Recording Surround on a mic?

R

ryan06

Member
I'm still not entirely clear on how sound is recorded professionally. How many mics are used on set? I assume 6 different tracks are recorded, and then joined later in post into DD or DTS.

Does any one know how this works, and/or has anyone ever gone this far with sound? For those who use Final Cut Studio 2, Compressor and Soundtrack Pro can mix surround into a single 5.1 audio file, however, you must have 6 different tracks for it to mix together. Hence my question of how this recording can be accomplished.

Thanks!
 
It's a little more complicated....

On-set, the dialog is the main focus. Capture that, an occasional a door slam or two, and that's the best case. Sometimes 1 boom mic is all that's used, sometimes 16 channels with wireless mics, plant mics, several boom mics, ect... but all they want is the dialog which is going to be in the center channel~99% of the time.

Later sound effects, background, Foley, ect... are recorded separately so they can be controlled in the mix.

You may find 5.0 surround mics, and those have been used in crowd scenes before for background tracks, but more commonly the surround tracks are made of layer and layers of mono and stereo recordings that have been panned around the audience.

The top post here is very helpful for more detail.... (I just gave an extreme summary)
http://www.dvxuser.com/V6/showthread.php?t=174562

A 5.1 mix is very challenging, and should rarely be attempted by an unexpereinced mixer. You can do a lot with 2 speakers.
 
You're confusing recording with mastering. On set, you usually have as many mics as there are sources (could be zero or a hundred). You may have each of them record to a discrete channel or you may be mixing them down to fewer channels. These tracks are sent with the video or logged and stored on a different device. Then sound mixers and engineers use these tracks with additional tracks like ADR, foley, and score and put all of these sounds in the 'space' allowed by 5.1 sound (or some other configuration).
You might find some cool reading by searching for "binaural recording".
 
5.1 Surround Sound is six channels/speakers - front left, center, front right, rear left, rear right and low frequency (the .1 of 5.1).

Most of the time the dialog is in the center channel. The bulk of the rest of the audio is in the front LR and the sub (low frequency) speakers. The rear speakers are used primarily as a "special effect". Occasionally the ambiences and some of the score is put in the rear speakers as well. The full use of the surround capabilities is much more prevalent in action films.

Although there are "surround" mics out there most surround effects are usually constructed in audio post.

Audio post production is a very deep subject - dialog editing, ADR/looping, Foley, sound effects, music editing/spotting (recording the score is a different department) and re-recording (the mix). It is not at all unusual for "Hollywood" films to have hundreds of audio tracks.
 
To sum it up: Surround for film is totally artificial, it is not recorded in situ with microphone arrays. The only exeption might be crowd scenes. One big reason is that also the picture is spliced up from small clips, if you have ever seen a movie being shot you can understand why there is no possiblity of recording back channels "live": the area behind the camera is filled with lights & crew and curious bystanders, also the noise form camera & camera crew make the "ideal" positioning of the surround mic above the camera impossible. Thus the question about mic tehnicue for film surround sound is largely irrelevant.

For classical orchestral sound Decca tree variations are usually used, see DPA pages for those. DPA also makes a compact 5-mic array for live surround recording. Google also Soundfield and tetramic.
 
As a (rare) example of recording surround on location, Wayne Pashley used a Soundfield ST350 to record ambience tracks for Baz Luhrman's "Australia." Interesting article here http://www.soundfield.com/news/news_australia.php. And you can see it in action in the sound recording episode of Lurhman's production podcasts on iTunes. But take note, these were ambience tracks, not music or dialog tracks, and were recorded completely separately from shooting the dramatic action, then added to the picture in post as environmental sound beds.
 
You can do surround with just 3 mics - Cardioid pointing forwards, cardioid pointing backwards and a side facing fig.8 - this will matrix down to 5.1 and you can get a plug-in for teh DAW to do it.

Remember the .1 bit is the LFE channel and *not* bass frequencies (though most domestic set-ups use the sub for both bass and LFE.
 
As most have said surround in films is created not recorded. It's rare even in FX to record surround. Part of the reason is perspective and part is control. If you record surround your perspective is pretty fixed, you can flop channels but to do much more gets complicated. That is not always a problem but it makes people leery. Second is control, it's harder to "layer up" surround tracks and a "Hollywood" style sound track is all about layering up and creating a dense sound scape. And lastly to be of much use you need to have surround edit rooms and they need to be calibrated daily. I'm sure it will evolve but there are very few surround edit rooms. Production sound (dialog) is often edited with headphones and many times edit rooms are shared, so at least one editor is on headphones. So in many cases you don't get a chance to hear the surround till your on a mix stage.
Cheers
SK

Scott Koue
www.scottkouesound.com
http://imdb.com/name/nm0468138/
 
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