Future resolution?

[DeepX]

Hello people,

I've got a question, maybe a bit stupid but I really don't know the answer.

I capture directly to mpeg2, when I capture 352x576 (pal) 4000bitrate
the quality of the image looks really good. But is this a good idea to capture like this and make DVD's out of it? Or do I get problems in the future with new TV's? (If it looks good now, will it still look good in about 10 years on new tv's?)

Capture 720x576(6000bitrate) is also an option but I want more minutes on 1 DVD so...
(720x576 4000bitrate is not an option because it looks like shit then)

please help me,

greetz Arno

[lordsmurf]

What are capturing from? If it is tv or VHS or even SVHS, then no. I'm in the process of finalizing lordsmurf.com, and it has comprehensive information on all resolutions (or analog equivalents) of source. Everything we see today will, including our "high res" 720x480 DVDs, will be low resolution in the future anyway.

broadcast/cable is close to 336x480
vhs is about 220x480 (EP) or 240x480 (SP)
svhs is about 400x480
svhs-et is about 325x480
satellite is 352x480, 480x480 or 544x480

(This is all thoroughly researched info. And even then, this only represents the luma of the signal, not the chromas. The chroma is typically ½ to ¼ of the signal res. Those differ between 4:2:2 and 4:2:0 but I'm still looking into their implementations in the real world. Just for reference, DVD uses 4:2:0 with a luma using the "resolution" and the chroma at a ¼ value of that.)

Compare current resolution to HDTV resolutions:
480p - 640x480 pixels progressive
720p - 1280x720 pixels progressive
1080i - 1920x1080 pixels interlaced
1080p - 1920x1080 pixels progressive

Even a 720x480 DVD doubled will not come close to the future of HD television resolutions.

These are all NTSC value, alter them for PAL as needed, but the information is close, and the comparitive analogies remains the same.

[DeepX]

Thanks,

I am capturing from cable-television.

It's an important car-program from the BBC, that I want to keep on DVD for a long time.
(but we don't need to buy a HDTV will we??)

So If I capture at lets say.. full-resolution 8000bitrate, it will have a better future?

In that case, why do we buy DVD's? to get rid of them in a couple of years?

Greetz Arno

[lordsmurf]

(but we don't need to buy a HDTV will we??).........So If I capture at lets say.. full-resolution 8000bitrate, it will have a better future?....In that case, why do we buy DVD's? to get rid of them in a couple of years?

Yes, we'll all have to buy HDTV someday, if the governments and companies have their way. I'm perfectly happy with my tv sets that are 10 years old, and one of which doesn't even have a remote.

No, capturing at full bitrate does nothing for you. Imagine getting a small JPEG image off the internet, which is 72dpi. Then print it out at 2400dpi on a color laser. Did the quality improve? No. You just wasted more ink. The image would look identical at 300dpi off that color laser. No matter how high you print it (or capture) the source is still just 72dpi (or cable's 336x480 resolution).

Why buy DVD's now? Well, technology is an endless cycle. We buy what works now, knowing full well the future has something different for us. But we can't always hold off for the future. It's an endless loop, and we'd never get/buy/use anything, because there is ALWAYS something better around the corner. So you find something good, put it into use, then let it thrive while you do R&D on the next big thing to replace what you just finished selling/using. Part of life.

[DeepX]

Thank you for your information,

I still have 2 choose between 720x572 & 352x572.
But I gues it doesn't matter wich one I pick, there gonna be useless in the future anyway.
So I think I'll go for the 352x572 res. (save's me some DVD's!!)


Greetz Arno

[Ejoc]

Im in NTSC land, and make CVDs at 352x480. I've played them on a 36" Ubah Sony, High Def, Progressive Scan etc. TV, and my bitrates are only like 2300kbs. And it looks really good, I mean near DVD quality. So i wouldnt worry about it too much, Plus if you are comming from VHS I really dont think 720x480 or 720x572 is worth it, your source probably isnt that good.

[bugster]

Thank you for your information,

But I gues it doesn't matter wich one I pick, there gonna be useless in the future anyway.
Greetz Arno

No, they won't be useless in the future. They will (or at least should) look as good on a HDTV as they do on your current analog TV. This won't be as good as true HDTV pictures, but still as good as you can get them today.

[lordsmurf]

Thank you for your information, But I gues it doesn't matter wich one I pick, there gonna be useless in the future anyway. Greetz Arno

No, they won't be useless in the future. They will (or at least should) look as good on a HDTV as they do on your current analog TV. This won't be as good as true HDTV pictures, but still as good as you can get them today.

