Hey guys
Ive had my Canon A1 for a couple months now and i've been shooting here and there with it, trying to get used to all the manual features on it.
Pretty fun learning all the features about it.

I had a question though.
Is it alright to mix framerates on a tape?

for example, i was messing around with it the other day testing some stuff out, and i started out shoooting 60i, then about 10 min later, i switched over to 24f.

Will this cause any problems when i go to capture? or dropouts or anything?

Not a good idea mixing framerates on the same tape, you would have to switch capture presets in you're NLE to capture at the correct rate.

Not a good idea.
I have experienced disk problems (Apple iMac with 750Gb external firewire drive) when trying to capture mixed frame rates.

Forgive me but isn't 24f on a canon still 60i?

Yea but when you go to capture 24f you do use the Easy Setup: HDV108024p as opposed to if you're capturing 60i footage you use the Easy Setup: HDV108060i.

Basically you have to reload the setup each time your frame rate changes. It's better to keep all the same frame rates on one tape. I just realized this and yea it's a big pain in the but to have to keep switching back and forth.

I'm confused as to how 60i and 24F could be the same thing? Isn't 60i interlaced and 24F progressive?

24F is Canon's "fake 24p". From what I understand, and someone jump in here if I'm wrong, it still gets put onto tape at 60i. In your NLE, when capturing, you use pulldown conversion to get 24p.

there is no pulldown with 24f. 24f is, for all intents and purposes, 24 frames progressive, and is put to tape as such.

http://dvinfo.net/conf/showthread.php?t=74964

Dangit! Wish I was told the "Correct" info when I had my XL1S, LOL... Cineframe 24 is 24p? hmmmmm....

The frame mode of the XL1s was not the same as the 24 frame HDV mode of the current cameras. You don't get the softening and noise, for one thing. This subject has been beat to death in a zillion posts on here, and Canon has a white paper on it.

Is it alright to mix framerates on a tape?

As note above, It can make your work flow more difficult, so most will recommend against the practice. But if you have to, you have to. So if it works for you, go for it ....but give it a test first before you do it on an important project, especially one with tight deadlines.

24F is Canon's "fake 24p". From what I understand, and someone jump in here if I'm wrong, it still gets put onto tape at 60i. In your NLE, when capturing, you use pulldown conversion to get 24p.I'll jump in. The consumer cams (eg Vixia HV20 or HV30) do use pulldown to record their 24p but the XL and XH cameras use Frame Mode for 24F, 25F, and 30F. The signal is encoded entirely progressively in F Mode. As has been discussed ad nauseum, the only thing not entirely progressive about F Mode is that the part number of the CCD is that of an interlaced chip, but Canon say they've modded it so all 1080 lines are read at the same instant. CANON FRAME MODE IS NOT "FAKE" progressive. It is progressive.

Anyway, if you put long leaders/handles on your footage, you can put footage of different frame rates on a tape and as long as you don't try to capture across the break point, it should be ok. But that's a bother I think most of us would avoid. As with the other folks who have responded, I just don't do it.

I've shot at 25p and 50i on the same tape simply as a test between the two and it worked fine using Sony Vegas 8 Pro.

Mark

thanks for all the responses guys.

i figured there wouldn't be any problems mixing framerates on a tape, but there would be just the hassle of switching settings when capturing to the footage.

Yeah, Nick, I've done it, but only if I'm shooting half and half, so I'm not constantly switching back and forth. And like someone else said, put a lot of leader and tail between the footage, meaning give like 5-10 seconds between the different frame rates.

Sony Vegas 7 seems to have no problem switching between frame rates.

Some people get upset when you tell them 24F has 3:2 pulldown flags added putting 24 progressive frames inside a 29.97 stream. I don't understand why the anxiety. It must harken back to the DV days or something. We're only talking about added repeat flags in the header, not wasted bandwidth from unnecessary encoded frames.

But the repeat flags ARE there, to state otherwise is counter to the observations of Nate Weaver and David Newman.

http://dvinfo.net/conf/showpost.php?p=547105&postcount=10
http://dvinfo.net/conf/showpost.php?p=547129&postcount=12
http://dvinfo.net/conf/showpost.php?p=547214&postcount=15

Having the repeat flags is good and bad. It's good because 24F clips can be natively dropped onto the same timeline as 60i clips if your editor supports it. The played back 60i video just seamlessly switches between 29.97 and 24 fps with nary a hiccup, which makes possible creative opportunities.

But the 60i containerized 24F flags confuse Blu-ray players like the PS3 which can be forced into true 24p progressive output modes for 1080p tvs that support 1080p24 modes, i.e. 72hz, 120hz. On those, 24F containerized inside 29.97 streams takes on a horrid, irregular judder IF you force 1080p24 playback mode from the Blu-ray player. Leave the Blu-ray output at 1080i60 and all is well.

What remains to be seen, is if a hybrid Blu-ray authored disk (24p mpeg2 inside an AVCHD wrapper on DVD5/9 red laser media) can be made to play on Blu-ray players. For that, the 24F pulldown flags would need to be stripped, to get the Blu-ray player to NOT see the stream as 29.97, and thus NOT have to force 1080p24 output, NOT impart its own reverse pulldown mechanisms on the 24F repeat flags (which causes the irregular judder), but just read 24p unforced from the disk.

It's not a huge priority for me as I'm not a big fan of Canon 24F. My resolution testing using the Imatest MTF50 imaging software and the Canon XH-A1 shows a drop in the vertical resolution to about 595 lines. Since the XH-A1 is an interlace scanned sensor, I think 24F is dropping half the fields and interpolating up, i.e. bobbing. The result is generally good, although the image staircases on diagonal lines.

The 60i interlaced mode is essentially artifact free because the 1080 field lines are blended. That too limits vertical resolution to around 700 lines, but I think it could be kicked up somewhat closer to the horizontal resolution by tweaking the [Detail Horz-Vert Balance] parameter, at the expense of introducing some possible twitter/moire artifacts into the XH-A1's otherwise organic 60i image.

As has been discussed ad nauseum, the only thing not entirely progressive about F Mode is that the part number of the CCD is that of an interlaced chip, but Canon say they've modded it so all 1080 lines are read at the same instant.

Hi Pete. Do you have any reference for this? The only Canon white paper I could find was very brief, and said this:

"These Frame modes have the same look as progressive frame rates, but are not labeled
“progressive” because they are created with an interlaced chip. The end result is exactly the
same to the editing system (and to our eyes) as 30p and 24p, respectively."

It does not mention anything about reading all lines at the same instant, which I thought was not possible with an interlaced CCD. I would be very interested to know how they do it if this is correct.

Richard