External TBC - always use, or only as needed?

[anitract]

While this has been explored a bit in the past, people's setups and opinions change. So, what's everyone _currently_ doing with their hardware chains & external TBCs?

I was using my TBC-1000 all of the time, but I'm considering taking it out of my hardware chain and ONLY using it if I have sync issues.

There are both positives & negatives when using an external TBC. Checkout this thread for a good start. IMO, things become more important when you consider using your TBC all of the time. Here is a little breakdown:

TBC Positives
1. Continuous sync / no dropped frames
2. Ease of mind

TBC Negatives
1. Softens images slightly
2. Lightens picture slightly
3. Vertical lines introduced
4. Checkerboard problem

...feel free to add/dispute these. The question becomes, which side outweighs the other?

[lordsmurf]

Your negatives can vary due to source and even variations in the TBC itself.

I would suggest TBC only be used as needed.
- Probably 99% of the time on VHS.
- Maybe 1% of the time on broadcasts.

[Cole]

I would like to add that since the https://forum.videohelp.com/viewtopic.php?t=283639&highlight=tbc thread you point to, I have (after Lordsmurf's suggestion) got a cheap end detailer (Copymate Video Copy Enhancer) and inserted this between the TBC and the capture device (ADVC-50).

The resulting capture is not spot on to what it would be without the TBC, but it is so near as to not be able to notice it without looking really closely.

I leave the TBC in the loop all the time for VHS captures, but if capturing off air (on the rare occasions that the stand alone DVD Recorder is already busy), I link the ADVC-50 straight to a digital reciever.

Ultimately, the TBC is required IMHO for all VHS captures because without it, I may find the tape could be bad from the off, or (as has happened) I get a sync error about an hour/two hours into the video.

The chances of a sync error are too great a possiblitly to take a chance without the TBC. Plus the fact that I don't sit and watch the video on the PC monitor when capturing, so I may only get to see the sync error on my completed DVD-R (again which has happened before). So for me, the postives outweigh the negatives.

[anitract]

Yes, the ease of mind of having the TBC in the chain is definitely there. That's what makes this tough for me. Of course, you start introducing other factors & it complicates things more.

For example, a lot of us (including me just recently) have switched to hardware DVD recorders. These types of machines usually have circuitry that syncs audio/video. If they did not include this, their products would not work for Joe Consumer who just wants to copy their VHS tapes. Of course, this does not replace a full frame external TBC, but you are still going to maintain audio/video sync in most cases. Right?

[davideck]

For example, a lot of us (including me just recently) have switched to hardware DVD recorders. These types of machines usually have circuitry that syncs audio/video. If they did not include this, their products would not work for Joe Consumer who just wants to copy their VHS tapes. Of course, this does not replace a full frame external TBC, but you are still going to maintain audio/video sync in most cases. Right?

The DVD Recorders that I have tested DO have full frame TBCs built in. They include the Panasonic ES20, the JVC M100, the LiteOn 5104, and the Toshiba RD-KX50. Of the bunch, the Toshiba has the best actual Timebase Correction performance, but they all provide the functionality of a TBC-100 (except for the MV elimination).

[lordsmurf]

I've not seen a DVD recorder to date that has a true TBC at all, much less full-frame. At best, some of them have various TBC-like filters (Panasonic ES10 sync filter, for example), but they're few and far between.

Most recorders vomit the first chance they get. LiteOn 5104 and JVC DR-M100 are in my arsenal too, and I don't know where you're getting that info on TBCs, but it's dead wrong. The economics alone (a $100 recorder, c'mon!) shows there not any sort of TBC parts inside. There's nothing like that found on the motherboards.

These types of machines usually have circuitry that syncs audio/video.

The whole idea of "locking video and audio" is silly too. It's a pretty marketing phrase that doesn't mean a damned thing. To "lock" audio and video, in the context of the tools we're talking about here, all you need to do is not drop frames, or if you drop frames then dump both audio and video. There's nothing magic here. The hardware is specialized, it's not going to drop frames like a software or hybrid computer method would have done.

[davideck]

I've not seen a DVD recorder to date that has a true TBC at all, much less full-frame.

I verified the Frame Synchronization capability of these four machines with a two channel oscilloscope by comparing video in to video out. They all have built in frame synchronizers, and they all provide continuous sync on their outputs (just like the TBC-100).

