PAL

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For other uses, see PAL (disambiguation).

PAL, short for phase-alternating line, phase alternation by line or phase alternation line, is a colour encoding system used in broadcast television systems in large parts of the world. Other common analogue television systems are SECAM and NTSC.

Contents 1 History of the PAL standard 2 Technical details 2.1 PAL vs NTSC 2.2 Multisystem PAL support 2.3 PAL-M standard (Brazil) 2.4 PAL-N and PAL-NC 2.5 All PAL systems interoperable except PAL-M (525/50) 2.5.1 Baseband interoperability (analog) 2.5.2 Baseband interoperability (digital) 2.6 Use with Progressive Sources 2.7 PAL speed-up 3 Countries and territories that use PAL B, G, D or K 3.1 Europe 3.2 Asia 3.3 Africa 3.4 Oceania 4 Countries and territories that use PAL-I 4.1 Europe 4.2 Asia 4.3 The Americas 4.4 Africa (all both VHF and UHF) 5 Countries and territories that use PAL-M 5.1 Latin America 5.2 Asia 6 Countries that use PAL-N or PAL-NC 6.1 Latin America 7 References 8 See also 9 External links

[edit] History of the PAL standard

PAL was developed by Walter Bruch at Telefunken in Germany. The format was first unveiled in 1963, with the first broadcasts beginning in Britain and Germany in 1967. ^[1]

Telefunken was later bought by the French electronics manufacturer Thomson. Thomson also bought the Compagnie Generale de Télévision where Henri de France developed SECAM, historically the first European colour television standard. Thomson nowadays also co-owns the RCA brand for consumer electronics products, which created the NTSC colour TV standard before Thomson became involved.

The term "PAL" is often used informally to refer to a 625-line/50 Hz (576i, principally European) television system, and to differentiate from a 525-line/60 Hz (480i, principally North American/Central American/Japanese) "NTSC" system. Accordingly, DVDs are labelled as either "PAL" or "NTSC" (referring informally to the line count and frame rate) even though technically neither of them have encoded PAL or NTSC composite colour.

[edit] Technical details

The basics of PAL and the NTSC system are very similar; a quadrature amplitude modulated subcarrier (typically at approximately 4.43 MHz for PAL, and 3.58 MHz for NTSC) carrying the chrominance information is added to the luminance video signal to form a composite video baseband signal (CVBS). The SECAM system, on the other hand, uses a frequency modulation scheme on its colour subcarrier. The name "Phase Alternating Line" describes the way that the phase of part of the colour information on the video signal is reversed with each line, which automatically corrects phase errors in the transmission of the signal by cancelling them out. (Lines where the colour phase is reversed compared to NTSC are often called PAL or phase-alternation lines, which justifies one of the expansions of the acronym, while the other lines are called NTSC lines.) Early PAL receivers relied on the imperfections of the human eye to do that canceling; however this resulted in a comb-like effect on stronger phase errors. Thus, most receivers use a delay line which stores the received colour information on each line of display; an average of the colour information of the current line and that of the previous line is then used to drive the picture tube. This reduces vertical colour resolution compared to the NTSC system; however, since the human retina also has a colour resolution that is much lower than its brightness resolution, this effect is not visible. NTSC, PAL, and SECAM all have chrominance bandwidth (horizontal colour detail) reduced greatly compared to the luminance signal anyway.

[edit] PAL vs NTSC

NTSC receivers have a tint control to perform that correction manually. Some engineers jokingly expand NTSC to "Never Twice the Same Color" or "Not the Same Color" while referring to PAL as "Perfect At Last", "Peace At Last", or "Pay for Additional Luxury"!

However, the alternation of colour information—Hanover bars—can lead to picture grain on pictures with extreme phase errors even in PAL systems, causing some engineers to alternatively expand PAL to "Picture Always Lousy" or "Pretty Awful Looking". Another expansion is "Pay Another Licence" in reference to the British television licence fee which is higher for colour sets.

A PAL decoder can be seen as a pair of NTSC decoders

• PAL can be decoded with two "NTSC" decoders.
• By switching between the two NTSC decoders every other line it is possible to decode PAL without a phase delay line or two phase PLL circuit.
• This works because one decoder receives a colour subcarrier with negated phase in relation to the other decoder. It then negates the phase of that subcarrier when decoding. This leads to smaller phase errors being cancelled out. However a delay line PAL decoder gives superior performance. Some Japanese TVs originally used the dual NTSC method to avoid paying royalty to Telefunken.
• PAL and NTSC have slightly divergent colour spaces, but the colour decoder differences here are ignored.
• The issue of frame rates and colour subcarriers is ignored in this technical explanation. These technical details play no direct role (except as subsystems and physical parameters) to the decoding of the signal.

