Talk:SECAM

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This article has much "general" information about how television signals are modulated, which compares SECAM to other television systems. Shouldn't this information go in another article (like Broadcast television system) instead? It's very interesting and informative but I don't think it's in the right place. Neckro 02:50, 7 Oct 2004 (UTC)

Contents

[edit] Speculation

Nonetheless, SÉCAM was partly developed for reasons of national pride.

Do we have indications of that? David.Monniaux 09:59, 14 Feb 2005 (UTC)

Many press articles of the era and recent literature about the subject document that the choice of SECAM vs PAL was a complicated political issue. Of course national pride was but one ingredient. Anorak2 04:32, 3 January 2006 (UTC)

[edit] History

The first colour television sets cost 5000 Francs.

This information is useless without saying something about how much was one French Franc worth in 1967. Please provide some info, be it 1967 average salary, exchange rate with 1967 US dollar, inflation-adjusted value in 2005 euros or cost of a typical black and white television set. Taw

Addition: It seems to me that saying that SECAM is only used in France at the top, and then listing a whole bunch of countries at the bottom, is a little misleading.

[edit] NTSC option

The previous version said

and because of frame rate differences (50 versus 60 Hz) and the requirement for compatibility with monochrome TV receivers, it was not possible for Europeans to adopt NTSC

This is not true as stated. Of course it would not have made sense to adopt the 525 lines/60 Hz system in Europe, but it would have been perfectly possible to introduce NTSC colour encoding on top of the European 625/50 systems. 625/50/NTSC signals were indeed tested in Germany and the UK, and AFAIK the UK seriously considered to introduce it as standard there. It was a matter of preference not to go for that system eventually, but to use PAL or SECAM instead. I changed the text accordingly. Anorak2 04:25, 3 January 2006 (UTC)

Addition: Someone edited my comment to the effect that the UK tested 405/25/NTSC signals. Both are true, they tested NTSC with both formats at different times. Anorak2 11:00, 4 April 2006 (UTC)

[edit] Accent

I was under the impression that accents generally aren't placed above upper-case letters in French. Is the title of this article correct? Fourohfour 13:38, 13 January 2006 (UTC)

Accents aren't required on upper case vowels, but allowed. The French version of this article uses both SÉCAM and SECAM inconsistently. But in non-French texts it's more common to omit the accent, IMHO. Regards Anorak2 17:08, 13 January 2006 (UTC)
This is a tricky issue. The accented ‘e’ comes from the second letter in the word séquential. It is customary (and, I do believe, proper) to omit all accents on capital letters in French. A Google search in French for “SECAM” (Google ignores accents) shows that “SECAM” is overwhelmingly used over “SÉCAM”, though the French language Wikipedia uses both, with the page named «Séquentiel couleur à mémoire». I do not think the page should be named “SÉCAM”, as that is not commonly used—“SECAM” should be used (as opposed to «Séquentiel couleur à mémoire», for consistency with NTSC and PAL).—Kbolino 07:39, 19 March 2006 (UTC)
The article name is SÉCAM (correctly, from the French expression). Whatever is used, it should be consistent. That is why I changed SECAM to SÉCAM in a number of instances. In anyone would write a bot to change all instances, either way, that's fine with me, but I would prefer it as it is. MH 16:39, 21 March 2006 (UTC)
It never was "proper" to drop accents in capitals. The usage was tolerated in the previous century very simply because typography (and older typewriters) couldn't handle the accents. This said, the accent-less "SECAM" is indeed in common use.
Urhixidur 12:00, 8 June 2006 (UTC)

[edit] How to Type the letter É in SÉCAM ?

If you want to use "É" instead of "E" in a SÉCAM, then use these keyboard stroke / keys :
Press "S". Then press ...
Alt + 0201 (it means, first press the "Alt" (Alternative/Alternate) key in your keyboard, and keep it pressing with your left hand, then press the digits 0 2 0 1 in sequence, one by one, in the right-side numeric keypad).
Then press "C", "A", "M".
Then you will get SÉCAM. To make it a linkable word (to goto this article,) use two third brackets at the beginning and end of the name, like this [[SÉCAM]], then you will get linkable SÉCAM.
If you want to link to this (English) article through URL, then use below code ...
http://en.wikipedia.org/wiki/S%C9CAM
or, http://en.wikipedia.org/wiki/S%C3%89CAM
For this type of other characters, see Windows Alt keycodes. ~ Tarikash.

