V.H.S. and Betamax versus 8 m.m.
 

Hello. People (especially amatoures) started to preffer videotape, especially after the introduction of more affordable format cameras using formats like V.H.S. and Betamax. But how was the qualty compared to 8 m.m. films?
Of, I forgot to mention Video 8 and Hi. 8.

Video8 isnt analogue is it??

8MM can be very beautiful and if done right you can I believe make a straight copy to a VHS/Beta tape and keep the quality http://www.videokarma.org/images/icons/icon7.gif

8mm camcorder tape had both analog and digital variants. I believe it had both low band and high band analog (think VHS vs SVHS) and also digital. The last tape based camcorder my parents bought was a Sony 8mm that supported all 3 (but defaulted to recording in digital)...It didn't seem to compress the digital at all so it's digital tapes were the clearest most detailed NTSC video I think I have ever seen...It looked better than Laserdisc.

I have a collection of 8mm films, the quality is kind of crap. I'd be surprised if even an early camcorder could not do a better job.

I also had a camcorder that did Video8 and Digital8. I don't think I ever tried a side-by-side comparison. It always just seemed to be good.

16mm film and full bandwidth standard definition analog TV were roughly the same quality.
VHS tape had less resolution than 16mm film, but better quality than 8mm film.

16 mm film shown on full bandwidth standard definition TV resulted in some reduction of overall sharpness, since each were contributing about the same amount of degradation.

35mm movie film, even fairly grainy high speed film, was pretty much transparent to full bandwidth analog TV, but the grain was quite visible when televised in high definition. This resulted in CBS in particular, and others, changing their production standards for scripted programs to be filmed on slower, fine grain 35mm stock. This in itself raised the production costs because more light was required.

In 1951, Otto Schade of RCA won the first SMPTE Sarnoff gold medal for his studies of the comparitive quality of film and TV. He developed the concept of trading resolution (film's forte) vs. sharpness (TV's forte), with the use of the JND or Just Noticeable Difference, and its calculation as the squared area under the modulation transfer function (MTF) curve. The MTF curve is a graph of the detail contrast of sine waves vs. frequency. Schade's work indicates how the perceived sharpness of analog TV can be roughly equal to or somewhat greater than 16 mm film, although the film has greater resolution.

Schade's work correctly predicts the visual sharpness comparison between VHS and full bandwidth analog TV or DVDs, as well as the comparisons to various film formats.
It also predicts the very sharp appearance of Kodachrome compared to other still films available at the time.

Well the thing about any movie film is that it really depends on the film quality, the recording camera, and the operator. Not that analog video differs much, but I think more factors are handled by preset adjustments, rather than the operator. At least for a camcorder, anyway.

16 mm was not considered HD quality in the late 1990s - early 2000s, but as broadcast HD quality dropped in 2010s and 16 mm got better, it started to be accepted for TV, especially after SD TV was phased out. In particular, "Scrubs" has been shot on 16 mm with the sides preserved for widescreen. One episode in season 5 I believe was aired in HD. Also, season 8 was aired in HD, shot with the same Aaton camera. I keep my fingers crossed, waiting for "Scrubs" remaster in HD.

Super 8 can look better than DVD, some say it can look like HD. I saw some spectacular looking Super8, but some crappy looking as well. VHS is more stable in quality, but you can see that it is analog consumer-grade video with its interlacing, its jitter, its spurious noise, its murky low-res color, ugh.

https://youtu.be/3Nh9BTMWj9M

Video8 was better than VHS, about 275 lines. Hi8 and SVHS are even better, but chroma resolution is unchanged, it is pitifully low.

From my experience video8 resolution on a Canon ES950 is about on the same level as VHS in SP mode or perhaps a bit less.

Checking with a Sencore booklet, they quote 272 lines for basic Video 8, 432 lines for Hi 8. As for VHS, 240 lines for basic one, 400 lines for SVHS.

Experience means nothing :) I have an SVHS camcorder that makes images not worth of regular VHS, I suppose the sensor is too low-res. But plays fine.

Video-8, standard VHS, Betamax and U-Matic are all about 240 to 250 horizontal lines of luma resolution and around 30 lines for color in the real world depending on how good the bandpass filters are and the luma carrier. During my early days I recall 16mm was about as good as 3/4 inch tape with a good photographer while 8mm film paralleled a single tube camera recording 6-hr VHS.

To me standard VHS is goregous,it looks just like analogue cable/TV!!

Erm... Umatic is 3/4-inch. Do you mean 16mm as good as Umatic, which is as good - or as bad - as VHS/Beta ?

I mean, this was one of my questions in another thread to get a straight answer whether Umatic was as bad as VHS/Beta/8mm as a first generation recording. I understand that pro versions of Umatic have all kinds of pro features like Y/C connector, genlock, timecode, 1-frame accuracy, remote console, etc, but I wondered whether the sheer video quality of the first generation is kind of the same as VHS/Beta, because this is what numbers show and this is what I see on old Umatic videos.

No, Umatic does not look as good as 16mm if only because of pitiful color resolution.

As for 8-mm comparable to VHS, here is a 1985 Super 8 processed on a DIY film scanner (YouTube video), I don't think you can get similar color resolution from VHS. There are even better examples of how Super 8 can look, but I don't want to post samples shot on a modern camera with precision electronic control and good mechanics.

Good analog TV looks much better than VHS. For example, this is analog TV from 1979 (YouTube video).

Color film inherently has color resolution equal to luminance resolution since the three dye layers (CMY) all have the same resolution. Conversion to digital typically uses full resolution luma and half-by-half resolution chroma (called 4:2:0), which is hardly ever noticeable as degraded.

