Real-time video capture from a laptop?

[Geoffrey Cox]

Hi,

I'm thinking of buying a Ninja 2 but not for field use or with a camera. Instead I want to record live streaming video coming out of my MacBook Pro. From what I can gather the Ninja 2 should do this - basically I use real-time video processing software in live performance situations but now want to capture what I do on the fly, for further editing in FCP6 to produce a fixed final product. The material is 1080i 50 and outputs via the mini-display port.

So the basic question is, if I get a mini-display to HDMI adapter and plug it into the Ninja 2 and start playing, would the recorder do a good job of capturing what I do? (I also use a Matrox mini interface and am hoping to get the video software (Jitter) to talk to it soon - basically some programming needed - so will have 'direct' HDMI output from the Matrox which connects to the Express port on the Mac).

Thanks

[Sareesh Sudhakaran]

For just recording, yes, the Ninja should do fine.

However: 1. Why not record internally in camera? 2. Why not record the original stream on computer?

I wouldn't recommend laptops for this kind of work, and instead of juggling three or four different tools, one good computer should be able to do it all.

[Geoffrey Cox]

Hi Sareesh,

Probably did not make myself clear - I'm not using a camera at all (and can't record to camera as they don't have any useful video inputs) - I'm doing the real time processing on my laptop from stored files and trying to record the output on the same laptop has proved problematic - I've tried screen capture software but the CPU is so taxed that frames are dropped continually. Hence my reasons for finding an external recorder to stream it into. I'm not sure that a more powerful machine would make that much difference and even then I'm still stuck as to how to actually record the output of the software I'm using on the same computer. By using the Ninja I'm only using 2 tools and it gets the recording process separate from the video processing which I think is what is needed.

The Ninja 2 could come in handy for other things of course like recording in the field.

[Geoffrey Cox]

Btw others have also suggested a more powerful machine might be better but apart from screen capture, no-one seems to have any idea about HOW one might record internally...

[Duncan Say]

Camtasia? They offer a free trial here.

Camtasia

[Geoffrey Cox]

Thanks for the suggestion Duncan - I'd heard it was good so gave it a go and it's not bad but like other screen capture software I've tried, it drops frames continually, at least on my machine. Maybe a more powerful computer would work but that isn't possible for me just now.

[Sareesh Sudhakaran]

Originally Posted by Geoffrey Cox

Btw others have also suggested a more powerful machine might be better but apart from screen capture, no-one seems to have any idea about HOW one might record internally...

What exactly is this 'processing' that you're doing? What application are you processing with? Once the processing happens isn't this application capable of rendering the results on to your computer?

What you're basically looking for is the ability to either render or transcode. The concept of 'recording' doesn't apply, or at least not as far as I understand your workflow.

The Ninja is basically a small computer designed for transcoding and writing media files. A computer can do that and a lot more. The major reason why people use devices like the Ninja are for portability and the ability to read SDI/HDMI streams off-camera. Nothing gives you the flexibility of a computer - you have a choice of codecs, applications, etc., that no other hardware device can match. Only a production switcher comes close.

If your workflow is not camera based, you are much better off doing everything in computer.

[Geoffrey Cox]

It's getting a little frustrating trying to explain this!

I am using software called Jitter which you programme to process video files. These files stay in the QT engine and in my case I get the software to randomly chose files (loaded into RAM), sometimes in very rapid succession. There is no way for the software itself to record this output as the files remain in QT, i.e the software just points to them and says play that one. I can control the speed of selection, choosing from different banks, and whether it plays the whole clip or jumps to another more quickly. I can also get the selection of files linked to other triggers like varying audio amplitude levels. There is no rendering going on as such, simply a random selection of files.

It's all very well saying the best thing is to record this random flow on the computer, but my question remains, how?

[Duncan Say]

I think you are right to try and record what you are doing outside of the computer as it must be under a fair amount of stress doing the tasks you are asking of it.

However can I recommend the solution you have suggested?

Well if you look at the FAQ on the Atomos site even they say "suck it and see".

I1 - Can you use the Ninja with a YUV to HDMI converter? - ATOMOS

I5 - Can I record the output of my PC with a Ninja? - ATOMOS

Which isn't very encouraging. You could try hiring one I suppose, or if there is a Ninja owner near you, you could get together and give it ago.

If you are nearby, I'm in Colchester, get in contact.

[Geoffrey Cox]

Thanks for the links Duncan - I do worry along the lines suggested. It seems by no means a forgone conclusion that what I want will work.

I tried today to get the Matrox working with Jitter - it does but the frame rate drops significantly in the process so that's a failure really. This leaves using a mini-display port to HDMI adapter. I emailed Atomos to see if they have any advice on whether this will work properly with the Ninja 2 but I'm not holding my breath.

Thanks very much for the offer of getting in touch - I might well do if I run out of other options!

Geoff

[Sareesh Sudhakaran]

Originally Posted by Geoffrey Cox

It's getting a little frustrating trying to explain this!

I wish I had the ability to read your mind. Then I could sell you things!

I am using software called Jitter which you programme to process video files. These files stay in the QT engine and in my case I get the software to randomly chose files (loaded into RAM), sometimes in very rapid succession. There is no way for the software itself to record this output as the files remain in QT, i.e the software just points to them and says play that one.

...It's all very well saying the best thing is to record this random flow on the computer, but my question remains, how?

First of all, I have zero experience with Jitter, but a quick google search gave me this page: Working With Live Video and Audio Input - which tells me after processing the video can be recorded as QT files via the jit.qt.grab object. With a fast CPU and a Hard disk dedicated for writes it shouldn't be any problem. Is this something like Isadora?

But let's assume you've tried this and it doesn't work. Or, maybe this isn't the software you are talking about. In that case, if your HDMI stream is a format that the Ninja understands, only then will it be able to read and record.

Sometimes these recorders are only meant to read SMPTE encoded signals, especially Y'CbCr based video samples. What is being delivered by HDMI via the GPU might not be the same, or might not be supported. The only surefire way of knowing is to find the signal format and ask the manufacturer directly. In fact, you might be better off with an HDMI consumer recorder, but I can't find any of those. However, a GPU outputting component video and audio will work - there are many recorders for such video - but none of these solutions are elegant, and who knows what signal processing happens under the hood?

All the best!

[Geoffrey Cox]

Thanks for the response Sareesh - yes looked at the grab object - doesn't work in this situation.

And certainly there could well be problems with the Ninja too...

Managed to get access to a MacPro so will try Camtasia on that next.

(And yes, an HDMI consumer recorder would be great, but there doesn't seem to be any!!)

[Geoffrey Cox]

And ... maybe component is the way to go - but need a converter now to get a component signal out of the Mac.

I dunno, this all seems far more complex than it should be.

[Eric Olson]

Originally Posted by Geoffrey Cox

And ... maybe component is the way to go - but need a converter now to get a component signal out of the Mac.

I dunno, this all seems far more complex than it should be.

There are a whole bunch of kids recording their PS3 and Xbox video game play using video capture cards connected to a second computer or stand-alone devices such as Blackmagic Intensity Shuttle and Hauppauge HD PVR. The process should be quite similar to recording the video output of your Mac. Search on something like "record PS3 gameplay" and you will get some tutorials.

[Duncan Say]

Originally Posted by Geoffrey Cox

I tried today to get the Matrox working with Jitter - it does but the frame rate drops significantly in the process so that's a failure really.

Geoff

What flavour of MacBook Pro do you have? Because that result suggests that it just isn't fast enough.