Using Shake for 24p

C

ciné-ernesto

Member
Hi all,

I am sorry if someone has already beaten this issue to death and I missed it.

Well, unfortunately I don't have a Mark II, but I just wanted to share that I do have some DV 30p footage that I have been converting to 24p using Shake and getting considerably better results than anything else. It's done basically via the Convert option in the FileIn node. It is a much cited feature of Shake that it does retiming and frame conversions using the "optical flow" pixel-vector method. The rendering time is a bit long (varies on the settings and footage, I've been having to wait some 4 seconds per frame) but it's a pretty good option for finalization when you already have your film edited, and if you are in FCP you can do a "Send to Shake". If it's in anyone's interest I can help you walk through the workflow from FileIn to FileOut nodes (not very intuitive, and a lot of options). Having said all of this, what are the other solutions people are using with success for 30p to 24p frame-rate conversions? My impressions here are based in comparisons with Compressor, After Effects, and other frame blending options available. But I haven't used Twixtor, for instance. Has anyone? Care to comment on it? Does anyone disagree with the After Effects and Compressor evaluation? Does anyone think that Twixtor is better than Shake 4 (I mean in terms of results, beacuse I am sure it's better in terms of practicality)?

Going a bit further: the only situation in which I've not loved Shake's optical flow results is when the shot is on a tripod, and a foreground object moves slowly against a static background (like a car cutting accross a frame in a slanted angle). Then, with some effort, you can make out the distortion applied to the background in order to compensate for the lack of information. I'm sure there's a name for this kind of artifact, it's a soft distortion, almost elastic-like effect on a small area around the foreground moving object. It's also possible that you only notice it if you know it's there, and I don't know if Twixtor deals better with this (Anyone?). But on general handheld shots Shake seems to excel over anything else I tried, if you are not in a hurry. And I've come to the conclusion that converting custom frame-rates like this (not normal pulldown stuff) is really best achieved using a combination of the three possible methods that most programs offer - vector-based stuff like this, nearest frame or frame blending, - depending on the specific case. Does anyone else agree with this assessment?

Cheers to all you happy Mark II users (I own a D90).

P.S Why don't you guys have stickies for the basic things like the ones over at the D90 section?
 
Last edited:
The MKII guys think they're superior to us D90 and GH1 guys hence no need for stickies. I haven't needed to try the 24p workflow yet but I've been closely following developments. Was this the method you used in compressor-

Superb 30p to 24p Workflow

1. Create copy of clip so you'll have two clips, one to convert to 24p and one to preserve audio.

2. Open Cinema Tool (part of Final Cut Studio), File, "Open Clip", choose "Conform", specify "23.98" to conform to.

Explanation: This keeps the same number of frames in the clip, it only changes the timebase from 30fps to 24fps, essentially creates overcranked footage by 6 frames, (desirable on some shots). As a result this makes the clip longer and slows the audio down which is undesirable where audio is important. At this point you've already created a copy of the original clip therefore preserving the original audio which we'll relink later in Final Cut.

3. Now we'll convert the clip to a desirable format for the workflow and effectively speed the clip back up so you get desirable 24p realtime results. Using Compressor 3 convert the clip to any of the following settings:

* Apple Pro Res
* Apple Intermediate Codec
* DVCPRO

Important: Make sure that no matter which codec you use that it remains as a 23.98 fps timebase.

Now open the inspector window so we can do some tweaking. Under "Frame Controls" tab, click the button to the right of "Frame Controls:" to enable this feature. Once enabled, select "On" for "Frame Controls:" Underneath the "Retiming Control" section is where we'll make changes. For "Set Duration to:" click the radio button where it will allow us to put in a percentage. The magical number we'll want to put in here is 79.996%, then depending on how well you want the footage to look also taking into consideration the time it will require to compress it choose the desired quality under "Rate Conversion:". I choose, "Best (High quality motion compesnation)" to get superb results, however this increases the compression time.

Now, what have we done here? We've converted the unusable H.264 format into a format we can edit in and sped the footage back up to original duration using Apple's Optical Flow Technology.

4. Now take the treated clip into Final Cut insuring the timebase is 23.98, delete the audio track and add the audio from the copy of the clip we made. Now relink and presto!

I've extensively tested this and find it to be the best way to convert 30p to 24p for the time being, or atleast until and hopefully Canon comes up with a firmware to address the issue.

Additional Tips: If you have multiple clips to treat, in Cinema Tools, choose "Batch Conform" locate one file where all the files are located. Then setup batch conversions in compressor, if you have a quad core or 8 core configure Q master to take advantage of all cores otherwise it will take longer.

One final note, depending on the specific needs of your project you may need to treat many individual clips or take your finished project (of course h.264 has been converted to an editable format) and follow the steps above to get great results. I've tested a 9 minute clip and was able to complete the compression on an 8 core in one hour and a half.
 
Hm, so that's why they don't have stickies! Though I think they should have them. This subject, for instance, is a major one. I think someone should start a thread with the main methods available (Compressor+CT, Twixtor, Shake). And then comparisons should ensue.

The thing is, even if Canon issues a firmware for this (I doubt it), people are still going to have tons of stuff made with the MII in 30p, so it's not like this question will be going away anytime soon.

Yeah, I saw the Compressor post back in January, I think (by denver***). And I also do it according to some rectification he made afterward that instead of using the percentile, it's good to use the exact duration of the clip with the audio.
 
You must log in or register to reply here.
Back
Top