multichannel audio for video ?

[Gints Klimanis]

I'm interested in recording the audio separately on a multi-channel PC-based recorder. Does anyone do Firewire in + multi-channel audio record ? Basically, I want to record video in sync with several tracks of audio to a PC. I suppose I can record the video + stereo audio track to miniDV, then manually sync the audio. However, this is more work. Any suggestions? Four audio channels are good for now, but I expect to expand to six or so.

[Edward Troxel]

The DV spec allows 4 audio channels (usually designated stereo 1 and stereo 2). Some MiniDV cameras (such as the XL-1) can record on all 4 while others can't. If your camera can record on all 4, you also need a capture program that can capture all 4. Some can and some can't. I use Scenalyzer Live to capture 4 channel tapes. It will capture Video + Stereo 1 into an AVI file while simultaneously capturing Stereo 2 into a separate WAV file.

[Gints Klimanis]

Thanks ! That's what I'm looking for !

[Peter Moore]

Gints,
Does your camera suppoert the 4 channels? Usually 4 channel support is also limited to 32 KHz, which is not that great.

I think your best bet is to use a clapboard to sync them later. I don't think you're going to be able to simultaneously capture DV footage over firewire and audio from a different firewire source and keep it in sync.

If you don't have a clapboard, just hit two rocks together or something, or clap your hands. You get the idea.

[Gints Klimanis]

Peter,

I have a Sony vx-2000 that doesn't support four channel audio record. Thanks for the "clap" suggestion.
My main issuse is that I'm start and stop the camera about 20 times over 1.5 hrs. That's a lot of sync work.

[Mike Rehmus]

Ah. Don't stop the camera if it's the sound recorder.

[Peter Moore]

Gints,

I feel your pain. Unfortunately it sounds like this is your only solution. Well actually there's time coding, but that's not going to be viable for you most likely.

In pro movie productions with surround sound, either time coding or clapboards are the only way to sync audio with video. Before each camera take, you say the scene #, take #, and strike the clapboard. Then when you look at the footage, you see the scene/take # on the board, and you find the corresponding audio from your multitrack, and you line up the clap sound (make sure it's close to the microphone to avoid speed of sound issues), with the video of the clap. That's how it's done, and the fact that it's still done that way (in the absence if timecode) is a testament to how good it works.

Or, don't stop he camera as often, if you can avoid that.

[Gints Klimanis]

Peter,

Thanks. I think I'll learn to structure
my session around reducing the # of times I stop the camera. Basically,
my situation is that there are about 20 bouts of martial arts sparring that take place over 1.25 hours. We start the camera, tape the fight, tape the post fight interviews while the players are still huffing, then stop the camera while the next set of players sets up. That way, the post-session video review is full of only the fun.

[Yi Fong Yu]

heard premiere pro is supposed to encode 5.1.

are there such a thing as 5.1 microphone? omnidirection.

[Rob Lohman]

Keep in mind that those are 4 MONO channels. So you have two
STEREO channels available. Hard to capture it seems though.

An audio friend of mine simply rents a multichannel disk recorder
which can record 32 stereo tracks realtime [you can get smaller
ones I think]. Depending on what you rent you hook it up to your
PC through USB or firewire and you can then connect to the device's
internal FTP server and simply download the files.

I don't think such devices are terribly expensive to rent...

[Mike Rehmus]

Keep in mind that 5.1 is a construct in the Sound Design Suite, not a recording of naturally occuring sound and its placement. If you go to a Sound Design Suite, you will find that the capture portion of sound is not accomplished with a 5.1 microphone but with one or two microphones per instrument/singer. Sound Effects (Foley) are recorded much later if they are needed.

Then, after the sound is recorded from all participating sources, the 5.1 sound system is set up and the mix-down to 5.1 starts. And that is just for the surround fields. The vocal and musical parts are normally mixed to a Stereo field at most.

In one of the latest studios to be built in San Francisco, the center-channel speaker moves in to cover the center of the window between the control room and the sound booth and then only when they are ready to build the 5.1 sound environment. It is not used during sound capture.

Very little Hollywood sound is even recorded in Stereo. Stereo is normally used (makes it to the final cut) only when sounds are obviously way off-screen. Speach and even a lot of the music is monophonic. Sound effects are mostly what you hear left and right screen or even in surround. Notice that the center channel speaker is almost always a little bit better and larger than the 4 corners? That's why.

Note that this has little to do with the importance of the surround sound cues with the aural richness of the surround field.

[Peter Moore]

"Basically, my situation is that there are about 20 bouts of martial arts sparring that take place over 1.25 hours. We start the camera, tape the fight, tape the post fight interviews while the players are still huffing, then stop the camera while the next set of players sets up. That way, the post-session video review is full of only the fun."

If the whole thing takes place over 1.25 hours, why not just use 2 tapes and record the whole thing? Just clap in front of the camera and mics in the very beginning and that's it. Then it's all EASILY synced once and only once. That'll save you far more work than starting and stopping the camera to get each take.

[Yi Fong Yu]

mike,

i'm not one of them but what about the jungle documentarist who is adament about 5.1/6.1 surround sound and who refuses to do post on it because it 'ruins' the nonfiction narrative? they are someone i see that definitely needs a 5.1 capture for the surround to record crickets and birds chirpping in rear speakers.

now onto 5.1 encoding, are the softwares that do 5.1 encoding expensive? do they let you do absolute positioning? i remember reading about somewhere. i'd like to move me dialogue OFF of the center channel and let it follow the actor even when they walk offscreen =)

[Mike Rehmus]

But how do you keep the right rear chirp out of the left front microphone. 5.1/ is a totally artificial technology brought to you by the folks who flopped with Quad sound way back when. If they had their way, we'd have something like 360.1 the next time around. That way they could sell more hardware and software.

Nice and I like it a lot but 5.1 is totally artificial. As are most of the 'stereo' CD's one buys.

Maybe an array of the $3500 AT shotguns could be made into a 4 point array. But they'd miss a lot of sound 45 degrees off axis. And the subwolfer microphone, that's going to be a hard one.

I'm joking. From the limited amount I know about affordable sound capture, it just is not practical. Today.

5.1 software is getting to a reasonable price-point, depending on what you need. Remember that if you want the voice to trail off to the left as the actor walks left, you have to record that audio as a separate track. All the other audio you want to move around the sound stage have to be individually recorded to. Or you will be moving the ambiance right along with the actor.

If you are serious about 5.1, I am not the guy to guide you. Other than to recommend you start looking it up on the Internet and subscribing to some of the 5.1 and other pro sound newsgroups and web sites.