Strange Problem capturing with Apple Intermediate Codec

Question

We have the following problem:
We capture with a blackmagic decklink studio card (but I could reproduce the same problem using a MacBook Pro and the internal camera) with a MacPro and CS4. When capturing a live video feed (1280x720) with the apple intermediate codec (set to 29.97fps or to 59.94fps) everything seems to work just fine. But the resulting videoclips happen to be exactly ONE half of the total capture time. So if we capture in Premiere for about 1 our the clip is only 30 minutes long. If we capture for 10 sec., the clip will be 5 sec. long. It's not that the captured clips play with double the framerate. Half of the actual footage is missing.
Any suggestions?
By the way: we live in a PAL50Hz country, but our video signal that needs to be recorded comes in as a 60hz signal.

Answer 1

Hi,
Well I did some googling...and I would bet that the problem is the 50hz vs 60hz...
Unfortunately most if not all info I got that even BRUSHES on this subject with the sort of material you're dealing with is the opposite....where they are in 60cycle land with pal stuff....rather than in pal land dealing with 60hz ...
This is a lot of misc stuff but if you get a little bit of info from various posts and make some notes you might be able to get an idea how to solve the problem...
In particular I was looking at how frames are flagged and new frames are created later ...( toward very end of these posts - the last four or so )
Also noted some timecode reading that was "doubled"....so if your deck thought you had a specific length and then it read the timecode doubled, it would be your problem in a nutshell...  have you checked the last frame you captured and compare that timecode to the overall length ??
anyway, here is a TON of stuff to breeze through...good luck...
THIS IS EDIUS RELATED..so keep in mind re: specific presets etc
Steve Sherrick
03-03-2008, 11:14 AM
Hi chaps,
Can I just confirm that the SDI/HDMI outputs are only live in build 14? I'm on 13 and going SDI - HDLINK - DELL24" gives me nothing. I'm in PAL land so have tried switching between 50hz and 59hz in camera.
So do I need build 14 or is it something else?
Cheers
Jeff Brown
#708
I'm in NTSC land but that same setup gives me picture just fine. Which Dell model is it? Is everything set up right from the camera side?
Jeff Brown
03-04-2008, 12:42 PM
Hi Steve,
I believe so. Set to Preview in th viewfinder settings, plugged in on preview mini sdi, cam set to 50hz..
Anything I'm missing?
Cheers
To counter this, the AJ-HD1400 offers two modes specifically for this called '25(SD)' and '25(HD)'. They output the 25fps signal with new timecode on a 50Hz carrier (only over SDI/Analogue the Firewire doesn't work in that mode).
It only works with 25fps material too, any other 'offspeed' rate has to be dealt with separately with the deck operating in 59/60 mode.
When operating in either of these 25 modes, the deck generates new 25fps timecode from the tape (although our tests have indicated that it is frame accurate of multiple playback passes).
Basically, Varicam, while a very nice idea, has only ever been properly designed to work in a 60Hz environment. It is pretty much a nightmare in 50Hz environments.
I think I may have found the cause of the problem.
For some reason when I started my project it had a Device Control profile set to 720p50 (rather than the 1080i50 that the deck is operating in).
What this seems to have done is double the frame number on any clip it encountered. So if I took a clip with in marked at 01:02:40:22 and dropped it in the Log and Capture tool the In Point that FCP decided to look for was 01:02:40:44 (which isn't going to exist on a 25fps timecode obviously).
Since you are using Pal
Go :
Generic OHCI HD 50hz -> 960x720 25p over 60p
Because if I am right you can't do Pal over 60hz but you can do PAL over 60P at 50hz.
( but I could be wrong)
But the other problem is that you are using an ntsc profile to capture pal recorded footage.
50 hz 960x720 over 60P yields a frame rate of 25 progressive
60 hz 960x720 59.94p yields a frame rate of 59.94 progressive which is far from your original footage . Mostly used for countries using natively ntsc
Neither myself, nor Ricksta (I don't think) are using NTSC-rate profiles.
The Preset setting I've been testing with is:
Generic OHCI HD 50Hz 960x720 25p over 60p
Indeed, I've just tried what Rick mentioned, and with the deck in 59.94Hz operating frequency, I can capture with all three 720p 59/60 input settings. This is technically wrong however, as the tape has been recorded at 60Hz. But like I said before, until Rick hears from the big geeks at Panasonic about this, I don't know what the real outcome of that difference in frequency is.
