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Author Topic: Convert Binaural recording to Stereo?  (Read 17183 times)

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Offline Gutbucket

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Re: Convert Binaural recording to Stereo?
« Reply #15 on: January 25, 2011, 10:25:23 AM »
binaural windjammer-

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Offline noam

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Re: Convert Binaural recording to Stereo?
« Reply #16 on: August 08, 2015, 08:39:46 PM »
Yes,  binaural is meant for headphone playback but I don't know how you can "convert" them.  You get phase cancellation when played back with speakers, but that is not something one can really fix- It is the nature of binaural recording.

I have been listening to binaural recordings made with a pair of omnies usually in croakies for 15 years, and has been making them myself for 11.  I have always played them on speakers in regular stereo position. If there is a problem in this premise I had to assume that it’s negligible and that I have to live with it. (Please don’t tell me to use headphones.)

Until a friend (a regular on this board) who has been sending me (by now) hundreds of these live binaural recordings started processing them with the “stereo expander” that comes with Wavelab software (it’s a plug-in if I understand correctly).

The improvement is so dramatic it is almost painful, because it makes it feel as though I’ve been listening to shit in comparison for 15 years. After comparing about 10 works recorded live, binaurally, to their stereo-expander-processed version I am certain that the stereo expander transforms the binaural recordings into stereo ones. In all works the improvement is dramatic. In all works the soundstage become deeper, bigger, with localization of instruments much more precise and specific. In a  Mozart sonata for violin and piano, in addition to the above it also places the violin to the left and the piano to the right very neatly. The bigger soundstage  (i.e., the hall sounds bigger, deeper, more real) means that the piano sounds smoother. Everything is more detailed but in addition individual piano notes scintillate in the bigger space. In all recordings everything falls into place with the expander. In a Haydn cello concerto the expander creates a stunning deep soundstage where the cello is very clearly up front. The sound stage is very clearly layered and the realism of the presence of the cello is stunning.

In other words it recreates exactly what you hear from your seat. Here is the proof that all you need to recreate what you hear live is a pair of omnis, contrary to what many sound engineers say.

But the problem is that I thought all my software editing needs are covered. I now need to go back and process at least my most important recordings with this plug in.

The question is how do I get it? I don’t mind the $499 a Steinberg WaveLab 8.5 costs, but I don’t have the energy and time to learn a completely new editing software. Do I need the Steinberg WaveLab 8.5 or is the Wavelab Elements software enough? At any rate, I read that installing a Steinberg software is a nightmare (see below) - is there a way to get just the stereo expander?

If I buy a laptop from Sweetwater loaded with iZotope and/or Wavelab software, do they provide real over the phone software support and guidance?

Thanks

Noam

(from an amazon review: “Steinberg products might be useful, if only you could install and use them without screaming at the top of your lungs and pulling your hair out at the absolutely mind-blowing set of hurdles and hoops they make you jump over into and through before the software will function.... I have a number of their products and swear each time I'm reminded of this ridiculous and agonizing process of registration, and authorization, even to the point that you are forced to install additional party software to facilitate the process, each step a nightmare of potential wrong codes and clicks for hours and sometimes days.... Never again!”














Offline rocksuitcase

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Re: Convert Binaural recording to Stereo?
« Reply #17 on: August 09, 2015, 11:59:58 AM »
having been part of a binaural crew in the mid eighties, this interests me a lot. OTH, I believe Moke when he says post processing the binaural 2 channel can remove some of the imaging qualities which makes binaural unique. i do tend to not like the overall sound of our binaural recordings as compared to our Beyer Hypercards same location. however, there are some aspects of those recordings which are so damn realistic. I do use wavelab, but not a newer version.
Does anyone have thoughts on this plug in- Gutbucket, Moke, 12milluz, Bueller?
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Offline Tom McCreadie

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Re: Convert Binaural recording to Stereo?
« Reply #18 on: August 10, 2015, 07:13:18 AM »
To get a better handle on the thinking behind what is needed to make binaural recordings (or even baffled omnis such as Jecklin disk) sound more satisfying on conventional 2-speaker playback, I suggest you check out some of the JAES papers in the  '80's and  90's of Michael Gerzon and David Griesinger.

For instance, the following and references therein:

1. "Equalization and Spatial Equalization of Dummy-Head Recordings for Loudspeaker Reproduction", D. Griesinger, J. Audio Eng. Soc., vol 37(1/2),1989, pp. 20-29.

2. "Applications of Blumlein Shuffling to Stereo Microphone Techniques",   M.A. Gerzon, J. Audio Eng. Soc, vol 42(8), 1994, pp. 435-453.

