any one used this method before?

http://www.sounddevices.com/notes/general/ms-stereo-basics/

would a decoding patch be as simple as:

M ~ S~ M ~ S~
/ / / /
/ / / /
+~ -~
I /
I /
I /
I /
DAC~

cheers for any help.

When I was studying sound recording, I got really into M/S recording. It is kind of like black magic. Certainly the most versatile stereo image you can get from two microphones. Interesting Trivia: M/S was actually invented by Engineers who were working on broadcasting orchestral performances on German TV. They needed to find a way that the music could sound good on the common mono TV sets as well as the more modern stereo ones. If you mix your M/S tracks back to stereo, they sound great. Then, if you sum them to mono, the side tracks disappear (because they are perfectly out of phase) and you are left with mid track only. Viola! Also, it is great fun to play around with the position of the microphones. Obviously, for a pristine recording it is best to get the capsules as near coincident as possible. However, if you move each mic about the room, you can actually create some pretty cool 'synthetic' stereo images.

can you use this to mimic surround sound effects?

Surround sound is a specific array of playback devices (speakers and subs.) 5.1 surround sound is similar to M/S sound in that is is a multi-channel image encoded onto 1 stereo track. The encoding and decoding is done with simple addition and subtraction, which is why when you add (sum) the stereo result of an m/s encoded stereo track, the differential is the mid track alone.

So if 5.1 starts as a stereo stream: You have track A (right), and track B (left). But there are five speakers right? Well, AFAIK, it is only possible to do a 4-channel matrix with a 2 channel source, meaning the two 'sorround speakers' are the same. Can anyone correct me?

I believe it is decoded as follows:

A=A (duh)
B=B (hmmm)
C=A+B (surround)
D=A-B (center)

The '.1' I guess is a crossover fed bass 'kicker' that the kids love so much.
Of course, with all digital signal flow to the home theater amp of the future, and cheaper and cheaper D/A, we could do 16.4 surround, which would kick ass.

As I understand it 5.1 is a special case of upmixing. Imagine the stereo field as 180 degrees or pi radians. This is now stretched out into 360 degrees by expanding the field and channeling the four new quadrants to each speaker. All that is happening is the reative LR balance is used to cancel out anything that doesn't belong in that quadrant when multiplied by a gain that corresponds to the angle.

Somewhere I had some papers on multi-channel upmixing, In theory it's possible to have 16 or 32 speakers encoded into a single stero channel if you are very careful with the phases.

What MPEG4 does is add one low bit rate side channel so you can also have tone control and panning of every part. Very clever.

The coolest part is that the beginning of this process was well before the digital age, before op-amps, before solid-state.

Interesting Nestor - this is tech from demultiplexing radio communications?
Any history lessons (links, papers)?

Obi, I wish I remembered where I picked up the little history I do know. My mind may be a sponge, but a sponge has no bibliography. I have a feeling it was from one of those "history of sound recording" books from the 60s or 70s (pre-wikipedia, remember?) that was gathering dust on some library shelf. It is clear in my totally fallible memory that the innovation came out of the broadcast field in Germany, and was perhaps one of the many great innovations which we liberated from the Nazis when we adopted their scientists after the Great War.

Glad this topic promoted discussion. Got some really good & malleable results using M/S, I thoroughly recommend it!

Hey guys,

Wikipedia these , ad netsearch - I had for my memoire a few years ago...

Walt Disney- Fantasia_ they toured with live mixers in surround for that film. They used the pan pots developed by Blumlein.

(Brit)Blumlein was the guy who said mono can imitate spac eby being panned between two distribution sources (speakers).

There was Fletcher (Am)- Mr WALL OF SOUND -
each source, a speaker... Too expensive - and impossible for mass distrib. Blum wins...

Nowadays, with PD...

Surround
dac 1 2 3 4 5 6 7 8 then link with adat 9 10 11 12 etc....

(Soundcards - Protools digi01, motu 828 now sell for under 300 used!! - Motut drivers are current, but ot for linux. RME is linux/win/mac ready)

(Sound on Sound has great articles on the following!!!)

if you follow dolby...
123 1 and 3 ambient front, 3 center voice
4 5 - left right behind, mix of front with 5-20 ms delay, depending on image, with high and low cuts, so it imitates how we hear sound when it is behind us.
6 Bass - dumped to woofer below 110-80 hz.

Haven't read up on DTS (check sound on sound)

all the numbers are different depending on your setup of your program of choice, and sound card..But the distro is l/r front, l/r rear with delay ad filter cut. Center front, and bass.

This creates a uniform distro method for cinema - good to know if you have mixed a film stereo, and do not want the dolby effect in place!!!
or, when you get a dolby mixer to work on your film, she or he is preparig your film for this in the cinema...

test it:
just do a surround mix, saving your work. play it back on multitrack through a dolby amp from a surround dvd with coaxial...

then connect to the amp from a dvd reader with each track connected by a coaxial cable...

then connect a multitrack sound card directly to your amp, with each track linked to an out.....

you should hear some differences...

But the man at IEM, Mr PD and GEM, has been working on their surround for years - and has distributed the patch recently. Plus ambison is around for max...and I thought, there was a PD port....

But it begs the question of mass distro versus unique design and experiences of sound....

> But it begs the question of mass distro versus unique design and experiences of sound....

That is an interesting thought, When visiting Fraunhofer intstitute I was lucky be given a demonstration of wavefield surround that can place sources outside the boundary of the room with amazing realism. But that system is unique to each installation and needs more than 100 loudspeakers. I think venue specific sound systems are a cool thing, they place the value back with the theater/concert hall rather than the media, which encourages people to go out for entertainment and make high quality installations an attraction now that everyone can have Dolby 51 in their home.

OTOH, finding engineers who can mix to strange formats is difficult and expensive. If you just made a film, finding an extra 100k$ to have it mixed in wavefield or ambisonic for less than 100 theaters in the world is not very attractive. The studios need an alternative to Dolby "standards", an ISO approved device independent digital format - multitrack with side channel information so that each venue can optimise the playback - this will probably be a flavour of MPEG4

@obiwannabe said:

> But it begs the question of mass distro versus unique design and experiences of sound....

...which nicely leads into this post from the SAN list, on mastering for youtube...

@Sanlist said:

Greetings all,

I was recently involved in creating an entry for the Doritos.co.uk ad
competition. Watch it here:

http://www.doritosinstantparty.co.uk

As you all know sound is often far more important than video in creating
the right impression so it was absolutely key to ensure that our entry
had fantastic sound. We discovered that there are certain things you can
do that will ensure that your foley and soundtrack sound great even
after it's posted to youtube and becomes low bit rate, highly compressed
mono.

Techniques include extensive use of M-S micing to ensure that everything
degrades gracefully to mono. Spend a lot of time toggling between mono
and stereo listening to individual tracks to ensure they are
translatable. When using reverb reduce the stereo width otherwise the
anti-phase will cancel and much of the reverb will be lost. Other tips
will be outlined in the 'Making of... Soundtrack' featurette.

We hope to post a 'tour' of the mix soon as a featurette on the
doritosinstantparty youtube channel so subscribe to make sure you see it.

Hope this has been inspirational

Alexander Rice

Just thought I'd update this thread incase people were looking into mid-side with Pd.
A mid-side to left-right encoder and decoder called +matrix~ is included with the Soundhack externals::::::::::::::::::
http://www.soundhack.com/externs.php