I've also tried a 50p over 60p project setting (as 720p50 is what I will be editing with in Avid) - but, predictably, this works but gives me double-speed footage. Which, while amusing, isn't a lot of help for me
A large part of the problem I'm facing here is to do with the Varicam format. It will record any framerate from 1-60fps. It has to operate and a system-frequency of 59.94Hz or 60Hz. That is what Rick and I are referring to. The limitation I face is that the Varicam format is not widely supported for PAL-based rates (25/50) as it requires communication with a deck operating in an NTSC-based system frequency (either 60Hz or 59.94Hz). This difference (between project/timeline framerates, and deck operating frequencies) is enough to ensure that IEEE1394/Firewire/OHCI capture is not possible in these modes in Final Cut Pro, Avid (any version) or any other NLE I have found.
We realise that the framerate and frequency we're working in has to be 50-based, and we're not making any mistakes in that respect.
So far Edius is the only NLE on the market, that I have been able to find, that supports Firewire capture from 60Hz DVCPro HD material in a 50Hz based framerate.
When you have captured the file in that project select a clip in the bin press alt+enter go to video info and tell me what the framerate is .
In a 50p over 60p project, when I capture footage shot 25p over 60 with the 'Constant Rate' capture profile I get a clip in the bin that is 50fps, but that plays at doubletime - which is what I'd expect.
I can change the framerate in the properties to 50fps, and it plays at the correct rate, but I'm not happy with the way to refactors the timing in that mode. It seems to create interpolated frames to fill the gaps, which provide an unusual appearance that I don't really like.
At present if I capture into 25p over 60p project, then import the resulting 25p footage into Avid, Avid doubles up the frames to produce 50fps material.
Some clarification here. The Varicam does indeed record at a constant 60fps. If the frame rate is set to 25fps for example it simply flags the active frames. This flag is carried in the vertical interval data. The reason for this system, is as suggested, it is very difficult to vary the speed of tape in a helical scan recording system. With the advent of solid state recording that Panasonic introduced in the AG-HVX200 it is now possible of course to only record the active (native) frames and this would be called 25pn for example.
Originally with the Varicam you used to use a device called a Frame Rate Converter. This box contained a hard drive with HD-SDI I/O. It would recognize the active "flagged" frames in the incoming signal and buffer them through the hard drive and then play them out at the correct frame rate.
More recently NLE's such as Avid, FCP and Edius have incorporated this flagged frame recognition and perform the extraction automatically. Thus when I tested a 25fps Varicam ingest on a 25 Frame timeline I am getting realtime playback. If I had recorded at 50fps and I placed that on a 25 frame timeline I would have very smooth half speed. Also the newer DVCPRO HD decks such as the AJ-HD1700 and AJ-HD1400 have the ability to decode "on-speed" frame rates such as 30fps, 25fps and 24fps.
The issue that Dylan is facing is that the NLE's will not accept a firewire input at 60Hz, they only accept it at 59.94, this is a .001 frequency difference and should be negligible. The other alternative is to ingest via HD-SDI via a Black Magic or AJA Kona card etc. These boards also support the variable frame rate function.
I hope that this helps clear things up a little.
Rick Haywood
Manager Broadcast & Display Systems
Panasonic New Zealand Ltd.
Further to what Rick is saying... The issues with most NLEs for PAL users is the disparity between the 59.94/60Hz operating frequency of the deck and the 50Hz based framerates the applications are working with in PAL framerates.
As for the constant 60fps - it is indeed recording 60 images per second to a tape, but as I said before, only a certain number are unique - only the flagged frames. In 25fps, the camera samples the sensor 25 times a second and records that frame to tape. Essentially you get frame 1 recorded for 2 frames, frame 2 recorded for the next three frames, frame 3 recorded for 2 frames, etc... The first frame with each unique image is 'flagged'. To rebuild the recorded framerate, only the flagged images are captured.
The big bonus of Edius for me here is that it can capture the PAL framerates from the 59.94Hz deck over Firewire directly. Something that Avid and FCP are unable to do.