DVHS as storage?
 

The DVHS decks are capable of recording high definition video and I was wondering if it would be possible to connect them to a camera head to record?

Do they have analog inputs?

love

Freya

The analog inputs only store analog SD data -- i.e. in standard VHS or SVHS format. There aren't HD analog inputs as these unit don't have HD MPEG2 encoders within them. The only way to record HD on DVHS is with an input from MPEG2 transport stream data. This means you would have to build an MPEG2 encoder into your camera. This is what HDV is all about.

Questions about DVHS and HDV
 

Are you saying that DVHS decks are recording in the exact same format as HDV? If thats true it surprises me. From the DVHS footage I've seen it looks like it has a hell of alot less compression than HDV. Could it be that they are both MPEG2 but DVHS has alot less compression than the MPEG2 settings for HDV? Are BOTH able to record 1080i or is HDV just 720P. I dont know. Some one that does - please share.

-Brett Erskine

What david is saying I think is that not only can they not create HDV data, they cannot create any data themselves, they can only record data that has already been digitised.

They can record analog but only as analog VHS/SVHS.

If you had a HDV camera however, you can backup your HDV files onto it as it records the mpeg2 data streams just fine, it just can't make any!

love

Freya

Ooops sorry Brett I just realised that that answer wasn't very clear!

As the decks don't compress any data but just record existing data, the amount of the compression is a function of the mpeg2 compressor and not of the decks, so if you record data that a tv station is broadcasting it will be at the rate of compression that the tv station used and obviously in the case of HDV it will be to the extent that the HDV camera compressed the data.

I guess it's a bit like having a cd-rom on which you can put stuff!

love

Freya

Re: Questions about DVHS and HDV
 

<<<-- Originally posted by Brett Erskine : Are you saying that DVHS decks are recording in the exact same format as HDV? If thats true it surprises me. From the DVHS footage I've seen it looks like it has a hell of alot less compression than HDV. Could it be that they are both MPEG2 but DVHS has alot less compression than the MPEG2 settings for HDV? Are BOTH able to record 1080i or is HDV just 720P. I dont know. Some one that does - please share. -->>>

HDV and DVHS both use DVB MPEG2 transport streams. The major difference is a normal DVB signal is longer GOP at 15 frames compared with JVC 6 frame GOP and the uplink encoders are simply much better than you can put in a camera. Otherwise they are identical, both typically at 19.2Mb/s. DVB can be either 720p or 1080i, the JVC camera is only 720p.

Now heres my next silly question. What exactly is a HD analog input? Does it output component video in the same kind of way that SD does? Could you connect a SD player such as a Beta SP deck to a HDcam deck via component video sockets and exchange video data in both directions?

It seems to me like you shouldn't be able to but then again the whole idea of analog hi-def video signals seems a little odd now I think about it. I guess I imagined that hi-def would have some sort of raw digital data derived directly from the ccd?

I've just started to realise I don't have a clue about it!

love

Freya

Analog High-Def exists as YPRPb or RGB, that digital link you are thinking of is HD-SDI.

So if that's the case what is stopping a mpeg2 encoder from encoding at say 50mbps instead of 19 for a super duper nice HD stream? Are the DVHS decks limited to 19mbps?
If one could do that then I would think that a dvhs MASTER would be ok for broadcast as the broadcasts are going to be lower bitrate anyway...am I wrong here?

DVHS is limited to around 27Mbits/s. Mastering to MPEG2 is possible, but you would need about 80Mbit/s to suitability match the quality of an HDCAM master.

what I am saying is that you NEVER see the quality of an HDCAM master over the air or on your dishNetwork you see a really bad mpeg2 stream. If I could master to 27m bits stream and submit that to a station then they will jsut compress it even more..how would that not work as a master for broadcast? not as a MASTER of a project but as a broadcast tape...

so in a few months when our local station starts airing HD I could fit right in with a DVHS

I believe there is software available to let you do this right now. I looked into it at one point. If I run across my links I'll post them here.

I like D VHS it's cheap and easy..maybe a HD DVD windows media 9 would be better but I am betting we will have more support for Dvhs in the near future for broadcast

<<<-- Originally posted by Freya Paget : Now heres my next silly question. <cut> Could you connect a SD player such as a Beta SP deck to a HDcam deck via component video sockets and exchange video data in both directions?-->>

- some of the hd decks can read component input from beta sp decks and upconvert it, so you can see it as upconverted SD component signal on HD deck.

-some of the hd decks are cappable do downconvert hd signal to standard definition component so you can record it on SP beta.

but none of the above is analog HD to analog component SD. always down/up converted signal.

if you use f900 cinealta camera - where you can find analog HD connectors (3xbnc) - you can connect it to SD component beta sp deck, but you will see nothing. :(

filip

"if you use f900 cinealta camera - where you can find analog HD connectors (3xbnc) - you can connect it to SD component beta sp deck, but you will see nothing. :("

I guess that would make sense because the resolution would be too high for it anyway, but could you go the other way and upconvert an analog SD signal to HD via analog inputs? I assume not but I don't really know! :)

love

Freya