Capturing HD XDCAM 720/24 over 60 to 24p timeline
by john sharaf
on
Aug 15, 2009 at 4:43:13 pm
Has anyone any experience with this workflow? Trying to create 24p timeline in FCP by capturing through AJA LHe because apparently there is no way to pull 24 from long GOP MPEG, nor would we want to edit our long form doc in that format.
Any suggestions would be appreciated. We are able to capture, but playback is in slow motion and out of sync. Obvious to us that Kona is not pulling the 24's. Maybe have wrong settings, but maybe cannot be done?
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by john sharaf on Aug 16, 2009 at 2:48:53 pm
Hi Shane,
I've learned quite a bit since we talked yesterday.
I shot 720/24 over 60p in the PDW700's upon the advise of an expert well known on these forums that is was "just like the Varicam" and conformed to RP188 TC standards, which I interpreted to mean that there were flagged "A" frames so that FCP or KONA could reverse telecine the media and I could capture a 24p timeline. This was important to us because we intend to bring this feature doc to film out for theatrical distribution and because we have 180 hours (so far) of material and storage economies are an issue.
I now know from communication with Jon Thorn from AJA and our own forensic examination, that the Sony camera does NOT write flag frames as part of its 2:3 pull down process and the material can not therefore be reverse telecined.
I chose this format reluctantly, as I would have much preferred 1080/24p, but the implementation of this format was delayed in delivery from Sony until just recently, in fact after I returned from the 60 day shoot abroad. It required both the new V1.5 software and a $5000 card in the PDW-HD1500 deck and a $4500 software key in the camera. In hindsight 1080/25p would have been a better choice.
I spent all day yesterday with my buddy Tony Salgado, who is very knowledgable about these things and he was able to design a workaround that we think is satisfactory. We'll capture at 720/59.94 in ProRes Proxy, which keeps the storage requirements within reason and the offline quality just fine, edit the project in a timeline of the of the same speed (there is also quite a bit of 50i archival footage) and then after on-line use a technique we found on Phillip Bloom's website to essentially play the 60 back in a 24 timeline as slow motion and then speed it up with cinema tools and compressor to match the length of the sound. It's very clever and looks quite good.
Of course we'll need to test the film out on this approach, as we are screwing with the temperal motion a bhit, but there is another advantage that we get a 60p video version and then a 24p film out version.
My wife has lowered the suicide watch and I was able to sleep soundly last night knowing that there is at least one version of a fix that can get the project to the movie theater.
Maybe this more complete explanation of the "problem", which of course came from own faulty assumptions based on reliance on advise of an "expert" who in this case did not really know what he was talking about, and then proceeding without testing, will help you or others think of another fix or suggested workflow. There is still a few days, as i wait for my XRAID to format to consider alternatives, and I welcome and seek other suggestions.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Rafael Amador on Aug 16, 2009 at 4:01:59 pm
[john sharaf]"I shot 720/24 over 60p in the PDW700" Hi John,
If I don't miss understand, you have recorded 720/p24 overcranked to p60.
isn't it?
The file you get is a p24 slow motion.
As long as I know, there is no pulldown involved here.
Cheers,
rafael
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by john sharaf on Aug 16, 2009 at 4:45:26 pm
Hi Raphael,
Yes, there is a 2:3 pulldown just like a Varicam, so that the 24 frames are repeated alternately twice or three times to add up to 60 frames per second, as opposed to 60p which is 60 distinct frames per second (which if dropped into a 24p timeline would give you a 2.5x smooth slow motion effect). One can confirm this by single framing through the media, you'll see two identical frames and then three more identical frames. This cadence is continued throughout.
The rationale for the 720/24p over 60p in the PDW700 XDCAM (as it is also in the Varicam) is to give a film look to video production, just like film would look after telecine processing (aka film to tape).
In the Varicam, the first of each repeated frame is marked by an "A" in the user bits as well as a "24" (or whatever the set framerate is) to tell the post processors (hardware and software alike) what frame rate the shooter intended. This allows the capture card or software in NLE programs to "pull" just the 24 distinct frames and create a 24fps timeline which is useful both for film out and to save hard disk space (as 24 is only 40% of 60, with a comparable savings in storage requirement). In addition, the framerate metadata also is useful in processing slow and fast framerates back to 24 or 30fps, but you probably knew all this.
