Talk:480i

480i never means fields

Some people prefer to use the line number of fields, which is half that of frames, in their nomenclature and thus call this mode 240i, likewise 288i and 540i.

Nobody who knows what they are talking about does this. If people start using 540i to refer to the field rate, it will permanently wreck the terminology.Algr 04:36, 21 June 2006 (UTC)

This was added in an attempt to stop the 240i edits by User:Brazil4Linux and his various sockpuppets. Didn’t work, though, because as it turned out he was not misguided, but is a tenacious vandal. The use of frame lines is nevertheless not ubiquitous—[1] received some attention for example—, although it seems to be sort of a silently accepted standard in Wikipedia. I think in this non-prominent form the sentence does no harm. It is even required as long as 240i etc. are redirects to the other respective articles. — Christoph Päper 11:03, 21 June 2006 (UTC)

I did a Google search on 240i, and it turned up nothing but Wikipedia. That's no good. I agree it might make sense to refer to interlaced video systems by their field count, but the 'XXXi' phrasing would become ambiguous if you did that. For example, some of the prototype versions of HDTV had 960 interlaced lines per frame. That would be called 480i if you counted by fileds! If you want to call 1080i by the field line count, then it ought to have a different letter, perhaps 540d. Algr 05:16, 26 June 2006 (UTC)

In the case of analog video, you can make a non-interlaced form with an even number of lines, such that the lines from each field overlap the previous one. I don't know if you can do that in the digital case, though. This used to be used for some computer displays. Gah4 (talk) 01:49, 30 December 2021 (UTC)

480i 680x480 and 576i 576x720

Hello. Well I am not a pro in all that stuff here (just came by to read some about pal conv. issue) but the article says that 480i has 680x480 and 576i has 576x720. Now that makes 4:3 on 480i and 3.75:3 which makes sense (about the pal issue) BUT the picture here says something different. Namely that NTSC is also 720 - now I think the picture is wrong but anyway I just wanted to know / say some about that. If I got something wrong here please tell me :-D

http://en.wikipedia.org/wiki/Image:Common_Video_Resolutions.svg Linking didn't work so I just post the url here - its the picture at the bottom. SECAM PAL and NTSC share that picture.

Moooitic

Are the pixels Square or Rectangular?

Does the 480i standard prescribe square or rectangular pixels for the image? Perhaps this should be tossed in the article. Daniel.Cardenas 20:17, 10 June 2007 (UTC)

480i is NOT an alternative nomenclature for NTSC (525 line)

The article starts by stating that 480i is an alternative nomenclature for an NTSC or 525 line video system. This is completely untrue. 480i is a description for a digital video system whereas NTSC or 525 line refers to an analogue video system. One can easily be converted to the other but they are not the same. 86.143.181.133 (talk) 17:02, 2 August 2009 (UTC)

Especially as the analogue NTSC system specified 486 active lines and would thus be 486i. 20.133.0.13 (talk) 15:16, 20 January 2010 (UTC)

Agreed, all that analog talk needs to be removed. 480i is a digital mode. Did a similar fix to the 576i article, will do the same here when possible 4throck (talk) 00:49, 30 December 2021 (UTC)

I suppose. But DVD and 480i were standardized when the usual display device was analog. If you were lucky, you used the component video output. Also, video sources commonly supply an analog signal to a ADC. So in that case, it was a storage medium for analog video, that happened to store it in a digital form. And note that DVDs commonly indicate NTSC or PAL, depending on where they are expected to be displayed. Also, since analog video still has scan lines, it isn't so strange to indicate the (approximate) number of visible scan lines and i/p for an analog signal. Gah4 (talk) 02:11, 30 December 2021 (UTC)

I edited the article so that (I hope) it becomes clearer that there's a legacy relation with NTSC, and the name carried over as a popular designation. Indeed it was/is used with digital sources (ex: you can find D1 NTSC resolution on Adobe Premier). But that's something to sort out on the NTSC article (or on a disambiguation page), not here. 4throck (talk) 01:27, 31 December 2021 (UTC)

Systems A and E even

The article quotes someone who probably has an illustration of systems A and E. This line should be removed, unless you have the illustration.

720 samples minus 16 is not 704 pixels but 704 samples. —Preceding unsigned comment added by 97.93.100.36 (talk) 17:45, 28 January 2011 (UTC)

what is number of vertical lines for analog televizors?