To do it in Linux, hold down Alt Gr, and press the ; button, followed by the compatable letter of choice, in this case "E". —The preceding unsigned comment was added by 195.137.112.253 (talk • contribs) .
Or, on Macintosh, hold down the "Option" ("Alt") key, press "e" (which "arms" the accent acute), release "Option", and press "E" (or any other letter compatible with accent acute). Et voila!
Atlant 21:41, 26 October 2006 (UTC)

[edit] SECAM is a dead system now

Contrary to what many people think there are no SECAM DVDs. I've called shops in France and Russia, which was the core-nations of this system, and they assured me they used PAL now with the transition from VHS to DVD. Later I bought two DVDs from each country and these was PAL that played OK on my R2 PAL player. Third proof is of course to go to Ebay and search for french and russian DVDs. Look then at the bigger backcover scans and it's written PAL on all of them. (All this confusion surrounding SECAM DVDs comes from the DVD Demystified page which is unclear on this point). After the slow death of the videocassette, SECAM is a dead system now. All SECAM countries have changed system to PAL now, except Cuba who has changed to NTSC for geographical reasons. And after the four South American countries using the local videosystems PAL-M and PAL-N, changed to NTSC with the introduction of DVD, there are only PAL and NTSC left on DVD.

Stein Sundqvist 84.210.117.113

Your whole search for "SECAM DVDs" was pointless, and you're drawing false conclusions from the answers you got. "SECAM", "PAL" and "NTSC" are strictly speaking meaningless terms when applied to digital media, because they are encoding schemes for analogue video signals. DVDs contain neither NTSC nor PAL nor SECAM signals. They contain digital information of various frame rates and pixel resolutions. The most common ones are 30 frames at 480 scan lines and 25 frames at 576 scan lines. These are commonly labelled "NTSC" and "PAL" respectively, but that does not mean they contain PAL or NTSC signals in the sense of the word. 25/576 discs could as well be commonly called "SECAM" and that would be just as correct (or wrong) as calling them "PAL discs". It is just not very common to do so. Likewhise 30/480 discs could as well be named "PAL-M" instead of "NTSC" using the same logic, it is just uncommon to do so.
The only place where true NTSC/PAL/SECAM signals exist with DVDs is when a DVD players plays them back and converts them into an analogue signal for viewing on conventional television sets. Players sold in PAL countries will convert 25/576 discs to analogue PAL signals, players sold in SECAM countries will convert the same discs to analogue SECAM signals (at least optionally, usually they can play them in PAL too).
It is true that a lot of former SECAM countries (notably in former eastern europe) have converted to PAL broadcasts in the 1990s. Not all have though, for example Russia, Ukraine and certainly France continue to broadcast in SECAM.
Meanwhile broadcasts are becoming all digital. The process is already gone quite far in the UK and Germany amongst others. When this process will be finished, all analogue standards will be dead, because digital signals are neither PAL nor SECAM. They are "DVB" of which there exist three variants for satellite, terrestrial and cable distribution. The resolution of DVB remains 25/576 for the time being and will therefore remain compatible with conventional PAL and SECAM equipment (the DVB boxes output PAL or SECAM signals). Analogue signals (PAL and SECAM) will probably continue to exist in domestic equipment for compatibility for quite a while. The standard is capable of HDTV resolution too, but that is another issue.
Incidentally, Cuba was never SECAM.
Anorak2 08:18, 12 June 2006 (UTC)
Regarding the 2nd paragraph: I never heard of, or seen DVD players outputting a SECAM signal in France, but I know that at least some cable and satellite boxes can output a SECAM signal for recording on the VCR. Overall, i have the impression that Stein Sundqvist did not fully read the SECAM article, as these issues are discussed there.Adam Mirowski 17:53, 29 September 2006 (UTC)

[edit] Analogue video tape formats Natively supporting Secam

Does anyone have a list of which analogue video tape formats ever supported SECAM of any variant? (Digital not relevant for same reasons as DVD). Please update / correct this list:

Secam recorded onto the tape:
VHS
Beta (Betamax)
Umatic (**UmaticSP and Umatic Hi-band unknown**)
N1700 (VCR-LP)
V2000 ??
Secam not recorded onto the tape but converted to PAL or not supported at all:
SVHS
Video8
Hi8
BetacamSP
N1500 (VCR)
SVR
CVC
V-Cord

Updates welcome. Colin99 13:06, 14 October 2006 (UTC)

