Recording for 5.1

[James Kuhn]

To all...I didn't participate in this discussion because I've always believed in the old saying, 'Tis better to keep your mouth shut and let others think you a fool, then open your mouth and remove all doubt." Heh, heh!

However, I have made a copy of the discussion and added it to my 'Recordist' info file. Thank you all very much.

Best regards,

J.

[Sareesh Sudhakaran]

Originally Posted by Rick Reineke

-- What do you mean by "final space"? If your referring to 'Room tone'.. that is different, and normally recorded in the EXACT same configuration, immediately after, or during a dialog scene. Outdoor and other 'ambient' sounds are often recorded in stereo. Clothing rustle, door closings and other point source sounds are usually recorded and used in mono, but 'could' be panned off center in post, however that is not without potential pitfalls. If you have a good 'stereo' mic, there's no reason why one cannot record in stereo. An M/S mic would be a good choice for those types of S/FX.
Two mono mics placed side by side would likely have phase abnormalities (or worse) when summed to mono..

By final space I mean what the audience listens to as the mixer's interpretation of the space shown by a scene shoot from many vantage points.

Which brings me back to my question: why is it that effects have to be recorded in stereo, but dialog needn't? What are the pitfalls of recording mono effects?

[Richard Crowley]

By final space I mean what the audience listens to as the mixer's interpretation of the space shown by a scene shoot from many vantage points.

That is a creation of the editing process. It may (but probably not) include ambient sound recorded in the actual place where the dialog was recorded. It probably DOES include ambient, "atmosphere", SFX, and Foley sounds. "Room tone" specifically is used in dialog editing to fill in gaps, etc.

In fact, when I am recording production sound, my preference would be that the space where the scene is shot (and the dialog recorded) is so QUIET that there IS NO other sound to record for background or atmosphere, etc. REMEMBER that the objective during shooting is to capture the dialog and ONLY the dialog as cleanly as possible. The fewer sounds there in that space the better.

Which brings me back to my question: why is it that effects have to be recorded in stereo

The real question is why do you think that effects have to be recorded in stereo? Consider that some really excellent sound mixes were created decades before stereo even existed. Effects DO NOT "have to be recorded in stereo". Does that answer your question?

but dialog needn't? [be recorded in stereo]

Not only "needn't" it be, but it SHOULD NOT be. What possible benefit do you think there is for recording dialog in stereo?

What are the pitfalls of recording mono effects?

Perhaps a little more work in creating the final mix.

Note that none of these work very well as generic questions. There are often exceptions on both sides. And very frequently you will need to make trade-off decisions based on your resources (equipment, personnel, schedule, experience, budget) vs. what the producer wants for the production.

[Paul R Johnson]

I guess the question is that when you are watching a movie, what you hear is rarely real. Certain things are required before you can edit sound. A clean track of dialogue - with as little background and as much artiste as possible, with no reverberation. You then have the choice of it sounding close - or, if you perhaps back off the low end, and add appropriate reverberation, you can make the person sound as if they are in any space, to suit the visuals. Reverberation is a subject in itself. Our brain uses reflections of the main sound to determine how far away it is, and what kind of building the subject is in.

So in my example, the sound of the priest at a distance would be the product of the editor working on the 'close' sound to make it sound distance. Then when we switch to closeup, the sound image changes too to reflect what a voice would sound like to match the new image.

If you go to a cathedral and record the ambients sounds there, then a stereo microphone technique such as X/Y or M/S would produce the nicest stereo image if we want realism. However, the differences between one mic, in mono, or these two mics is subtle, and rarely overt. If you use a spaced microphone technique - recording sounds in two or more separate tracks, then you get much better separation. You also get time delays. Let's say your two spaced mics are a long way apart - maybe 25m each way. Then there will be real sync problems if somebody near the left mic claps their hands. The other mic may pick this up as a separate event, when the sound arrives there. So to our ears this sounds wrong. You could sync them up, but then some sounds will be even further apart time wise. An X/Y or M/S recording would not have this problem.

For work in post, what you need are enough sources to let you create what you need. So maybe you want to add bells, where there weren't any - so you use sound effects. Mono bells, with some matching reverb to simulate what they really would have sounded will work fine.

It's not real, you are creating a sound stage - you are creating a 'space' where one doesn't exist. It's magic.

The person who told you that recording in mono is standard is probably quite correct. However, if you wish to record more than one thing, you need more channels. Note not specifically stereo. This is why pro cameras never label their audio channels as left and right, just A and B or 1 and 2. I can't say I ever record stereo with my bigger cameras, I have the on camera mic and maybe a radio receiver - but it isn't stereo.

You mentioned dialogue in stereo - this again should be two channels if you have two people and two microphones. The editors nightmare is distant sound. It's almost impossible to make a distant perspective sound close. No magic plug-in yet to remove reverberation and coloration.