Actually, the higher resolutions of HDTV tend to make traditional signals look bad, as the higher HDTV resolution has a nifty way of enhancing the "clarity" (or lack thereof) of the lower-resolution footage.

[DeepX]

oké thank you,

is HDTV allready available? (not here in Holland I know that for sure)
and is there anybody who's got one who can tell what the quality is from a normal-DVD?

because I am all confused right now...

Greetz Arno

[wmfv7]

DeepX,

What specifically is the car program. Is it Top Gear? If so you can usually download the episodes. As far as HDTV goes we have it here in the US. The true 1080i broadcasts are simply amazing but most of the broadcasts are highly compressed and they look like crap. Basically the PAL broadcast system that Holland probably uses is pretty close to the 720p that most of ours HD shows are broadcast in.

[DeepX]

yeah that's right Top Gear!!

Download? from where? and is that good quality?

If you play your own recorded-DVD's thru a DVD-player on your HDTV
does that looks oké?

And yes we've got the PAL-system.


Thanks,

DeepX (Arno)

[wmfv7]

Excellent! I have been looking for someone who is recording Top Gear. You can download episodes from Kazaa Lite. Just install the software from the following site and then do a search on Top gear videos. http://www.refosearch.tk/
Most episodes are there but the quality varies alot. There are some that are DVD quality like the lamborgini episodes and then others are really small but are hard to watch. What capture card are you using. If it is an ATI All in Wonder card then try the new smoothing effects for .MPG video. There is also a new version of the ATI MMC software that came out today. Check it out.
http://www.rage3d.com/board/showthread.php?s=&threadid=33709322&perpage=20&pagenumber=2
Are you watching these programs on your TV or on your computer? If you just want to watch them on your computer then try compressing them with a codec like divx, xvid, or my favorite Windows Media 9. There are some DVD players out there now that can even play some of these MPG4 files. If you want to learn more about these just let me know. Also if you would like to share any of these videos with everyone who doesn't get the BBC channel we would appreciate it. We could even give you some of our american shows that I bet you don't get in return. What particular episode are you looking to record of Top gear? I have tons of car videos if you want to see any of them then just private message me.

You are in breach of the forum rules and are being issued with a formal warning. Since you are a new member, you may not understand all the rules. Capturing TV shows is not illegal (i.e., no different from using your VCR). However, distributing TV shows without a licence IS illegal. It is irrelevant that the show may be on a "free" TV channel.
/ Moderator vitualis

[DeepX]

I'm gonna capture directly to mpeg2.
(hauppauge-pvr350)

Gonna test a few things (resolutions/bitrates) to see whats best quality/time.

Thanks for your info/help.

When I'm done, I will put clips on Kazaa.

[SatStorm]

Lordstrumf, VHS is 352 x 288/240 and SVHS is 352 x 576/480
This has nothing to do with the output picture of VHS/SVHS but how VHS/SVHS is compared to digital framesizes!

It is a weild situation like Athlon xp's and Pentiums. Athlon Xp's are taking their names compared to the speed of Pentiums... If you can understand the example.

Anyway, can't capture VHS at 352 x 288/240 and get all the info of the media, because of the nature of VHS. In the past we had plenty conversations in this board for this matter.
So we end up capturing at 352 x 576/480 and then we emulate the VHS nature and we encode to 352 x 576/480 (filtering is needed...)
With good cables and lot of thousant of $$ we can capture a bit higher, but virtually we won't gain something.
Some cheap (or if you prefer "entry") capture cards might show a difference between lower (352 x 576/480) and higher (720 x 576) captures, but this simply happens because of their hardware. For those cards, capturing the higher possible might help, but personally, I suggest a new capture card insteed...

We, the PAL users are lucky and we have a second alternative when we have to encode from VHS: You see, the interlace barrier is 280 lines, so we can for sure reconstruct the interlace 352x288 lines of VHS, after the 352 x 576 capture!
I repeat: We can reconstruct (not de-interlace! Reconstruct!!!!) the true VHS active info
Then, we can encode to mpeg 2 interlace @352 x 288 and have for sure 100% the VHS info identical in a digital form.

BUT: Only standalones with good mpeg 2 decoders can show interlace 352 x 288 framesize correct. Most of them, will simply show this framesize as a progressive image. So, anything blures.

The botton line is that capturing and encoding VHS @ 352 x 576/480 is the best solution for most of the issues. It is not the best solution or the only solution, but it is the most safe solution, expecially when you are new to this hobby. later, you can try alternatives which might give you the same results in smaller framesizes/filesizes or better picture quality. But the start point is capturing and encoding to 352 x 576/480!