The papers by Gerzon are always thorough and lucid. And my understanding is that he had some involvement in the original development by Waves of their S1 shuffler/imaging  plug-ins...which may well form the nucleus of the other manufacturer's plug-ins mentioned in this thread?

Offline rocksuitcase

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Re: Convert Binaural recording to Stereo?
« Reply #19 on: August 10, 2015, 10:04:44 AM »
Gerzon is a great reference. we read his stuff and used his knowledge widely in our psychoacoustic research on human processing At SU in the early 1980's. Also, early writings from Hafler, Bose (especially), and Dolby have some good insights into playback of different stereo sources.
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Offline Gutbucket

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Re: Convert Binaural recording to Stereo?
« Reply #20 on: August 10, 2015, 11:18:19 AM »
I have been listening to binaural recordings made with a pair of omnies usually in croakies for 15 years, and has been making them myself for 11.  I have always played them on speakers in regular stereo position. If there is a problem in this premise I had to assume that it’s negligible and that I have to live with it. (Please don’t tell me to use headphones.)

^^^
That's not actually binaural, but rather head-baffled omnis*.  Binaural requires the microphones to be placed within the ear, at the opening of the ear-canal at a minimum, which is the easiest way to do it and what I'd recommend for anyone wanting to try it.  That is necessary to achieve the complex 3-dimensional spatial high frequency response imparted by the shape of the outer ear, which is a core aspect of 'binaural' recording and playback.

David Griesinger argues that binaural is not actually truly accurate unless microphone probes are placed deep within the ear canal.  However doing that requires special equipment and equalization and Griesinger goal is the careful study, categorization and quantization of acoustic phenomena, rather than music recording with the simpler goal of listener enjoyment.  For most, binaural-recording means either placing miniature omnis at the opening of one's own ear canals, or recording with a relatively anatomically accurate dummy head with head and ear shapes based on those of humans.

*(Around TS, you'll also commonly find the head-baffled omni technique - typically mounted with 'croakies' -  refered to as "HRTF", which like binaural isn't a strictly accurate usage, as the Head-Related-Transfer-Function [shorthand = HRTF] includes the response imparted by the fleshy portion of the ears as well as the head between them)


I don't know what plugin your friend is using, so I can't be certain about what the stereo expander is doing, but it is likely making a simple Mid/Side adjustment.  The Left/Right signals are first converted to Mid/Side signals, the Mid/Side ratio is then adjusted, and the signals converted back to Left/Right stereo again.  The basic technique is to increase the Side signal with respect to the Mid signal, which increases the "width" of the resulting recording.  You can do that without a plugin by setting up some signal routing in your DAW, or with an analog mixer, but there are many plugins which make it very simple. Some are free and work just as well as others that are not.  It's is a simple thing for a plugin to do.

A more advanced technique is to equalize the Mid and Side signals differently when doing the above, which changes the ratio by frequency instead of by the same amount across all frequencies.  That can, for example, widen the bass frequencies more than the higher frequencies, which is appropriate for adapting head-baffled omnis for loudspeaker playback.  That can be done by signal routing combined with an equalizer, but again, plugins do it easily.  Some stereo width adjustment plugins will allow independent adjustment across several frequency bands.  Alternately many EQ plugins now offer a Mid/Side mode.  That mode does an L/R>M/S conversion before the EQ and M/S>L/R conversion afterwards for you.  Once channel of the EQ controls the Mid signal and the other the Side signal.

Quote
In other words it recreates exactly what you hear from your seat. Here is the proof that all you need to recreate what you hear live is a pair of omnis, contrary to what many sound engineers say.

Nah, it's just a somewhat better, more-convincing illusion!  It does not recreate what you actually experience live- your brain is doing most of that for you, in combination with your willing suspension of disbelief, and a slightly more convincing playback experience.  To actually get as close as possible, you'd need to record using Griesinger's in-ear-probes, equalise to accommodate for the ear-canal resonance, and playback over a headphone system calibrated to accurately match the HRTF response of your head and ears.  At that point the signal at the each ear-drum would be as accurately reproduced as possible, but that still would not completely recreate what is experienced at the live event.  The low frequency sensation would not be the same as it would be lacking tactile "body feel" and bone conduction present at the live event.

