Put 180 min of VHS on DVD - DL disc or not?

if you are going to do a dual layer disk, use verbatim. depending on the content of your video and since your source is vhs, you may get away with doing a 2-3 mb/s encode for a single layer disk, but not really recommended. not sure what you mean by 352x576???

Whatever you might be putting on the disc, and no matter what players might play back the discs you are burning, if you are using DVD Studio, you'll be making a spec-compliant (mostly) video DVD, which will either be NTSC or PAL. You'd be wasting your time and messing uup the quality of your video by trying to use any weird non-standard frame sizes such as you are describing.

I know that it is possible to put other images and mpeg files on a DVD-ROM data disc, and that some computers and set-top players will play those files, but they will by no means be universally compatible, nor will they technically be video DVDs. It is not that the player is capable of scaling the video, it has to be able to transcode the media to standard video from whatever weird format you are using.

Use a bit rate calculator such as the one at
http://dvd-hq.info/Calculator.html
to figure out the correct bit rate to fit on whatever size disc you will be using. For quality purposes, I usually draw the line at 2 hours for a DVD5, but you can probably squeeze 3 hours on there. Just follow what the calculator recommends, factor in your audio bit rate, leave room for your menus and ROM, and you should be good to go.


Hope this helps -

Max Average

I've put 320 minutes of video onto a double layer disc. It came out way better than VHS quality. Just try a test at 3 mbps, and don't forget to use AC3 for the audo, that will save over 1 mbps on its own.

I don't think it would be necessary to use DL in theory.

VHS supports 240-250 lines of resolution.

And of course DVD is much greater 540.

Have you ever used a dvd player that did not accurately scale?

I would suggest the scale you tried, and test the disk extensively.

BUT

to answer your other question.

You can use DL with DSP with NO PROBLEM. I have extensively.

Mickey

Sorry, DVD does not support 540 lines -- it's 480 for NTSC and 576 for PAL. Obviously you should design NTSC menus at 720x540 to compensate for the pixel aspect ratio, but they of course need to be scaled down to 720x480 before importing them into DVDSPro. They are NOT scaled back up to 540 lines, and even if they were, you wouldn't get any of the lost detail back. They are displayed at 480 lines, but the reason they look normal (like your original 720x540 image) is because of the rectangular pixels on a TV display as opposed to the square pixels of your monitor.

I think you may both be wrong. When talking about resolution, as in VHS = 240 lines, s-video = 400 lines, etc, those are counted across the screen, not down the screen. I believe in those terms SD DVD-Video would count as 640 lines.

Completely wrong. They're not counted as "across the screen". Look at a TV -- scan lines are horizontal, not vertical.

Read the DVD FAQ -- SD DVD is 720x480 for NTSC and 720x576 for PAL... MAXIMUM. The only exception is half-D1, which is still 480 or 576 lines, with the horizontal resolution cut in half.

As for the difference in resolution, VHS material stored on DVD-R is still 480 lines, regardless of what the native resolution was. It's like taking a photo of your screen with a digital camera -- sure, your screen is only 72dpi, but the resolution of the photo is determined by your camera's chip, not the resolution of the source.

A lot of people use the limited "resolution" of VHS as an excuse to use half-D1 resolution, but you often end up with sub-VHS video quality. Using the digital camera metaphor again, it doesn't matter if your screen resolution is only 640x480, if you take a photo of your screen with one of those cheapie 640x480 digital cameras, you won't get an image that's identical to the screen display, it will be visibly worse.

How can this be if the resolution of both the screen and the camera are both 640x480? Because the 640x480 resolution of the camera limits its capability to create a clear digital image of the analog world (pointing a camera at your screen isn't a digital transfer, even if you have a digital monitor). If you could plug a device into your monitor port that would extract a digital image from it, then yes, you could get a pixel-for-pixel representation of what was on your screen, but analog-to-digital doesn't work that way.

