HVR-V1U 24p vs. 24p SCAN A

[MLCinema]

So what is the difference? I am a little lost. :violin:

HVR-V1U - 24p vs. 24p SCAN A


Thank you :smile:

[magi1500]

Basically, if you shoot 24p and capture it you'll notice the cadence isn't even over cuts. To see this: Shoot footage, pause camera, shoot more footage. Capture both shots as one capture. Frame advance over the cut between shots and count the 3:2 cadence. It should be 3 clean frames and 2 interlaced frames. In order to pull down the whole clip, this cadence would need to be even for the entire file. Count the cadence over the cut and you'll see it breaks. So if I pulled the clip down to 24p based on the cadence during the first shot, the footage in the second shot would look screwy. Or vice versa. I imagine this has something to do with the long GOP structure of HDV, but, at any rate, Sony probably saw this was happening and came up with a solution: 24p SCAN A.
24p SCAN A resets the cadence EVERY TIME you pause the camera. Now shoot the two shots like described above, and when you go to capture them, the computer will force a new clip for the second shot (this is what Final Cut did for me, even though I didn't want it to.) Count the cadence at the beginning of each shot and you'll see that it starts at the beginning of the 3:2. i.e. each shot immediatley has three clean and two interlaced frames. Now you can batch reverse telecine and tell your pull down program (cinema tools for the FCP users) that each clip's A frame is the second frame.
Maybe none of this will matter when our software is updated to remove the interlaced frames on capture. For example, if the frames are flagged properly, maybe it won't matter that the cadence isn't clean over clip breaks as the computer will just remove the interlaced frames. This certainly would work for the DVX100. But then the DVX100 didn't have the long GOP issue HDV has (14 out of every 15 frames don't exist without the help of that first I frame...)
So whether 24p SCAN A mode is a temporary solution or something that will be even more needed when our software is updated is anyone's guess.
Anyone have any ideas about this?
If you plan to cut at 29.97 and finish at 29.97, 24p vs. 24p SCAN A doesn't matter. Personally, I always pull down my footage regardless of the delivery medium.

[btdig]

Thanks for the info on cadence, do you know what the best 24 workflow is for
FCP?
Is cinema tools the only way for 24p? HV1U
Thanks.

[magi1500]

The workflow I had success with this past weekend was shooting 24p Scan A and capturing in FCP as AIC. I then used cinema tools to pull it down to 23.98 and the footage was nice and clean. The sequence I cut with in FCP was AIC, but I obviously changed the frame rate to 23.98. It was a pain in the butt and no doubt will continue to be so until Apple releases an update to FCP to support the V1U. I don't know of any other way to do it right now. I made a super detailed post on the Apple FCP discussion forums about the workflow I successfully used if you want to check that out.

[btdig]

Thanks Magi, there seems to be quite a few posts on the FCP site.
How about a link.
bt

[magi1500]

I'll just copy & paste below:

Shoot in 24p on the V1U. Capture using the Apple Intermediate Codec 1080i60 (this is AIC). This is converting your footage into all I frames (14 out of every 15 frames of native HDV do not really exist... this is why cinema tools cannot pull HDV footage down...) Capturing AIC can take longer than real time depending on the power of your computer and it will take up about 4 times as much space on your hard drive. Every time you paused the recording a new clip will be created. I'm pretty sure this means losing all timecode so hopefully you won't need to recapture your tapes. The footage will look exactly like the native HDV would look.

When that is done, go to your cap scratch location and right click one of the AIC quicktime files you just created. Choose "Open with Cinema Tools". You should be running the newest version of CT because older versions had a file size limitation (that may not be a problem depending on how long your clips are...) The clip opens in CT and you need to set the playhead on an A frame. Normally you would simply press the right arrow and stop on the second clean frame. (Frame advancing on 24p footage inside 60i means three clean frames and two interlaced frames... hence the 3:2 pull up. The frame you want the playhead on is the second clean frame.) CT seems to be a bit glitchy with AIC (I tried older and current versions of CT, all had the same problem). Right frame advancing doesn't seem to work, but jumping to the end and left frame backing up does work. Another glitch, it isn't clear which frame is which in CT. Normally it shows fields and the interlaced frames are exagerrated, but with AIC it seems to show frames. I had to open the clip in quicktime and jump to the end and count back to the right frame and then go back to CT and just count back that many frames. I suppose you could also just keep pulling it down until you lucked onto the correct frame (only five possibilities anyway...)
So once you have your playhead on the second clean frame, choose reverse telecine. The default selections in the reverse telecine box should be correct, but make sure Conform to: is set to 23.98 and the Standard upper/lower box is checked. Frame advance on your footage when complete. If you see any interlaced frames, you had your playhead on the wrong frame.
If you use 24pSCAN A mode, then all the A frames will be in the same place (the second frame of every clip.) There is probably a way to batch reverse a folder full of clips when every one has an A frame in the same spot, but I haven't experimented with that yet.
Anyway, this method worked for me and all my footage is super clean 24p.
Now I'll simply create a sequence in FCP with AIC 1080i60 defaults and then change the frame rate to 23.98.
Someone chime in if you know of a simpler way to do this. At any rate, when FCP supports this cam I'm sure it will be MUCH easier.
Have fun!!