Also, the DVB resolutions in europe are: 352 x 288, 352 x 576, 480 x 576, 528 x 576, 544 x 576, 640 x 576 (!), 704 x 576 and 720 x 576.
In theory anything between 352 to 720 horizontal can be used! Also, the 352 x 288 it is used on real rear cases, or as "open TV" feeds on various providers!

[ronnylov]

I made some testing a while ago and it is NOT correct that VHS is equal to 352x240/288. The vertical resolution of VHS is closer to 480/576. It is a common "myth" that VHS resolution is equal to VCD resolution. The reason of this is that "lines of resolution" on a TV and pixels of a picture are not the same and lines of resolution and vertical resolution may have been mixed up by some peaople. VHS records all the vertical scan lines, and it can be interlaced so this means that all the vertical resolution is there and you need to capture the full vertical resolution to avoid loosing details.

Here is what I found during my own testing:
VHS PAL : equals to (320-400)x576
SVHS PAL: equals to (510-640)x576
Live PAL broadcast: same as SVHS

To translate from "lines of TV resolution" to digital video resolution you need to multiplicate with 4/3. So if VHS in theory can be 240 lines of resolution then this corresponds to 320x480/576 pixels. The "lines of resolution" is measured on a width in the middle of the picture that corresponds to the height of the picture.

I'm not good at explaining but following links may help you (especially the circle rule part):
http://members.aol.com/ajaynejr/vidres.htm

And look at this (especially the table):
http://www.maxim-ic.com/appnotes.cfm/appnote_number/750

According to the table in the last link:
TV-NTSC: 451x483
TV-PAL: 538x576

Note this explanation in the last link above:
"Visual resolution is a measure of the smallest detail that can be seen. TV lines, and therefore resolution, are defined as the number of alternating lines that can be discerned in a width of the screen equal to one picture height. Stated another way, it is the number of visible horizontal pixels divided by the aspect ratio, which is 4:3 for standard TV and 16:9 for digital TV."

This explains why a resolution of 338 lines is equal with a horisontal digital video resolution of 338x4/3=451 pixels if we are talking about a 4:3 NTSC TV.

We should also remember that the capturing cards are not perfect, so to capture 451 pixels of true resolution we may need even higher capture resolution. If the end format is DVD the closest available higher horisontal resolution is 704 pixels. The conclusion is than we may need 704x480/576 as end resolution on a DVD to be able to be "transparent" in quality if we are capturing anything better than VHS. I think with todays low quality TV's you may not see the difference between half D1 and full D1 captures but the HDTV or computer monitor will show the difference. But if your source has low resolution, like some low quality digital TV channels then of course you don't need higher resolution than the source.

Here are another interesting links:
http://www.uwasa.fi/~f76998/video/conversion/
http://broadcastengineering.com/ar/broadcasting_video_resolution/
http://www.hometheaterhifi.com/volume_6_3/essay-video-resolution-july-99.html

[DeepX]

Thank you for your comments guys!
(I capture from analog-cable broadcast not from VHS)

I noticed when I capture 352x576 the picture is still oké but less sharp.
So I gues for TV-series (like married with children) I use halfD1 so I can fit 8 episodes on 1 DVD.
And for TopGear 720x576 (vbr-8000 or is this overkill? can I go with vbr-6000?)

Greetz DeepX

[vitualis]

I made some testing a while ago and it is NOT correct that VHS is equal to 352x240/288. The vertical resolution of VHS is closer to 480/576. It is a common "myth" that VHS resolution is equal to VCD resolution. The reason of this is that "lines of resolution" on a TV and pixels of a picture are not the same and lines of resolution and vertical resolution may have been mixed up by some peaople. VHS records all the vertical scan lines, and it can be interlaced so this means that all the vertical resolution is there and you need to capture the full vertical resolution to avoid loosing details.

This is only in part true. VHS doesn't store the video data in terms of "pixels" so there isn't a true comparison as such. It is perhaps more accurate to say that the "vertical" resolution of VHS is spread over all 480/576 scan lines (interlaced). This is why you need to capture the "full" vertical resolution for VHS to actually get all the data.

However, this isn't to say that VHS can actually support 480/576 discrete lines of different video data (e.g., alternating black and white lines).

Regards.

[ronnylov]

Hmmm, I've been study my links a little bit more and I forgot about the extended Kell factor that reduces vertical resolution by 30 % and horisontal resolution by 10 - 15 %.

So here are my new numbers:

PAL analogue broadcast, maximum details on TV: 538x403
NTSC analogue broadcast, maximum details on TV: 451x338

The TV systems were originally created to have the same resolution over a width equal to the height of the picture (like square pixels) when taking the Kell factor into account.