To recreate that "signal at each eardrums" with the same degree of accuracy using loudspeakers is far, far more complicated and error prone.  Regular stereo doesn't even come close.  Fortunately we're gullible, and a not very technically accurate reproduction can be good enough for our brains to trick us into thinking it sounds exactly like it did live, you from your seat. 
« Last Edit: August 10, 2015, 12:37:08 PM by Gutbucket »
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Offline Gutbucket

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Re: Convert Binaural recording to Stereo?
« Reply #21 on: August 10, 2015, 12:09:35 PM »
To get a better handle on the thinking behind what is needed to make binaural recordings (or even baffled omnis such as Jecklin disk) sound more satisfying on conventional 2-speaker playback, I suggest you check out some of the JAES papers in the  '80's and  90's of Michael Gerzon and David Griesinger.

For instance, the following and references therein:

1. "Equalization and Spatial Equalization of Dummy-Head Recordings for Loudspeaker Reproduction", D. Griesinger, J. Audio Eng. Soc., vol 37(1/2),1989, pp. 20-29.

2. "Applications of Blumlein Shuffling to Stereo Microphone Techniques",   M.A. Gerzon, J. Audio Eng. Soc, vol 42(8), 1994, pp. 435-453.

The papers by Gerzon are always thorough and lucid. And my understanding is that he had some involvement in the original development by Waves of their S1 shuffler/imaging  plug-ins...which may well form the nucleus of the other manufacturer's plug-ins mentioned in this thread?

It's been a while since I read those, but I'm familiar with them. 

IIRC, the Griesinger paper addresses the last part of the "as accurate as we can get" binaural reproduction chain I described briefly above.  That's the part about matching the response of the playback headphones to the listener, and applies to not just binaural recordings, but anything heard over headphones.  It basically requires equalizing to adjust for both the response of the headphones and the HRTF of the listener, to achieve a flat response for a sound source located directly in front of the listener.  This can achieve the 'out of head' listening experience over headphones, and is a requirement for truly accurate binaural reproduction. [Edit- again, the only ones who are that interested in truly accurate binaural reproduction are specialist investigators like David Griesinger, for ordinary binaural listening enjoyment, the good-enough threshold is much lower]

"Blumlein Shuffling" is somewhat related to the Mid/Side ratio adjustment.  It is a technique for converting the phase-difference information which results from a spaced microphone technique into the level-difference information which results from a coincident microphone technique.  That was important for Blumlein in his early investigation of stereo (which he referred to as "Binaural reproduction", although his use of that phrase actually became what we now would call "loudspeaker stereo") in the late 1920's/early 1930's, because at the time he only had available to him omni-directional microphones.  He used them with a baffle between them, then converted the phase differences to level differences for reproduction over two speakers arranged 90 degrees apart.  When figure-8 microphones became available to him, he eliminated the shuffler circuit and invented the coincident figure-8 microphone technique which bears his name.  As a coincident array it produces only level difference information, setup in either a L/R or M/S arrangement.

Michael Gerzon took the original Blumlein concepts and expanded upon them.  Ambisonics is basically Gerzon's extension of Blumlein two channel Mid/Side theory to 3-dimensional spherical harmonics.  In addition to Ambisonics, Gerzon was a recordist himself and explored plenty of 2-channel stereo techniques and manipulations based on the original Blumlein stuff and his Ambisonic mathematical work.  His paper linked above has to do with that.  Many Some of Gerzon's papers are available for download from a website setup in his honor, which is named something like Gerzon photos or something like that (I'll check on that and post a link to the site here). The site is http://www.michaelgerzonphotos.org.uk/ put togther by Stephen Thornton. Although many of his papers and articles are not hosted there (the cited one's are), Appendix 1 page lists all of his papers, many of which can be found on-line with a subsequent web-search.

Jorg Jecklin experimented with "Blumlein shuffling" and at one point sold a hardware shuffler for use with his Jecklin-disk technique (J-disc is basically a reinvention of Blumlein's original omni technique), but as far as I'm aware it's rarely if ever used, even by Jecklin himself in later years.

Edited to include the link to Stephen Thornton's Gerzon site.
« Last Edit: August 10, 2015, 04:28:02 PM by Gutbucket »
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Offline WiFiJeff

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Re: Convert Binaural recording to Stereo?
« Reply #22 on: August 10, 2015, 10:16:15 PM »
To recreate that "signal at each eardrums" with the same degree of accuracy using loudspeakers is far, far more complicated and error prone.  Regular stereo doesn't even come close.  Fortunately we're gullible, and a not very technically accurate reproduction can be good enough for our brains to trick us into thinking it sounds exactly like it did live, you from your seat.

I don't think Noam is asking about theoretical constructs.

