EX1r+Vegas+Cineform=smooth editing?

[Chris Young]

Personally with EX footage I use Sony Clip Browser, current version is 2.6 a free download from Sony, and export the EX clips as ‘MXF for NLEs’, a pretty quick process on an i7. The MXF files are much nicer and smoother to work with than the EX MP4 files. These files are also smaller than if you had converted them with the Cineform codec.

Mind you I use the current Cineform codec frequently and without a doubt if you have a lot of compositing to do with the EX files Cineform is the way to go. On your i7-820 both options work very well in Vegas.

Chris Young
CYV Productions
Sydney

[Bruce Quayle]

Hi Chris,
Thanks for your advice. As I mentioned, I’m ignorant technically, but am concerned that the quality of my pictures will suffer when I encode/decode them for editing purposes. I imagine that Sony would not include this application if there was any degrading of the material, so it sounds like the answer.
I doubt if my material will require any compositing, but colour correction is always necessary. Do you think 4:2:2 is essential for this, or could I stay in 4:2:0?
Once you complete your edit, what file type do you use to export your finished product? I’m guessing this will depend on what platform you use for distribution, but if I needed to distribute on three different platforms (HD Broadcast, Internet and DVD/BD), how would I be exporting my finished product?
I am preparing for an extended period offshore and need to have as many of these details cleared up as possible before I leave.
Thanks again,

Bruce Quayle

[Chris Young]

Bruce ~

What one has to realise is that all long GOP files have to be decoded because of their ‘Interframe’ GOP structure. Without getting too technical, every time you do an edit with any long GOP (Group of Pictures) file the file has to be decoded and then re-encoded to match up the GOP structure of the file it is going to be joined with in your edit.

The more complex your editing the more decoding/re-encoding you will do and the more hits your quality will take. By decoding once to the Cineform codec you create an ‘Intraframe’ file where all information for each frame is contained within each frame. When you do an edit between two frames all that happens at render time is that they are stitched together, unless there is a dissolve or transition etc in which case it creates a new Intraframe file. There is no having to decode back to previous frames to recover missing information.

With long GOP editing one has to ensure that the edit point occurs at the end of a GOP to coincide with an I-frame, this negates the possibility of an unclean edit through trying to link to a motion-estimated frame or broken reference. Well unless your artistic decision to create an edit at any given point happens to be on an ‘I’ frame the edit point you have just created will have to be reconstructed from the preceding frames in that GOP and re-encoded with the incoming edit material to recreate an new contiguous unbroken GOP. In other words a complete decode and re-encode of the sequence of frames that are involved on both the outgoing and the incoming bit streams involved at that edit point. Not a nice way to edit!

Believe it or not Vegas 8.xx had the Cineform codec built in as part of the ‘render as’ templates. This was a 1440×1080 Intermediate template specifically designed to handle the long GOP structure of HDV files when editing. FWIW I believe from hearsay that Cineform and Sony couldn’t agree on going forward with this partnership with Vegas 9.0. A shame I think. For me Cineform in Vegas is like the ProRes codec in Final Cut Pro and like the DNxHD codec in Avid.

Regarding your question re 4:2:0 or 4:2:2. Cineform is 4:2:2 when you convert your files. This broadcast 4:2:2 ITU.Bt.709 HD compliant color space and the Intraframe codec structure is by far and away the best thing to edit with, it’s very robust. You can go through more levels of compositing and color correction with less quality loss plus have the benefit of a smoother running timeline to boot. As we say in Aussie “It’s a no brainer Mate!”

For us down here the networks are now taking XDCam 1920×1080 4:2:2 50-mbit MXF files on XDCam discs for broadcast. No more expensive VTRs required. Couldn’t be better for us.

For output to Blu-ray/DVD we just use our master XDCam 1920 files or uncompressed files [large!] in DVD Architect as it handles them fine.
We don’t do much for the web but some colleagues use Canopus Procoder or its big daddy Carbon Coder for H264 or Flash output. The main thing is to maintain the integrity of your original image as much as possible. Good luck on project.

Chris Young
CYV Productions
Sydney

[Bruce Quayle]

Hi Chris,
Sorry for the delay in replying to your most excellent and detailed explanation. I really appreciate your clarity. I certainly understand the GOP concept better now. I guess editing with GOPs creates a similar problem we used to have (back in the olden days…), when we lost quality every time we went down a generation during the VT editing process. I’m of the old school as you can see.
I’m heading to NAB next month and following your lead will explore this option further. Sounds like Cineform will be a sound investment for my project.
Thanks again for the time and effort you put into your explanation – I really appreciate it!
Cheers for now,
Bruce
PS: Hope your boys are doing well in the Super 14 this year!

Bruce Quayle