GUIDE LIST: Stereo-to-Surround Conversion Guides

[ursamtl]

The following is a list of the various guides and methods posted in this forum for converting stereo to surround sound. It is meant to provide readers with a listing of all the methods posted as well as useful, related information.

Surround discussion and additions
For general discussions related to stereo-to-surround conversion, the methods, or for questions, you can post in the thread specific to a particular method or in the following general forum:

Additions and comments on "GUIDE LIST: Stereo-to-surround Conversion.." (http://forum.doom9.org/showthread.php?s=&threadid=83937)

An Overview of Plogue Bidule-based Methods
Many of the methods documented in this forum use a software package called Plogue Bidule, available from http://www.plogue.com. This program is currently free to use because it is still in a beta testing phase. The better you learn to use Bidule, the more successful your stereo-to-surround conversion will be.

For a detailed, step-by-step guide for conversion using Bidule-based methods, see Step-by-Step Instructions for Plogue Bidule-based Stereo-to-Surround methods (http://forum.doom9.org/showthread.php?s=&threadid=83844)

A basic overview of the conversion method is as follows: Install and configure all related software.
Plan your project.
Prepare your source file.
Load the .bidule layout file and make any adjustments.
Load your source file and use Bidule to create a 6-channel .wav file
Process using Besweet
Encode using AC3 or DTS encoding software
Server for surround projects
Most of the software and PDF versions of most guides with step-by-step instructions are available at Daphy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=33004) and @ndy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=46752)'s server:
http://www.needfulthings.webhop.org/. If you have problems with this server, try ftp://daphy.mine.nu/. You can also check for announcements concerning the server status in the announcement thread, Needfulthings - dedicated 2.0to5.x host (http://forum.doom9.org/showthread.php?s=&threadid=67354).

Daphy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=33004) has put together a helpful Besweet installation package (http://www.freewebtown.com/andiz/audio/tools/besweet/BesweetInstaller.zip).

Visual guides
You can also check out some helpful Shockwave-based (Flash) visual guides:
6-wave Bidule-based process (http://www.needfulthings.webhop.org/) by Daphy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=33004)
Splitting a 6-channel wave file into six single mono wave files (http://www.needfulthings.webhop.org/) by Daphy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=33004)
Shockwave demo of using SIR Impulse Response Plugin with V.I (http://stevethomson.ca/audio/guides/siruse.exe) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
Shockwave demo of using Nuendo routing with V.I (http://stevethomson.ca/audio/guides/Routing.exe) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)

List of methods
General methods
UpmiX: tool to automate stereo to 5.1 conversion (v0.71) (http://forum.doom9.org/showthread.php?s=&threadid=57179) by Kpex (http://forum.doom9.org/member.php?s=&action=getinfo&userid=35767)
Experts multichannel mixing (http://forum.doom9.org/showthread.php?s=&threadid=74248) by Arturjose (http://forum.doom9.org/member.php?s=&action=getinfo&userid=26432)
MaroonMike's Goldwave method (http://forum.doom9.org/showthread.php?s=&postid=395801#post395801) by MaroonMike (http://forum.doom9.org/member.php?s=&action=getinfo&userid=43641)

AVISynth-based methods
BeHappy/MeGUI - AviSynth based audio transcoding (http://forum.doom9.org/showthread.php?t=104686) by dimzon (http://forum.doom9.org/member.php?u=42156)

NEO:6 methods
Encode 5.1 Wav with Creative DTS NEO 6 in Graphedit (http://forum.doom9.org/showthread.php?p=814330#post814330) by fat0n3s (http://forum.doom9.org/member.php?u=86968) and wonderbra (http://forum.doom9.org/member.php?u=87896).
DTS NEO:6 upmixing/Audigy 2 (http://forum.doom9.org/showthread.php?p=561534#post561534) by asscore (http://forum.doom9.org/member.php?s=&action=getinfo&userid=59763)