[anitract]

I don't think we can use price as a sole means of whether or not the have TBCs. Anyway, I haven't heard anything about TBCs either, davideck. Is this based on your own research, and if so, how did you determine this.

My Toshiba D-R4 that I have does not mention having any sort of TBC-like device in it so far as I see, but I'd be interested in knowing if there was.

[anitract]

Can you elaborate a bit? Did any of the product manuals mention this feature? I'd be interested in checking / testing my toshiba to see whether or not I get the same results.

[davideck]

None of the manuals mentioned anything about timebase correction or frame synchronization.

For more elaboration look towards the end of;
https://forum.videohelp.com/viewtopic.php?t=289311

[anitract]

davideck, I hadn't looked at that thread for a while. Interesting stuff you're looking at. What I don't understand is this: frame synchronizers found on dvd recorders you tested will give similar results as a TBC-1000 when examined with a two channel oscilloscope....if this is so, how come macrovision is left alone with the recorders?

So what is the difference between frame syncing and an external TBC that removes the macrovision? They appear to give the same results, but yet....?

For someone like me, the recorder vs. external results are very important. If macrovision is the only thing that is left alone, I could stand to loose the external TBC & allow the DVD recorder and my JVC TBC to do a good enough job.

[slacker]

davideck, below is the only thing I could find for the Panny.

Another new feature is what Panasonic calls "VHS Refresh". This feature offers improved quality when Dubbing VHS to DVD. When connecting a VCR and the DVD recorder to record VHS videotape images onto a DVD disk. Something similar to a "Time Base Corrector", helps reduce jitter and also performs signal conversion to create a stable signal.
At the same time, 3D Digital Noise Reduction, detects and virtually eliminates randomly generated noise and color errors to help minimize flicker. Thanks to these two technologies, the tape input signal is automatically detected and optimum processing is performed to provide an easy way to even more beautiful digital pictures. The 3D Digital Noise Reduction, also helps clear up recordings made in the EP 6(or) 8) hour speed. This unit has an option to allow up to Eight (8) hours of record time.

[davideck]

So what is the difference between frame syncing and an external TBC that removes the macrovision? They appear to give the same results, but yet....?

Eliminating MV involves blanking the appropriate lines within the Vertical Interval and is independent of the frame synchronization operation. The TBC-100 blanks these lines, the DVD Recorders do not.

For someone like me, the recorder vs. external results are very important. If macrovision is the only thing that is left alone, I could stand to loose the external TBC & allow the DVD recorder and my JVC TBC to do a good enough job.

If MV is not an issue, then an external TBC is not necessary. Try it and see...

[lordsmurf]

I never said price was the only reason, but it should stand out as one of the most obvious tell-tale signs that TBC is totally lacking. Those things are not cheap.

The TBC does not "blank" lines. That's what wannabe-TBC devices do (like SIMA brand items). The TBC strips the signal out and replaces it with it's own data.

[davideck]

The TBC does not "blank" lines.

Yes it does. The lines in the Vertical Interval which contain MV, etc. are replaced with black lines. The SIMA boxes do the same thing.

Many professional TBCs provide adjustable Vertical Blanking to let the user decide which lines in the Vertical Interval to pass or blank.

The DVD Recorders don't do this on purpose because that would make illegal copying too easy.

[anitract]

Ok, so the recorders do not blank the lines...

With regards to the frame synchronization, what are they doing that makes them keep audio-video in sync?

[davideck]

A Frame Synchronizer provides continuous sync at its output at all times. Regardless of what happens at the input (dropouts, record gaps, etc.), the output sync is always an uninterrupted sequence of valid frames. This keeps audio and video in time with respect to each other. In the same way that an external frame synchronizer (TBC) eliminates audio/video sync issues with many capture devices, the built in frame synchronizer in DVD Recorders eliminates audio/video sync issues there as well.

[slacker]

On a side note, SOMETHING exists in many of these digital camcorders. I don't know if it's a true full frame TBC. In using my Canon Optura 500 for analog to digital pass thru of VHS material I am astonished at the total elimination of any and all tracking errors and/or 'jitteriness' in 1 or 2 of my videos. It comes out PERFECT. It is simply amazing, I can't begin to tell you. Is this what a TBC does?

[lordsmurf]

Many cameras have TBCs in them, but most of them are only for playback of tapes, do not work on passthrough. A few can do passthrough, especially DV cameras.

