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how to produce virtual 3D surround in mp3 for headphones?

post #1 of 11
Thread Starter 

hello one and all,

i know that i can record holophonic audio using the foam head and binaural microphones, then pass it through hrtf.

however i am looking to do a more simple thing. i would like to place a narrator in front of the listener and say soft ocean, wind, or forest sound behind the listener. i should be able to author such placement of mono or stereo recordings in a 5.1 software like apple soundtrack pro or adobe soundbooth and then create a multichannel audio file, like wav or so.

where i am stuck, is, is there a way to take that exported 6-channel audio file and use some utility to compress it down into an mp3 file that will preserve the 3D spatial holophonic effect when the user hears it in nice stereo headphones, like the barber shop or matches demonstrations that are all over the web.

so, i know that mp3 can store the holophonic effect, i just want to know how that mp3 file is created. and really i just want to do a simpler thing then recording in full 3D.

thank you in advance and have a great day. lucas

post #2 of 11

I came across some software that can do this a while ago. Can't remember the name anymore, but it wasn't free. Mind you the result won't be as good as measuring real HRTF with in-ear microphones. And then there are about 50 terrible ones.

post #3 of 11

This is NOT a simple task.


I'd find a Dolby Headphone processor and feed it a 5.1 encoded signal and then digitise it's two-channel headphone out, and then compress it to an MP3.  But that's prolly not the answer you're looking for.


Good luck.

post #4 of 11

I've never tried it but foobar has a DSP that's called "downmix 5.1 to stereo", just drag your files in a playlist, right click - convert - ... and select the DSP.


Isn't the barber shop a binaural recording?

post #5 of 11
Thread Starter 

actually the dolby headphone is a good idea tyll.  i was going in the direction of faunhofer mp3D and they had a free encoder/compressor but it created no discernible 3D location data.  and i know that i am creating real 5.1 (6 channel) wave files because i created them in apple soundtrack pro and saved the master mix in the wav file and verified the 6 waveforms in adobe soundbooth.  all good, except the faunhofer mp3D encoder.


ok, so do you know where i can get a Dolby Headphone encoder?  i would love a software based one that runs on the mac osx.  i searched and haven't found one yet.


also, i did a bit of research and the dolby looks like the direction because i saw on their website that creating 3D sounds for headphones is quite natural, as opposed to 5.1, because we only have two ears anyway, as opposed to setting up 6 speakers.  that makes a lot of sense to me and i think it should be natural to have that 2 speaker interference pattern through hrtf to present it in 3D.


anyway, i have soundtrack pro v2 and it does have a Dolby Professional export to AC3.  that export dialog also has a 2 channel output, but i don't know if it has the hrtf built into it to maintain the 3D spatial information.  i am going to test it.


anyway, i would like a dolby headphone encoder to compare to the possible AC3 2 channel export, so please help me find a suitable encoder.  thank you in advance, lucas

post #6 of 11
Thread Starter 

ok, so i tried the Dolby Professional AC3 export in apple soundtrack pro 2 and it doesn't seem to work at all.  it exports a file with no audio and no waveforms.  maybe i am doing something wrong but i tried many different settings and i just get an empty file with no audio.  weird right?  lucas

post #7 of 11

I don't really like the dolby headphone method for 5.1 audio... it does sound "behind you" for the rear channels but the whole thing has such a reverby sound it irritates me and sounds so out of place compared to all my stereo stuff. Not to hijack your thread or anything but if anyone knows any better methods for converting 5.1 to virtual surround stereo I'd love to try them. I've also tried ATSurround and it's not much more to my liking unfortunately.

post #8 of 11

why compromize with mixing down to "Stereo" Smyth SVS Realizer gives multichannel "these loudspeakers in this room" sound with headphones


of course the full effect can't be had without the processor and headtracking

Edited by jcx - 5/17/10 at 1:19pm
post #9 of 11
Originally Posted by jcx View Post

why compromize with mixing down to "Stereo" Smyth SVS Realizer gives multichannel

The Smyth mixes down to stereo. Both the dolby and Smyth stuff are audio virtualizers for surround sound with separate HRTFs for the various speakers.


The Smyth does sound way better though, and does the best job I've heard of getting the sound out of your head---which isn't much, still the best I've heard.


And I agree with Vkamiched, dolby synthesizes a fake room with walls and reflections and I think it sound boxy, I like the processors that focus on the hearing cues and not so much the room.



post #10 of 11

why the "--which isn't much" qualifier?


my recollection of SVS demos with personal calibration and head tracking did give the loudspeaker&room sound - do hear problems with longer use? - I don't see disillusion among owners in the SVS thread

post #11 of 11
Originally Posted by jcx View Post

why the "--which isn't much" qualifier?

It's the best out there, but it didn't really sound like it was coming from outside my head.


Yes it had a space of its own, and yes the head tracking did work fairly well and it felt relatively organic.


But I was never continuously fool that it was outside my head. Some sounds here and there, yes, but not continuously convincing.


Not a big knock on them because I've not ever found anything that was, and have felt claims to be overbloated on most of these devices.

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