Canon 30p video recorded at 60i ?

WayneM wrote on 3/7/2015, 5:17 PM
I was trying to pin down the 30p at 60i format to see if any special handling was needed and finally found mention of Benign PsF and Malignant PsF in terms of how video editing software handles them.

While not every author seems to get it, a really important issue is if the camera actually creates the two 60i from a single frame (buffer) or if the two frames are actually 1/60th of a second apart.

Source: http://www.rassoc.com/gregr/weblog/2011/12/02/editing-canon-30p-pf30-footage-in-fcpx/

"It’s not obvious, but it seems that the “PF30″ footage (as the Canon cameras call it in their configurations) is recorded as “Progressive Segmented Frame“. In layman’s terms (and believe me, I’m a layman when it comes to this), this means an entire frame is captured in the camera, and then it’s recorded into two separate fields in the 60i recording. The two fields, together, make up the frame."

Handling the Canon 30p/60i isn't mentioned in terms of Vegas. Does anyone have recommendations on how best to work with this in VP13 in terms of the Project properties and when it comes to Rendering? For some of my projects it may not make much of a difference but for some upcoming work I want to try to get it right the first time.

I'm also trying to figure out how to create a test to determine if two 60i fields are actually from a single image unless someone out there already knows.

Thanks.

Wayne

Comments

Chienworks wrote on 3/7/2015, 5:45 PM
Do a fast pan across a vertical line. Load it into an interlaced project in Vegas. Pause on a frame. If it's truly a progressive frame split in two then you'll see the solid line. If it's really interlaced then you'll see combing. You'll need to have your preview set to full and disable preview window scaling.
videoITguy wrote on 3/7/2015, 6:18 PM
As has been stated countless times - there really is never any need established to shoot Canon PSF 30 video when you might as well just use the native sensor ablility to shoot 60i and then brought into a non-problematic timeline in VegasPro.

Now does that stop you from wanting to shoot in PSF 30 just for kicks? NO! - But there is no need to do so. If you choose to just shoot this kind of video, then just remain consistent for the entire timeline of source footage and you are good to go.
WayneM wrote on 3/7/2015, 7:03 PM
That's on my To Do short list. I was also digging into the manual and at the highest 'quality' the frame rate can't be changed and doesn't show up in the menu which had me confused. But at the top end it is 60i so I'll have to do a couple tests to see what's going on and get it clear in my head.

Thanks!
jeff92k7 wrote on 3/8/2015, 7:13 PM
I do this all the time to mix video from my Canon camcorder with video from my DSLR (and other various cameras) that are all set to true 30p.

In Vegas, I go to the media properties for the clips from the camcorder, then set 'field order' to progressive scan.

I don't know if this is the 'right' way to do it, but the results are much clearer than having Vegas treat it as interlaced footage. I don't see any interlacing artifacts or weird line scanning doing it this way. To me, this gets me what I need so it's the right way for me.
astar wrote on 3/8/2015, 8:44 PM
In my experience 30PF switches the sensor scan to progressive, then captures the whole progressive frame to buffer, then copies that frame to a hardware encoder that only handles writing 60i. This is one of the main reasons that camera is cheap by comparison. There is delay in this processing which can be seen when trying to sync to a camera that does not have this delay. If you are trying to use this video mode in a live setting this delay can be noticeable. I generally use an intermediate format with my Vexia 30PF like XDCAM and convert the footage to 1080x30p, this clears any interlacing issues on the time line and make the footage like for like with the dslr true 30p.
WayneM wrote on 3/8/2015, 11:38 PM
I did a quick and nasty set-up for the pan. Sharp white line on black background. Too lazy to set up lights so to use 1/2000 shutter had to crank Gain to Max. . .more noise but it did the job. I shot at each of the frame rates the XA20 offers for AVCHD.

I dragged all four clips into VP13, beginning with the 59.94i one. I let VP set the Properties to match this incoming file. Then I dragged in the other three clips: 59.94P, PF 29.97, and
23.98P.

At a fast pan all clips showed the top to bottom skewing of the vertical line. Actually I thought there was a possibility that modern cameras would build the frames from a single digital capture of the entire frame. Well the XA20 doesn't. I imagine high-end cameras do that, but I don't know what that capability is called. (Maybe I'll have to rig up a test to see if a modern DLSR exhibits the same top to bottom skew on fast moving objects?)

To make the Preview enlarge the detail I needed to inspect I made a small Pan/Crop box in the middle of the frame. The results (below) are as hoped for. To me it looks like all the files I would think would be progressive are, unless I'm missing something here.

59.94i: Combing evident
59.94P: No combing
PF 29.97: No combing
23.98P: No combing

One anomaly was that with the 59.94i clip the two interlace fields would snap out of register on the preview if the Pan Zoom was not at the full frame. What I see is the line becoming two lines spaced a fair distance apart, one made up apparently of even frames and the other with the odd frames.This ONLY happened to the 59.94 i interlaced shot, not with any of the P or PF. Disable Resample was set if that matters. I could email a couple Preview snapshots if anyone is interested.

Now back to real work. . .but I feel better informed.

Wayne