V.I-based methods
GUIDE: V.I Stereo to 5.1 Converter VST Plugin Suite (http://forum.doom9.org/showthread.php?s=&threadid=85446) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
GUIDE: Using the V.I Stereo to 5.1 Converter in Nuendo and Cubase (http://forum.doom9.org/showthread.php?s=&threadid=85694) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
V.I Stereo-to-5.1 Converter Suite version 1.1 released (http://forum.doom9.org/showthread.php?p=773084#post773084) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
GUIDE: Converting stereo to 5.1 surround for FREE (http://forum.doom9.org/showthread.php?t=105684) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
Creating a Pseudo 5.1 Mix from Stereo Source Using V.I. (uses Sound Forge and Vegas) (http://forum.videohelp.com/viewtopic.php?t=292142) by videohelp.com forum user guns1inger (http://forum.videohelp.com/profile.php?mode=viewprofile&u=105706)]

Steinberg Wavelab-based methods
GUIDE: Using Wavelab to create 5.1 files (http://forum.doom9.org/showthread.php?t=106494) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
NEW ->GUIDE: WaveLab 5 - Stereo to 6.1 (V.I Suite) (http://forum.doom9.org/showthread.php?p=936460#post936460) by Elektra999 (http://forum.doom9.org/member.php?u=103285)

Adobe Audition-based methods
GUIDE: Using Adobe Audition 1.5 or 2.0 to create 5.1 files (http://forum.doom9.org/showthread.php?t=106500) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838)
Adobe Audition My Chosen Method (http://forum.doom9.org/showthread.php?s=&threadid=90957) by tlavell (http://forum.doom9.org/member.php?s=&action=getinfo&userid=64533)
CCE settings (http://forum.doom9.org/showthread.php?s=&postid=622555#post622555) by soundz (http://forum.doom9.org/member.php?s=&action=getinfo&userid=67581)
Stereo to 5.1 AC3 (http://rj-elektronik.de/avideo/PDF/Stereoto5.1AC3.pdf) by SurroundBoy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36474) and Amnon82 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=43382)
Stereo to 5.1 Surround (NEW METHOD) (http://forum.doom9.org/showthread.php?s=&threadid=61757) by DSP8000 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=41032)
My Guide For Stereo to 5.1 (http://forum.doom9.org/showthread.php?s=&threadid=59949) by SurroundBoy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36474)
Update to SurroundBoy's method (http://forum.doom9.org/showthread.php?s=&postid=562086#post562086) by SurroundBoy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36474)
5.1 Surround Method for Motown Fans (Using Acapella & Instrumental sources) (http://forum.doom9.org/showthread.php?s=&threadid=84448) by SurroundBoy (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36474)

GraphEdit/DirectX-based methods
Encode 5.1 Wav with Creative DTS NEO 6 in Graphedit (http://forum.doom9.org/showthread.php?p=814330#post814330) by fat0n3s (http://forum.doom9.org/member.php?u=86968) and wonderbra (http://forum.doom9.org/member.php?u=87896).
Guide: 2- to 5-channel upmix using Dolby Pro Logic II (http://forum.doom9.org/showthread.php?s=&threadid=57736) by Bleo (http://forum.doom9.org/member.php?s=&action=getinfo&userid=37327)
Guide: Stereo to 5.1 upmix using DPLII (2nd Ed.) (http://forum.doom9.org/showthread.php?s=&threadid=83384) by Joshbm (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36871).

Ambisonics-based methods for real B-format files
Decoding B-format in Nuendo (http://forum.doom9.org/showthread.php?p=824240#post824240) by UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838).

