Upconverting to uncompressed?
 

Hi

I have seen the following gadget:

http://www.symbiosiseu.com/index.php?m=11

which is meant to successfully upconvert hdv to uncompresses, adding back colour info etc. Can anyone on the tech side tell me if this is actually possible in any 'quality gaining' meaningful way?

Thanks

Trevor

Well, it isn't going to make the quality of your footage any better in the same way that copying VHS to DigiBeta does not improve the inherent quality. What it does is limit the degradation of the image from that point forward. All editing, processing, colour correction, compositing, titling etc. carried out from this point forwards can occur as part of a lossless uncompressed process. This is how we have carried out post production for DV for a long time using a studio deck with SDI outputs and finishing uncompressed on Avid Symphony. However, HD uncompressed means HUGE amounts of data and huge data rates, for which you need high-end equipment. We will be using Avid Symphony Nitris to finish our current project in uncompressed HD using the Convergent interface for ingest.

Essentially, the Convergent box is a great tool for finishing but don't think that it can put back any information squeezed out by the HDV encoder. It will not improve the quality of your footage per se.

HDVin and what is out?
 

in short, there's no way to make any better than the orginal HDV, but it may prevent further degrading. and uncompress give more versatile with any other conversion. this is at the expenses of space and perhaps impossible to play back in real time.

it's worth to do if necessary , such as converting into different formats.

JY

Hi

Thanks for this, very helpful. I always thought that you can't put information back to improve quality.

I wish really that JVC had put more user friendly outputs than just composite for uncompressed. It becomes so expensive to capture.

Thanks

Trevor

Don't forget you have component as well as nasty old composite for SD and you'll need component for uncompressed HD output. Composite is SD only, of course. You can always use a component HD to HDSDI converter (or the SD equivalent, for that matter) if you're coming live off the camera. If you're not going via tape, there's no point going via the HDV encoder and then the Convergent box.

What about "upconverting" to DVCProHD? I use this codec to edit, captured via analog. Should I think of this as off-line, and do a recapture as uncompressed (is 8-bit enough?) for color correction and effects, or once it's in DVCProHD, is that good enough to eliminate rounding errors in color correction and other post processes? As has been observed, the real hit is taken in the HDV encoding; I guess the question is what level of upconversion is necessary in order to prevent any further image degredation?

I think it depends on your needs and budget. DVCPro is not an ideal editing codec, although it is certainly a good deal better than HDV. Avid's DNx codec is very good and designed for editing with data rates similar to uncompressed SD so I'd go for that every time if I had access to AXPro or MC. If you're happy with DVCPro and your edit system can handle it well then why not stick with that? I don't know much about the Blackmagic codecs but many here are impressed. You could get hold of a card and digitise component or converted SDI and I believe you have a choice of compression options. The jump up to uncompressed HD is huge in terms of storage and data rates.

Do you have a broadcaster to consider? What is the final destination of your product? If you don't have any technical standards imposed on you and you have a good monitor then let your own eyes be the judge: if DVCPro in your existing set up is working for you and your clients then why spend any more money?