[Transmission2]

I'm beginning a documentary tomorrow and need to make a decision about which mode to shoot on with the Sony V1U.

I read your workaround process about pulling down to get a clean 24p in Cinema Tools. That would be way too much hassle if I had to do that for this entire project, but its a smart workflow for the time being. I will be beginning post around mid-march, early-april so I was wondering if you think FCP will have an update by then to do this pulldown on capture? Should I risk shooting an entire documentary in 24p even though final cut doesn't really support it?

As well, are there any downsides, (ie lower resolution) to shooting on 24p? Would 30p be much better for resolution? I assume 60i would be the sharpest, but I want to stray from the 'video' look as much as I can.

Any info you had would be such a help. Thanks for listening!!

[btdig]

Hello out there...
anything new on the fcp workflow and 24p??? (v1u)
Thanks in advance...

[magi1500]

I do have a slight update regarding the workflow. It is slightly easier.

Shoot 24p scan A mode. capture AIC 1080i60 (this is the same as my previous post).

Now open the cap scratch folder and right click on the first clip. choose open with cinema tools. DO NOT MOVE THE PLAYHEAD OR PLAY THE CLIP. choose reverse telecine.

leave cap mode as F1 - F2 and leave file on New (smaller). Be sure conform to says 23.98 and standard upper/lower is checked.

Where it says fields, you'll see that AA is checked. SELECT THE FOURTH OPTION:

_CD_

and click OK.

Basically this saves you the trouble of finding the A frame so you can do each clip very quickly. This only works if you shoot 24p SCAN A mode and it will work the same for every clip. So you can pull these things down without having to watch them.

The downside is that you still have to do it one clip at a time. If you try to do a batch reverse telecine, you can't change the Fields selection (it stays on AA) and all your clips will be pulled down incorrectly.

Transmission2, sorry I didn't respond sooner but I was at MacWorld. I think shooting 24p Scan A mode is easier right now for the new method I outlined in this post. But if you shoot with the other 24p mode, you'll still be able to pull it down, it will just take a lot more of your time.

There was nothing at MacWorld to indicate there would be any update to FCP for the V1U prior to NAB. I'm sure we'll at least hear an announcement in April at NAB, but that doesn't mean they'd be shipping right away. So I'd guess the soonest would be April, but I expect May or June before we have a real solution.

Also, I don't understand how you can pull out frames that could potentially be I frames. If an interlaced frame was an I frame and they pulled it out, wouldn't it kill the other 14 frames that were a part of that long GOP structure?

So my guess is, they'll have to do something like turn it into AIC on capture and then remove the frames, but I could be way off.

[btdig]

Thanks Magi,
I just read that info on the apple support site...must have been you.
Thanks again, I will try it today.
PS searching for frames in cinema tools is difficult and you cant enlarge the window...

[btdig]

I have jut tried the 24pa approach and I have frames...great.
Cant get to the prefs on cinetools to make batc adjustments.

[magi1500]

Yes, searching for those frames in cinema tools is a pain. That is why I came up with this new method. It will at least save you that trouble. (Using this new method, the frame you are looking for is always the first frame so you don't have to look.)

[btdig]

I may have spoke to soon, I did everything as specified.
I have one clean clip. the rest of the clips, the 4th frame is way outa-wack...
willtry capturing again...

[btdig]

magi,
Heres another question for you, when you capture are you capturing through the cam?
if so, are you letting it run and capturing all clips or are you start and stopping with each clip.
try 60secs. start and stop recording every 15secs or so for 4 clips. capture the full 60secs. use cinema tools, convert and check each of the 4 clips, check the clip anaysis and see if they are all the same. (if you have a chance)
Thanks
The reason I ask, is that I found that I need to start and stop capture for each clip
befor all are the same.

[magi1500]

Are you capturing as AIC 1080i60?

With AIC, it creates a new clip every time you paused the cam whether you want it to or not. I'm just capturing in one pass from the cam, but FCP is creating new clips every time I paused the cam (start/stop detection is on and cannot be turned off.)

Not sure if it was you, but someone on the apple forums was trying this with an old version of FCP and I'm not sure how well that would work.

[btdig]

Yes, I am capturing in one pass, yes I am cap. AIC 1080i60...
I just mailed my upgrade to FCP, that may be my problem. fcp 5.0.4
Thanks again...

[btdig]

Received my FCP upgrade, cinetools works great with 24pa as instructed...thanks Magi
bt