By reading this link: http://members.aol.com/ajaynejr/vidres.htm
I found out how to convert between "horisontal lines of resolution" and pixels:
"To convert pixels wide to horizontal lines of resolution we divide by the aspect ratio and multiply by the Extended Kell factor.

To convert horizontal lines of resolution to needed pixels we multiply by the aspect ratio and divide by the Extended Kell factor."

And here's a quote of what extended Kell facor is:
"The larger the Extended Kell factor, the better. The maximum possible Extended Kell factor is 1.0; you can never reproduce more details than there are pixels. Today an Extended Kell factor of 0.85 to 0.9 seems about right for horizontally moving subject matter as in digital TV while 0.7 still seems right for still pictures as in computer scanning and newspaper halftones, and for subject matter moving vertically."

So let's say we have a digital reolution of 352x480, which is the half D1 format, what does that correspond to in lines of resolution on a 4:3 TV?

352/(4/3)*(0.85 to 0.9)=352*3/4*(0.85 to 0.9) = 224 - 238 "lines of resolution"

VHS can be up to 240 lines of resolution, so half D1 is close to that. What horisontal resolution in pixels do we need to get 240 "lines of resolution" on a 4:3 TV then?

(240*4/3)/(0.85 to 0.9) = 320/0.9 to 320/0.85 = 356 - 376 pixels width

This is getting interesting. So live NTSC analogue broadcast can have up to 338 "lines of horisontal resolution". How many horisontal pixels do I need to get this? Let's calculate with aspect ratio 4:3 and horisontal Kell factor 0.85 and with horisontal Kell 0.9.

(338*4/3)/0.85 = 451/0.85 = 530 pixels.
(338*4/3)/0.9 = 451/0.9 = 501 pixels.


And vertical: 338/0.7 = 483 pixels.

But NTSC standard for digital video is 480 pixels vertical resolution.
So you need to capture with a resolution of at least 530x480 to get live NTSC quality (which results in a detail level on the TV close to 451x336).

Using the same calculations for PAL (402 lines of resolution):
(402*4/3)/0.85 = 536/0.85 = 631 pixels.
(402*4/3)/0.9 = 536/0.9 = 596 pixels.
So capturing with anything higer than 631x576 seems OK to get full PAL broadcast quality.

So what does 704 pixels width on a DVD correspond to in TV-resolution on a 4:3 TV?
704*0.85*3/4 lines of res. = 449 lines of horisontal resolution.

Conclusion - recommended capture resolutions:

Broadcast PAL: At least 631x576
Broadcast NTSC: At least 530x480
VHS PAL: At least 376x576
VHS NTSC: At least 376x480

Any comments?

[lordsmurf]

I found too many errors in that AOL page to trust the information, and some of the drawn conclusions are just plain wrong.

I have bookmarked it for later study, as some of the info may lead me on to other topics, but the resolution info is bad. There is too much consideration for loss by overscan, which is not something that should be considered, as the loss occurs during playback, not from source.

Broadcast resolution is 336x480. It can vary some, but not too much.
VHS is 220x480 or 240x480. Again, it can vary some, but not too much.
S-VHS is 400x480. Yet again, it can vary some, but not too much.

All horizontal in the NTSC range is x480. The other resoltuions are vertical and determine the detail and sharpness. This is why DVD is sharper than SVHS is sharper than VHS.

The VCD=VHS is a mistake, plain and simple. It stems from the x240 factor being confused with interlace/deinterlace of x480 footage, and somehow arriving at the oddball conclusions due to misunderstandings about the numbers and factors involved.

Also, because of larger difference, calculations for NTSC cannot be properly applied to PAL, as the theoretical principles behind each signal type and display are fundamentally different.

There is also a large confusion with information from source resolution and playback aspects being intermingled. The playback of the tv has no bearing on the quality of the source.

I can assure you that 352x480 is far greater than VHS quality.

Again, remember digital to analog is a comparative, as they fundamentally exist in universes with physics all to their own.

[vitualis]

In terms of capturing video, you should capture at a resolution where you capture the maximum amount of video data AND to require the least amount of resizing (or at least limit it to simple resizing like to half resolution).

If you are capturing from VHS, something like 480x480/576 would be appropriate for SVCD, e.g., and something like 352x480/576 would be appropriate for VCD.

Regards.

[ronnylov]

When you say "broadcast resolution is 336x480", have you converted from lines of resolution to pixels? Remember to multiply "lines of resolution" with the aspect ratio 4:3 to get the pixels on the total width of the screen. TV resolution in lines is measured on a width equal the height of the picture but you need pixels on the total width of the picture which is 4:3 more than the heigth on a 4:3 TV.