SVHS is not "unknown", it is already discussed in the article. N1700 did support SECAM.
I don't know what are "rare machines": up to the 1990s there were not many multistandard
VCRs. (From the marketing point of view, VCRs sold in France were cheap SECAM-only or
more expensive SECAM+PAL. Then SECAM+PAL+NTSC-mono arrived and finally the NTSC-stereo
feature was added.) Does having an internal converter count as "support", was it "rare"?
Some info at
http://www.picsound.be/services/les_formats_video_que_nous_traitons_2.html Adam Mirowski 15:19, 14 October 2006 (UTC)

By "unknown", I meant unknown to me, I was asking the question. So I've updated it in the list. Also removed "rare", it either is or isn't then (I used the rare tag because some formats such as V2000 may have supported SECAM on just one model). I've also taken some information from the web link you provided. However I would take issue with the labels of "proprietary format" which that author has stuck on almost everything including Video8! What we don't know about then is BetacamSP and N1500 in particular, and some variants of Umatic. Thanks for your help in compiling this list, when it's finally tied down it could join the main article.Colin99 23:11, 27 October 2006 (UTC)

Having read some more, I see that SVHS and Hi8 decks did not RECORD in secam. So I've altered the heading to "natively" support secam, as opposed to convert to PAL and maybe back. I see you did mention this above. So SVHS and Hi8 move to the not supported group.

The point of all this is to find what selection of video recorders would be required in order to play any tape from anywhere in the world. So "standard" PAL S-VHS and Hi8 decks will play SECAM recordings. Is this your understanding? Colin99 19:00, 2 November 2006 (UTC)

There's no such thing as SVHS or Hi8 SECAM recordings. SVHS or Hi8 machines sold in SECAM countries are PAL and produce PAL tapes. The machines "support" SECAM by transcoding it to PAL prior to recording, but that is entirely a hardware issue and not a property of the tape format. It can be done with any format capable of PAL - using an external transcoder if the VCR doesn't have one -, therefore it's meaningless to make a list of formats which "support" this method. All do. Anorak2 03:50, 4 November 2006 (UTC)
Some SVHS recorders could transcode PAL back to SECAM, even theoretically mine, except that this feature - documented in the manual - is not actually implemented in the apparatus. It is a SVHS+DVD combo and I guess they saved on costs by eliminating a pretty useless feature, given that DVD does not output SECAM.
It has the standard feature of transcoding NTSC to PAL: setting this on PAL tapes gives quite funny effects, as the tape speed changes and the image is warped. It prolly can transcode SECAM to PAL from SECAM tapes too, but this is hard to guess because my TV set automatically adapts to both formats and does not even say which signal it gets.
BTW, why is Video8 still in the "supported" list above. The article says it was not supported. Adam Mirowski 23:39, 4 November 2006 (UTC)
Some SVHS recorders could transcode PAL back to SECAM Sure, my point was that this is not a property of the tape format, but a feature of specific machines.
It prolly can transcode SECAM to PAL from SECAM tapes too, but this is hard to guess because my TV set automatically adapts to both formats and does not even say which signal it gets. With a trained eye you can tell SECAM by the typical artefacts it produces: red & blue noise mostly at sharp edges, like here: http://www.pembers.freeserve.co.uk/World-TV-Standards/SECAM-Flare.jpg Anorak2 10:14, 6 November 2006 (UTC)
Hmm, this picture seems to rather show the effect of a poorly constructed video overlay, in a satellite box. I never saw such problems on my VCRs when they were overlaying information on the signal and I don't think I saw them in satellite boxes either for analog secam signals for public channels. Adam Mirowski 12:26, 8 November 2006 (UTC)
It's actually an artefact of the SECAM decoding process wherever it occurs, the overlaying is not its cause (merely an example where the artefacts are very pronounced due to the sharp edges of the computer generated characters). I have those streaks on all SECAM VHS tapes I own (some from East German TV, some from France), I remember them from SECAM broadcasts wheren they were still on air here, and even nowadays I occasionally see them on PAL stations when they happen to play archived SECAM footage which must inevitebly have gone through a SECAM dedoder at some stage. Anorak2 16:46, 8 November 2006 (UTC)


Corrected Video8 as pointed out. As mentioned earlier, the point of this list is to catalogue a list of formats for which a SECAM video recorder/player is required in order to play a tape recorded in a SECAM country. I wonder now whether V2000 and N1700 machines record a SECAM signal, or if they too transcoded to PAL. Anyone know the answer? Colin99 20:05, 5 November 2006 (UTC)

