On Set Audio IR Capture & convoluted reverb post workflow ... best practices ?

[PatrickFaith]

I've decided to go with convoluted reverb using impulse responses from the real life sets for "Puddles of Light". For Puddles everything is shot in MOS, and I was having some problems mixing in post to get my sound design to "feel" right ... so I dropped standard reverb and went with convoluted reverb.

[ For people that are not hip to Impulse response and convoluted reverb, it is basically like a "bat" where you ping a room to get the rooms spatial response ... and that ping goes into a mathematical model ... so when you mic something in post you can have that recording sound like it was recorded in a specific place. For example you can individually record a mouse, a drop of water and a person singing, then have those sounds mixed in simulation of a church ... where it sounds like everything was recorded in a church even though the individual recordings were done in a room that was acoustically dead. ]

Anyway, I am going with the "Altiverb" convoluted reverb that has IR samples of almost all the places/scenes I have. Also I like how Altiverb has done multiple IR samples in a room, that way i can "place" the recordings into the different spots for a complete sound design. My current thought process is that my IR recordings are too crappy, but are good enough for altiverb to search it's database to find something close, and I will use the rooms that altiverb sampled as the final. (btw ... the Waves "360" bundle is really nice, but i'm not doing dolby 5.1 so was a bit overkill for my low budget needs)

There is a "clapper" IR importer and a full IR importer if you do that sine wave speaker setup. I was wondering if most people do the the "clapper" approach or do they go through all the trouble of doing the sign wave thing? If they do the sign wave (speaker/recorder setup) ... what is the simplest way of doing that for easy setup (i.e. a ipod with a simple integrated speaker would be my preference, but the speaker needs some "punch")?

I've searched all over the place, but I haven't found a good place for practical experience with FILM IR and film based workflow of convoluted reverb? Any references that I may have missed will be greatly appreciated. As always I greatly appreciate any and all comments, sometimes I'm a bit dense on this and it takes some time for me to learn.

 

[Marc Wielage]

I believe you mean convolution reverb. It can work, but you need an expert re-recording mixer with a lot of experience in order to get the best results out of it.

Ideally, convolution reverb is supposed to be used to capture impulses on location to better match ADR and SFX later on in post. This has been discussed at length on the Gearslutz Audio Forum's Post section.

My observation is, if the original footage was shot MOS (and I'd kind of wonder why, since you really need reference sound in order to do ADR and effects), there's no need to use convolution reverb. All you need is for the new sound to sound good, which does not always mean accurate or real. Sound communicates emotion and feeling, so it's more than just technical accuracy. It's also much more about skill and nuance than a plug-in per se, and only an experienced re-recording mixer and/or sound editor can achieve this, at least in my experience. In some cases, I've seen them achieve in five minutes what I can't do in 5 hours. EQ, noise level, microphone position, the acoustics of the room used for ADR, the natural of the material... all of these things are just as important as reverb per se.

I just read an interesting discussion in the post section about a major, $500M+ Hollywood film where the director specifically ordered the mixer not to use any reverb on some ADR'd lines, because he felt it cluttered up the intelligibilty. The audience did not care, the movie got great reviews, sounded really good, the studio loved it, and it made huge money. The reverb would have made zero difference either way.

 

[Phil Holland]

I've searched all over the place, but I haven't found a good place for practical experience with FILM IR and film based workflow of convoluted reverb?

As far as I know there isn't a "standard" real way, but just different folks employing different techniques.

I use the clapper method and sample those (I mostly sample in quiet spaces). I tend to use flat omni mics for sampling and still will crack out SIR1's VST, but there are other tools now. If you are trying to capture 5.1 worth of IR then it's a more elaborate process. I tend not to go "that crazy" for feature audio use, because I'm going to play with and tamper things anyways. I'd rather capture directional and different variations from a single space really.

 

[PatrickFaith]

Hey guys, thanks ...

I believe you mean convolution reverb. It can work, but you need an expert re-recording mixer with a lot of experience in order to get the best results out of it.
Ideally, convolution reverb is supposed to be used to capture impulses on location to better match ADR and SFX later on in post. This has been discussed at length on the Gearslutz Audio Forum's Post section.
My observation is, if the original footage was shot MOS (and I'd kind of wonder why, since you really need reference sound in order to do ADR and effects), there's no need to use convolution reverb. All you need is for the new sound to sound good, which does not always mean accurate or real. Sound communicates emotion and feeling, so it's more than just technical accuracy. It's also much more about skill and nuance than a plug-in per se, and only an experienced re-recording mixer and/or sound editor can achieve this, at least in my experience. In some cases, I've seen them achieve in five minutes what I can't do in 5 hours. EQ, noise level, microphone position, the acoustics of the room used for ADR, the natural of the material... all of these things are just as important as reverb per se.

