatibility, is that MESECAM differs from regular SECAM in how the color component is processed. SECAM uses an FM modulated subcarrier whereas MESECAM uses an AM modulated subcarrier. Naturally, the two systems as far as color is concerned are incompatible. Color recordings will only play back in black and white between SECAM and MESECAM systems. Thus an MESECAM VCR is required to play MESECAM tapes in color. They couldn't have it both ways !
Since the line count and frame rates are similar, you'll observe a nice picture..... it'll just be in "living" black and white, since PAL & SECAM process the chroma information differently. Conversely, the same will be true by attempting to play a SECAM tape in PAL equipment.
Simply put: You Don't !
There is no such thing as a SECAM DVD. All DVD's viewed in France and other SECAM countries are in fact PAL. The very limited market resulted in no manufacturer (including even the French) making a SECAM DVD player/recorder. Unlike the US, just about all French TV's are in fact multi-standard and support the PAL standard.
Since NTSC is recorded at 60 frames/sec as compared to PAL and SECAM's 50 frames/second, it stands to reason that NTSC will consume more tape per given amount of recording time.
Note that the "T" tapes are sold for NTSC, while the "E" tapes are for European PAL/Secam. There is absolutely no difference in the tape itself; the only difference being the amount of tape spooled on the cassette. Thus an E-120 European cassette which would hold up to 120 minutes of PAL/SECAM video, would hold only 86 minutes of NTSC video. Conversely, a T-120 could hold up to 169 minutes of PAL or SECAM.
The table below depicts the approximate time relationships.
Tape Label Length
(Meters)NTSC
(minutes)PAL/SECAM
(minutes)T-30 64 30 42 T-60 125 60 84 T-120 246 120 169 T-160 326 160 225 E-30 45 22 30 E-60 88 44 60 E-120 173 86 120 E-180 258 129 180 E-240 346 173 240
The heart of any standards conversion is the converter itself. All converters are not created equal however. They range in price from under $170 to over $60,000 for the Snell & Wilcox Alchemist Ph.C.® ...... Not surprisingly, the quality that results is directly related to the cost of the converter. Think the $200 converter will match or even come close to matching the performance of Snell & Wilcox's Alchemist ? - Better think again..... What is truly amazing is that everyone claims their converters to be of "Broadcast Quality" - even the manufactures, mass marketing converters to the home consumer for less than $200 are sadly making that false misleading claim as well. The $200 converters are anything BUT broadcast quality. Inexpensive converters are lacking in image detail, loaded with motion artifacts and full of jitter. (referred to as "judder" as it relates to format conversion).
Perhaps the following will shed more light on the subject....
Converting between different numbers of lines and different frequencies of fields/frames in video pictures is not an easy task. Perhaps the most technical challenging conversion to make is the PAL to NTSC. Consider that PAL is 625 lines at 50 fields/sec as opposed to NTSC's that is 525 lines at 60 fields/sec. Aside from the line count being different, it's easy to see that generating 60 fields every second from a format that has only 50 fields might pose some interesting problems. Every second, an additional 10 fields must be generated seemingly from nothing. The converter has to do no less than ‘create’ new output pictures from those available at the input - and all this must be done in real time. So, even going from 525 line 60 fps NTSC to 625 line 50 fps PAL for example (technically the easiest), requires a skillful use of the existing information to provide a quality conversion.
So how is it done ?....... Just think of it this way.....
A video picture can be thought of as a series of individual picture elements or pixels arranged in a two-dimensional array (grid if you will) across the screen: the number of rows for the sake of argument, being the number of lines in the displayed image. To produce an output number of lines different from the input requires a bit of mathematical processing from the input side to calculate the placement, hue and luminance for each pixel on the output side. This process of where to place the pixels in the output buffer is known as "interpolation".
Who can forget the wonderful times we had in school, when presented with: X=2, Y=7 (input side) when X=4, Y=11(output side) and then being expected to find the value of Y when X=3. Bring back fond memories ? (the answer is Y=9 by the way). In case you're a bit "rusty", X=3 is halfway between 2 & 4. Therefore, it follows to reason that Y must be halfway between 7 & 11.... or 9. So we just took a pixel from the input buffer side (the video source) and placed the pixel at the appropriate position on the output buffer side. Thus we just performed interpolation employing the use of an algorithm (the scheme or reasoning if you will) to perform the conversion. That's the simplified concept anyways.
