Real uncompressed, useable codec – please help

[Ramona Howard]

Andras,

Please forgive as I have not read every word in the conversations back and forth between everyone. Also if this covers anything you already know. I am simply going to point out a few things that may or may not have come up and or you and or others don’t know. Use what you can. Hope it helps.

Oh I remember the quicktime days when we did Sin City, yes it was rather frustrating….

DPX is really straight forward once you know the rules and once you know how things interact. It sometimes gets a bad rap, when it really isn’t the true fault of what is happening…

Within a DPX you can pack anything, any raster, and bit depth, any colorspace, log, lin, full range or SMPTE range, etc…..

In addition you can pack metadata in both the header and user space of the header. Within the header there are defined SMPTE standards of packing timecode, reel, keycode, etc. The user space is a free for all and almost anything can be put here. We pack audio chunks and other metadata that the Rave reads and writes. When done properly anything packed in user space DOES NOT EFFECT if a DPX can be used in anything else.

This is why DPX is so prominent in the high-end workflows, it is fairly versatile.

Here are some items that may be worth checking out to see where things are going wrong for you 🙂

Start with your original files, what colorspace and range are they? When converting to DPX, make sure you are converting to the same. ie, if it is 0-1024, make sure the DPX is the same, log to log, etc….

This way the conversion from your original files won’t be the issue and they should match bit for bit, if they don’t, here lies the issue. If your using shake you should be able to open both and compare.

Next.

Are the original files 4:4:4? is the DPX sequence being converted to 4:4:4? and is the Pro-Res 4:4:4?

Next.

Find out what range or format the ProRes works in (Full or SMPTE) and that it matches the DPX files

i.e, most products default to a SMPTE range for these types of codecs and or can’t support full range. So if you start with a full range DPX and convert to something else, they will not match. Same goes for 4:4:4 to 4:2:2. Most tape decks, monitors, etc do not support full range and or 4:4:4!

So if this isn’t the issue, check.

Some products have issues with sharing DPX files between MACs and PCs and reading the header info correctly. This may require you to do some digging (maybe someone here can answer) if this infact is part of the problem. We support both big indian and little indian in Rave, so we don’t care where the files originate from and we don’t see this issue but I have know other products that have. It is an old problem and surprises me to still see programs with this issue.

Last, call AJA, they will bend over backwards to help you get to the bottom of things if they can. The AJA hardware has settings that support pretty much all scenarios and you will see issues if you have the wrong one selected.

You may be asking why in the heck would I start with a sequence that is out of SMPTE range to begin with? Because, in the film-world we do it everyday, as film does not have the limitation that video does. The workflows that use full-range are also using LUTS (Look Up Tables) to do a remapping and or colorspace conversion to go out to TV/video and some monitoring. And, yes there can be good remapping and bad, so it will depend on where it is being done.

I hope that helps you get your head around the issue and the workflow, as honestly it isn’t that difficult when it works, which BTW I see almost on a daily basis. Just gotta know the rules 🙂

Cheers,
Ramona
https://www.spectsoft.com

[Arnie Schlissel]

[Andras Sarkadi] ” We tested the bandwidth and it’s around 2 Gbytes/sec with two machines reading at the same time. I feel that should be enough. What do you think?”

That’s 2 gigabits per second. Nothing on earth delivers 2 gigabytes per second.

Arnie
Post production is not an afterthought!
https://www.arniepix.com/

[Andras Sarkadi]

Ramona, and Everyone reading and writing
I am not abandoning the topic, sorry for the long pause, just had to finish a couple of projects in these days. Ramona thanks for the tons of information and questions, going to answer. and yes. I am learning the rules. 🙂
I just realized yesterday, that the other computer connected to our Xsan is reading 3x quicker than mine. around 650 Mbyte/sec. We are looking into that problem as well, will be interesting to see what causes it.
Andras