To understand the concept behind VHS-to-DVD transfers, it might help to look at it as a film-to-video transfer. Film does not really have a "resolution", strictly speaking. The grain of the film can limit image quality, but if you use the absolute minimum resolution to transfer film to tape, you won't get very good results. In the same way, you really need all 480 lines of an NTSC DVD for VHS transfers, and you don't really have the option of using less. You're essentially taking a picture of the signal from the tape -- it's not a line-for-line transfer.

For the same reason, cutting the horizontal resolution in half is the worst thing you could possibly do, since the horizontal lines in VHS or other analog formats isn't broken up into "pixels" as digital formats are. Therefore, using half of DVD's available 720-pixel horizontal resolution means you get an image that's only half as good as the picture you'd get using the full 720 pixels. If you had the capability to cut the number of lines in half so you only had 240, it would actually have less of an effect than using half-D1 resolution would. Unfortunately, that option is not available.

The bottom line is, if you go by the "resolution" figures of VHS to justify using less than the full 720x480 resolution of DVD, you're gonna end up less-than-VHS-quality. If you're okay with that, great -- it just blows a hole in the myth that simply transfering VHS content to DVD is an automatic improvement.

Scan lines are horizontal, but the lines of resolution quoted for VHS and s-video are how many points across the screen you can resolve, so if you had vertical lines on the image, how close together can there be and be resolved. That's why 525 scan line VHS can have a resolution of 240 lines, and 525 scan line s-video can have a resolution of 400 lines. 525 scan line DVD-Video can be thought of as either 720x480 or 640x480, as there is no information in the overscan area, and the horizontal scale is different to the vertical scale, causing the 720 pixels to fit into 640 pixels of space.

Read here for more definitions:

http://cinemadave.com/Projector/FAQ.html

in particular these two entries:

http://cinemadave.com/Projector/FAQ.html#svideo
http://cinemadave.com/Projector/FAQ.html#hv

I think you're confusing the fact that "vertical resolution" is how many horizontal lines you can stack on the screen, and "horizontal resolution" is how many vertical lines you can make out. It's confusing, but less so if you don't come at it as if it were a digital signal.

The bottom line is, there really aren't any "pixels" in an analog display, just horizontal scan lines. A raster display draws horizontal lines from top to bottom, then returns to the top, shifts a half-line, and draws the other field.

Anyway, regardless of what you're getting from the completely unrelated projector FAQ, the source material on a DVD is 720x480, period. Obviously DVD playback ends up as 640x480 on a computer monitor, but again that's only display scaling so the picture maintains its original aspect ratio on a square-pixel screen, which is not what DVD was designed for.

Furthermore, there IS information in the overscan area. That's why you need to be make sure you don't put important stuff in that area when designing DVD menus. When you play DVDs on a computer screen, you see the entire image -- when you play them on a TV, part of the picture is overscan.

Overscan may not have been the best word to use. I'm talking about the lines in 525 NTSC that are presumably beyond the 480 scan lines in the video image. In the case of PAL those are sometimes used for teletext information. I'm not sure what they're used for in NTSC.

This page talks a little about the part of the overscan area I was referring to:

http://en.wikipedia.org/wiki/Overscan_amounts

Look at the entry marked as "625/525 or 576/480".

Yeah, that's more like it. I have seen DVD material that's 704x480, but that has been the minimum (with the exception of half-D1 of course). Speaking of half-D1, that's where the 352x480 comes from -- it's half of 704x480. Nevertheless, you can actually get 720 vertical lines on DVD, and you WILL see them if played on a digital monitor that does not do overscan/underscan, such as a computer monitor.

There's just a lot of confusion when people try to apply the concepts of digital graphics to analog video, and I wanted to make sure that didn't happen here. My point regarding half-D1 was that you can't expect not to lose quality if you use a lower resolution, even if your source is an analog format that purportedly is of an even lower resolution.