[Brian P. Reynolds]

Its an interesting subject and upon thinking on it further of why FX were recorded in mono years ago, the answer might be that mono recorders were the standard for location sound guys, then came the stereo Nagras and DAT machines but were there great stereo mics and easily available for location at that time?
These days multi track FX recordings are easily possible (and easily handled in a work flow) so maybe its time we all think at possibly a better way of doing FX recording and not be locked in with preconceived paradigms of the past.
Almost of these hand held / portable digital recorders used today (no names mentioned) are way superior to any analogue tape machine used for location sound recording in the past.

[Gary Nattrass]

It's all about contrast and whilst location buzz tracks can be useful for filling in dialogue edits or adding filler to mask edits I tend to prefer creating all my stereo and surround backgrounds from scratch as it means I can control them and layer up ready for mixing or panning in the 5.1 sound field.

Dialogue is best recorded in mono as that is what it will end up as in the final mix but multi track recording to allow clean tracks is also OK, yes the dialogue may be panned or even placed thru processor to give space or depth but it all originates in mono.

Sound effects can be recorded in mono or stereo depending on what they are but I have never encountered any 5.1 recording in all my years as a dubbing mixer or editor.

Yes it may have its uses for sport and live event and the calrec soundfield mic is still used on such events but it is not a 5.1 mic just a multi channel mic that can produce several channels of sound in the same way that taking several shotgun or other mics and panning them around the 5.1 soundfield can produce.

The .1 or LFE is not designed to be active all the time anyway and is there to add "low frequency effects" as a when required, if you leave it on or feed sound to it all the time you are doing it wrong and just adding low frequencies when they may not be required.

All the 5.1 I have ever done has been created in post using specialist mixing hardware such as the AMS Neve DFC and the source material was pretty much all mono or stereo.

For the past 15 years my main mic for FX recording has been this sony prosumer mic into a mini disc or a marantz recorder:

Amazon.com: Sony ECM-MS957 Stereo Microphone with Rotating Mid Capsule: Sony Accessory: Electronics

 

Amazon.com: Sony ECM-MS957 Stereo Microphone with Rotating Mid Capsule: Sony Accessory: Electronics

[Steve House]

Originally Posted by Brian P. Reynolds

Its an interesting subject and upon thinking on it further of why FX were recorded in mono years ago, the answer might be that mono recorders were the standard for location sound guys, then came the stereo Nagras and DAT machines but were there great stereo mics and easily available for location at that time?
These days multi track FX recordings are easily possible (and easily handled in a work flow) so maybe its time we all think at possibly a better way of doing FX recording and not be locked in with preconceived paradigms of the past.
Almost of these hand held / portable digital recorders used today (no names mentioned) are way superior to any analogue tape machine used for location sound recording in the past.

Think about cutting multiple camera angles together to make the final. Let's say we do a wide shot of a bagpiper entering the frame screen left, crossing, and exiting screen right. We record the sound of his playing in stereo and the motion of the piper and the apparent motion of the sound match up, well and good. But halfway through the shot we cut to a MS of an assassin readying his rifle for a shot off camera and then to a CU of the piper seeing him out of the corner of his eye and reacting to it - what do we do with the sound in the sound field? The acoustic perspective in the original stereo recording no longer makes sense in the context of what is happening on-screen.

[Gary Nattrass]

If its bagpipes I would personally recommend that the director makes it a oscar winning silent movie like The Artist!

More seriously most surround desks also have a divergence control for surround so you can adjust the sound stage and in the case of the AMS Neve consoles I helped to design when I worked for them we have an A/B wide control that you can use to change the width of any stereo signal, you can also automate it so it is possible to adjust the soundstage dynamically to suit the shot.

As for sound stage you make it suit the flow of the pictures and it may be that locking a stereo sound stage suits the overall sequence more than trying to pan things around to create soundstage movement.

[Sareesh Sudhakaran]

Originally Posted by Richard Crowley

That is a creation of the editing process. It may (but probably not) include ambient sound recorded in the actual place where the dialog was recorded. It probably DOES include ambient, "atmosphere", SFX, and Foley sounds. "Room tone" specifically is used in dialog editing to fill in gaps, etc.

In fact, when I am recording production sound, my preference would be that the space where the scene is shot (and the dialog recorded) is so QUIET that there IS NO other sound to record for background or atmosphere, etc. REMEMBER that the objective during shooting is to capture the dialog and ONLY the dialog as cleanly as possible. The fewer sounds there in that space the better.


The real question is why do you think that effects have to be recorded in stereo? Consider that some really excellent sound mixes were created decades before stereo even existed. Effects DO NOT "have to be recorded in stereo". Does that answer your question?


Not only "needn't" it be, but it SHOULD NOT be. What possible benefit do you think there is for recording dialog in stereo?

Perhaps a little more work in creating the final mix.

Note that none of these work very well as generic questions. There are often exceptions on both sides. And very frequently you will need to make trade-off decisions based on your resources (equipment, personnel, schedule, experience, budget) vs. what the producer wants for the production.

Thanks Richard! Your reply has answered all my questions.

