VHS to DVD - concerning resolution

[ulTRAX]

Where did you get these specs from? (rfb is an NAB/SBE/FCC licensed broadcast engineer)

Where did I get those numbers? I had to research on this back in the 90's but I was more interested in the comparitive value of video formats for historical preservation. I felt the 3/4 screen method of measuring resolution too confusing for my clients... mostly members of historical commissions and societies.

But I did look it up now and NTSC has a theoretical horizontal resolution of 452 not 440. Oops. Good... now I can correct whatever I wrote then. That's based on bandwidth calculations from

http://broadcastengineering.com/infrastructure/broadcasting_horizontal_resolution_pixels/

The horizontal resolution defines the capability of the system to resolve vertical lines. It depends on the camera and display capabilities, as well as the bandwidth and the high-frequency amplitude and phase response of the transmission medium. In a 4:3 aspect ratio television system, it is expressed as the number of distinct vertical lines, alternately black and white, which can be satisfactorily resolved in three quarters of the width of a television screen. A system with a horizontal to vertical aspect ratio of 4:3, as in conventional television, needs to allow for (4:3) NV horizontal details to be resolved over the width of the display.

In the NTSC system, this results in 339 × 4/3 ≈ 452 horizontal details to be resolved. Due to the limited system bandwidth, exploring a pair of contiguous white and black fine details (line-pair) results in a sinewave with a positive half-wave corresponding to the white detail and a negative half-wave corresponding to the black detail. Scanning 452 horizontal details results in an electrical signal with 226 complete cycles during the active horizontal scanning line.

Actually the worst format to be put out there in the consumer market was 1/4" C open reel format. This may be a bit before your time but was the only thing around them days. It sported 170 lines H res and no color. Ran at 7 1/2 ips on 7 inch reels.

Not sure what my time is. I'm older than NTSC color LOL. Still think FP PixelVision has it beat... It came out in 1987, had 120x90 pixel screen resolution and used used audio cassettes. http://en.wikipedia.org/wiki/PXL-2000. Imagine what these things are getting on eBay!

[ulTRAX]

The only thing a TBC is going to give you is stable sync pulses and color burst frequency. It may give you some adjustment control over brightness, luminance and chroma saturation and color phasing (hue or tint control), other than that it wont clean up the already low grade VHS video signal at all.

I don't understand.

You wrote earlier:

There really isnt any way to get increased quality from VHS onto a DVD. The VHS should be as clean as possible for a decent transfer to any digital medium.

There are numerous quality problems with old analog formats like VHS. So preserving whatever quality there is seems crucial. So having stable sync.... the ability for all horizontal lines to line up so a vertical line is straight... seems crucial to preserving video quality.

Yet you seem to be dismissing TBC as not important? What am I missing? Do all modern VCRs include TBC?

[RFBurns]

I don't understand.

You wrote earlier:



There are numerous quality problems with old analog formats like VHS. So preserving whatever quality there is seems crucial. So having stable sync.... the ability for all horizontal lines to line up so a vertical line is straight... seems crucial to preserving video quality.

Yet you seem to be dismissing TBC as not important? What am I missing? Do all modern VCRs include TBC?

Oh no no no!! What I was saying was the TBC's benefit is the sync. Since the playback stright off a VHS without one, the sync is really unstable. A TBC provides the stable sync for the transfer.

The TBC however wont do any cleaning of the luminance or chroma signals at all. It will however allow adjustment of these signals, bright, black level, chroma level and chroma phase.