My hopelessly obsolete land-line phone is severely restricted in frequency response and dynamics, more so than most mp3 files or anything recorded by anyone on TS in the past 20 years.  Yet when I answer it, I am more apt to comment "That's Herman, he says he's going to be late" than "my brain is tricking me into hearing what sounds like Herman, though his actual voice has much more frequency bandwidth, he says he is stuck in traffic, or may he is stuck in taffy, not sure."  The psychoacoustical explanation for this generally comes after the recognition of its empirical truth, which we've know since Alexander Graham Bell.

I have done quasi-binaural or quasi-HRTF recording, also Jecklin disc recording, for more than 15 years.  For classical music of all sorts it plays back (when done right) on headphones in a manner recognizably close to being there, and more realistic than most commercial classical recordings heard on headphones, though the commercial recordings can provide more instrumental detail via spotting.  Commercial recordings are more transparent but also generally more tiring to listen to on headphones, I find, the sound space is usually detectably more artificial.  YMMV, and clearly the world is happy enough even with mp3 crap to drive classical CD sales to all-time lows.  (I live in a NYC apartment, a large hi-end system disturbing the neighbors with realistic volume levels is not in my future, but I do have lots of headphones, from Sennheiser 650s to Stax electrostatics to HiFiMan magneto-planar, with Ultrasones for editing etc, etc, and can testify also that some things sound better on one headphone set and others on other sets, even when recorded with the same mics in the same space on the same piano, different pianists have different sounds).

Noam listens on speakers, and has discovered that a simple procedure makes quasi-binaural recordings sound way better for him (on his system, in his space - part of the problem with speaker reproduction is the variability of equipment placement and room acoustics).  The Wavelab VST stereoexpander is a one parameter plug-in, so it is perhaps only a modest change that is having for him a really big impact.  I think two interesting questions are 1) has anyone else tried this, or noticed such an effect; and 2) are more flexible expanders, like the one in Ozone 6, able to do even better?  This is an empirical question, requiring listening, ideally by someone with a good hi-end system.  Anyone?

Jeff

Offline Gutbucket

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Re: Convert Binaural recording to Stereo?
« Reply #23 on: August 11, 2015, 11:50:01 AM »
I hear that, and agree completely.

Just wanted to define some of the underlying constructs behind the empirical listening experience.  I find there is a critical threshold of believability, and once across that threshold we can let go and fully recreate the experience even with limited data.  That's when I feel as if I was there once again, transported back to that time and space.  I'm quite sensitive to it, and it's pretty much the entire reason I record.  Yet there is nearly always better still, room to improve.  The interesting psychological phenomena to me is that crossing that threshold is entirely enough, complete in itself, really all that matters.. and when I find there is still better yet it is almost surprising in a way.  Welcome, better and even more real.  The bar gets raised.  But crossing the threshold is the critical part, the rest is gravy.

There are numerous elements which contribute to achieving that minimum threshold level, and an appropriately immersive ambient soundstage width is an important one for me.  Headphones can often achieve that more easily than stereo speakers.  Headphone listening is more akin to surround playback over speakers to me than stereo speaker playback.

Here's an observation-  Making quasi-binarual / HRTF recordings more stereo loudspeaker compatible via "stereo-expansion" is basically the inverse of making loud-speaker stereo more compatible with headphone listening though the use of "cross-feed filters".  Cross-feed filtering is in essence a "stereo-contractor" doing the opposite of a "stereo-expander".

I use a somewhat different method for recording which achieves a wide soundstage and also provides control over the distribution within it after the recording has been made.  It allows me accomodate both headphones and stereo speaker playback more easily with an appropriate width for each. I gravitated in that direction years ago partly because I could not achieve the same realistic width for loudspeaker playback without doing some stereo-expanding (and partly because I prefer not wearing the microphones on my head).  I got there empirically and then realized why it works based on the applicable theoretical constructs.

I'll sometimes use some stereo-expansion if it helps.  Typically I'm doing so using the advanced panning mode in Samplitude which changes the balance control on a stereo track from a Left>Center>Right control to a mono>stereo>superstereo control.  It's nothing more than a M/S ratio width control.  When centered, the M/S ratio is 1:1; with the knob turned leftwards towards the mono side, the Mid component increases verses the Side component; turned right to the "super-stereo" side the Side component exceeds the Mid component.  Turned all the way right it's 100% Side, with each channel is 180 degrees out of polarity with the other and it sounds phasy and inverted, turned all the way left its fully collapsed mono.  Finding the most appropriate balance can make a huge difference in realistic ambient width. Its 100% empirical, just listening for what sounds most "right"

I've not used the Wavelab VST stereoexpander but it sounds like it is probably a simple M/S ratio adjustment tool doing exactly same thing.  I've not used Ozone 6, but I would guess it may be a multi-band version of the same.  If so, expanding the width of the lower frequencies more than the higher frequencies may be useful for this application.

