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-   -   What is a TBC? Time Base Correction for Videotapes (https://www.digitalfaq.com/forum/video-restore/2251-tbc-time-base.html)

S1RIUS 10-23-2020 01:40 PM

Hi,

I can't find a decent TBC, is a Videonics MX1 with TBC included is better than nothing ? Or it would affect the image quality.

dpalomaki 10-23-2020 02:44 PM

The MX-1 is a video mixer. Its TBC capability was intended mainly as a frame synchronizer to allow transitions from separate video sources, live and/or tape. In this process it did provide TBC benefits. The main issue is it is not as forgiving of poor signals as the recommended units, but I've not had any problems with my source material. The original MX-1 did not provide proc amp capability, but could do chromakey.

Its specifications include 4:2:2 internal 8-bit quantization at 13.5 MHz sample rate, and 5 MHz video bandwidth, and 56 dB S/N. It has 4 input channels, composite and s-video inputs, and audio can be remapped. In about 1998 it was replaced in the Videonics line by the MX-Pro about which was more capable and used 10-bit internals for the Y/C inputs.

Be aware that back in the 1990s some MX-1 users reported issues with overheating that they addressed by ensuring there was good air flow around the unit. I don't know if it has any unusual component aging issues. Also, there were separate units for NTSC and PAL.

S1RIUS 10-23-2020 02:53 PM

Thanks you, I'm running PAL/SECAM VHS, i'ill look into it.

Unit are sold in France so I guess its ok but i'll double check that.

lordsmurf 10-23-2020 03:05 PM

There's been a number of MX-1 posts over the years, with detailed feedback.

The main conclusion is that it has some weak frame sync ability, with side effects to video quality. It's just not a TBC. The main use was live camera switching for low-budget productions (high schools, colleges, local cable companies of old). Not really even videotape sources. You don't need strong corrections for live camera work. When tapes, not VHS, but S-VHS, maybe Hi8, sometimes even better broadcast tapes formats, later DV.

As mentioned, heat issues, and it's not aged well, so you see damaged and "as is" units, problem units, and just less units whatsoever.

It's not too different from the weak DataVideo DVK units, or SE mixers, though a decade older.

In my search for TBC alternatives, this was on my list. But it was disqualified fairly early.

Bogilein 10-24-2020 01:11 AM

Quote:

Originally Posted by S1RIUS (Post 72327)
Hi,

I can't find a decent TBC, is a Videonics MX1 with TBC included is better than nothing ? Or it would affect the image quality.

Save your money and buy a panasonic dmr-es10/15....... dvd-recorder. You can read a lot about the device here in the forum.

lordsmurf 10-24-2020 01:47 AM

Quote:

Originally Posted by Bogilein (Post 72343)
Save your money and buy a panasonic dmr-es10/15....... dvd-recorder. You can read a lot about the device here in the forum.

It's really not an either/or situation. :2cents:

You must remember than line TBC (or field TBC), and frame sync TBC ("frame TBC"), are separate items.

The ES10/15 mostly has an unusually strong line TBC, with a mere non-TBC frame sync. However, the unit (and thus the line TBC) is compromised, forced to pass anti-copy errors. Anti-copy is an artificial video error, but naturally occurring video errors can (and often do) look the same to the detections. So what you can have is a nice line-corrected image that still will not capture, or exhibits other odd anti-copy type visual errors.

The DataVideo DVK units, or the weaker TBC-5000 -- and potentially some other devices, maybe this MX-1 (?) -- integrate weak frame TBCs as part of the intended function. These units are broadcast or broadcast-like, expecting non-consumer sources, either live camera or S-VHS shot on a pro camera. Not something shot on low-end consumer camcorders, not VHS or Video8/Hi8, or VCR recordings. When fed consumer sources, choking is not uncommon, weirdness and problems happen on the transfer attempt. The errors can be visual, or balking at transfer, or both.

When you combine the strong (but still compromised) line TBC and frame sync, with the weaker frame TBC, you arrive at something that is purifying a signal more like an actual TBC.

The main drawback is incurred extra processing noise. The ES10/15 has some posterization (color palette compression, easily seen on gradients and shadows), aggressive NR that is always on even when "off" (off=less, not truly off), and in PAL apparently some luma issues (noting that Panasonic NTSC luma isn't perfect either, but the PAL is just a tad worse).

This is a TBC(ish). Not a true TBC, but in combo can act like one.

The ES10/15 alone is a minimalist uber-budget approach to TBC that will still have a fail rate. Either refusal to capture, poor capture, or other problems. Some folks may have zero errors, some may have nothing biu errors -- but more often it's both successes and failures that are observed and experienced by users.

The DVK+ES10/15, and 5000+ES10/15, are definitely approved methods, I've tested those extensively. The MX1 is not something I ever tested in a TBC(ish) combo, but there is a chance that the MX1+ES10/15 is a budget option. However, that said, the DVK is a better unit, especially having that proc amp. It's also what I refer to as a "99%" unit, as it can still have source problems (though, to be fair, some actual TBCs can as well).

An actual TBC is better. Far, far better. Both for quality, and functionality.

But it's not all negatives. Since the line TBC of the ES10 is active, the VCR doesn't need a TBC. (However, S-VHS decks are still suggested, due to build quality, affecting both playback and longevity.) In fact, there are times that a TBC(ish), for some projects, with some source tapes, can actually be superior to an actual TBC. I've run into those situations before.

As always, video is not binary, not either/or. It has nuance, variables. :cool:

ENunn 03-30-2021 03:46 PM

Sorry for bumping a dead thread, but since this is related, has anyone had any luck with a Datavideo MP-6000 as an external TBC? I saw a delisted eBay listing that proudly proclaimed it to be just as good as a TBC-1000, so that means it must be true because it says so :wink2:

joonas 04-15-2021 04:08 AM

Any opinions regarding Kramer FC-400 (PAL/NTSC?).

davidluab 09-10-2021 09:03 AM

The panasonic AG-MX70 works with internal TBC ??

I have read that yes

thanks

hodgey 09-10-2021 12:17 PM

Yeah most of these panasonic video mixers featured frame synchronizers as far as I know, including this one. (i.e TBC that is capable of synchronizing multiple inputs). It's needed for seamless transitions and effects between different inputs. How well this one in particular works on VHS input I have no idea though, maybe someone else has tested one.

I have two older Panasonic video mixers, they seemed to do fine on a normal VHS tape on some quick tests, though they have some noise/image issues which I haven't sorted so I haven't tested them much yet. This one is a fair bit newer than those so the decoding circuitry is probably a bit changed compared to those old ones.


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