Interpolation in actual standards converters work in much the same way, except that the relationship between different values happens in three dimensions – horizontal and vertical dimensions plus the added dimension of time to account for motion between fields. Things are now starting to get a bit more complicated (consider the added complexity of 3 dimensional chess). We now require a 3 dimensional array (or grid) - the third dimension representing time, required to accommodate the fact that we have motion from field to field..... Thus the relationship of input to output is not nearly as simple as that of a straight-line graph used in the example above, where simple straight line interpolation is used.
To effectively process motion, requires that motion and it's direction can be detected in the first place. Inexpensive converters don't even bother to account for motion (what do you expect for $200 or so !) Better quality standards converters track motion over only 2 fields (one frame, or 1/30 second) while professional grade converters track up to 6 fields. The greater the number of fields tracked, the more accurate the motion predictions (and also the greater the complexity and resulting price tag !)
Now that we understand these basic concepts we'll discuss in a little more detail how a conversion takes place, the various types of algorithms and their weaknesses. In the following discussion, we'll use a PAL to NTSC conversion as an example
In the case of converting PAL (625 lines @ 25 frames/sec) to NTSC (525 lines @ 30 frames/sec) it can be seen that every second 100 lines must be dropped and 5 additional frames must be created. Less expensive converters simply drop 100 lines equally spaced through each frame to reduce the 625 line PAL down to NTSC's 525 (that's pretty easy !) To create the 5 additional frames, they just sample and repeat a single frame, then repeat the process 5 times per second, thus effectively "adding" 5 frames. This simple algorithm is fast, inexpensive and works like a charm..... UNLESS that is, there's ANY MOTION. Consider that if the image is static, then no one notices the repeating frames. You could have taken a single frame of PAL, lop off 100 lines and repeat the very same frame 30 times each second and you'd still have a perfect conversion. Actually, most of the inexpensive consumer converters employ this technique.
Video however, is a dynamic medium. Add the element of motion, and suddenly the 5 repeating frames each second start to stick out like a sore thumb. The effect is called "Judder" ..... the greater the motion difference between frames, the greater the apparent judder (the name is sort of play on the words jitter and stutter). Overcoming judder requires a much more sophisticated means of first measuring the nature of motion within the material, and then employing more sophisticated algorithms to dynamically produce in real time a correct motion compensated output. Things are now starting to get a lot more complex and expensive.
The next step up from the "cheapie" converters are those that employ inter-field interpolation. It's a somewhat more involved as it creates the new frames not just by repeating a frame, but by averaging adjacent fields. Likewise, instead of dropping or adding scan lines, they also use averaging by sampling and "schmooing" together adjacent lines. There are simple 2-line and 4 line converters. The 2-line converter creates a new line by comparing two adjacent lines, whereas a 4-line model compares 4 lines to average the 5th. Again, the greater the complexity and resulting price tag ! Inter-field interpolation reduces (note: I didn't say eliminate) judder, but at the expense of picture smearing. The greater the averaging to smooth out the judder, then the greater the picture smear . It's a bit of a crude trade off.
As it's name implies, the amount of processing done is dependent on the amount of motion detected. This algorithm takes inter-field interpolation one step further. It capitalizes on the way the human eye and brain process moving images. Our eyes simply don't perceive detail on moving objects . Adaptive interpolation requires that the converter store in memory successive fields and then sample those fields to detect the amount and type of motion. Where little motion is detected, the converter may revert to simple linear interpolation for those fields that exhibit no motion. When greater motion is detected then they switch to a more advanced inter-field technique. Less expensive converters may analyze and convert only on a field by field basis, or be more sophisticated, and analyze and convert on smaller parts of the picture. When there's little motion, the picture is nice and sharp, but will start to smear or be "fuzzy" when motion is encountered. Since the eye doesn't perceive detail in moving objects anyway, the technique is quite effective.
Adaptive Motion Interpolation and it's variations, is used in the midrange converters. The quality and cost is dependent upon the accuracy in analyzing the type and amount of motion, and the selection of the most appropriate algorithm for processing the type of motion. The specific types of algorithms employed are well kept secrets by the manufacturers of higher end converters. But some use a general form of Block Matching, which is our next topic.