Stereo-to-surround methods using Ambisonics plugins on non-Ambisonic material
Ambisonic Bidule layout using Panorama VST encoder (http://forum.doom9.org/showthread.php?s=&postid=416951#post416951) by Kempfand (http://forum.doom9.org/member.php?s=&action=getinfo&userid=1289)
Bidule layout using 3_B-Pan and 3rd_order VST plugins (http://forum.doom9.org/showthread.php?s=&postid=451435#post451435) by Specise_8472 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=18999)
TrapVector's Guide to switching 2.0 songs to 5.1 (http://forum.doom9.org/showthread.php?s=&threadid=71342) by Trapvector (http://forum.doom9.org/member.php?s=&action=getinfo&userid=47256)
A Guide for Ambisonic processing using CoolEdit and Aurora (http://forum.doom9.org/showthread.php?s=&threadid=29277) by Eye of Horus (http://forum.doom9.org/member.php?s=&action=getinfo&userid=13465)
Bidule groups based on 3rd-Order Ambisonics (http://forum.doom9.org/showthread.php?s=&postid=447033#post447033) by Kempfand (http://forum.doom9.org/member.php?s=&action=getinfo&userid=1289)
All-in-one VST with Ambisonic surrounds and Center (http://forum.doom9.org/showthread.php?s=&postid=471126#post471126) by Specise_8472 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=18999)

Ambiophonics-based methods
Ambiophonics (http://forum.doom9.org/showthread.php?s=&postid=419670#post419670) by Specise_8472 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=18999)
Ambiophonics version 1.5 (http://forum.doom9.org/showthread.php?s=&postid=421787#post421787) by Specise_8472 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=18999)
Circle Surround II to Neo6 (http://forum.doom9.org/showthread.php?s=&postid=426004#post426004) by Specise_8472 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=18999)

Miscellaneous methods
LCR Upmix Bidules (http://forum.doom9.org/showthread.php?s=&threadid=70678) by Kempfand (http://forum.doom9.org/member.php?s=&action=getinfo&userid=1289)
SAD5.1 Bidule (http://forum.doom9.org/showthread.php?s=&postid=484616#post484616) by Eye of Horus (http://forum.doom9.org/member.php?s=&action=getinfo&userid=13465) and Kempfand (http://forum.doom9.org/member.php?s=&action=getinfo&userid=1289)
Mono-to-Stereo (http://forum.doom9.org/showthread.php?s=&postid=498287#post498287) by Specise_8472 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=18999)
Voice Center, Voice-Non Center or Instrumental, & Instrumental bidules (http://forum.doom9.org/showthread.php?s=&postid=508505#post508505) by Eye of Horus (http://forum.doom9.org/member.php?s=&action=getinfo&userid=13465) and Kempfand (http://forum.doom9.org/member.php?s=&action=getinfo&userid=1289)

List history
The original version of this list was proposed by Ursamtl on July 1, 2004 (http://forum.doom9.org/showthread.php?s=&postid=518731#post518731) and then co-compiled by Ursamtl (http://forum.doom9.org/showthread.php?s=&postid=520143#post520143) and Eye of Horus. The list was updated and put in a new "sticky" thread with moderator approval on October 12, 2004. Updates and categorizations were requested by moderators on October 13-14.

Additions or changes to the list
If you have any questions or comments about specific methods, please post in the forum related to the method. Send any additions, changes or comments concerning this list in a private message or email to UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838).

For a discussion of this guide list, you can also post in the following thread:

Additions and comments on "GUIDE LIST: Stereo-to-surround Conversion.." (http://forum.doom9.org/showthread.php?s=&threadid=83937)

Updates
Because the system does not display an unread message icon when an existing message is updated, I'll post a message at the end of the thread whenever there are updates to the list. When it's time to update again, I'll delete the existing update message, and post a new one. I'll also place a "NEW" or "UPDATED" beside an affected items in a different color.

This way, you'll always be aware when there are changes to the list.

[ursamtl]

Additional resources
To help improve your surround experiments, the following is a list of additional software tools and surround-related information free on the internet.