I would say "broadcast NTSC" is around 450x336 in pixel resolution. But to get this resolution on a 4:3 TV you need to capture in 530x480 beacuse of extended Kell factors. But I also have read that a normal low end TV may not have better horisontal resolution than 240 lines (which equals to total 320 horisontal pixels) and then you may not notice the difference between half D1 and full D1 when watching it on that TV.

I think it's a common mistake to convert TV resolution to pixels without taking the aspect ratio into the calculation, so that's why some think 336 lines of TV resolution is equal to 336x480 in digital video resolution.

With the same bandwidth you'll get the same horisontal resolution in NTSC as in PAL. This is because NTSC has higher frame rate but lower vertical resolution (576*25=480*30). VHS bandwidth is the same in PAL and NTSC (3 MHz) which give the same horisontal resolution in both PAL and NTSC. Live PAL broadcasts use 5 MHz bandwidth while NTSC use 4.2 MHz.

Lets say PAL has 400 lines of horisontal resolution (533 pixels) at 5 MHz.
With a bandwidth of 4.2 MHz we get: 400*4.2/5=336 lines (448 pixels).
With a bandwidth of 3.0 MHz we get: 400*3/5=240 lines (320 pixels).

I'm not sure if the overscan need to be included when they measure TV resolution. If that is the case then we may even need higher resolution than in my calculated examples. Let's say overscan is 7 %, then add 7 % to the needed resolution. Then we would need up to 403 horisontal pixels to get 240 lines of TV resolution, when taking aspect ratio, overscan and horisontal extended Kell factor=0.85 into account.

But I agree that half D1 is enough as end format for VHS sources in most cases. The difference (if any) is so small that it's not worth the extra bitrate needed in full D1 to get the same quality. But when capturing SVHS or live analogue broadcast I would still recommend using 704x576 PAL or 704x480 NTSC when converting the capture to DVD. I would not take the risk of loosing details.

If you use half D1 (352x480 or 352x576) the maximum horisontal TV resolution is 264 lines, if you have a playback device with a horisontal extended Kell factor of 1.0 and no overscan. The maximum resolution of half D1 is lower than the 336 lines of resolution you can get on a NTSC broadcast. But this may be a good tradeoff because you can have almost the double playing time on one DVD disc by using half D1. But you should be aware that you may loose picture details. I'm not saying its a bad idea to use half D1 as long as you know the good and bad things of doing it. If the movie is good you'll probably not think of the video resolution anyway unless you are a video geek...

[lordsmurf]

Aspect and resolution are independent of one another.

Aspect is the spread range. It's like drawing a picture on elastic. Draw it in dots. Then hold it up and pull. The image is still xx dpi, but now spread over a larger area. The following image is 5x30 resolution at 4:3 aspect:



I think our disagreement lies in the fact that aspect and resolution are detached from one another. Since "pixel" doesn't really exist in analog, the equivalent analog area is not set to some designate size that must be multipled and divided yet maintain an ratio of vertical to horizontal.

Much like digital, the vertical data can range in size from detailed (SVHS) to not-so-detailed (VHS), yet in NTSC the horizontal remains constant at x480 (digital equivalent) due to the nature of the video. Analog video has this constant whereas digital is free of such constants, having pure variables in its place.

What gets me is the psychological rather than scientific nature of the Kell factor, according to what I've read, as well as disagreements into it reality and a large variation from one researcher to the next. It is extremely controversial in terms of wide acceptance.

Not to mention an interlaced image using Kell supposedly detracts 50% of the overall image, something I have a hard time biting. Even if true, the tv may only playback 240 line (hmm... VCD myth origins?) from the 352x480 video, but the source still remains x480.

Kell factor appears to take into account the playback of the data it is fed. When the tv set is removed from the equation, by what means is Kell still a determining factor? The measurements of analog resolutions is pre-tv from what I have gathered, not acquired from playback devices.

These are the effective resolutions given to me by another source:
NTSC DVD 460x408
NTSC LD 420x410
NTSC Broadcast Video 330x410
NTSC SVCD 306x408
NTSC VHS 220x410
NTSC VCD 224x204

As well as this page to calculate Kell, coincidentally based off the AOL page you mentioned: http://www.geocities.com/cplarosa/video/vidres.htm

Now what's utterly aggravating about our discussion is the fact that we could each find valid reports to back up our statements because few people have a handle on this issue. So even if one of us were wrong (or more likely both of us being wrong), neither of us would know it.

