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Discussion Starter · #1 ·
Last week at work we were demo'ing some HD recording hardware. So I decided to take some of it home along with some cheap converters we allready had for the weekend and make my own free HDTV PVR.


Here's what I did-


RGB from my VOOM box to a HD-SDI converter

HDSDI to a
Sony HDCAM VTR


Used some SPDIF to AES converters we had at the office for audio in and out.


For playback I took the HDSDI from the VTR into a HDSDI to DVI converter.


I have a few HDCAM tapes now of HBO-HD from VOOM, and the quality is good. Maybe Ill start building these recorders and selling them... What would YOU pay for one?? :) (The HDCAM VTR is not a viable option, taking the HDSDI down to 38mbps would make PC recording more managable!)
 

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Nothing. You're recording the analog output of Voom. Whoopee. It can already be done with a WVHS deck, and for a lot cheaper than what you did. Capture the digital stream and you'll have something to brag about ;)
 

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Good luck with the digital stream. Several members have studied this box and concluded it is pretty resistant to tapping the MPEG bus at a point where it's in the clear (a DVB-SSI interface is available but the bitstream is still encrypted).
 

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Discussion Starter · #4 ·
WVHS deck? I thought they only recorded firewire. I bet I can find a DVI-SDI converter so I can record a digital out.
 

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Good job, Bob. There's nothing wrong with using the analog outs for this. With good gear, PQ should be significantly better than WVHS.


How much does your HD analog to SDI converter cost? Does it send multichannel audio along with the video?


Instead of the 40,000.00 Sony VTR, the Decklink SDI capture cards are reasonably priced for uncompressed HD now. The Doremi Orca PCI card supposedly will capture HD SDI and encode to MPEG2 on the fly for ~2000.00.


Still not practical for most of us, but it's getting there.


Joe
 

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Quote:
Originally posted by sat_uplinker
WVHS deck? I thought they only recorded firewire. I bet I can find a DVI-SDI converter so I can record a digital out.
You're thinking DVHS. WVHS records analog 1080i from component. You can't record off the DVI because Voom uses hdcp. Jamoka, I doubt all the conversion processes he goes through are going to signifantly improve it over the WVHS deck.
 

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Maybe you're right. But the only conversions he listed are one AD and one DA with broadcast quality gear.


I read somewhere that the frequency response of those WVHS decks is actually quite poor and even under ideal circumstances the video output is on par with about 720P. Is that incorrect?
 

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I wonder if this could be used the with the SDI modded cards for the pci?
 

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Quote:
Originally posted by jamoka
Maybe you're right. But the only conversions he listed are one AD and one DA with broadcast quality gear.


I read somewhere that the frequency response of those WVHS decks is actually quite poor and even under ideal circumstances the video output is on par with about 720P. Is that incorrect?
A good 720p source would be noticeably better than a W-VHS recording of analog 1080i. I believe the frequency response is about 13Mhz for W-VHS. I would think a single analog>digital encoding of a 1080i source using a commercial HDTV encoder would also be superior to W-VHS. A first generation W-VHS copy might very well beat a D>A>D>A string of conversions. Still everything considered W-VHS is an exceptional analog video tape format and I have watched a couple dozen movies using W-VHS and the results were always very good. The W-VHS tape is much too expensive to record something and keep it for long time, sort of like investing in a CD with a negative rate of return. If you own a few of those tapes, you want to use them.


Chris
 

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Yup.
 

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Quote:
Originally posted by HDHTPC
This is exactly the kind of discussion that probably led to all the "downrezzing" plans for the analog outputs.


(The title of the thread alone is classic)
Really. This discussion seems to indicate to me that HDTV recording of analog component video is still way too expensive to make any sense. W-VHS has been around about a decade and the media costs still make archiving to that format prohibitive. The format is now completely dead. HDTV encoders may become affordable in our lifetime but the results still won't be comparable to direct digital recording. Recording analog HDTV was never a serious threat in my opinion.


Chris
 

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Yep. It requires a serious investment, and is hardly convenient. A pity really.
 

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Whats needed is an HD capture card which can output DVD quality pic/5.1 sound to a hard drive... in some form which can easily be burned to DVD using readily available SW. Whats missing?
 

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Discussion Starter · #17 ·
A $2000 HD-SDI capture card is reasonable, Ill have to check that out. Doremi makes HDD-based video servers for broadcast. Good stuff. I don't know the price of the RGB>HDSDI converter. Its probably not that bad.


I don't know much about the DVI>HD SDI converter but perhaps it does not follow HDCP? There is no provision in the SMPTE HD-SDI standard for copy protection? If it can see a valid DVI signal, it will output serial digital. Being SDI, its aimed at the broadcast market where copy protection is not in the picture.


I'm not after DVD quality, I want HD. Imagine if you could just leave this recorder sitting on HBO or Shotime. You could have a library of HD-quality (or close to it) movies on your PC, in an open MPEG format you can move over your network with no restrictions. Id say thats worth a few thounsand dollars.

Here is a standard PCI card that takes HD-SDI and encodes on the fly to WM9HD. $2500. Not bad. I have been impressed at the PQ from WM9HD at low data rates.
 

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I would be very, very surprised if the converter didn't follow the HDCP rules.
 

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Quote:
Originally posted by sat_uplinker
WVHS deck? I thought they only recorded firewire. I bet I can find a DVI-SDI converter so I can record a digital out.
It would be great to be able to archive HD but it's not going to happen with DVI.


All of the DVI outputs on HD boxes are copy protected.


If your equipment doesn't support the copy protection the DVI output won't talk to it and you'll have nothing to record.


If it does support the copy protection you'll have nothing to record because it will be copy protected.


If you single handedly break the copy protection you'll have too much to record. Where are you going to store this massive stream? I don't think you are going to find a real-time MPEG encoder for a few hundred bucks. Thus you'll have nothing to record.


Someday maybe - but not today!
 
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