Component HD vs HD-SDI

F

fiercecurry

Well-known member
Hello,

Does anyone know the difference in quality of analog component HD compared to HD-SDI? Both will do 10 bit 4:2:2.... right? Is it an issue of noise levels?

The HVX offers component HD out like the JVC Pro HD cam, but will it be processed to 8 bit 4:2:2 when its outputed through the component? Or will it be 10bit?
At what res: 720 or 1080?


Any answers will be helpful.
thanks.
 
Component HD is analog. HD-SDI is digital. Becuase your recording is digital, it has to be converted to analog to be transfered over component HD. That means a very slight degredation in quality. Plus, because it is analog, you have the potential that noise can be introduced in the cable run. Then (if you're recording back to digital or editing on an NLE) the footage will take another slight quality hit as it is converted back to digital.
 
Thanks Alex, i know its analog. But does the HVX ouptut the analog at 10 bit or 8 bit? Does it process the data at 8bit using the DVCPRO HD codec before it records to p2?

To put it simply, when bypassing the P2, and outputing through its analog out, will it deliver 8bit or 10 bit.
 
fiercecurry said:
Thanks Alex, i know its analog. But does the HVX ouptut the analog at 10 bit or 8 bit? Does it process the data at 8bit using the DVCPRO HD codec before it records to p2?
Click to expand...

That's a very good question...
 
It won't be 8-bit or 10-bit, it won't be any bits at all because it'll be analog.

If you're asking how many bits it would take to hold the color precision of the output signal, that's a different question; one that we can't answer with any specificity. It'll likely be a D-To-A conversion of the signal straight out of the DSP, so it could be whatever the bit depth of the DSP is, since the signal is coming from the DSP, not the compression engine (the analog output happens before the DVCPRO-HD compression stage). So if the HVX has a 14-bit DSP (which I'm guessing it does) then it could be the analog equivalent of 14-bit 4:4:4. It depends on when the chroma decimation to 4:2:2 takes place as well -- if the DSP processes the signal as fully-sampled full-color resolution, it'll stay that way throughout the component output stage. But if the first thing the DSP does is lop the color in half, then the final analog output would be no more accurate than 4:2:2.

But what it could do, and what it does do, are not necessarily the same thing.

Does it process the data at 8bit using the DVCPRO HD codec before it records to p2?
Click to expand...
DVCPRO-HD is an 8-bit format, so all P2 recordings will be 8-bit. Before data gets written to the P2 card it gets run through the compression engine, whether DV, DVCPRO25, DV50, or DVHD. That step is unrelated to the analog output.
 
Barry, that helps clarify some issues, thanks.

So, in theory, the HVX could process a 10bit 4:4:4 or 4:2:2 via its analog component output.

What would be the ideal deck to best preserve that signal? Clearly not a DVCPRO HD deck.
One could attach a AJA analog to SDI converter to the camera and than connect that to a SDI capture card (for HD capturing). But if a computer with a RAID drive is unavailable, what deck would you connect to the serial converter that best preserves the signal?
 
The best would be HDCAM-SR or perhaps D5-HD. HDCAM-SR is about the only high-def 4:4:4 recording system out there. D5-HD handles full 10-bit 4:2:2.
 
Thank you! I posted the same reply on the Canon thread.
Do you know the average rental price for these decks (not the HDCAM)
 
I agree.

I wish we would have voiced about an SDI output sooner, than Panasonic might have offered it.
Is it still too late?
Looks like the Canon has the advantage in that area.
 
For chroma keying, would 4:2:2 uncompressed be any noticeably better than DVCPRO HD? It's still 4:2:2, but would the mosquito noise really be reduced that much? Is compression or color sampling more important?
 
Both degree of compression and chroma sampling lead to the "keyability" of video. The only tape format I'd be happy keying off, in the SD world, is DigiBeta as it's so lightly compressed and 4:2:2. The nearest HD equivalent to DigiBeta in the SD world is D5 or HDCAM SR, neither of which are affordable in any way.

Then again, if you can pull a key off VHS or DV, then you can pull a key off anything, and really it comes down to lighting more than video tape.

Graeme
 
Graeme_Nattress said:
The only tape format I'd be happy keying off, in the SD world, is DigiBeta as it's so lightly compressed and 4:2:2.
Click to expand...

Isn't DVCPRO50 pretty darn close to Digibeta? Also, does compression or resolution work better for keying? HD is higher resolution but more compressed. Would the mosquito noise dampen the fact that there is more rez?
 
low compression, and high chroma sampling is what is needed. Resolution neither helps nor hinders if you want the resolution of the key to be equal to the resolution of the video...

Graeme
 
Would HD keyed and downconverted be as good as shot in SD? I have noticed that when video is scaled down, the key line seems to tighten up and less noise is visible.

When I have taken footage from the DVX of a whole body and scaled it down in a compositing program, the noisy edges seem to improve, and the key appears better.
 
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