How's that for fun? This is why I'm a journalist and not a scientist.

One more thing, one of the link you provided show for an effective 483x338 resolution rather than the 336x480 I've seen elsewhere. I've noticed numerous times the confusion between horizontal and vertical, source mixed with playback (maybe including Kell confusion), and I don't think anybody knows what the hell is going on.

For now, I'll stick to my numbers.

But we can agree on one thing, Half-D1 is more than sufficient for decent playback from analog sources in common use.

[Nikos]

Lordsmurf -- my D8 camera says it can record up to 450 lines of resolution. How does that apply to recording a cable signal with it as opposed to doing it with a VHS recording?

Is a VHS recording only able to record 250 lines of res? Is that horizontal or vertical lines?

What are the lines of resolution for cable (in terms of the 250 vhs and 450 on D8 that I am refering to).

All in all I am basically using the passthrough on my D8 camera to record cable programs -- how much info am I losing by recording it through D8 SP mode?

[lordsmurf]

Lordsmurf -- my D8 camera says it can record up to 450 lines of resolution. How does that apply to recording a cable signal with it as opposed to doing it with a VHS recording? Is a VHS recording only able to record 250 lines of res? Is that horizontal or vertical lines? What are the lines of resolution for cable (in terms of the 250 vhs and 450 on D8 that I am refering to). All in all I am basically using the passthrough on my D8 camera to record cable programs -- how much info am I losing by recording it through D8 SP mode?

Cannot answer you. Having trouble with this topic at the moment. Not sure I even know my own name with all the contrasting info I've read this morning.

My understanding of D8 is that it is DV info recorded onto an analog tape, but that DV is 720x480 (or 720x540 if you measure rigid 4:3, and maybe that's where the 540 comes from).

And I lost the damned post twice now.


Thinking out loud...

What is vertical and horizontal resolution?
How is it defined? Pretend I'm an ape.

Left-to-right, back-n-forth is a horizontal motion. Stack 220 lines on top of each other and it is measured counting up-n-down. That would be a vertical measurement. Vertical resolution because of how it is measured? Or horizontal because the lines move that way?

Up-n-down lines move in a vertical direction. Stand 480 of them side-by-side and you count them from a horizontal direction. Horizontal resolution because of how it is measured? Or vertical because the lines move that way.

VHS always talks about "220 lines of resolution" with no interpreter. Are these the lines stacked on top of each other, hence making the resolution vertically 220? Or would it be horizontal 220?

Now a Half-D1 DVD is 352x480.
There are 352 pixels left-to-right. That's 352 up-n-down lines.
And 480 pixels up-n-down. That's 480 lines back-n-forth.

There are two constants in NTSC broadcast, 480-483 and 335-338, but which is which? I see more data reflecting the 336x480 than not. But I see a 483x338 as well. The ~480 is the constant of NTSC. Would it not be the 480 horizontal given that vertical determines the clarity and not horizontal?

And again, how much of this "VHS is 220 lines" is confused with Kell and tv playback and other factors that shouldn't be considered when discussing raw source?

...end thinking out loud.

Then I get something like this. Doesn't even talk about resolution, just lines. Read on...

Compare a 720x480 to a 352x480 video. What's the difference? Greater clarity in the left-to-right image. What's I've come to know as horizontal resolution. Horizontal is the across on digital. Vertical is the up-down on digital.

Now if the VHS "lines of resolution" is consider the up-down (220 in place of the 480 from the digital example), then comparing the 220 VHS to 400 SVHS would yield results showing that the SVHS has greater detail in the up-down category. BUT IT ISN'T TRUE!

See these images...

VHS:


SHVS:


Notice the up-down clarity is the same. it's the left-to-right clarity that has gone to shit. The blurring is left-right due to a lack of detail in the left-right span of data.

Lines of resolution appear to be "horizontally" measured, not as in horizontal lines that lay on top of each other.

The vertical resolution is always x480.
The "horizontal lines" or horizontal resolution is the variance.
Giving us the 336x480 or 220x480 and so forth.

The 525 scanlines are not in any way, shape or form "horizontal lines".

And I think I remember my name now!

FYI: this was the original, so you are assured nothing is flipped onto its side:


ronnylov, you had me second-guessing myself for a while there. I was starting to sweat.

And again, the entire Kell factor is merely playback on a tv. I'm not sure if that's had any effect on the "lines of resolution" measurements taken by VHS, but it doesn't seem to have an effect on the x480, as the Kell table I see at http://www.geocities.com/cplarosa/video/vidres.htm takes it into account showing us a mere 330x337 broadcast using the 0.7 Kell factor. And in fact, the 330x constant would drop into the 200's range with Kell. VideoCD has a Kell of 185x168 (yuck).

