Billy responded:
> No, but NTSC in North America uses setup of 7.5% and equipment that is
>intended to record broadcast signals and ignores that I would consider
>to be buggy.
Without a configuration option, or switch, a DV recorder (or analog <->
firewire converter) that blanket strips setup on record and adds setup
on playback is wrong as well. There are situations where the analog
video might not have setup and recording this would drastically violate the
DV standard. It is better to not screw with the incoming video, than it
is to blanket strip it. The best is to add a switch/configuration option
for setup, as Sony has done on some of their products.
I agree that it is not right, but it was designed that way on purpose.
> Well this is why I was asking for specific examples of cameras or
>recorders, since I want to know how they were intended to be used. In
>my opinion though, if you have a consumer DV camera with analog inputs,
>I would consider it a bug if they took analog NTSC input and mapped 0
>IRE to black.
See above. Without an option, it is best to leave the NTSC signal well
enough alone, otherwise you could end up with 0 IRE at 0 DV, which is
worse than 0 IRE at 16 DV (when the NTSC video doesn't contain setup).
> I'm sorry, I really did read it, and I thank you for your patience.
>I've been learning a lot from this discussion. However, you did
>misunderstand me as I did mean camera. The GL-1 has analog inputs just
>fine, and by transcoder I'm sorry, I meant recorder box like the DSR-40
>DVCAM recorder which I have used in the past.
Yep, I think we had a minor error in communication.
> That said, research shows that at least on the analog outputs for the
>DSR-40, they don't add setup. Sigh. I do believe you that these
>devices exist and operate like this.
They don't remove it either :-) I have two DSR-20s and they record the
analog signal as provided, 0 IRE to 16 DV and 100 IRE to 234 DV.
> However! This really has nothing to do with DV itself, this is all
>the fault of the device. Any DV file where black is at 32 instead of 16
>is broken and the result of a hardware misconfiguration. Fixing it in
>software is a band-aid solution, you've lost way too much resolution.
>Don't use hardware that wasn't intended to record broadcast video if
>that's your application. Software should never see these broken files.
BTW, all DVCAM decks, no matter the series, are intended to record broadcast
video. They are there to record NTSC video, which has setup. Yes, it isn't
right to record the setup onto the DV tape, but it happens a lot in the
industry. This has been discussed on a DV forum that I used to subscribe to.
And how do you propose to get Sony to recall all of the DSR line that doesn't
give the user the option of removing setup and replacing the motherboard so
that it will (based upon user selection of a menu item)? It isn't
hardware misconfiguration in the case of the DSR series, it was poor design,
or they did it on purpose. One has to work with what was provided. In the
case of the DSR series, NTSC analog is recorded as given and the only way
to fix it is in software, or place a framestore TBC before the DSR deck and
remove setup that way. But that could add some more noise to the video and
it will result in some lip-sync slippage (if the audio isn't sent through
a digital process that receives delay info from the TBC. I prefer the
software method as it doesn't introduce TBC artifacts.
As for resolution, you don't lose any resolution. Resolution is normally
used in reference to video frequency response. I believe you really mean
video dynamic range. Yes, recording setup onto DV results in some dynamic
range loss, as you lose 16 levels.
What is interesting with DV is that you actually lose video dynamic range,
since the original 256 digital units used in most broadcast equipment [TBCs
and the like] (actually 237 when setup is involved) gets recorded as 218
digital units (234 peak white less 16 for black = 218). DV is actually a
dynamic range loser.
When I record the 4:2:2 digital sat feeds onto DV, I keep the original
dynamic range of the MPEG-2 data, since I don't let the receiver add setup
just so that I take it away in software (losing some dynamic range). I don't
have that choice with the analog receivers.
MB
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