[Sareesh Sudhakaran]

Originally Posted by Paul R Johnson

... Then there will be real sync problems if somebody near the left mic claps their hands. The other mic may pick this up as a separate event, when the sound arrives there. So to our ears this sounds wrong. You could sync them up, but then some sounds will be even further apart time wise. An X/Y or M/S recording would not have this problem.

For work in post, what you need are enough sources to let you create what you need. So maybe you want to add bells, where there weren't any - so you use sound effects. Mono bells, with some matching reverb to simulate what they really would have sounded will work fine.

It's not real, you are creating a sound stage - you are creating a 'space' where one doesn't exist. It's magic.

Thanks Paul! That's exactly the kind of answer I was hoping for.

[Sareesh Sudhakaran]

Originally Posted by Gary Nattrass

It's all about contrast and whilst location buzz tracks can be useful for filling in dialogue edits or adding filler to mask edits I tend to prefer creating all my stereo and surround backgrounds from scratch as it means I can control them and layer up ready for mixing or panning in the 5.1 sound field.

Dialogue is best recorded in mono as that is what it will end up as in the final mix but multi track recording to allow clean tracks is also OK, yes the dialogue may be panned or even placed thru processor to give space or depth but it all originates in mono.

Sound effects can be recorded in mono or stereo depending on what they are but I have never encountered any 5.1 recording in all my years as a dubbing mixer or editor.

Yes it may have its uses for sport and live event and the calrec soundfield mic is still used on such events but it is not a 5.1 mic just a multi channel mic that can produce several channels of sound in the same way that taking several shotgun or other mics and panning them around the 5.1 soundfield can produce.

The .1 or LFE is not designed to be active all the time anyway and is there to add "low frequency effects" as a when required, if you leave it on or feed sound to it all the time you are doing it wrong and just adding low frequencies when they may not be required.

All the 5.1 I have ever done has been created in post using specialist mixing hardware such as the AMS Neve DFC and the source material was pretty much all mono or stereo.

For the past 15 years my main mic for FX recording has been this sony prosumer mic into a mini disc or a marantz recorder: Amazon.com: Sony ECM-MS957 Stereo Microphone with Rotating Mid Capsule: Sony Accessory: Electronics

Thanks Gary! I have a question: why do you use a stereo mic for FX? Is it just a safety thing (to get two channels), or is there a distinct advantage when mixing? I ask this because in the case of movies, when the visual space tends to change in a scene due to inter-cutting different points of view, wouldn't the stereo sound recorded from a single vantage point (the microphone) restrict you in post?

[Gary Nattrass]

Originally Posted by Sareesh Sudhakaran

Thanks Gary! I have a question: why do you use a stereo mic for FX? Is it just a safety thing (to get two channels), or is there a distinct advantage when mixing? I ask this because in the case of movies, when the visual space tends to change in a scene due to inter-cutting different points of view, wouldn't the stereo sound recorded from a single vantage point (the microphone) restrict you in post?

The mic I use for FX is a sony M/S mic so it gives good wide stereo ambience that I can adjust in width from 90 or 120 degrees but it also gives good mono performance if I need to make spot effects into mono,

it outputs in A/B format but my consoles also had the A/B wide controls so I could remove the S signal and just have the M or mono content if required.

If you are not familiar with M/S mics they are basically a mono cardioid mic forward facing with a figure of eight mounted in the same sound plane, you then matrix the signals together to get a stereo output adn if you adjust the level of the S signal you can change the width of recording.

The stereo matrix to get an AB output is as follows:

Mono= cardioid capsule

Left= M+S cardioid and fig of eight out of phase

Right= M-S cardioid and fig of eight in phase

So if I record everything FX wise in stereo and then remove the S content using my A/B wide control I am left with what the mono capsule picked up.

As the mic if very phase coherant it is also possible to sum the A/B stereo output to get a good mono signal.

[Sareesh Sudhakaran]

Thank you for the explanation. I'll do a bit more research into all this, now that I know what to look for. Appreciate it.

[Greg Miller]

I've always understood that:

L = (M + S)
R = (M - S)

In other words, the "front" or "positive pressure" side of the figure-eight is pointing to the left.

And, incidentally, the same technique is used for FM stereo broadcasting. You sum (L+R) / 2 and use that to modulate the main carrier (which is the only thing picked up on a mono receiver). Then you subtract (L-R) / 2 (which is equivalent to the "side" signal) and use that to modulate the 38kHz stereo subcarrier. The receiver converts what is essentially M/S back to L/R stereo.

Anyway, the formulas I have always seen appear to be the opposite sign (for the side mic) compared to the formula you give. Not a huge issue, except the wrong formulas would effectively exchange the left and right channels (and the violins really should be on the left). I'm curious where you found the info that you posted.

[Gary Nattrass]

You are probably right Greg as it's 25 years since I did my stereo sound training course so I think I got them the wrong way round and I have corrected my original post.

M/S mic's are very useful and having the ability to control M and S content of an A/B signal on the AMS Neve DFC consoles I have used has been very useful.

You can also get this free plug in which allows you to adjust the width of any stereo signal: http://www.brainworx-music.de/en/plugins/bx_solo