So this means analog TV max resolution is either 400*480 interlaced (interlaced means 30 Hz horizontal odd lines and 30 Hz horizontal even lines; this means 240 odd lines @ 30Hz and 240 even lines @ 30 Hz and total 240*30+240*30=28800 horizontal lines per second) or 400*480 progressive (480 horizontal lines * 60 Hz = 28800 horizontal lines per second). I only know, that there is about 3(RGB) * ~411 colums. I imagine what is problem because very hard to find information about number of vertical lines (I calculated about 400*3, because 3 colours, so about 400 vertical red lines). — Preceding unsigned comment added by Versatranitsonlywaytofly (talk • contribs) 11:07, 14 June 2012 (UTC)

Will modern 2013 televisions show interlaced video at all?

If I have a 480 x 720 interlaced mpeg video such as an older DVD containing older television circa 1990, and play it on a modern hi-definition TV, will it show me a new field every 60th of a second, or will it combine fields and show me one frame every 30th of a second? Because I know that no monitor will show me a new field every 30th of a second, even if its refresh rate is that, or higher: it will combine fields and show me one frame every 30th of a second. (yes, I am rounding, I am a video professional and I am quite aware of 30000/1001). But I am not an owner of, or a specialist in, high-definition TVs available for sale. Mydogtrouble (talk) 14:49, 19 March 2013 (UTC)

For CRT monitors (you might have been around that long), there is persistence in the phosphor that reduces flicker. LCD also have some persistence, such that some number of lines can be written to the screen. Note that many LCD screens have the physical resolution different from the display resolution, such that they are interpolated to the actual resolution. Gah4 (talk) 02:00, 30 December 2021 (UTC)

Pixels and Samples and Blanking

Over and over we read the myth that 704 out of 720 leaves room for horizontal blanking--it does not. Digitization of NTSC is covered in BT.601 and makes it clear that there are exactly 858 samples taken per line at a 13.5 MHz sample rate. The digital frame starts 'logically' at sample number 0 which is the first of the 720 samples of active content. Following the final sample number 719, samples numbered 720 through 857 contain the horizontal blanking, color burst, and so forth. The entire 720 samples are active content, zero of those samples are for blanking or "nominal blanking" or any other non-picture-sampling purpose. The reason there are 720 is that the analog input signal is expected to be 710.85 samples wide, and it's not entirely certain when it will start. So a fudge area of 8-ish samples on either side will likely be at black or blacker-than-black level. This is not imposed, it is an artifact.

All 525 lines per frame are sampled. Some specs say there are 485 active lines (20 lines of vertical blanking per field) and others 483 active lines (21 lines of vertical blanking per field). There is a half line at the top of one field and a half line at the bottom of the other field, but an entire line of samples need to be recorded, thus the D1 frame is 720 samples wide and 486 lines tall. The 4:3 visible picture area is defined as the total line length of 63.555... microseconds minus the horizontal blanking length of 10.9 microseconds, that being 52.6555... Therefore, the 4:3 visible picture area is defined as 710.85 samples wide and 485 lines tall. Not 704, not 720.

It's uncertain why 704 was chosen. But it's based on post-sampling handling of content to put it on media, it's not related at all to capture of analog NTSC video. 704 is the nearest modulo 16 number to 710.85. And it is unclear about what to do about the discrepancy between 480 lines (the nearest modulo 16 number to 485/486 lines). Is it merely coincidence that 704x480 times a PAR of 10:11 is 640x480, i.e. 4:3 DAR? Is the "true" visible area literally 704x480 for digitally-sampled content, or is the "true" visible area actually the slightly larger box of 710.85x485 (of which the top and bottom have been cropped away)? It's not that important, really.

What is important is that whatever the content of the DV specification, the reality is that most or all consumer camcorders (but I don't know about consumer DV VTRs recording video line-in) use the ENTIRE 720x480 window as their 4:3 display area box. So if one transcodes 720x480 DV straight to MPEG2 to make a DVD, it will be stretched horizontally as appearing to the viewer. Empirical tests with actual consumer cameras and consumer DVD players demonstrates that 720x480 DV rescaled to 704x480 MPEG2 plays with the correct aspect ratio. (Converting the 8:9 PAR of recorded DV to the 10:11 PAR of recorded DVD MPEG2.) Since I've not seen the actual DV spec, I don't know whether this is by spec, or incorrect by spec. 146.115.66.42 (talk) 18:04, 27 May 2013 (UTC)