HV20: Understanding Frames/Sec. w/Capture at DVinfo.net

Nathan Shane · June 3rd, 2007, 10:58 AM

It's Sunday, only my second day of owning this HV20 and I'm trying to understand this camera better.

I've never previously dealt with changing the frame rate, so could others please explain. When I capture recorded video (HDV 1080i) from tape under Vegas 7e, it reports 29.970 fps...not too hard to understand that.

However, when I change the frame rate to 8, 24, 48, or any of the others, record the video to tape, then capture to Vegas...why does it still report the captured clip as having 29.970 fps? (example - I captured using 8 fps. and it was obvious looking at the captured playback that it was a very low frame rate, but am I just supposed to remember what frame rate I recorded at?

Is the "recorded frame rate" setting not somehow embedded into the data stream so that it can be identified when captured? Otherwise, how are you supposed to know/remember what the frame rate was you actually recorded with?

Chris Barcellos · June 3rd, 2007, 11:31 AM

Nathan:

It appears you are confusing frame rate with shutter speed. This camera shoots only in two frame rates, 60 frames per second interlaced, which is 30 full frames per second, or 24 full frames second in the non-interlaced mode.

Adjustment of shutter speed is where you are getting 1/48, 1/100 or 1/8. Needless to say, at 1/8, you will gett some pretty funky looking stuff...

Vegas reports all the footage at 29.97 because that is the "wrapper" it all comes in. The 24p footage is still in the 60i stream, though it should show up fine when you play it to your HD monitor as 24 fps looking.

To process the 60i to 24p, you have to do "pull down" removal. From my understanding, that means you are removing the extraneous frames, creating a real 23.97 fps file. It also eliminates potential issues with ghosting, etc., associated with working with the 24p in the 60i file...

Vegas does not do pull down removal from the HV20 camera. Canon did not include necessary flags in the resulting footage, for the common editors to work from to do the removal. There has been some attempts to convince Canon to do so.

There is thread in the HV20 forum about a process developed using some available "free" programs, and putting it into a scripts to use with Vegas. I did not attempt to use it, and I bought Cineform's NeoHDV instead which does the pull down removal as you capture....

That's how a non-technical person understands it,.... other will probably explain it better.

Nathan Shane · June 3rd, 2007, 03:57 PM

Hey Chris, thanks for your reply. Doughhh!!! I actually get it now thanks to your post and was just not thinking correctly about frames/sec. and shutter speed, but it all makes sense now.

June 3rd, 2007, 10:58 AM	#1
Nathan Shane Regular Crew Join Date: May 2007 Location: Addison, Texas Posts: 178	HV20: Understanding Frames/Sec. w/Capture It's Sunday, only my second day of owning this HV20 and I'm trying to understand this camera better. I've never previously dealt with changing the frame rate, so could others please explain. When I capture recorded video (HDV 1080i) from tape under Vegas 7e, it reports 29.970 fps...not too hard to understand that. However, when I change the frame rate to 8, 24, 48, or any of the others, record the video to tape, then capture to Vegas...why does it still report the captured clip as having 29.970 fps? (example - I captured using 8 fps. and it was obvious looking at the captured playback that it was a very low frame rate, but am I just supposed to remember what frame rate I recorded at? Is the "recorded frame rate" setting not somehow embedded into the data stream so that it can be identified when captured? Otherwise, how are you supposed to know/remember what the frame rate was you actually recorded with?

June 3rd, 2007, 11:31 AM	#2
Chris Barcellos Inner Circle Join Date: Nov 2005 Location: Elk Grove CA Posts: 6,838	Nathan: It appears you are confusing frame rate with shutter speed. This camera shoots only in two frame rates, 60 frames per second interlaced, which is 30 full frames per second, or 24 full frames second in the non-interlaced mode. Adjustment of shutter speed is where you are getting 1/48, 1/100 or 1/8. Needless to say, at 1/8, you will gett some pretty funky looking stuff... Vegas reports all the footage at 29.97 because that is the "wrapper" it all comes in. The 24p footage is still in the 60i stream, though it should show up fine when you play it to your HD monitor as 24 fps looking. To process the 60i to 24p, you have to do "pull down" removal. From my understanding, that means you are removing the extraneous frames, creating a real 23.97 fps file. It also eliminates potential issues with ghosting, etc., associated with working with the 24p in the 60i file... Vegas does not do pull down removal from the HV20 camera. Canon did not include necessary flags in the resulting footage, for the common editors to work from to do the removal. There has been some attempts to convince Canon to do so. There is thread in the HV20 forum about a process developed using some available "free" programs, and putting it into a scripts to use with Vegas. I did not attempt to use it, and I bought Cineform's NeoHDV instead which does the pull down removal as you capture.... That's how a non-technical person understands it,.... other will probably explain it better. __________________ Chris J. Barcellos

June 3rd, 2007, 03:57 PM	#3
Nathan Shane Regular Crew Join Date: May 2007 Location: Addison, Texas Posts: 178	Hey Chris, thanks for your reply. Doughhh!!! I actually get it now thanks to your post and was just not thinking correctly about frames/sec. and shutter speed, but it all makes sense now.