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Laserdiscs are awesome but they degrade as well. Not from use, just from time/exposure. Quality control on laserdisc manufacturing was pretty poor. The disc halves end up separating enough to allow oxygen in and the reflective layer oxidizes. Laserdisc uses an analog format for video so you end up with artifacts onscreen.

Also the fact that they can get damaged much more easily and unlike CDs they don't even have any means to correct for errors caused from that.

Mandelbrot fractal (generated by FRACTINT), with JPEG artifacts standing in for MPEG2 artifacts: Same mandelbrot fractal, filtered to VHS constraints:Especially note the right side of the fractal.

lidnariq wrote:Mandelbrot fractal

Yes, the difference is quite obvious when these are seen through today's movitors/TVs, but not nearly as obvious on TVs from when VHS was the dominant home video technology.

Sure. I specifically chose the mandelbrot with a garish palette specifically because it would show both VHS and DVD encodings in the worst possible light, as they are designed for real-world video.

None-the-less, the point is that the differences and errors are representative of the actual signal quality degradation caused by the corresponding encoding.


A more representative sample of what VHS felt/looked like can be seen e.g. here.

On a CRT, you have the advantage of low persistence so offsets between fields of video don't look as bad. Also CRTs were built with PLLs to allow for wide variations in signal timing while most video capture devices sample on a rigid 3.58 mhz *4 pixel clock and have limited room to adjust that. VHS captures look a lot better with a time base corrector but apparently this guy doesn't have one.

Laserdiscs do have about the same bandwidth as broadcast NTSC video (twice the chroma bandwidth of VHS and less noise in the color), but since there's no error correction at all, any problems with the disc surface will lead to visible issues. Usually this is line dropouts or rainbow speckles ("laser rot"). Also on a lot of cheaper players, the analog audio carrier is not notched out completely leaving a bit of texture on the image.

Besides that, a lot of early laserdiscs were not made from quality film sources so you get the dust and scratches and optical flaws that were on the original scanned film print.

Sik wrote:Also the fact that they can get damaged much more easily and unlike CDs they don't even have any means to correct for errors caused from that.

That's partially true.
Most newer (and by that I mean later 80's) discs started having digital audio encoding (same as CD's), so at least there's that. And the means to correct for video errors was to make sure to have at least 3 frames of video for still slides. Heh. practical I know.

The worst Laserdiscs are the ones that look like they were literally mastered from VHS tape . Worst of both worlds, that muddy-dim picture, interference, and weak audio encoded on the disc... forever!

It's fun when you're using a smarter kind of laserdisc player, and it interprets a patch of scratches and scuffs as encoded commands... It's only happened a few times in hundreds of hours of viewing, but it results in a random, immediate jump to some other part of the film (kind of like a record needle jumping).

Heh, I was unaware that there were disc rot problems with Laserdisc. I only know one person who had a collection, and he took good care of 'em, but of course nowadays he's replaced everything in it with DVD/BR, so I have no idea how his collection held up long-term. I mostly just enjoyed them for the big heavy discs and a sense of superiority over those rattly plastic VHS cassettes.

I love this video that deliberately compounds the signal loss from making a VHS copy over and over until the video completely degrades: https://www.youtube.com/watch?v=mES3CHEnVyI

It sort of magnifies any inherent problems in VHS by turning them up as strong as they can go. Colour goes long before intensity, and it seems like both colour and intensity suffer from horizontal blurring a lot faster than noise. Audio degradation seems to be more dominated by noise, but maybe that's because audio is lower frequency information.

I'm trying to find the exact specifications on VHS frequencies, and I keep finding conflicting information. Some sources say the FM luma carrier is from 3.4 Mhz to 4.4 Mhz, other sources say it's from 3.8 to 4.8 Mhz.

tokumaru wrote:

rainwarrior wrote:On that kind of TV a VHS and a blu-ray would look just as good.

Having acquired a Blu-ray player a couple of years before an HDTV, I can say that DVD and Blu-ray look exactly the same on a CRT SDTV.

Probably depends on how you had it wired up. I gutted one of those Wii VGA cables to get at the component to RGB transcoder so I could build an adapter so I could plug my Blu-ray player into my old 28" widescreen CRT.