[edit] Multisystem PAL support

Recently manufactured PAL television receivers can typically decode all of these systems except, in some cases, PAL-M and PAL-N. Many of them can also receive Eastern European and Middle Eastern SECAM, though usually not French SECAM, unless they are made for the French market. Many of them can also accept baseband NTSC-M, such as from a VCR or game console, though not usually broadcast NTSC.

[edit] PAL-M standard (Brazil)

In Brazil, PAL is used in conjunction with the 525 line, 29.97 frame/s system M, using (very nearly) the NTSC colour subcarrier frequency.

• Almost all other countries using system M use NTSC.

The PAL colour system (either baseband or with any RF system, with the normal 4.43 MHz subcarrier unlike PAL-M) can also be applied to an NTSC-like 525-line (480i) picture to form what is often known as "PAL-60" (sometimes "PAL-60/525" or "Pseudo PAL").

See PAL-M (television)

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[edit] PAL-N and PAL-NC

In Argentina, Paraguay and Uruguay, PAL is used with the standard 625 line system, but again with (very nearly) the NTSC colour subcarrier frequency (3.58 MHz); these variants are called PAL-N and PAL-NC.

• PAL-N and PAL-NC should not be viewed as wildly incompatible versions of the PAL system, only the choice of colour subcarrier is different.
• Most PAL recorders, DVD players etc support baseband (colour subcarrier free) connections -- so PAL-N and PAL-NC systems are not as problematic as they used to be.

[edit] All PAL systems interoperable except PAL-M (525/50)

The PAL colour system is usually used with a video format that has 625 lines per frame (576 visible lines, the rest being used for other information such as sync data and captioning) and a refresh rate of 50 interlaced fields per second (or 25 full frames per second), such as systems B, G, H, I, and N (see broadcast television systems for the technical details of each format).

• Some countries in Eastern Europe which formerly used SECAM with systems D and K have switched to PAL while leaving other aspects of their video system the same.
• However, some European countries have changed completely from SECAM-D/K to PAL-B/G. ^{[citation needed]}

On RF (i.e via a Modulator or TV Aerial) the difference between I, D/K and B/G is sound. These use different sound subcarriers, so with mismatch on Modulator Settings or an imported TV there will be perfectly normal Colour Video, but possibly no audio. Some TVs and VHS tuners have multiple filters in parallel or switched for the 6MHz, 5.5MHz, 6.5MHz or 4.5MHz sound carriers. Nicam is an additional 6.5MHz offset carrier carrying stereo digitally, on 6.0MHz PAL I systems. Germany particularly uses two separate FM sound carriers on PAL B/G. (Stereo FM Radio uses a mono signal with a DSBSC L-R audio centered on 38kHz with a 19kHz pilot to aid decoding. Hence the German Zweiton and Nicam both give better performance than FM Radio).

[edit] Baseband interoperability (analog)

When PAL video is transmitted via baseband (via consumer device cables, not RF), most of the differences between the "one-letter" systems are no longer significant, other than vertical resolution and frame rate.

In this context, unqualified PAL invariably means

• 576 lines
• 25 frames per second
• interlaced video
• with PAL colour (4.43 mhz or 3.58 mhz (PAL-M, PAL-N & PAL-NC))
• FM audio (mono) as only French SECAM uses AM modulaton for audio
• mono or stereo audio if sent via connector cables between devices

[edit] Baseband interoperability (digital)

In digital video applications, such as DVDs and digital broadcasting, colour encoding is no longer significant; in that context, PAL means only

• 576 lines
• 25 frames/50 fields {second}
• interlaced video
• PCM audio (baseband)

There is no longer any difference (in the digital domain) between PAL and SECAM. Digital video uses its own separate colour space, so even the minor colour space differences between PAL and SECAM become moot in the digital domain.

[edit] Use with Progressive Sources

When PAL is used to transmit content which was originally composed of 25 progressive full frames per second, the odd field of the frame is transmitted first. This is opposite to NTSC. Systems which recover progressive frames, or transcode video should ensure that this 'Field Order' is obeyed, otherwise the recovered frame will consist of a field from one frame and a field from an adjacent frame, resulting in 'comb' interlacing artifacts.

[edit] PAL speed-up

Motion pictures are typically shot on film at 24 frames per second. When telecined and played back at PAL's standard of 25 frames per second, films run 4.2% faster. [1] Unlike NTSC's telecine system, which uses 3:2 pulldown to convert the 24 frames per second to the NTSC frame rate, PAL results in the telecined video running 4.2% shorter than the original film as well as the equivalent NTSC telecined video. It also increases the pitch of the soundtrack by 70.67 cent — ⅔ of a semitone, which people with absolute pitch will notice immediately.