The problem is that the Sony PDW700/800 does not write these markers, so the KONA card and FCP have no way of identifying the discreet 24 frames to make a 24fps clip, which is useful both to create a project for film out and also to conserve storage space, as 24 is just 40% or 60 and you realize a similar savings in hard disc space.
Furthermore many people including myself and the "expert" I consulted before the shoot, mistakenly assumed that Sony had implemented a similar strategy as Panasonic vis-a-vis this 24 over 60 feature, but we were all mistaken. This is how you really learn things, by making big mistakes!
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by john sharaf on Aug 17, 2009 at 12:48:17 am
Hi Jeremy,
Must have forgot to mention that that is precisely how we determined that there was no A frame nor frame rate info, by looking at the TC tab on the Kona CP. There was nothing there, zilch, nada, zeros. When we attached a Varicam, voila, all the stuff we wanted to see. Also confirmed by connecting PDW700 and 800 directly to Kona whilst set at 720/24 over 60 and same results, nothing.
As regards going file based with XDCAM Transfer, that would be great but only options are 720/50i and 720/59.94, no 720/23.98 as in EX XDCAM, and besides, no A frames no reverse telecine, simple as that. Sony has given me another reason to hate them. Don't get me started!
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Jeremy Garchow on Aug 17, 2009 at 1:59:47 pm
[john sharaf]"As regards going file based with XDCAM Transfer, that would be great but only options are 720/50i and 720/59.94, no 720/23.98 as in EX XDCAM, and besides, no A frames no reverse telecine, simple as that. Sony has given me another reason to hate them. Don't get me started! "
Bummer. Sorry, John. What I would try though, is to see if Compressor can pick up the A frames on a test clip. Use the reverse telecine option. If you need help with that, I can guide you through a preset.
I'd be curious to see if it works on 720p footage, I know it works on 29.97i footage with 3:2 pulldown.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by john sharaf on Aug 17, 2009 at 8:55:35 pm
Shane,
To be honest, we're still exploring options, as the "MacGuyver" fix described earlier does result in objectionable motion artifacts. Best fix would be a real time reverse telecine on injest to FCP which identifies cadence probably from time code frame "zeros" and "fives". But that still leaves conforming issues. This is a complex one-of-a-kind problem that does not lend itself to simple fix.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Jeremy Garchow on Aug 17, 2009 at 9:09:13 pm
Compressor? It auto detects A frames on standard 3:2 material, it might just do the same on 720p. You just have to use the reverse telecine feature of Compressor.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Shane Ross on Aug 17, 2009 at 9:12:51 pm
There we go...yeah. I have a boatload of HDV footage shot with the HV20 intermixed with DVCPRO HD 720p 23.98. The HDV footage is 29.97...you cannot capture it as 23.98 via a Kona or MXO (no flags), and you cannot use Cinema Tools on it as it cannot Rev Telecine GOP formats.
BUT...i was able to use compressor to convert to DVCPRO HD and 23.98 reverse telecine in one pass. You should try that.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Ian Cook on Aug 18, 2009 at 3:07:14 pm
I am trying to test the reverse-tele (23.98p scan recorded at 60p, XDCAM HD422) using Compressor and the issue I am running into is that the frame rate remains 60p unless I change it in the encoder settings or the duration settings. If I change the encoder settings, I get a 23.98 file that imports into FCP, has 24 frame code and no motion issues and looks ok but aren't I just shaving frames and NOT removing the pulldown? If I leave REVERSE TELE selected with no changes to the encoder rate or the duration the output file is 59.94p.
Also, since there is no 720/24 XD 422 encoder in Compressor/FCS I am choosing the 1080p24 XD422 encoder and manually changing the frame size to 1280 x 720.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Ian Cook on Aug 18, 2009 at 4:55:34 pm
Ok, but the question remains-- should I be changing the actual encoder settings to begin with to affect the reverse-tele? Isn't this just shaving off frames? I'm guessing that it does, though so far the converted files look ok.
Re: Capturing HD XDCAM 720/24 over 60 to 24p timeline by Jeremy Garchow on Aug 18, 2009 at 5:26:34 pm
[Ian Cook]"should I be changing the actual encoder settings to begin with to affect the reverse-tele?"
You need to tell the encoder what frame rate the movie needs to be, so in that case, it needs to be 23.976.
The reverse telecine operation should remove the appropriate frames, as it does with standard 3:2 pulldown interlaced material. Yes, it's the removal (shaving) of the appropriate frames, just like any reverse telecine, to get your the real frames for 24p, sans pulldown.