Block matching involves dividing the image into mosaic blocks - say perhaps for the sake of explanation, 8x8 pixels. The blocks are then stored in memory. The next field read out is also divided up into the same number and size of mosaic blocks. The converter's computer then goes to work and starts matching up blocks. The blocks that stayed in the same relative position (read: there was no motion in this part of the image) receive relatively little processing. For each block that changed, the converter searches in every direction through it's memory, looking for a match to find out where the "block" went (if there's motion, the block obviously had to have gone somewhere..). The search starts at the immediate surrounding blocks (assuming little motion) and if a match isn't found, then it searches further and further out until it finds a match. When the matching block is found, the converter then knows how far the block moved and in which direction. This data is then stored as a motion vector for this block. Since motion from frame to frame is often predictable owing to Newton's laws of motion in the real world, the motion vector can then be used to calculate where the block is likely to be in the next field - saving a lot of search and processing time. If the image was panning from left to right for the past 10 fields, it's safe to assume that the 11th field will be similar or very close. Anyways, you can think of block matching as the "cutting and pasting" of image blocks.
The technique is highly effective but it does require a tremendous amount of computing power. Consider a block of only 8x8 pixels. For each block, the computer has 64 possible directions and 64 pixels to be matched to the block in the next field. Also consider that the greater the motion, the further out the search must be conducted. Just to find an adjacent block in the next field would entail making a search of 9 blocks. 2 blocks out would require a search and match of 25 blocks - 3 blocks further distant and it grows to 49 etc etc. The type of motion exponentially compounds the compute power required. Consider a rotating object, where a simple straight line motion vector is of little help in predicting where the next block should match.... It can quickly be seen that the more inter frame motion introduced, the much greater the processing power required. This is the general concept of block matching. Block match converters can vary widely in price and performance depending on the attention to detail and complexity.A weird artifact of block matching owes to the size of the block itself. If a moving object is smaller than the mosaic block, consider that it's the entire block that gets moved. In most cases, it's not an issue, but consider a thrown baseball. The ball itself has a high motion vector, but it's background that makes up the rest of the block might not have any motion. The background gets transported in the moved block as well, based on the motion vector of the baseball, What you might see is the ball with a small amount of outfield or whatever, tagging along. As it's in motion, the block may be "soft" depending upon what additional techniques were used and barely noticeable unless your looking for it.
Block matching requires a staggering amount of processing horsepower, but today's microprocessors are making it a viable solution.
Perhaps the most complex of the general algorithms. It's effective on rapid motion, doesn't easily get confused by rotating or twirling objects for example, and yields excellent resolution.
The solution is elegant as well as technically and conceptually complex. It's intelligence is derived by performing a Fourier Transform to each field of video.
Just what is a Fourier Transform you're probably asking yourself ? A Fast Fourier Transform (FFT) is an algorithm which deals with the transformation of discrete values (in this case image pixels). When applied to a sample of finite values, a Fast Fourier Transform expresses any changes (read: motion) in terms of frequency components.
So what's the big advantage of a FFT over simply trying to predict the motion vector on a pixel by pixel basis you ask ? Mathematically, it's far easier and faster to recognize and process frequency signatures from which very accurate motion vectors can then be calculated. Rather than having to measure where every pixel goes from frame to frame (a massive undertaking), the FFT rather results in representing just the changes from one frame to the next. Since the result of the FFT represents only the inter-frame changes in terms of frequency distribution, there's far less data that has to be processed in order to calculate the motion vectors. Unlike other motion vector calculating methods, the FFT technique is not easily fooled by objects that have rotational or spiraling motions.
What results from the FFT is a three dimensional frequency distribution represented mathematically by peaks in a three dimensional wave pattern - the third dimension representing subsequent fields of video. The objects in motion are represented by the peaks in the frequency distribution. Once the FFT is performed, it's now a simple matter for the computer to track just the peaks (the objects in motion if you will...) and assign a motion vector. The depth of processing and height of the peaks tracked is dynamically changed dependent on the type of motion detected and is quite complex - beyond the scope of this page. However, this is the general concept. The technique is both elegant and complex - requiring sophisticated software, massive amounts of processor "horsepower" and complex electronics. Consider that all this must be done in real time.... Snell & Wilcox uses phase correlation on its Alchemist Ph.C model standards converter.
