What is the difference between 720 60p and S&Q set to 60 frames?

[Michael Maier]

I'm wondering what is the difference between recording in 720 60p and using S&Q set to 60 frames per second? I mean, 720 60p in a 24p timeline will be treated as slow motion anyways. The only advantage I can see for using S&Q at 60 frames is that you can review playback in camera in slow motion (or quick motion if under cranking). Am I missing something else? Thanks.

[Perrone Ford]

I think you get audio with one and not the other. And I also think with S&Q motion, you get more data rate, but I'd have to verify that.

[Michael Maier]

Yes audio, sure. I didn't consider that because I was talking from a slow and quick motion point of view and you never really record audio in these situations. But yes, if you need 60p to be played as 60p you may want audio and S&Q doesn't allow that.
The data rate detail is interesting. Looking forward to more on that. Thanks.

[Mitchell Lewis]

In Final Cut Pro, when you drop 720 60p into a 24p timeline, it will conform the footage to 24p and throw away the additional frames. When you shoot 720 24p at S&Q 60fps, it will drop into the 24p timeline (but it is 24p) and play with the slow motion you're expecting.

Maybe different on a PC....dunno.....

[Matt San]

if u put 60p in to Edius time line it retains its correct frame rate thus plays properly on a 25p timeline thus making slowmos easy as anything. None of this throwing away frames business - Poor old FCP users

[Craig Seeman]

720p24/60 (overcrank) records at about 87.5mbps. 720p60 records at 35mbps.

Which do you think has more data per frame? Which do you think will look better slowed down to 24p?

[Mitchell Lewis]

^^^^^^^I didn't know that. Thanks Craig! (how do you find out about this stuff?)

[Craig Seeman]

You'd think Sony would put this stuff in the manual.

Just a little math. XDCAM codec plays back at roughly 35mbps (it's VBR so it can vary a bit). That playback rate is regardless of record frame rate.

720p24 is 35mbps and 720p24/60 is 2.5 times more frames per second. Then 35mbps times 2.5 equals 87.5mbps.

You can also test this physically. Using 8GB SxS card set camera to 720p24/60 and time how long it takes to fill the card (use a watch since the EX counter shows the playback rate not the record rate). Normally it takes about 28 minutes to fill the card. You'll find it'll take just under 11.5 minutes to fill the card.

Originally Posted by Mitchell Lewis

^^^^^^^I didn't know that. Thanks Craig! (how do you find out about this stuff?)

[Mitchell Lewis]

Impressive. You make it sound so simple. (I never would have thought of that).
Thanks again Craig.

[Bob Grant]

Something is not quite adding up here. 60p is 60fps regardless of how it's played back, either you're recording 60 frames per second or you're not. I think the difference is that in S&Q the camera records I frames only.

[Craig Seeman]

It certainly adds up. Do the math.

We're talking about data rate playback per second of playback. That's how XDCAM codec decode works.

720p24, 720p60, 1080p30, etc. are all the same approximate data rate playback.

The overcrank record is also flagged so it plays back at the data rate set in camera whether 24p, 25p, 30p. You can see this info in the metadata.

As I said before, watch how fast the SxS card fills up. The data rate is much higher in overcrank record.

One of the BIG differences between P2 DVCPro vs XDCAM is that DVCPro is per frame whereas XDCAM is per second regardless of frames. That's why you can shoot 720pn24 on a P2 card and get a longer record time than 1080p30.

XDCAM playback data rate is per second, not per frame.

Originally Posted by Bob Grant

Something is not quite adding up here. 60p is 60fps regardless of how it's played back, either you're recording 60 frames per second or you're not. I think the difference is that in S&Q the camera records I frames only.

[Michael Maier]

Originally Posted by Craig Seeman

720p24/60 (overcrank) records at about 87.5mbps. 720p60 records at 35mbps.

Great to know that. Thanks!

Originally Posted by Craig Seeman

You'd think Sony would put this stuff in the manual.

Just a little math. XDCAM codec plays back at roughly 35mbps (it's VBR so it can vary a bit). That playback rate is regardless of record frame rate.

720p24 is 35mbps and 720p24/60 is 2.5 times more frames per second. Then 35mbps times 2.5 equals 87.5mbps.

Does that mean that 1080p24/18 is 26.25mbps instead of 35mbps?

[Michael Maier]

Originally Posted by Mitchell Lewis

In Final Cut Pro, when you drop 720 60p into a 24p timeline, it will conform the footage to 24p and throw away the additional frames. When you shoot 720 24p at S&Q 60fps, it will drop into the 24p timeline (but it is 24p) and play with the slow motion you're expecting.

Maybe different on a PC....dunno.....

Really? There's no way around that?
I have never worked with 60p in FCP but I shot some 720 60p which was meant for slow motion yesterday. I hope I can get it to work in FCP.
From now on though I will use S&Q 60 frames for slow motion instead of 720 60p.

[Craig Seeman]

Originally Posted by Michael Maier

Great to know that. Thanks!

Does that mean that 1080p24/18 is 26.25mbps instead of 35mbps?

I haven't tested it but playback should be at 24fps at about 35mbps. The camera alters the record data rate in my testing.

I have never worked with 60p in FCP but I shot some 720 60p which was meant for slow motion yesterday. I hope I can get it to work in FCP.
From now on though I will use S&Q 60 frames for slow motion instead of 720 60p.

Keep in mind the issue is what the camera does. Different NLEs may have different controls regarding this but if you record at 720p60 it's at 35mbps so your bits PER FRAME is significantly lower than 720p24/60. With fewer bits per frame the slow will not look as good.

[Michael Maier]

Originally Posted by Craig Seeman

I haven't tested it but playback should be at 24fps at about 35mbps. The camera alters the record data rate in my testing.

I see.

Originally Posted by Craig Seeman

Keep in mind the issue is what the camera does. Different NLEs may have different controls regarding this but if you record at 720p60 it's at 35mbps so your bits PER FRAME is significantly lower than 720p24/60. With fewer bits per frame the slow will not look as good.

I know that now and will use 720p24/60 from now on. But as long as I can at least get slow motion out of the 720 60p I recorded. I can't re-shoot it with 720p24/60.