Recording 720pn direct to a laptop

[dvxStephen]

I've noticed in the HVX FAQ and elsewhere that the amount of space needed on a P2 card drops by 40% if working in "native" (true 24fps) mode, aka 720pn. Pretty cool.

Can one also record 720pn via firewire direct to a laptop, with similar space savings regarding file sizes?

If so, that would suggest that the Firestore could do 200 minutes or more of 720pn, as 720pn seems to be about the same data rate as DVC50pro, right?

Thanks,

Stephen Gagne
Westwood Studio

 

[ullanta]

Unfortunately, anything streamed over Firewire has to conform to pre-"native mode" standards... so HD modes (720 or 1080) are ALWAYS 100Mbps that way. In fact, there's no firewire output for native modes at all - you can't record native to a P2 card while also streaming Firewire.

I have not confirmed this yet, but it's been stated that FCP can remove pulldown during capture of 720p material, so the actual storage space benefit may be there for FCP. But that's an effect of the NLE, not the camera. I don't know if the Firestore will do the same... I doubt it! The Cineporter, seen by the camera as a P2 device, promises to capture native mode direct to HDD - but it's also still in development.

-BArry

 

[nsoltz]

If you shoot 24p Advanced, FCP can remove the pulldown on capture. If you shoot 24p Normal, then you must remove the pulldown in Cinema Tools. I must admit that after the shorthand of 24pN for "normal", it's quite an adjustment to think of 24pN as "native." In that regard, Cineporter holds even greater promise if it ultimately has the ability to handle 24p native.

Ned Soltz

 

[David_M_Payne]

Unfortunately, anything streamed over Firewire has to conform to pre-"native mode" standards... so HD modes (720 or 1080) are ALWAYS 100Mbps that way. In fact, there's no firewire output for native modes at all - you can't record native to a P2 card while also streaming Firewire.

I have not confirmed this yet, but it's been stated that FCP can remove pulldown during capture of 720p material, so the actual storage space benefit may be there for FCP. But that's an effect of the NLE, not the camera. I don't know if the Firestore will do the same... I doubt it! The Cineporter, seen by the camera as a P2 device, promises to capture native mode direct to HDD - but it's also still in development.

-BArry

Will FCP remove pulldown if you are shooting in 1080 24p firewire to a G4 and raid drive?

David

 

[dvxStephen]

Thanks, Barry and Ned for your helpful replies.

One thing that confuses me -- when I shoot my DVX in 24pa, and capture in final cut with pulldown removal, I do get a size reduction, as I recall, it's not the 40% or even close to it, bit instead more the ratio you'd expect when removing 6 frames per second, going from 30 to 24.

Do you know why it is that 720pn has so much less data than 720p? According to Panny's FAQs, if I read them right, it goes from 1minute per gig to almost 2.5 at a normal frame rate...

What am I missing here?

Thanks,

Stephen

 

[Barry_Green]

You're missing that the DVX is recording an interlaced stream so you're looking at a reduction from 30 "frames" to 24 frames, but on the HVX it's a 60p progressive stream so it's reducing from 60 frames to 24 frames.

 

[dvxStephen]

Thanks, Barry, for the clarification.

Incidentally, when do you anticipate having copies of your HVX book available?

"...on the HVX it's a 60p progressive stream so it's reducing from 60 frames to 24 frames."

Somehow I've missed this important sounding point in reading to date about this camera on DVXuser and elsewhere. So the camera's HD output via firewire streaming is ALWAYS 60p when in any HD mode?

And streaming is disabled when in the HDX's native modes?

I gather then that it's up to the capture software to redefine the 60p into the desired format while capturing, depending on what you're using it for?

I'm not saying this is bad, but it does raise some other questions.

Sounds like one might be able to capture via streaming firewire to a laptop in 60p and later, in post, decide what frame rate you wanted, with minimal quality hit (?), which could be pretty cool.

Is that correct, though?

Also sounds like this approach would be pretty inneficient in terms of drive space if using the firewire streaming option for 24fps work, unless one captures at 24p.

Barry, have you verified that Final Cut will do a streaming "live" capture on location of the HVXsignal at 720p/24p with the 40% reduction in file size that's suggested?