The better the algorithms and the more complex the circuitry to support the algorithms, then the better the pixels can be juggled to smoothly and accurately respond to movement information.
Thus it's now easy to understand that all standards converters are not created equal !
The manufacturer of any true broadcast quality converter will proudly list the critical specs such as the depth of bit processing employed, the number of lines and fields interpolated, number of sample points, the interpolation method employed, video bandwidth and signal to noise ratio. NONE of the manufacturers of any of the low priced converters list these critical specs - - - - - perhaps for good reason. Most use the most simplistic linear interpolation scheme as in the school example. The result: picture judder - often dropped frames, motion artifacts and often poor resolution. In all fairness though, what do you expect for $200 bucks !.......
By comparison, the highest quality of any converter on the market today is probably the Snell & Wilcox Alchemist Ph.C
® priced originally at $230,000 (this is not a "typo). The latest incarnation of this technical masterpiece released in April of 2004, reduced the price point to $60,000. Compared to a consumer grade converter about the size of a large calculator, the high end converters are huge - taking up to 3 rack units of space. They have much more complex circuitry to handle the conversion. Converters of this quality typically RENT for $1200 PER DAY or more - the rental cost per day alone is greater than 5 times the cost of a home consumer grade converter purchased outright. The highest end production houses and international broadcasting require and demand this this level of quality and have the budgets to afford it. Most clients do not require, nor are willing to spend the $ to achieve this level of technical perfection. A good balance between price and performance is a mid range converter. A mid-range converter offers close to true broadcast quality at much more affordable price. In the case of the mid range converters, resolution is maintained and sync meets NTSC RS-170A specifications - though there will be more motion artifacts and some flicker owing to their less sophisticated algorithms and less circuitry required to support those algorithms. For most clients, it's a cost effective tradeoff.Many operations are claiming "Broadcast Quality" VHS PAL to NTSC conversions for as low as $9.95 for a two hour tape. For less than $5.00 per hour, you can be absolutely certain it will be anything BUT broadcast quality or much of any quality for that matter. (If it does turn out to be true broadcast quality, let us know - we want to buy stock in their company before the major networks & Wall Street finds out and beats a path to their door). Anyways, if you don't mind a LOT of motion artifacts , picture judder, dropped frames and poor resolution, then this is undoubtedly a great bargain. If you just need it converted to see what's on the the tape or haven't the budget to spend more, then this is also the way to go. Most clients desire something better.
