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Jeff Mack
IOHD and VTR Exchange
on Jan 31, 2010 at 8:45:22 pm

This is more of a question about VTR Exchange. I capture a 45 minute set with my IOHD via 1080i60 HD SDI to my IOHD, with VTR Exchange and capturing to 10bit pro res lt 1920 x 1080. I accidently let the dropdown box remain "best" for frame rate instead of selecting 29.97. When I got back home, I noticed the video didn't appear a full 29.97. I captured to a MBP to my system drive and had no notice of dropped frames.

Any suggestions? I'll be doing another test tonight and will surely click 29.97 to see if there is a difference.

BTW, in that VTR Exchange dropdown list is a host fo rates including 59.94. Now I thought they are the same with 29.97 being frames per second and 59.94 being fields per second. Why would there be both choices?

Jeff


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gary adcock
Re: IOHD and VTR Exchange
on Feb 1, 2010 at 2:18:24 am

[Jeff Mack] " I noticed the video didn't appear a full 29.97. I captured to a MBP to my system drive and had no notice of dropped frames. "

define what you mean by not full 29.97, do you mean full frame raster size or full frame 29.97 frame rate?

have you turned off the Drop Frame warning?
is your timeline RT Setting forcing to show all frames?

"n that VTR Exchange dropdown list is a host fo rates including 59.94. Now I thought they are the same with 29.97 being frames per second and 59.94 being fields per second. Why would there be both choices? "

1080 60p is clocked as 59.94 (think stereo pairs at 30 frames per eye) 720p can also be recorded at 59.94p, the various settings allow for compression variations and conversions. You have to remember that VTRx is used across the aja product line so it can handle formats that your LHE cannot.




gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

http://blogs.creativecow.net/garyadcock


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Jeff Mack
Re: IOHD and VTR Exchange
on Feb 1, 2010 at 4:37:50 pm

Gary,

Thanks for the response. In VTR Xchange, I unchecked to abort on dropped frames. I did do a test though prior to the show and left that box checked. I had no dropped frames. Here's where the issue is. Upon stopping the capture, I used quicktime to preview. My zooms and moves appear jumpy - definitely not smooth. The action of the guitar player just doesn't seem to be in real time. Audio sounds great.

Next I opened up FCP and believe it or not, all is well. I wonder if playing back the 1920x1080 on 1680x1050 MBP screen is creating a scaling issue. In any event, it plays fine through final cut and I will hook up my monitor this afternoon to preview that way.

Thanks for the 59.94 lesson. Can you explain to me though why I would NOT want to select my frame rate for 1080i60 as 59.94. I still really don't understand how the selection would affect my footage.

Jeff


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gary adcock
Re: IOHD and VTR Exchange
on Feb 1, 2010 at 6:56:00 pm

[Jeff Mack] "Thanks for the 59.94 lesson. Can you explain to me though why I would NOT want to select my frame rate for 1080i60 as 59.94. I still really don't understand how the selection would affect my footage. "


You can thank Sony for that they still label 1080i60 as 1080i29.97. (the first is fields the second is frames)

IMHO they did that so the could fool the old gray haired TV engineers into thinking that working in HD was going to be no big deal, since it had the same frame rate as NTSC. ( too bad they left out all of the other frame rates they would need to deal with, and a new color space.)




gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL

http://blogs.creativecow.net/garyadcock


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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