Simply FAQ for video resolutions
Video Resolutions
By SatStorm
Even if the subject isn't exactly "how to", I think it can help the "how to" process of Video Grabbing/encoding in general. So, I post it here and if it is needed, moderators will move it to other sections.
Which are the "legal" resolutions for DVD/VCD/SVCD/CVD?
Many people ask about the "legal" resolutions of digital video. So, I decided to write a few words for this subject, hoping I'll help some people out there:
First of all, just for the info, the term "resolution" isn't exactly the correct term. The correct term is "frame size" (pixels x lines). But most people use the term "resolution" and because this is a simply FAQ, I'll use it too! So...
The official (legal) resolutions for optical media are:
720 X 576 (480 NTSC). Used by most DVD.
704 X 576 (480 NTSC). Used by some DVD
480 X 576 (480 NTSC). Used by SVCD
352 X 576 (480 NTSC). Used by DVD and China Video Disc (CVD). It is also the "official" SVHS resolution, determined by the creator of HS, JVC.
352 X 288 (240 NTSC). Used by VCD and DVD. It is also the "official" VHS resolution, determined by the creator of VHS, JVC.
The official names for those resolutions, come from the US. Those names are:
720 X 576 (480 NTSC): Full CCIR-601 , or CCIR-601 D1. It is the Full PAL/NTSC Studio resolution. Most of the time, people call it simply CCIR-601
704 X 576 (480 NTSC): CCIR-601 1/1 D1 or cropped CCIR-601 D1. Most of the time, people call it 1/1 D1. Very rare, you can see this resolution as 702 X 576/480. It is the TV Broadcast resolution
528 X 576 (480 NTSC) is defined as 3/4 D1. It is supposed to be the Laser Disc resolution, but ain't. I'll explain later
480 X 576 (480 NTSC) is defined as 2/3 D1. It is the SVCD resolution.
352 X 576 (480 NTSC) is defined as 1/2 D1. Used by DVD and CVD
The VCD resolution is 352 X 288 (240 NTSC) and it is called CIF- 601.
In some parts of Europe and especially Far East Asia, people tend to use other names to describe the legal DVD - Video resolutions. So, very often you see or read the terms D1, D2, D4 and D3 . Those names stands for:
D1 (or D-1) for 704 X 576
D2 (or D-2) for 352 X 576
D4 (or D-4) for 352 X 288
D3 (or D-3) stands for the 704 X 288 framesize. This resolution is very interesting, because is totally useless but fully supported by DVD - Video!
Those names are basically used a lot for -X- formats PAL based. Most known are the D4 DVD (a DVD with VCD resolution and VCD bitrates mostly VBR) and D2 DVD, which is a DVD-R with 1/2 D1 resolution mpeg 2 files. Many also call as "D4 SVCD", the xSVCD with a VCD resolution/bitrate. Those names are unofficial, so better use the US name system.
To make things even more confusing, CCIR officially changed its name to ITU-R, and the standard is now properly called ITU-R BT.601. Very rare, you could see things like ITU-R 1/1 D1, or ITU-R BT.601 1/1D1. Well, in 30 or more years (a generation later that is...) maybe that turns mainstream. Meanwhile, it is "good old" CCIR-601 for us!
The "other" common picture resolutions - (non CD/DVD based)
The Laser Disc resolution story
The Officially Laserdisc resolution is 528 X 576/480, but many titles in US, after 1990, are using the 544 X 480 resolution.
That happened because the first "cheap" video projectors in US, were using the VGA standard for video in. Of course, those machines were for professional use with PCs. But with the use of special (and cheap) connectors/adaptors or the "famous" VGA - out connection of specific Laserdiscs, it was possible for the very first time, for US video enthusiast, to have big picture at there houses. It was the only true solution for the first home theatres (the term "home cinema" came later...).
Unfortunately, VGA is not based on CCIR-601, so a picture adaption is needed (VGA is 640 X 480). In other words, the picture aspect was wrong and always a part or some parts of the picture was not in use. Because of Laser Disc limitations, the use of pan and scan method (like DVD - Video) wasn't possible. The only solution without compatibility problems and no cost, was to "upgrade" the laserdisc resolution, unofficially, to 544 X 480. And so it happen.
In Europe, the success of Laserdisc was minimal, so the few released PAL titles, continue to use the official resolution for PAL (528 X 576). In theory, there is a 544 X 576, but I never saw a Pal laserdisc using this resolution.
The DVB/ -s -t -c resolutions
The DVB transmissions became mainstream in Europe in 1996 and today are mainstream in US too. The last five years, the European Union (E.U.), force all television and radio providers of E.U. Members, to turn their services digital, for various reasons. So, except Germany and partly France (which the interest for analogue satellite TV still is huge), anything today is digital, on most cases not with the best possible results...
Technically speaking, DVB is based on mpeg 2 (like DVD) and support resolutions from full CCIR - 601 (top quality) to CIF (lowest quality). Almost any resolution between those limits can be a DVB picture resolution, with any bitrate up to 15000Kb/s. The correct output picture aspect is succeeded (if needed), by the use of the pan and scan method, which take place between the Digital/Analogue conversion, before the final picture signal goes to our TV/Videoprojector.
