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Old August 20th, 2010, 10:59 AM   #1
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Recording multi-channel Sound with SI2K mini

Is it possible?

SiliconDVR only seems to allow 2 channels of audio.

So I was thinking, since I'm recording to the laptop, would it be possible to run an audio recording application (Audacity?) concurrently w DVR to get multi-channel in Audacity?

And the sync in post.

This way we can get say 4 channels in Audacity and 2 in DVR, so 5.1 sound becomes reality.

(I already do have a USB interface that does feed 6 channels of sound into the laptop. Need to figure how to capture it in sync with video.)
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Old August 22nd, 2010, 05:36 AM   #2
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Alex. Looks like no takers.


Multichannel is something I have not investigated. We sort of went four-channel with the symphony recording into two Zoom H4n recorders but only used one stereo pair in the end.

Lynx Studio equipment might be worth a look however I think all their stuff is for desktops not laptops or standard rack mounts.
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Old August 22nd, 2010, 08:21 AM   #3
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>> Looks like no takers.

What do you mean? I just got a treply from the only other Si2K owner in the world! (or so it seems from looking at this forum, haha!)
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Old August 22nd, 2010, 10:29 AM   #4
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Yes, but do compulsive-obsessive posters count?


Seriously now. Steve Rice and the camera which is named "Der Alte Bruder" are likely to be off to Bangalore to do two features in September. One project was deferred from June.

The two cameras here have been used in a attempt to do 3D binocular-microscopy. So far no footage actually shot yet but the moments we get to see something it is a wicked look.

Just getting the cameras to harmonise through the scope for framing, brightness and getting rid of a hotspot in the left split is a big ask right now. It is moot whether you get a true 3D but you can get the illusion of depth with some trickery which I won't go into right now because it was an accidental discovery, may not be controllable, indeed maybe not repeatable.

Just thinking now this moment, the hotspot might have been some stray overhead light going down the third eyepiece which is the normal camera port on the scope, which I now recall was uncapped in the first tests but had an eyepiece lens in it this last time when the hotspot turned up,

The artifact is as happens when leaving a film camera viewfinder eyepiece iris opened. - Thanks for the post triggering off an imagining. May be a dead-end, may be a solution.
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Old August 22nd, 2010, 10:35 AM   #5
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>> do compulsive-obsessive posters count?

Clearly you are not the one. Otherwise you'd know it's obsessive-compulsive! :)

..so I heard.
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Old August 22nd, 2010, 11:31 AM   #6
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Thanks for that re-assurance. I feel quite sane now.
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Old August 23rd, 2010, 08:36 PM   #7
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Multi-channel audio recording in sync with Video - it is a GO!

I just did some tests, and they look fantastic.

Recorded multi-channel sound (3 mono channels at this time) using RME UC as input device, via REAPER software. ...simultaneously with capturing video on the same laptop (2.5Ghz Intel i5) by SI-2K's Cineform RAW with regular 2-channel stereo sound. (Due to the SiliconDVR limitations, it can only capture stereo sound and not multi-channel.)

So, effectively, I have just recorded a 5-channel sound in perfect sync with video.

Well, stereo channel is in sync automatically as it is the same AVI file; other 3 mono WAV files have to be sync'd manually (but as a group).

So. Now I can actually use one of the video channels (and one of the audio channels) to record audio slate, and still I'll have enough "clean" channels left over to use for mics etc., due to this newly found multi-channel capability.

I'm thinking, I even can feed audio TC (called LTC I think?) continuously now, as constant audio slate. Then in post, apparently, it all will sync in NLE that understands audio TC.

Did not try that last part, but am very excited with the results so far. Capability is there. To me, this means: extremely cheap and relatively low-maintenance TC sync between all video and sound sources.

Next step: feeding the same audio slate signal to one of the stereo channels of Canon 7D, or *any* other second cam (iPhone) that otherwise would not be syncable. Bingo - everything is illumina... synchronized!

(Field tests are due of course.)

Joy.
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Old August 24th, 2010, 07:59 AM   #8
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I'm howling a big tantrum because I likely won't be able to do this with the standard recorder unit body.

I had a delusion for a while about having a larger CF C: drive in the full camera-recorder, with dual boot and a barebones NLE installed in the second partition for quick in-field assembly of rushes or EFP without need to drag more gear around.

Then the analogy of not using tape cameras for capturing etc., emerged. Simply consuming much of the finite life of the camera's computer just as an editing hack would not make much sense.
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Old August 24th, 2010, 08:22 AM   #9
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I think you need a fairly fast machine to pull this trick.

My laptop is 2.5Ghz i5 with self-installed IBM SSD and 2Gb memory, running Win 7 optimized for fastest operation, SSD, and minimum services. I've noticed that WiFi radio on/off did not make any noticeable difference, so personally I tend to leave it On.

CF card as OS drive would be very slow to load Win and programs, and probably to process Pagefile as needed.

I'd recommend utilizing modular structure inherent with SI-2K, and just use Mini head with a capture PC you build to your own specs as needed. That's what I've been doing for a year now with good success.

This way you are completely free to build whatever the system you need (at the expense of more effort and less mobility than the standard body provides, I think.)

Now if only I could find an elegant, yet flexible solution to handle all the cables...
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Old August 24th, 2010, 10:01 AM   #10
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Alex.


I had been encouraged in the NLE direction by the camera being able to play its .avi files in Windows Media Player.

A bit off-topic. - Greenscreen is something I have avoided on a "Do I need to know this right now? - No" basis.