Thanks,

Stephen

 

[ullanta]

Somehow I've missed this important sounding point in reading to date about this camera on DVXuser and elsewhere. So the camera's HD output via firewire streaming is ALWAYS 60p when in any HD mode?

And streaming is disabled when in the HDX's native modes?

I gather then that it's up to the capture software to redefine the 60p into the desired format while capturing, depending on what you're using it for?

I'm not saying this is bad, but it does raise some other questions.

Sounds like one might be able to capture via streaming firewire to a laptop in 60p and later, in post, decide what frame rate you wanted, with minimal quality hit (?), which could be pretty cool.

Is that correct, though?

Also sounds like this approach would be pretty inneficient in terms of drive space if using the firewire streaming option for 24fps work, unless one captures at 24p.

Well, all HD streaming over firewire is 100Mbps. Some of it is 1080i (interlaced) and some is 720p. Using the same pulldown technique as the DVX, the 1080i stream can carry 24p images... and you'd see a similar 24/30 storage requirement (once pulldown is removed, which FCP currently does NOT do on capture for 1080i/24p streams). Since the FORMAT is 1080i60, 1080p60 can't be recorded - but the 60i stream can carry 24p or 30p images.

Now, 720p60 allows you SOME flexibility in post, but there's a lot more to good variable-framerate imaging than just the speed. For a "filmlook", you want to match exposure to the framerate so you get the right amount of motion blur; and that's something you really can't do in post as well as in-camera. I think it does give you some more power and options for doing such things in post... but you can get even better results in-camera.

 

[Barry_Green]

Incidentally, when do you anticipate having copies of your HVX book available?

Probably sometime around mid-March, with any luck!

Somehow I've missed this important sounding point in reading to date about this camera on DVXuser and elsewhere. So the camera's HD output via firewire streaming is ALWAYS 60p when in any HD mode?

No, as Ullanta points out, when in 1080 mode the firewire output is 1080/60i, when in 720 mode the firewire output is 60p (which conforms to the way the Varicam works).

And streaming is disabled when in the HDX's native modes?

Correct.

I gather then that it's up to the capture software to redefine the 60p into the desired format while capturing, depending on what you're using it for?

Correct.

Sounds like one might be able to capture via streaming firewire to a laptop in 60p and later, in post, decide what frame rate you wanted, with minimal quality hit (?), which could be pretty cool.

Not really though. I mean, if you want to decide what frame rate you wanted in post, you'd be limited to those that are evenly divisible into 60 (so, you could shoot 60 and then convert it to 15 or 30); any other rate wouldn't have proper motion sampling. And you wouldn't get proper exposure motion blur either. So no, it's not too practical of an idea, although I'm certain we'll see it put to good use in some special-effects ramping shots by one of our resident wizards sooner or later!

Also sounds like this approach would be pretty inneficient in terms of drive space if using the firewire streaming option for 24fps work, unless one captures at 24p.

FCP does, so it's not inefficient at all. Don't know about the other programs.

Barry, have you verified that Final Cut will do a streaming "live" capture on location of the HVXsignal at 720p/24p with the 40% reduction in file size that's suggested?

Yes, someone on DVInfo reported that they'd tested it and verified that that is indeed how it works.

 

[dvxStephen]

Probably sometime around mid-March, with any luck!

That's great news. Will this be coming with new HVXs after that, and do you know how it will work for people that have already gotten theirs?

Will you be taking pre-orders?

Not really though. I mean, if you want to decide what frame rate you wanted in post, you'd be limited to those that are evenly divisible into 60 (so, you could shoot 60 and then convert it to 15 or 30); any other rate wouldn't have proper motion sampling. And you wouldn't get proper exposure motion blur either. So no, it's not too practical of an idea, although I'm certain we'll see it put to good use in some special-effects ramping shots by one of our resident wizards sooner or later!

Makes sense. And thanks once again for your thoughtful reply.

Still, I can see cases where I 'd be rolling without being sure what portions would stay normal speed, and what portions would benfit from slo-mo in the edit. While not as optimal as deciding ahead of time what's to be slow mo and compensating technically with shutter speed, etc., this sounds like an amazing improvement when you want to hold out some choices for the editing stage -- particularly when compared to the current options with DV footage, where most slo-mo is generated by simply doubling the frame count in post!