However, some movie enthusiasts prefer PAL speed-up over NTSC's 3:2 pulldown, because the latter results in telecine judder, a visual distortion not present in PAL sped-up video. ^[2]

Software which corrects the speed-up is available for those viewing PAL DVD films on their computers, WinDVD's "PAL TruSpeed" being the most ubiquitous. This method results in a slight decrease in audio quality.

[edit] Countries and territories that use PAL B, G, D or K

[edit] Europe

Albania Austria Belgium Bosnia and Herzegovina Bulgaria Canary Islands Croatia Cyprus Czech Republic Denmark Estonia Faroe Islands Finland Germany Greece Greenland Hungary Iceland Italy Latvia

Liechtenstein Lithuania Luxembourg Malta Montenegro Netherlands Norway Poland Portugal, including Madeira and Azores Republic of Macedonia Romania Serbia Slovenia Slovakia Spain Sweden Switzerland Turkey Vatican City

[edit] Asia

Afghanistan Bahrain Bangladesh Brunei China (mainland) Gaza & West Bank India Indonesia Iran Iraq Israel Jordan Kuwait Lebanon Maldives Malaysia

Myanmar Nepal North Korea Oman Pakistan Qatar Singapore Sri Lanka Syria Thailand Timor Leste United Arab Emirates Vietnam Yemen Saudi Arabia

[edit] Africa

Botswana Cameroon Cape Verde Egypt Eritrea Ethiopia Gambia Ghana Guinea Guinea-Bissau Kenya Liberia Malawi Mozambique

Nigeria Seychelles Sierra Leone Somalia South Africa Sudan Swaziland Tanzania Tunisia Uganda Zambia Zanzibar Zimbabwe

[edit] Oceania

• Australia (uses PAL-B (UHF band), but Zweiton for stereo)
• Christmas Island (see Australia)
• Cook Islands (see New Zealand)
• Easter Island
• Fiji will probably convert to DVB-T by 2010
• New Zealand (uses NICAM for stereo)
• Norfolk Island (see Australia)
• Papua New Guinea
• Solomon Islands
• Tonga, Tonga is converting to NTSC and probably ATSC
• Vanuatu

Note about Australia & NZ with respect to stereo audio:

• Australia & NZ have identically allocated UHF TV bands.
• NZ's use of NICAM means that imported Australian TV sets only work in mono.
• NZ and Australia have incompatible VHF TV bands, namely the primary carrier frequencies are different. In some cases the offsets are minor, but in others very significant.
• DVB-T (using UHF band) may eliminate the incompatibility issues between Australia and NZ's TV frequency allocations.

[edit] Countries and territories that use PAL-I

[edit] Europe

• Gibraltar
• Republic of Ireland (VHF and UHF)
• United Kingdom (UHF only)

[edit] Asia

• Hong Kong [2]
• Macau [3]

[edit] The Americas

• Falkland Islands (UHF only)

[edit] Africa (all both VHF and UHF)

• Angola
• Ascension Island
• Lesotho
• Namibia
• South Africa
• Tristan da Cunha

[edit] Countries and territories that use PAL-M

[edit] Latin America

• Brazil (PAL-M)

[edit] Asia

• Laos (SECAM & PAL-M)

[edit] Countries that use PAL-N or PAL-NC

[edit] Latin America

• Argentina (NTSC & PAL-NC)
• Paraguay
• Uruguay (PAL-N)

[edit] References

[edit] See also

• PALplus
• Broadcast television systems
  • ATSC
  • BTSC
  • NTSC
  • NTSC-J
  • RCA
  • SECAM
• Moving image formats
• Oldest television station

[edit] External links

• More information about TV standards
• Review of the different refresh rates of PAL, NTSC and motion picture films

Digital video resolutions

Designation	Usage examples	Definition (lines)	Rate (Hz)
			Interlaced (fields)	Progressive (frames)
Low; MP@LL	LDTV, VCD	240; 288 (SIF)		24, 30; 25
Standard; MP@ML	SDTV, SVCD, DVD, DV	480 (NTSC, PAL-M)	60	24, 30
		576 (PAL, SECAM)	50	25
Enhanced	EDTV	480; 576		60; 50
High; MP@HL	HDTV, HD DVD, Blu-ray Disc, HDV	720		24, 30, 60; 25, 50
		1080	50, 60	24, 30; 25
This table illustrates total horizontal and vertical pixel resolution via box size. It does not accurately reflect the screen shape (aspect ratio) of these formats, which is either 4:3 or 16:9.