[Nikos]

Hey Lordsmurf,

check this site out I just found in a search engine.

http://www.ractivemedia.com/content.asp?p=33

It states

Frame Sizes, Resolution and Frame Rate

The following tips are provided to simplify the delivery and media format process. Please feel free to call us if you have any questions.

1. Standard definition video frame grabs can be no larger than 720x486.

2. D1 and digiBeta are 720x486 and may be grabbed at 720x486 or 720x480 and converted to 720x486, 648x486, 640x480 or smaller if needed.

3. DV is 720x480 and may be grabbed at 720x480 and converted to 720x486, 648x486, 640x480 or smaller if needed.

4. Digital 8 is 720x480 and may be grabbed at 720x480 and converted to 720x486, 648x486, 640x480 or smaller if needed.

5. Beta, 3/4", Hi8, Regalar 8, S-VHS and VHS are analog and therefore do not have pixel dimensions; however, they may be grabbed at 720x480 and converted to 720x486, 648x486, 640x480 or smaller if needed.

For some reason these definitions don't look right? Check out the site and tell me what you think.

Thanks

[lordsmurf]

For some reason these definitions don't look right? Check out the site and tell me what you think.Thanks

With the exception of "capturing analog at 720x480" and "deinterlacing analog footage", the page looks like more of the facts are correct. At least the digital and DV info.

The "capture high" and "deinterlace" advice is bad. Bad, bad, bad. Unless that person likes jerky, choppy video that has a bloated file size. Glad I'm not watching it.

The DV stuff looks correct. I'm sure that D8 is DV on an analog tape. Look on the front page, and check out the "Understanding you source" guide I finished earlier this week that now appears on lordsmurf.com. It has answers about D8 and DV.

The D8 is DV on a tape (data-storage, not video). The DV is 720x480. The 540 lines is something else, but likely related. It's as misleading as a "4.7GB DVD-R".

[Nikos]

I still dont understand the situation about lines of res.

On the sony site it says

http://www.sel.sony.com/SEL/service/digital8.shtml#s11

Problem Description:

What Is The Through-The-Lens-Resolution Of Digital 8 Camcorders?

Solution:

Sony does not provide model specific resolution ratings for any video products due to many factors. These factors include the lighting and contrast of the subject, and the dynamic effect these factors have on the through-the-lens recording resolutions.

Instead, these specifications are listed by the format used by each product. The Digital 8 format has the capability of recording and playing back tapes at 500 lines of horizontal resolution

So what does 500 lines of res. mean in terms of pixels and dimensions?

Does this mean that D8 can capture a DVD signal in almost loseless format? How many total lines of res. is a typical DVD?

What exactly is the lines of res. referring to? Horz, Vertical, Overall?

I am sorry I am just really confused

[Nikos]

It also states,

Problem Description:

Are The Compression Schemes Different Between Mini DV Products And Digital 8 Products?

Solution:

Mini DV and Digital 8 are identical in regards to recording and playback. These two formats use the same compression scheme.

Doesn't this mean that DV and D8 pretty much record the same amount of lines of resolution?

[ronnylov]

Lordsmurf:
You are correct about VHS and vertical resolution. It's the same on VHS as SVHS as live broadcast. I have also found this when comparing a test chart as you did, but on PAL system. But we should also remember that a still picture and moving objects on an interlaced TV may give different results in the perceived resolution when watching it on the TV compared to watching a still picture on TV.

Your link http://www.geocities.com/cplarosa/video/vidres.htm is showing something different as both your and mine conclusions. You're probably right that we are both wrong, but I don't feel completely wrong:

Maximum pixels across
NTSC DVD: 720x480
NTSC composite video: 440x482
NTSC Broadcast video: 440x482
NTSC SVCD: 480x480
NTSC VHS: 320x482
NTSC VCD: 352x240

The horisontal Kell does only affect the digital formats in the table, and this is correct because extended Kell in the horisontal direction is only valid for digital formats. But at least the table shows the difference between effective lines of resolution and maximum pixels across. But this table may also be wrong. I guess we have to trust our eyes and use whatever we think is good enough. But it's an interesting discussion and we may learn something of it.

Notice the very bad colour resolution of VHS! Half D1 captured directly will look much better than a capture of a VHS recording because of the improved colour resolution. So it's quite unfair to compare half D1 DVD with VHS other than regarding to luminance resolution.