I just read an interesting discussion in the post section about a major, $500M+ Hollywood film where the director specifically ordered the mixer not to use any reverb on some ADR'd lines, because he felt it cluttered up the intelligibilty. The audience did not care, the movie got great reviews, sounded really good, the studio loved it, and it made huge money. The reverb would have made zero difference either way.

The "reverb" word I think has added a lot of confusion to the discussion as you have noted. This technology is about creating a 3d sound scape that matches the story. I think a lot of people initially thought about this type of "reverb" as replacing spring/plate algorithm based reverb, which it really doesn't. Since what this actually does is digitally reconstructing a space from a time domain, allowing creative story telling. Thus I view this as a tool for cinematography (gives spatial tools story telling). If a director wants a story event without spatial clues, then that should support the story. What I'm specifically looking for are types of sound scapes that are inspired by Andrei Tarkovsky "the mirror" and some other spaces from "stalker" (i.e. the scene at the end where the house is placed inside that ancient church ... but I want that as 3D as a time domain rather then the event/visual domain).

As far as I know there isn't a "standard" real way, but just different folks employing different techniques.

I use the clapper method and sample those (I mostly sample in quiet spaces). I tend to use flat omni mics for sampling and still will crack out SIR1's VST, but there are other tools now. If you are trying to capture 5.1 worth of IR then it's a more elaborate process. I tend not to go "that crazy" for feature audio use, because I'm going to play with and tamper things anyways. I'd rather capture directional and different variations from a single space really.

This looks like some real cool software, there is a lot of great open source software out there now. My first time seeing this type of stuff work was on submarine IR sensor, where the reflected signal actually went to a 3D monitor (you visually saw the effect of the ping by looking down into this box, which had glasses that had mirrors to two different monitors ... and you saw the ocean floor in actual 3d). This stuff now is common for Bass fishermen, where they can tell an entire story by looking down at their monitor. From a film perspective, this is all kind of new, and is a big opportunity for us digital cinema types to tell stories in more compelling ways at much lower cost.

 

[Marc Wielage]

What I'm specifically looking for are types of sound scapes that are inspired by Andrei Tarkovsky "the mirror" and some other spaces from "stalker" (i.e. the scene at the end where the house is placed inside that ancient church ... but I want that as 3D as a time domain rather then the event/visual domain).

I think you're obsessing over something technical when the reality is that it's an artificial creative choice. I strongly recommend that you hire a professional re-recording mixer and/or visit a sound stage -- even a small facility -- to get an idea about how reverb is used. I think you're clinging to a belief that the reverb alone makes the effect real, when in reality, it's many, many other factors that contribute to that kind of sound. For all we know, it could be multiple layers of effects, tons of different kinds of reverb, different microphones, different locations, real and synthesized effects.

The link I gave you to Gearslutz can open up a whole new world on how working professionals do this kind of work every day. To me, it's every bit as difficult to do sound editing and mixing as it is to do cinematography, acting, or writing. The choice of reverb is just a single tool. As a buddy of mine says: "it's the archer... not the arrows."

 

[PatrickFaith]

I think you're obsessing over something technical when the reality is that it's an artificial creative choice. I strongly recommend that you hire a professional re-recording mixer and/or visit a sound stage -- even a small facility -- to get an idea about how reverb is used. I think you're clinging to a belief that the reverb alone makes the effect real, when in reality, it's many, many other factors that contribute to that kind of sound. For all we know, it could be multiple layers of effects, tons of different kinds of reverb, different microphones, different locations, real and synthesized effects.

The link I gave you to Gearslutz can open up a whole new world on how working professionals do this kind of work every day. To me, it's every bit as difficult to do sound editing and mixing as it is to do cinematography, acting, or writing. The choice of reverb is just a single tool. As a buddy of mine says: "it's the archer... not the arrows."

Well I am firmly in the Michel Chion camp ... so when I want to do something it is based on film theory not a technical detail. I have been reading gearslutz for a long time, it is a great site, but it does focus on the gear rather then the story(I don't think I have ever seen a discussion on Chion's film theory in gearslutz - Chion being in my opinion one of the greatest theorist on audio cinema film theory). BTW, my impulse response transforms have been embedded in major systems for decades, so it's natural for me to align IR transforms (and the corresponding reverse transforms) to the audio-vision theory of Michel.

A 1st reel test screening of my film is coming up(first 11 minutes of the movie), and that's where I know if I totally missed my mark and actually am obsessing on something which is totally invalid. Surprisingly though, I was worried of my heavy use of an acousmetre in my film ( http://filmsound.org/chion/metre.htm ) , so did shots with and without the acousmetre's face showing ... and the tests showed that the audience really hated it when the acousmetre's face was shown to early - which kind of surprised me how much the audience "got it".