Time Base Corrector - Always a good thing

[echo1434]

Hi,

I have a high-end unit that converts PAL to NTSC and vice versa, and it also doubles as a time base corrector. My capture card is a Canopus MVR-D2000V, which also has a built-in time base corrector, but I don't think it's quite as strong as the one in my standalone unit.

The TBC feature cannot be toggled on either device, so I'm wondering if there is any advantage or disadvantage to using the external TBC when I'm not doing converting from PAL.

I'm especially wondering about this when my source is very clean (laserdisc, new VHS tape). I use high quality cables, and the one connecting my standalone converter/TBC is very short.

Basically, I just want to know if I could could do all my conversions and leave my full rig connected all the time, regardless of the source. Note that there are two TBC's going at the same time. Could this and the extra generation be a bad thing? Or is a TBC always useful when using solid connections?

Thanks in advance.

[davideck]

Using both TBCs may actually be the best thing to do.

Hopefully, the TBC in the standards converter is frame based and provides continuous sync at its output. This will prevent Audio Video skew and other problems associated with tape/source dropouts during capture.

The TBC in the Canopus is most likely line based and hopefully improves the picture quality.

As long as the final picture quality looks as good or better than when using only one or none, my guess is that they both provide benefits.

[davideck]

After thinking more about this...

It may be that the TBC in the standards converter prevents the TBC in the Canopus from eliminating the timebase errors in the original tape. An interesting test would be to compare the picture quality (in terms of stability and chroma purity) captured through both TBCs versus just the Canopus. It may not matter if the standards converter TBC does a good job of timebase correction. Or it may be a tradeoff between the benefits of the frame based TBC versus the picture improvement when using just the Canopus; if its not one thing its another...

[lordsmurf]

The Canopus "TBC" has been an issue of debate in the past. It may not truly be a TBC. More of the Canopus marketing machine at work. Search the forum for details, I've long forgotten all the facts on it.

[anitract]

There are always a couple of threads going on TBCs. For a recent one, see:
https://www.videohelp.com/forum/viewtopic.php?t=282757