Some DVB examples:
The Holland channels Canal+ Rood and Canal+Blauw (Astra 1G - 19.2 East), are transmitting in full CCIR 601 resolution with VBR bitrate up to 15000kb/s (!). That is BETTER a standard DVD video.
TMF for Belgium and MTV Italy, both on Eutelsat W2 (16 East) are transmitting in full D1 resolution and bitrates up to 7500kb/s
The MTV/VH1 Channels on Astra 1G, are using 544 X 576.
Viva TV on Astra 1G and Onyx TV on Hotbird 3, are using 480 X 576.
352 X 576 is very common at almost all the Italian Free To Air music channels on Hotbird satellite series.
An example of very low picture resolution, is the Cnes channel (Hotbird 5, 13 east, Freq: 12558, S.R. 27500, F.E.C. 3/4). This channel transmits 352 X 288 with CBR bitrate up to?. 700kb/s!!!).
The known DVB resolutions till today in Europe are: 720 X 576, 704 X 576, 544 X 576, 528 X 576, 480 X 576, 352 X 576 and 352 X 288.
The last addition to the known DVB resolutions, comes from the Polonian subscription service Nowa Cyfra+ (Hotbird 13east). It is using (for some channels) the framesize of 640 X 576. Unfortunatelly, there is no correct pan and scan flags in this transmission and many satellite digital recievers are unable to Pan and Scan correct those channels. This is not a limitation of the DVB standard, just a "cheap" trick of the polish Nowa Cyfra + to make the subscripters choose and use only the "official" recievers of this package and not other alternative DVB recievers. The official DVB recievers of Nowa Cyfra + have those pan and scan flag infos embedded, so they are able to show those channels with no aspect problems.
This cheap trick does not effect DVB PC cards, only standalone DVB recievers.
Resolutions used with PCs :
With the "explosion" of the home Video enthusiasts the last couple of years, more resolutions appear.
DV for example, is using 768 X 576/480, and mpeg 4 (divx, xvid, asf, etc) is using resolutions like 384 X 288. This "mess" happens because PC enthusiasts and Power Users simply want to watch their DiVX/Xvid/Asf/etc at Television sets, with the use of the TV-out feature, most cards today offers.
Unfortunately, those TV-outs are made for PC resolutions, based on VGA (640 X 480) and not TV resolutions based on CCIR-601. So there are problems in the correct aspect of the picture (4:3 and 16:9, don't mention others, like cinamascope etc...). Generally, if you use typical CCIR based resolutions, you have unused part of your monitor screen, when you watch them through PC. You can use of course "pan and scan" methods, but most of the users out there don't seems to like them, or cards don't support them. There are also some software solutions (example: TvTool for nvidia based cards), but ain't always 100% accurate.
This time the mess is more than LDs, 'cause now and PAL users are interest for the subject, and for them, the situation is even more complicated. You see, with NTSC the VGA resolution is vertically compatible. So you adjust the length of the horizontal lines and you are OK. But with Pal, there 96 more vertical lines! (or 80 for D1). So, the monitor has to increase the resolution to 800 X 600, and then you have other probs, etc.
In general, it is much easier to grab from the begging to a suitable for PC monitors resolution, than to adjust later the picture and correct the borders or the aspect.
The result is the appearance of various resolutions, especially in DiVX community. Those resolutions are adjustments for PC - monitors.
For Pal, the best resolutions are: 768 X 576, 640 X 512, 400 X 320 and 384 X 288. For NTSC, 640 X 480 is fair, but the true 4:3 aspect is 672 X 488 and some people use 624 X 488. Since I am not an expert for NTSC, I can't suggest and propose nothing for NTSC.
The suggested resolution from experts of DiVX/XviD/ASF are: PAL: 480 X 384, NTSC: 480 X 320 (4:3 picture).
For realtime grabbing to DiVX/XviD/ASF, I found that the resolution of 384 X 288 is the most suitable (for PAL, I don't know for NTSC). I suggest this resolution 'cause:
1. It is close to VHS/VCD resolution, so a later re-encoding would be easier (even if mpeg 4 ain't the best source for VCD/SVCD)
2. Doesn't need much powerful processor (500mhz is enough)
3. De-interlace the TV broadcast "naturally"
4. You can use some filters in realtime, if you have a faster CPU ( about 1000mhz)
The perfect would be the 768 X 576 resolution, but that need currently expensive hardware.
Also, keep in mind that with the use of alternative media players (like the excellent "Zoom Player"), you don't have limitations on the framesize you can use for your PC based target media (like mpeg 4). Those alternative players, got great flexibility, during the playback! The resolution you use, ain't a problem ain't more, the correct aspect is easy restored manually with those players! So, if you prefer other framesizes for your reasons, try and see yourself the results!
Well, that's it for resolutions, you are welcome to add stuff or correct my mistakes.
Have fun
SatStorm
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