Capturing Digital Betacam into Prores.

[Ian Withnall]

Hi there,

I am looking for answers to this problem before I hire in a replay machine. So suggestions of things to try are welcome. This is a long and boring post by the way! But you guys can handle it.

I have a Mac Pro 2.26 16 core with 12 GB ram and a Blackmagic Deckling Extreme HD card and FCP 7 point whatever!
Ingesting off a Sony J3 Digi Beta machine (Rented and expensive) running through SDI .
Mixing 12 hours of SD interlaced Digital Betacam with about 10 hours of Canon 7D 1080x1920 25P material.

I have JES Deinterlacer, mpeg streamclip, and of course compressor ....at my disposal.

So here it is.....

I have made a rather large mistake in that I tried to Deinterlace some Digital Betacam during capture. 12 hours of it actually. I just selected progressive material in a customised capture setting with the Interlaced button NOT ticked! It looks BAD.

Anyway moving on ...

So this Time I am thinking about injesting though the SDI port at 1080x1920i 50 (25 fps interlaced) and keeping it interlaced but up converting to HD, which apparently is a good idea anyway right???

Would it work to bring it all in with a custom Capture setting on the Blackmagic to compress it into Prores 422 1080x1920 50i....with the aim of not having to send it all (Uncompressed 10 bit it'll be over a terabyte) through compressor to turn it from uncompressed 10 bit SD 720x576 into 1080x1920 50i prores 422. A lengthy and time consuming job, which I am up for and have the processor speeds for - but would rather avoid...and also it's another process the material has to go through.

The capture preset wants me to interlace at top field first. Should I?

The timeline is much - MUCH happier with everything prorezzing which is my motivation for Prores files and timelines and the fact that the canon stuff is transferred straight into prores 422. ....

Then I just keep the whole Project interlaced and leave the 7D progressive material to sort out in export? A good idea I am lead to understand! Mixing interlaced and Progressive on an interlaced timeline some seems to work OK. I seem to run into problems when it's SD, HD anamorphic vs native 16:9 etc..! .

The Progressive 1920x1080P should go better down converting to interlaced SD on export than the other way round, Right? I mean it LOOKS OK. At least it can't be any worse than blurry SD deinterlaced and badly up converted Digi Betacam!!!! Correct?

So in a nutshell…..

Bring the SD Digital betacam in through SDI to upconvert to 1920X1080 50i prores 422. Can you see any problems with this? Any suggestions.


Sorry for the long post but these tend to be complex issues that are based on individual circumstances. And finding facts on anything Digital Betacam on the web or anywhere for that matter is pretty hard.

Ian.

[Craig Parkes]

Hi there, I run a Kona LHe so don't know a lot about the Blackmagic Decklink extreme, but looking at the website I believe it does a hardware upconvert.

As such, as you say in the end of you post, upconverting from SD to 1080i50 Prores is going to absolutely standard workflow in practice and should deliver as satisfactory result you can deliver in realtime.

The first question I would have is what are you delivering to, because you will find that unless web is your only deliverable for broadcast in your current format is going to be 1080i50.

There is no broadcast 1080p25 standard so it makes no sense to master to that if you are thinking of a broadcast deliverable.

Also, if you are converting from PAL SD on Digibeta to 1080p25 not only are you blowing up your footage by 500% (1920 x 1080 is 5 times as many pixels as 720 x 576) in terms of scale, you will also be decreasing your temporal resolution by 50% and/or decreasing your vertical resolution again by half or there abouts (depending on whether you are throwing away the second field or 'interpolating' it into the frame, which isn't an ideal solution on fast moving subject matter.) So basically you'll be trying to fill a frame 10 times larger than the amount pixels than you started with...

So, what's your deliverable? If it's broadcast 1080 50i then work 1080 50i and deliver a deinterlaced version for web.

If it's not broadcast you will still need to ingest 1080 50i as I imagine that would be the only format that the Decklink will understand (being again the only broadcast format) and then you can deinterlace in software (either on the timeline by working on a timeline with none for field order or using JES deinterlace etc before editing.)

Either way, your decklink is designed to ingest straight to Prores, and designed to upres, so neither should be a problem.

[Ian Withnall]

Thanks for the reply. Good to see our nearest neighbours care enough about us to offer a technical helping hand.

I have been calling in a few favours - all of whom agree with you... So if anyone is googling this topic the straight answer is in Mr parkes's reply and below.

1080x1920 interlaced in Apple prores 422 would save me the most time. If I bring it all in at 720x576 uncompressed I will then have to crunch it through compressor to get it to be A: progressive and B: HD. I will then Interlace the 7D material in export.

I