Like everything else, you get what you pay for....
Just think..... And all this time you mistakenly thought that world standards conversion was confusing.
World Standards Lookup Table
One worldwide standard would be a dream come true, but will never be realized in the foreseeable future due to the large installed base of receivers and equipment throughout the world. In the meantime we'll all have to refer to charts such as this.
COUNTRY VHF UHF AFGHANISTAN
PAL/SECAM-B
ALBANIA
PAL-B
PAL-G ALGERIA
PAL-B
PAL-G ANGOLA
PAL-l
ARGENTINA
PAL-N (Cable: PAL-NC)
PAL-N (Cable: PAL-NC) AUSTRALIA
PAL-B
PAL-G AUSTRIA
PAL-B
PAL-G AZORES
PAL-B
BAHAMAS
NTSC-M
BAHRAIN
PAL-B
PAL-G BANGLADESH
PAL-B
BARBADOS
NTSC-M
BELGIUM
PAL-B
PAL-H BERMUDA
NTSC-M
BOLIVIA
NTSC-M
NTSC-M BOTSWANA
PAL-I
BRAZIL
PAL-M
PAL-M BRUNEI
PAL-B
PAL-B BULGARIA
SECAM D
SECAM-K BURKINA FASO
SECAM-K1
BURMA
NTSC-M
BURUNDI
SECAM-K1
CAMBODIA
NTSC-M
CAMEROON
PAL-B
PAL-G CANADA
NTSC-M
NTSC-M CANARY ISLANDS
PAL-B
CHAD
SECAM-K1
CHILE
NTSC-M
NTSC-M CHINA
PAL-D
COLOMBIA
NTSC-M
NTSC-M COSTA RICA
NTSC-M
NTSC-M CROATIA PAL-B PAL-G CUBA
NTSC-M
NTSC-M CYPRUS
PAL-B
PAL-G CZECH REPUBLIC
PAL-B-G
PAL-B-G DAHOMEY
SECAM-K1
DENMARK
PAL-B
PAL-G DJIBOUTI
SECAM-B
SECAM-G DOMINICAN REP
NTSC-M
NTSC-M ECUADOR
NTSC-M
NTSC-M EGYPT
SECAM B/PAL-B
SECAM-G/PAL-G EL SALVADOR
NTSC-M
NTSC-M EQUATORIAL GUINEA
PAL-B
ESTONIA
PAL-B/SECAM-D
PAL-G/SECAM-K ETHIOPIA
PAL-B
PAL-G FIJI
PAL-B
FINLAND
PAL-B
PAL-G FRANCE
SECAM-L (French SECAM)
SECAM-L (French SECAM) FRENCH POLYNESIA
SECAM-K1
GABON
SECAM-K1
GAMBIA
PAL-I
GERMANY
PAL-B
PAL-G GHANA
PAL-B
PAL-G GIBRALTAR
PAL-B
PAL-H GREECE
PAL-B
PAL-G GREENLAND
NTSC/PAL-B
GUADELOUPE
SECAM-K1
GUAM
NTSC-M
GUATEMALA
NTSC-M
NTSC-M GUINEA
PAL-K
GUYANA (FRENCH)
SECAM-K1
HONDURAS
NTSC-M
NTSC-M HONG KONG
PAL-I HUNGARY
PAL (Formerly SECAM-D)
PAL (Formerly SECAM-K) ICELAND
PAL-B
PAL-G INDIA
PAL-B
INDONESIA
PAL-B
PAL-G IRAN
SECAM-B
SECAM-G IRAQ
SECAM-B
IRELAND
PAL-I
PAL-I ISRAEL
PAL-B
PAL-G ITALY
PAL-B
PAL-G IVORY COAST
SECAM-K1
JAMAICA
NTSC-M
JAPAN
NTSC-M
NTSC-M JORDAN
PAL-B
PAL-G KENYA
PAL-B
PAL-G KOREA NORTH
PAL
KOREA SOUTH
NTSC-M
NTSC-M KUWAIT
PAL-B
LATVIA
PAL-B/SECAM-D
PAL-G/SECAM-K LEBANON
SECAM-B
SECAM-G LIBERIA
PAL-B
PAL-H LIBYA
SECAM-B
SECAM-G LITHUANIA
PAL-B/SECAM-D
PAL-G/SECAM-K LUXEMBOURG
PAL-B/SECAM-L
PAL-G/SECAM-L MADAGASCAR
SECAM-K1
MADEIRA
PAL-B
MALAGASY
SECAM-K1
MALAWI
PAL-B
PAL-G MALAYSIA
PAL-B
MALI
SECAM-K1
MALTA
PAL-B
PAL-H MARTINIQUE
SECAM-K1
MAURITANIA
SECAM-B
MAURITIUS
SECAM-B
MEXICO