As DVtyro stated, analog color systems reduce the horizontal chroma resolution drastically. And VHS looks much worse than full bandwidth analog, in both luminance and chrominance resolution.

I would note that early digital satellite transmission (especially the early "MPEG 1.5" of General Instrument) often looked worse than full bandwidth analog transimission. This was due to highly visible artifact levels, mainly due to the unrefined encoding algorithms, not the ultimate capability of the digital coding. Early coders were prone to things like I frame pulsing, "mosquito noise," and noticeable sudden decrease in quality immediately after scene changes. These were all alleviated by better codec algorithms that had better buffer management to allocate data among frames and better allocation of data between pixel data and auxiliary data such as motion vectors.

Around 220 TVL is what I got out of it on a test chart. Direct from the camera I was getting about the 240 lines or a bit better. The recorded video on that camera has kind of a soft look compared to VHS like EP mode VHS. Not quite as soft, but noticable.

Not a very subjective test, a test DVD would have a good NTSC resolution chart along with many others that will run the tapes thru their paces.

Another dumb question about color-under formats, I think I haven't asked it before:

• why raising "sync tip" of luma frequency without increasing the luma frequency bandwidth? Like, Umatic low band has it at 5.4 MHz, high band at 6.4 MHz, and SP at 6.6 MHz, but the deviation is 1.6 MHz in all three cases. What is the benefit?
• What exactly is improved and why by increasing chroma carrier frequency? I suppose the deviation remains the same? Hi-8 has the highest frequency of all the color-under formats, in fact all numbers are better than Umatic SP.

Do keep in mind it was more about the prevailing technology of the day along with other factors like tip writing speed (drum diameter) and tape characteristics. The color under (downshift carrier) isn't as important as the actual bandwidth of said carrier and its transient time window to shift the phase, this window is roughly 10% of the actual color subcarrier before down conversion which would be about 100KHz wide giving a working differential of 50KHz or 30 horizontal lines of chroma resolution in the real world.

Um, thanks, but I think I am still in the dark. Once again, the question is why moving the whole luma band to the right, if its width is not changed? What does it improve? Similarly, does moving chroma carrier to the right improve color resolution if the width is the same? Unless the luma was moved to the right to free more bandwidth for chroma and to reduce the interference with hi-fi audio? Could you explain to someone who understand algebra and calculus, but is not a radio engineer? :)

There's probably noise and headspeed factoring into those choices. All tape has noise characteristics that vary with head speed and head speed varies with drum size and tape speed. There's probably noise advantages in placing the color and video at certain places with certain drum sizes/head speeds.

Ok, so simply moving the bandwidth up does not improve the picture (aside of maybe tape noise)?

Has to do with the Nyquist frequency rate at the high end of the carrier frequency, moving the white clip (high end) will give an increase in the resolution (slight) and improve the white dynamic range without clipping or compromising the signal/noise ratio. Take a look at the attached pdf as this may give you some insight.

I have this document. It was one of the reasons I am asking the question :)

Regarding VHS, it says: "Two limitations occur due to the frequency and deviation limits selected. The lower frequencies of the luminance signal mix slightly with the down-converted chroma signal."

Ok, I can see that chroma mixes with luma.

Then they say "In addition, the frequency range limits the resolution to 240 lines", is it the same as deviation? Because if deviation defines white to black ratio (S/N, right?), then how both S/N and resolution can be defined by the same parameter?

They say, "Super VHS and Super VHS-C VCRs have higher resolution capabilities by raising the overall frequency of the luminance signal. Thus, the FMed signal is placed farther away from the chroma to reduce luminance and chrominance mixing." So, by moving luma to the right, they have increased the resolution of luma, because it is not smeared with chroma? Chroma resolution remained the same because the chroma bandwidth is not changed? This I can understand.

On the first picture with letters they say A is sync tip. A is at the start of the band. So, is the left side of the band always the sync tip or not?

Next, they say "In the case of Super VHS and Super VHS-C, the sync tips produce a modulator frequency of 5.4 MHz with 100% white level producing 7.0 MHz. Maximum deviation of the modulated signal equals 1.6 MHz." So, deviation is S/N? Absolute frequency is luma resolution? How exactly absolute frequency and resolution are related? I wish I saw this graph over time to understand how it looks for each line, for each sample.

If the deviation is 1.6 MHz, and sync tip is 5.4 MHz, what is happening between 1-something... let's say 2 MHz and 5.4 MHz?

FM modulation is described by Bessel functions - college level theory for sure.

What this means is that video frequencies produce a spectrum covering the sync tip to white frequency range, PLUS some sidebands beyond that range.

Low video frequencies produce only a little extra spread beyond the deviation, while higher video frequencies produce additional sidebands that are at least as far away from the background gray frequency as the higher video frequency, above and below the low-frequency deviation they are riding on.

So, for example: say sync tips are 5.4 MHz and white is at 7 MHz. If there is a high frequency pattern of 2.5 MHz video riding on a gray background that produces an FM frequency of 6.2 MHz, sidebands will be generated that extend at least from 3.7 MHz (6.2-2.5) to 8.7 MHz (6.2+2.5) (well beyond the deviation of 5.4 to 7).

Because of the limited upper frequency of the heads and tape, the high-side 8.7 MHz sideband will be attenuated, and the signal becomes a sort of single sideband (or vestigial sideband) narrow-deviation FM when read from the tape.

The lower sideband of 3.7 MHz MUST be present in order to demodulate the entire video including the gray background video component at that point AND the 2.5 MHz video component. If the system bandwidth was strictly limited to the deviation, no high frequency video patterns could be recorded.

No matter what deviation you choose, you must have these sidebands to reproduce higher video frequencies.