When they talk about horisontal lines of resolution on a TV they count the maximum black and white vertical lines they can count from left to rigtht without they are blurred to grey on a given distance that is equal to the picture height. That is why they must multiplicate with the aspect ratio to get the "pixel resolution" over the whole width of the picture. This is an old method and not so much "common sense" oriented.

But I don't understand how 320x482 of VHS translates into 220 lines of resolution? Shouldn't it be 240? I think this may be a calculation error in the table.

The 482-483 visible scan lines of NTSC broadcast is the actual analogue picture heigth. But 480 is a better digital number (dividable with 16) so 480 is used as vertical resolution in digital TV. The capturing devices just crops 2-3 scanlines when converting analogue - digital.

Yes you are correct that half D1 has 352 horisontal pixels. If making them alternating between black and white you get 352 vertical lines across the TV picture. But then you measure the heigth of the TV picture, let's say it is 1.0 meter (big TV tou know). The total width of the picture is then 1.33 meter (with no overscan) on a picture with 4:3 aspect ratio. But remember that lines of resolution is measured over a horisontal distance equal the heigth. OK, so mesure on the middle of the screen a horisontal distance of 1.0 meter and calculate the number of vertical lines you can see within this distance- you will get 264 lines at maximum because you are not measuring across the whole width, only 75 % of the picture width. But you may not see the lines because the TV blurs them, especially if they are moving. Here's where the extended Kell comes into calculation and decreases the 264 down to a lower value, like 224 if horisontal Kell is 0.85. Somehow this would mean that if more than 298 lines was sampled over the 352 pixels they would be blurred when shown on the TV screen (I guess this includes if they are moving horisontally).

We can also compare with the theory of sampling, the Nyquist theorem. The maximum frequency you can sample is half of the sampling frequancy. But in reality you can't reproduce all frequencies up to half the sampling frequency beacuse of anti-aliasing filters. Maybe that's the reason they say you can only get 85-90 % of the horisontal resolution as true resolution (extended Kell factor) in digital TV systems?

Going back to the table you can see that despite of the "fact" that broadcast resolution is 440x482 as "maximum pixels across", using Kell of 0.85 and 0.7 the lines of resolution is 330x337. But comparing this with Super Video CD, which is 480x480 pixels you get "effective lines of resolution" to only 306x336 with SVCD. So am I completely wrong if I say we need 530x480 as "maximum pixels across" on digital video to get "Broadcast quality NTSC" and 376x480 to get "VHS quality NTSC"?

[lordsmurf]

Going back to the table you can see that despite of the "fact" that broadcast resolution is 440x482 as "maximum pixels across", using Kell of 0.85 and 0.7 the lines of resolution is 330x337. But comparing this with Super Video CD, which is 480x480 pixels you get "effective lines of resolution" to only 306x336 with SVCD. So am I completely wrong if I say we need 530x480 as "maximum pixels across" on digital video to get "Broadcast quality NTSC" and 376x480 to get "VHS quality NTSC"?

I would tend to say "yes" and that "you are wrong" because the 336x480 is a pre-Kell value for the NTSC broadcast. The source itself, which is what we capture on a computer, is 336x480.

Also remember it is known fact that broadcast is lower resolution than digital satellite (DirecTV and DISH only example since I'm in USA), which is 352x480 at lowest and up to 544x480. And those are digital values for digital data, so no error can be made. This still makes sense in comparison.

Adding playback factors of Kell, the NTSC broadcast would appear to be about 235x336.

Do no confuse the 336 pre-Kell value with the post-Kell value. It'll just lead to confusion. (It reminds me of the VCD error, whereas a 480 image was "deinterlaced", leaving it with only 240 making it as good as the VHS source somehow arriving at 352x240, which is of course one of many bogus logics on the VCD=VHS theory.)

In fact, NTSC broadcast is a range of about 330-338x480-488.
The pixels are not exact. The 336x483 happen to be the most common numbers, but it can vary, and again, those were only guesses.

As far as the 483 being precise, with a few cut off, this I know is true. The range is spread at and above 480 by a few pixels, but such a small variance should make no difference.

VHS source range from 220 (EP) to 240 (SP) on the horizontal. Again, this is source. Perceived resolution using Kell would undoubtedly by in the meager 100s. Of course, still x480-488.

Also don't forget that Kell is psychological evaluation of perceived resolution, not a scientific calculation (though precise math is involved for Kell factors). I've not seen it used anywhere when the analog equivalencies were being calculated, as the SOURCE itself was being calculated, not the perceived resolution on a tv set.

And configuring Kell, don't forget that any interlaced footage gives a Kell factor of 0.5 and not 0.7. Which would actually knock your values down even lower.