For "Udyan Express", Steve Rice wil be shooting most of the carriage interiors in a studio set with portholes or breakaways in the carriage compartments. Where a window is in shot they will have a greenscreen set back about 3 metres behind it.

That part is relatively easy. Not so easy will be shooting the background plates from a moving train, day and either day-for-night or genuine night ansd getting the angles and perspectives right for the side-on two-shots, close-ups and reverses. There's obvious solutions like keeping accurate records of studio setups for each shot, the angle of each shot from directly towards the window and the prime lens used.

They are however going to be working very fast. There may be two or more languages involved on set, so my wild guessing is that the accessability of the notekeeping or the ability to use the notes might not be as versatile as one might hope for.

The SI2K recorder unit has a cool function which I have not yet got the knowing of. Apparently when shooting a background plate, you can layer your greenscreen shot over it for matching purposes. Have you had a play with this function yet?

I can see this being a handy if not essential tool on this project for getting the angles of view and focal lengths of lenses right to match the studio window in background shots.

What might be better for the night scenes may be to use some semi-mirror window tint sheet over a pane of glass and shove that in the window frame to create some internal reflection from the set as would seem to be during genuine night time in a carriage cabin. I am still in the thought stage on that one.

Any thoughts or advice of your experiences with the greenscreen function would be greatly appreciated.

Here is a link to the facebook page. I don't know if it is a restricted page. I can view it so my guess is you will be able to as well.

http://www.facebook.com/#!/pages/Udy...10686668961974

Last edited by Bob Hart; August 24th, 2010 at 10:22 AM. Reason: errors
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Old August 24th, 2010, 12:05 PM   #11
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Hey Bob

I wouldn't do it for you, but looked at that FB page and Ayi Jihu is hot, so I will tell you.

...just kidding! :)

Anyways, here's what you do.

Use greenscreen paper (I usually go for Savage brand rolls, they come in different sizes up to 107" wide), works great and no wrinkles. Of course you take care of hanging/rolling down in such way that the paper is never wrinkled.

Best way to light it is with extremely soft fluos, either via diffusion (softboxes), or bounced off of silver umbrellas. 3m distance should be OK to light the greenscreen evenly with the soft light, and it is far enough so there's no green spill on the talent.

Do lock your camera. You don't want it to move in any way during the shoot, or you are looking at matchmoving in post - yet more time/$$$$ unnecessarily spent. If you need camera movement in SFX shot, fake it.

Having said that... do whatever you can with the real, practical effects. Only do impossible shots with greenscreen. SFX are not easy, usually are very time-consuming, and are very very hard to pull convincingly. I do an OK job with that usually, but really it costs too much time/money.

So. If you can shoot a practical train car, by all means do so.

Or, why not project a backplate footage on the screen (white, not green) and shoot it with live action. I tried SI2K with my Epson movie projector, and it worked fine without any rolling lines or other phase artifacts.

I was so irked by horrid SFX in Shutter Island, especially in the jeep ride scene, and the opening ocean scene...

Here's the good news: angles are more or less forgiving. Unless you are really off, you should be able to match with the backplate just fine.

But you must always match lighting on the actors vs backplate, or it will look very fake very fast.

Also you don't need a fancy keyer like Primatte etc. Just use After Effects' own Keylight, it is great. Note that in many cases you WILL have to process parts of the image in a couple separate passes of matte keying, not a single pass. That's normal.

Obviously make sure whatever crosses the greenscreen, is in no way colored similarly. You don't want to spend the night rotoscoping, do you?

On top of it, no wispy hair or anything fluffy. That's gonna be a bitch to pull a key on.

Some people think that you also should increase shutter speed when taping greenscreen, so to eliminate motion blur that tends to blend the object with the background and make pulling the key harder. I am not sure I agree with this. Increasing the shutter speed means you are losing temporal data that otherwise could be useful to pull an accurate key. Do experiment.

Yes, SiliconDVR has a live keyer. No, I never used it yet, because I tend to create backplates *after* I shoot my greenscreen footage. (This workflow is highly dependent on the particular project and you are absolutely correct, normally it should be the other way around. I am not normal. I just like having a card blanche and create the backgrounds according to the mood as I build up my sequences.)

Detailed enough? ...that would be a dollar, mister!

Last edited by Alex Raskin; August 24th, 2010 at 04:25 PM.
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Old August 24th, 2010, 09:17 PM   #12
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"I'll buy that for a dollar". AU$ or US$ ?


Thanks for your advice.

You know, you should take a vacation in Mumbai and Bangalore, get a set pass and drop in on them.

I could have gone across as camera-assistant, stand-by cameraman and data-wrangler. Hot weather does not worry me as I lived in hot climates for about 35 years.

However I am now a bit long in the tooth and a bit overweight for all-days on foot and lugging stuff around as would be needed, upon a failing knee-joint.

Realistically, I would be a liability in a tight schedule so I chose to bow out. Elliot Rice, Steve's son will be doing the job, younger, fitter with a great work attitude and personal ethos.

Family obligations were also a factor as was the idea of little things like typhoid, cholera, hepatitises and a few others you need to get stuck for. So I am staying at the home camp for this one.

Last edited by Bob Hart; August 24th, 2010 at 09:24 PM. Reason: error
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Old August 24th, 2010, 10:52 PM   #13
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I'm booked solid till the end of October.

And, I'm not a huge fan of hot climate. It seems to give me hot flashes. Wait, is that the climate?.. Just kiddin'
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