[edit] Problem with a country mentioned

According to this article, Greece uses the SECAM-B&G standard. However, according to the 2005 edition of the WRTH, Greece uses the PAL-B&G standard, not the SECAM-B&G standard. Is it right to assume that Greece made the transition from SECAM to PAL? -Daniel Blanchette 17:17, 8 August 2006 (UTC)

Greece is among the countries who migrated from SECAM to PAL. The process has been finished some time ago, they're all PAL now. Anorak2 08:55, 26 October 2006 (UTC)

[edit] The "SECAM has no dot crawl" nonsense

I think the paragraph about dot crawl in SECAM is technically inaccurate and generally misleading. I wrote it originally (mea culpa), anonymously, together with many other parts of this article, but made wrong guesses. When I started feeling something is fishy about this stuff, I was hoping someone more qualified would correct this, but it has been almost 2 years now. If this article is supposed to become GA-class, this should be fixed.

In my current opinion SECAM is even worse at dot crawl than PAL or NTSC. I think that the complex FM spectrum prevents any miraculous comb-style intermixing of the baseband luminance signal and of the chrominance subcarriers. (BTW, the article should finally say that SECAM uses different sub-carrier frequencies for Red and Blue signals.) The old books I have do discuss the interference of both signals, and say how SECAM uses tricks to minimize the visual impact (I forgot the details since, the books are burried somewhere currently after my recent move; the presence of 2 different subcarrier frequencies might be part of that scheme). But I am not sure if this was really implemented this way, because it might not work so well. So I am afraid that in real implementations, if a color signal is transmitted, a SECAM receiver will simply cut out the top of the spectrum to get the luminance undisturbed. For B&W this is not necessary. I wonder what happens at the transmitter. I guess that the top of the luminance does not need cutting there, as the FM chrominance subcarrier is not that easily disturbed.

PAL lovers, do not rejoice too soon! I am not sure SECAM is actually worse than PAL here as far as broadcast TV is concerned. Given that PAL receivers do not have comb-filters in general, they also must plainly cut out the high-frequencies or just display the dot-crawl.

BTW, if one carefully observes the classic Philips PM5544 test pattern in PAL and SECAM versions, one can notice that the series of vertical line patterns which go denser and denser from left to right, and which allows to appreciate the horizontal resolution of the receiver is different. In SECAM, after the middle point, it goes less dense again.

That SECAM is unable to play the comb-filter trick, might be a major reason why DVD players do not output it. Indeed, whatever tricks are used, it will not offer better horizontal resolution on DVD than than on broadcast, while with PAL/NTSC and a comb-filter, one might hope to "go to 11" more easily. But then it is easier and better to just use RGB signals.

Additionally, someone has speculated that the introduction of SCART in France (compulsory for sets sold after January 1981, or maybe already January 1980), and especially the presence of RGB input had something to do with the fact that the frequency modulation of SECAM is problematic with set-top boxes. SCART has been devised around the same time as the Antiope teletext system. People probably noticed it was hard to take a SECAM signal, decode teletext and insert it back into the color signal (for subtitles) before giving it to the TV set. So they considered passing the SECAM signal unchanged but have the "fast switching" feature in SCART to insert RGB areas here and there. Adam Mirowski 16:19, 14 October 2006 (UTC)

Can't say much about the frequency considerations, but one obvious drawback concerning cross-luminance is that the SECAM carrier is always at full amplitude and thus causes distortion in all regions of the image, whereas in PAL and NTSC its amplitude is reduced to zero in non-coloured regions of the image, and therefore crosstalk is reduced. I remember watching SECAM signals on East German television, they used to completely switch off the SECAM carrier (the switching was visible) when showing black&white movies for this reason. Anorak2 18:41, 14 October 2006 (UTC)
I remember these transitions as well, but only because the "tint" of the image changed, rather than because the image was less distorted. Yesterday, I tried to visually compare two versions of a cable channel, one in SECAM, the other one digital, transmitted as RGB to the TV set. This was on a live talk-show, with a very good picture, and on a classic TV set, without any kind of digital processing, 100 Hz, etc, which can alter the picture. It appears that dot crawl is indeed visible in SECAM, along edges, but only when objects move, so it is akin to motion blur. Once people stop moving significantly, it becomes invisible and the image is not very different from the RGB signal which of course has never any problem. I still need to compare with the PAL signal generated by the set-top box instead of RGB and maybe with the SECAM signal the box can only generate on the "VCR" SCART socket. Adam Mirowski 14:45, 15 October 2006 (UTC)
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