NTSC-M
NTSC-M MONACO
SECAM-L
MONGOLIA
SECAM-D
MOROCCO
SECAM-B
MOZAMBIQUE
PAL-B
NAMIBIA
PAL-I
NEPAL
PAL-B
NETHERLANDS
PAL-B
PAL-G NETH. ANTILLES
NTSC-M
NTSC-M NEW CALEDONIA
SECAM-K1
NEW GUINEA
PAL-B
PAL-G NEW ZEALAND
PAL-B
PAL-G NICARAGUA
NTSC-M
NTSC-M NIGER
SECAM-K1
NIGERIA
PAL-B
PAL-G NORWAY
PAL-B
PAL-G OMAN
PAL-B
PAL-G PAKISTAN
PAL-B
PANAMA
NTSC-M
NTSC-M PARAGUAY
PAL-N
PAL-N PERU
NTSC-M
NTSC-M PHILIPPINES
NTSC-M
NTSC-M POLAND
PAL-D
PAL-K PORTUGAL
PAL-B
PAL-G PUERTO RICO
NTSC-M
NTSC-M QATAR
PAL-B
REUNION
SECAM-K1
ROMANIA
PAL-D
PAL-K RUSSIA
SECAM-D
SECAM-K RWANDA
SECAM-K1
SABAH / SAWARA
PAL-B
ST. KITTS
NTSC-M
NTSC-M SAMOA
NTSC-M
SAUDI ARABIA
SECAM-B
SECAM-G SENEGAL
PAL
SEYCHELLES
PAL-B
PAL-G SIERRA LEONE
PAL-B
PAL-G SINGAPORE
PAL-B
PAL-G SLOVAK REPUBLIC
PAL
PAL SOMALIA
PAL-B
PAL-G SOUTH AFRICA
PAL-I
PAL-I SPAIN
PAL-B
PAL-G SRI LANKA
PAL-B
ST. MARTIN * PAL/SECAM/NTSC-M * PAL/SECAM/NTSC-M * SUDAN
PAL-B
PAL-G SURINAM
NTSC-M
NTSC-M SWAZILAND
PAL-B
PAL-G SWEDEN
PAL-B
PAL-G SWITZERLAND
PAL-B
PAL-G SYRIA
SECAM B
TAHITI
SECAM-K1
TAIWAN
NTSC-M
NTSC-M TANZANIA
PAL-B
PAL-B THAILAND
PAL-B
TOGO
SECAM-K
TRINIDAD TOBAGO
NTSC-M
NTSC-M TUNISIA
SECAM- B
TURKEY
PAL-B
PAL-G UGANDA
PAL-B
PAL-G UKRAINE PAL / SECAM UNITED ARAB EMIRATES
PAL-B
PAL-G UNITED KINGDOM PAL-I UPPER VOLTA
SECAM-K1
URUGUAY
PAL-N (Cable: PAL-NC)
PAL-N (Cable: PAL-NC) USA
NTSC-M
NTSC-M VENEZUELA
NTSC-M
NTSC-M VIETNAM
PAL-B
PAL-G YEMEN
PAL-B
YUGOSLAVIA
PAL-B
PAL-G ZAIRE
SECAM-K1
ZAMBIA
PAL-B
PAL-G ZIMBABWE
PAL-B
PAL-G * The island of St. Martin has all the bases covered ! The "standard" used varies from station to station - Anything Goes !
World Standards Conversion Formats Supported
PAL to NTSC or SECAM Conversion
| PAL Source |
NTSC |
SECAM |
MESECAM |
Price | ||
|
VHS
VHS-C |
To |
Any |
or |
|
VHS |
0 - 60 Min $20.00 61 - 120 Min $30.00 |
|
BETA II, III
|
To |
Any |
or |
VHS |
0 - 60 Min $30.00 61 - 120 Min $45.00 |
NTSC to PAL or SECAM Conversion
NTSC Source PAL
MESECAM
SECAM
Price
Any
Format
We
SupportTo
VHS VHS-C
S-VHS S-VHS-C
DV MiniDV DVD-R
Video8, Hi8, Digital8or
VHS
VHS-C
3/4-UVHS
VHS-C
0 - 60 Min $20.00
61 - 120 Min $30.00Any
Format
We
SupportTo
BETA II, III
3/4-U, DVCAMBETA II, III
3/4-U0 - 60 Min $30.00
61 - 120 Min $45.00
SECAM to NTSC or PAL
SECAM Source
MESECAM
NTSC
PAL
Price
VHS VHS-C
S-VHS S-VHS-CTo
Any
Format
We
Supportor
VHS VHS-C
S-VHS S-VHS-C
3/4-U DV MiniDV
Video8, Hi8, Digital80 - 60 Min $20.00 61 - 120 Min $30.00
BETA II, III
3/4-UTo
Any
Format
We
Supportor
BETA II, III
3/4-U, DVCAM0 - 60 Min $30.00 61 - 120 Min $45.00
Snell & Wilcox Alchemist PhC Conversions
Format
Spot 15 min 20 min 45 min 60 min 90 min 120 min D1, D2, D3, D5, D9, Beta SX, DVcam DVpro, plus Formats noted above 155 185 250 310 360 425 480 570
Modified Dec 30, 2005
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