All that matters in the end is the listening experience, and not how one gets there.. the "recognition of the empirical truth" as you put it, comes first.. and last.   The theoretical stuff just helps us leverage and manipulate those empirical truths more consistently.   

Curious to hear others experience with these things.
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Offline Gutbucket

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Re: Convert Binaural recording to Stereo?
« Reply #24 on: August 13, 2015, 05:34:54 PM »
Michael Gerzon's paper on "Blumlein Shuffling" from 1986, which relates directly to this conversation- http://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf

In it he references the EMI Stereosonic system from the 50's, which incorporated shuffling in their early stereo mixing desks, described in a link I posed somewhere here years ago (will try to find it and link here).  Its a really interesting read for anyone interested in this stuff.  About as information rich as the original Blumlein patents, also highly recommended.

Edit- found it: Stereosonic Recording And Reproducing System (1957 AES paper on stereo) http://taperssection.com/index.php?topic=153319.msg1940365#msg1940365
« Last Edit: August 13, 2015, 05:40:15 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

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Re: Convert Binaural recording to Stereo?
« Reply #25 on: August 13, 2015, 06:17:11 PM »
I've got nothing to add, regarding processing.
I don't like to mess with anything, as I've only ever managed to screw things up. I just don't like processing. In fact, recording more than two channels, and trying to mix them, totally burned me out on recording. So, for now, I'm listening to 35 years of HRTF, and true binaural, until I find the urge again, to get back to two channel stereo recording.. I find that I enjoy HRTF, immediately, thru speakers.  True binaural takes a bit longer, but I find that my mind assimilates the sound in a brief period, and I'm back to locked in. It does seem to get it straightened out, and it makes sense in speaker playback; its just not an immediate sensation (regarding true binaural protocol).

Offline Gutbucket

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Re: Convert Binaural recording to Stereo?
« Reply #26 on: August 14, 2015, 09:20:26 AM »
No problem there.  That's totally legitimate.  The most important thing is simply enjoying the recordings.  You're crossing the threshold, and your brain is a willing participant in that, helping you to do so.  You've trained it well and it is serving you admirably!
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Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

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Re: Convert Binaural recording to Stereo?
« Reply #27 on: September 09, 2015, 03:04:04 PM »
late to the game here, interesting topic.  have any of you tried this VST plugin, called Proximity? http://www.tokyodawn.net/proximity/
it's free, and seems to have a lot of flexibility around stereo width manipulation, and other techniques to alter the depth of recordings. 
i have not used it yet, but am curious if to see what you all think about it...thanks

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Re: Convert Binaural recording to Stereo?
« Reply #28 on: September 09, 2015, 05:25:23 PM »
I guess my subject should have said "Convert Binaural recording for loudspeaker playback".

I'm late to this party; I apologize for that. Also, I've just skimmed the replies not taking the time to read in depth. But what I see in the replies talks mostly about the phase issues. I don't see much of anything that talks about the frequency attenuation issues.

When you record the way the OP has said he records, the head in question casts an acoustical shadow. That is, things that happen on the right side of the stage have to travel around the head to get to the left side mic; it's not a straight line. Low frequencies can do this without much trouble. Higher frequencies are more line-of-sight and have a more difficult time getting around the head. So you get some attenuation. As you might expect, it's not linear because the head isn't a sphere.

This non-linearity in frequency response for one "ear" across the sound stage is one reason that binaural works so well. You play it back through headphones and you get all those head-shadow queues right where they should be, and that gives you a "shock of realism" that kicks your willing suspension of disbelieve into gear. It's... glorious.

But it's this same non-linearity in frequency response for one "ear" across the sound stage that makes it difficult to make a conventional playback anywhere near as convincing as head phone playback. And... you can't fix it in post. You can't even scratch it, much less put a dent in it. Because EQ applies to the entire channel, not just the bits of that channel that originate from one particular side of the sound stage. You can't separate out the right half and EQ that while leaving the left half alone, because the EQ doesn't have any way to pull the signal apart like that and just work on bits and pieces. You can't do this any more than you can remove the salt from the cake you just baked. Once it's baked (or recorded) then you're done.

I'm just sayin' that you can't make binaural into ORTF, just like you can't make ORTF into binaural.

 

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