[davideck]

In using my Canon Optura 500 for analog to digital pass thru of VHS material I am astonished at the total elimination of any and all tracking errors and/or 'jitteriness' in 1 or 2 of my videos. It comes out PERFECT. It is simply amazing, I can't begin to tell you. Is this what a TBC does?

Yep. The same is true of my JVC MiniDV Camcorder used as a passthru. Its TBC performance is every bit as good as the internal TBC in my JVC 7600 and 9600 machines.

The frame synchronizers in the DVD recorders all provide continuous sync like an external frame based TBC, but their actual timebase correction capability varies among different manufacturers. The best TBC performance that I have found in a DVD Recorder is on the Toshiba, easily outperforming the DataVideo TBC and essentially matching the performance of a professional FOR.A TBC that I have been using. At the other end of the spectrum, the LiteOn and JVC units are very susceptible to tape jitter, provide little if any actual timebase correction, and sometimes make things worse. The Panasonic is in between with a TBC performance similar to the DataVideo TBC. For analog tape capturing, the Toshiba is the clear winner of the ones that I have tested.

[FulciLives]

In using my Canon Optura 500 for analog to digital pass thru of VHS material I am astonished at the total elimination of any and all tracking errors and/or 'jitteriness' in 1 or 2 of my videos. It comes out PERFECT. It is simply amazing, I can't begin to tell you. Is this what a TBC does?

Yep. The same is true of my JVC MiniDV Camcorder used as a passthru. Its TBC performance is every bit as good as the internal TBC in my JVC 7600 and 9600 machines.

The frame synchronizers in the DVD recorders all provide continuous sync like an external frame based TBC, but their actual timebase correction capability varies among different manufacturers. The best TBC performance that I have found in a DVD Recorder is on the Toshiba, easily outperforming the DataVideo TBC and essentially matching the performance of a professional FOR.A TBC that I have been using. At the other end of the spectrum, the LiteOn and JVC units are very susceptible to tape jitter, provide little if any actual timebase correction, and sometimes make things worse. The Panasonic is in between with a TBC performance similar to the DataVideo TBC. For analog tape capturing, the Toshiba is the clear winner of the ones that I have tested.

Very interesting what you say about the Toshiba DVD recorder.

Any chance of adding it to the thread where we were testing TBC devices? You know record that "line" pattern to a VHS tape then play the VHS tape to the Toshiba then post a pic of it to show how well the Toshiba TBC deals with it ... of course you would want to use nothing between the VHS and the Toshiba and if using a JVC S-VHS VCR you would want to turn off it's TBC.

If the TBC of the Toshiba is that good maybe I'll just get a Toshiba instead of a TBC even though I already have a DVD recorder (Pioneer DVR-531H-s)

- John "FulciLives" Coleman

[anitract]

I wonder if the Toshiba D-R4 & RD-XS34 use the same frame synchronizer as the one davideck's Toshiba? I'm not sure if gshelly61 is monitoring this thread, but maybe he could say either way since he's a big Toshiba pusher.

[davideck]

Any chance of adding it to the thread where we were testing TBC devices?

Chances are very good. I have already performed that test on the Toshiba and captured an image. I will post it tonight.

[davideck]

I have posted the capture;
https://forum.videohelp.com/viewtopic.php?p=1482771#1482771

[anitract]

davideck, the JVC TBC still looks much better than the Toshiba to me. But comparing to external TBCs, yeah, it does seem better.

I still like that external TBCs correct macrovision though. I would hope that most DVD recorders deal with fairly poor quality tapes w/out being fooled into think they have macrovision. I remember trying my ATI All-In-Wonder w/out a TBC....yikes!

[davideck]

davideck, the JVC TBC still looks much better than the Toshiba to me.

Very true, but keep in mind that my test tape is an extreme case of timebase instability.

Just this weekend I was capturing an old VHS EP tape. My JVC 7600 / 9600 VCRs had trouble maintaining Vertical lock (the picture kept jumping up and down) while my JVC 6800 was rock solid. The TBC performance of the Toshiba was more than adequate for this tape, so I used it along with the 6800.

I still like that external TBCs correct macrovision though. I would hope that most DVD recorders deal with fairly poor quality tapes w/out being fooled into think they have macrovision. I remember trying my ATI All-In-Wonder w/out a TBC....yikes!