First of all, a HD image resampled down to SD resolution in RGB should have a greater colour resolution than DVD. I may have the terminology wrong, but I can say that, on the same SD screen, the Terminator 2 blu looks miles better than the PAL DVD.

Secondly, DVD resolution is 4:3, widescreen content is compressed in width to fit when recorded and then stretched to fill your TV screen when played back. Depending on the player, it might outputting a native 16:9 image when it downscales to SD, but I have no way of verifying this.

Thirdly, in most cases (at least to my eyes) the HD compression artefacts get smoothed away in the down scaling, leaving a near crystal clear SD image.

In the end, it's all down to your connections, equipment and eyes. If you are using a PAL or NTSC based connection then you might as well stick with the DVD

On the subject of VHS tapes, where I work we offer a simple VHS to DVD transfer service. I've seen badly recorded tapes and competitively good looking tapes. Both look equally bad once they've been through a DVD recorder's encoder.

Hojo_Norem wrote:First of all, a HD image resampled down to SD resolution in RGB should have a greater colour resolution than DVD.

This is true.

Hojo_Norem wrote:I may have the terminology wrong, but I can say that, on the same SD screen, the Terminator 2 blu looks miles better than the PAL DVD.

Using PAL already makes this comparison quite difficult to do correctly (the movie is almost guaranteed to be 24 FPS, which doesn't convert nicely to PAL), but even if you've taken that into account, resolution may not be the only difference between DVD and Blu-ray.

Hojo_Norem wrote:Secondly, DVD resolution is 4:3, widescreen content is compressed in width to fit when recorded and then stretched to fill your TV screen when played back.

DVD resolution is typically 720x480 (NTSC) or 720x576 (PAL), and the same resolution is used for both 4:3 and 16:9 content. The player must stretch the image to one of those two ratios in order to display it correctly.

Hojo_Norem wrote:Depending on the player, it might outputting a native 19:9 image when it downscales to SD, but I have no way of verifying this.

NTSC has no way to display a native 16:9 picture; all NTSC DVD players must either reduce the vertical resolution or crop some of the picture from the sides. (I think I read somewhere that PAL is capable of signalling a widescreen picture, but I don't know anything about this because PAL equipment is uncommon in North America.)

Hojo_Norem wrote:Thirdly, in most cases (at least to my eyes) the HD compression artefacts get smoothed away in the down scaling, leaving a near crystal clear SD image.

This is true, unless the artifacts are quite extreme.

Hojo_Norem wrote:On the subject of VHS tapes, where I work we offer a simple VHS to DVD transfer service. I've seen badly recorded tapes and competitively good looking tapes. Both look equally bad once they've been through a DVD recorder's encoder.

You can get much better results by doing the encoding and mastering on a PC.

Neither NTSC nor PAL can signal that their content is anamorphic 16:9 in-band, however, almost all PAL markets use SCART connectors. With the advent of 16:9 TVs, SCART magically grew trinary signaling to indicate that content was 16:9.
I'm wrong! There is an in-band 16:9 signal- https://en.wikipedia.org/wiki/Widescreen_signaling

I use both VHS and DVD. VHS isn't so bad in SP mode. Many VCRs these days cannot record in LP mode though, so you have to use EP mode, or waste a DVD even if you don't need to keep the recording! I have used them in the past month actually, both recording and playback. In the past few months I have recorded Slugterra on VHS in EP mode. I once noticed some text on the screen for perhaps one frame or a few frames during what was probably supposed to be a commercial break, and I could not read it even though trying to pause the tape. How much do you think it is change depending on animated show, live action, etc?

zzo38 wrote:In the past few months I have recorded Slugterra on VHS in EP mode. I once noticed some text on the screen for perhaps one frame or a few frames during what was probably supposed to be a commercial break, and I could not read it even though trying to pause the tape. How much do you think it is change depending on animated show, live action, etc?

I think that's more the result of commercial producers making fine print smaller than SDTV is capable of showing.

tepples wrote:I think that's more the result of commercial producers making fine print smaller than SDTV is capable of showing.

O, OK. I didn't know that.