False macrovision detection seems to be a real problem. I have read several posts about various DVD recorders refusing to capture non-macrovision tapes. I had the same experience trying to capture a tape with the JVC M100, while the Panasonic ES20 and the Toshiba recorders captured it just fine. The Toshiba hasn't let me down yet.

It is a shame to subject a video signal to additional Analog to Digital to Analog conversions in order to utilize an external TBC just to blank out a few lines in the Vertical Interval for MV removal. Also consider that using an external TBC between a VCR and a DVD Recorder will prevent the DVD Recorder from performing any timebase correction itself as the external TBC will embed any timebase errors that it fails to correct into the video signal. Additionally, the DataVideo TBCs in particular soften the image a bit. In this situation, a SIMA type box might be a better choice for MV issues, but YMMV.

[jeffshead]

Thought you folks might like to read the response I got from TV One Tech Support. Makes sense to me and I really have to compliment them on their willingness to help with support issues.


Hello Jeff,

Yes, the AVT-8710 can change the image quality in some cases. Since it only has 8-bit color processing, there will always be some loss when converting from analog to digital then back to analog again. Generally I would not recommend using leaving a TBC always inline unless your source was known to always have poor timing or synch signals. In your case, if you can capture a full tape without any frame drops or loss of picture, then you don't need the TBC in-line in that instance and you're better off not adding additional processing to it. However if there are bad spots on a tape where the synch or timing drops out and causes capture issues, then you should put the TBC in-line to correct them.

As for a comparison with professional grade TBCs, of course a pro TBC will provide you with better quality (our pro-grade TBC has 10-bit color processing), but it will also generally give you expensive features you don't need (such as genlocking, BNC connections and SC phase controls) and will cost around 5-10 times as much as an AVT-8710.



> Dana,
>
> Thanks for your help with the checker boarding effect I have been getting
> with the AVT-8710.
>
> I find the AVT-8710 also changes image quality. Is this common with this
> TBC? If you compare jvc7_TBC.jpg to JVC10_VCR to DVD.jpg, you will notice
> jvc7 is a bit washed out and brighter than JVC10 which bypasses the TBC. You
> will also notice the TBC adds some artifacts and causes a loss in contrast.
> All proc amp functions have been reset to neutral.
>
> The link below is the forum I have been discussing this with some folks who
> have been working with video restoration for quite sometime.
> https://forum.videohelp.com/viewtopic.php?t=295160
>
> I am wondering if a professional grade TBC would do a better job.
>
> Will you please comment?
>
> Thanks,
>
> Jeff

[davideck]

IMO, 8 bits versus 10 bits is of little importance here; many broadcast quality TBCs are 8 bits and look virtually transparent. The artifacts introduced by the TBC-1000 and AVT-8710 are not inherent limitations of 8 bit processing but instead are the result of other design compromises.

One thing that Tech Support did not discuss is how good their TBC is at actually correcting timebase errors.

For instance, since the Toshiba DVD Recorder has such a good internal TBC, it would be best to connect it directly to the VCR whenever possible. The first TBC in the signal path is the only one that has an opportunity to correct timebase instability. Any residual timebase error remaining after the first TBC is embedded into the video signal on top of stable sync, such that another TBC downstream sees no timebase instability even though it still exists. So if more than one TBC must be used, the best TBC should be the first one in the signal path.

On the other hand, the JVC and LiteOn DVD Recorders are not very tolerant of timebase instability and would therefore benefit from a TBC-1000 or an AVT-8710 between them and the VCR.

[anitract]

I had a chance to test my Toshiba RD-XS34, and the TBC (or whatever it is thats in there) seems pretty impressive. Combined with my JVC TBC, I haven't encountered many problems thus far. So I agree with davideck for the most part. There are, however, cases where TBC-1000s are definitely needed (macrovision & false macrovision, for example).

Since I'm not going to use my ATI AIW any more for caps, I put my TBC-1000 up for auction on ebay (which actually ends in 12 hours). Someone else can use it more than me.

[davideck]

anitract -

Since the JVC VCR TBC/DNR system is the first TBC in your signal path, it must be turned off in order to demonstrate the TBC performance of the XS34.

When the JVC TBC/DNR is on, the XS34 is still providing the necessary frame synchronization. The JVC TBC/DNR system is a great TBC, but it does not guarantee continuous sync.