Related threads and posts in the Doom9 Audio Encoding forum
Simulate Hardware Stereo to Quadraphonic (http://forum.doom9.org/showthread.php?t=100389)
Does it make sense to convert a stereo audio track of a movie to surround? (http://forum.doom9.org/showthread.php?t=97975)
Determining channel order and output monitoring on Audigy 2 and Audigy 2 ZS systems (http://forum.doom9.org/showthread.php?s=&threadid=87496)
Guide: Transcoding DTS files in Foobar2000 (http://forum.doom9.org/showthread.php?s=&postid=566664#post566664) by Kurtnoise13 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=19312)
Confirmation that SurCode outputs 24-bit files (http://forum.doom9.org/showthread.php?s=&postid=563441#post563441)
Stereo to AC3 5.1? (http://forum.doom9.org/showthread.php?s=&threadid=84330)
DTS NEO:6 upmixing / Audigy 2 (http://forum.doom9.org/showthread.php?s=&threadid=84376)
5.1 Surround and 6 channel Gain groups for Plogue Bidule (http://forum.doom9.org/showthread.php?s=&postid=374596#post374596) by Joshbm (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36871)
Update to 5.1 Surround Bidule group (http://forum.doom9.org/showthread.php?s=&postid=410780#post410780) by Joshbm (http://forum.doom9.org/member.php?s=&action=getinfo&userid=36871)
Upsampling before converting stereo to surround? (http://forum.doom9.org/showthread.php?s=&threadid=83936)
Prologic II to AC3 conversion? Prologic II to AC3 conversion? (http://forum.doom9.org/showthread.php?s=&threadid=75833)
SixWAVE to AC3 (http://forum.doom9.org/showthread.php?threadid=75833) by Amnon82 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=43382)
UHJ and Ambisonic equations suited for Dolby Pro Logic material (http://forum.doom9.org/showthread.php?s=&threadid=60331) by Sycho (http://forum.doom9.org/member.php?s=&action=getinfo&userid=30371)
Preliminary version of Cool Edit/Aurora Ambisonics method (http://forum.doom9.org/showthread.php?s=&threadid=29198) by Eye of Horus (http://forum.doom9.org/member.php?s=&action=getinfo&userid=13465)
Best ways to encode output (http://forum.doom9.org/showthread.php?s=&postid=365851#post365851) by Eye of Horus (http://forum.doom9.org/member.php?s=&action=getinfo&userid=13465)
Rear surround reverb suggestions??? 1 (http://forum.doom9.org/showthread.php?s=&threadid=76385)
Rear surround reverb suggestions??? 2 (http://forum.doom9.org/showthread.php?s=&threadid=76246)
mono to stereo to 5.1....possible? (http://forum.doom9.org/showthread.php?s=&threadid=76246)
DTS surround? (http://forum.doom9.org/showthread.php?s=&threadid=76370)
Taking CD tracks and converting to 5.1 audio (http://forum.doom9.org/showthread.php?s=&threadid=74496) by Trooper11 (http://forum.doom9.org/member.php?s=&action=getinfo&userid=49488)
SAD5.1 Bidule (http://forum.doom9.org/showthread.php?s=&threadid=76216)
from single 6-WAV file direct to prologic? (http://forum.doom9.org/showthread.php?s=&threadid=75081)
GUIDE : *.DTS to *.WAV (DTS/WAV) (http://forum.doom9.org/showthread.php?threadid=74017)
upmixing mono to 5.1 (http://forum.doom9.org/showthread.php?s=&threadid=73952)
Simple 5.1>WXYZ>5.1 using AC3 Filter (http://forum.doom9.org/showthread.php?s=&threadid=71846)
5.1 to WXYZ and Back (http://forum.doom9.org/showthread.php?s=&threadid=68646)
The Dolby Surround Pro Logic II Matrix (http://forum.doom9.org/showthread.php?s=&threadid=27936)
2 Channel Stereo WAV file to AC3 5.1 Dolby Digital? (http://forum.doom9.org/showthread.php?s=&threadid=56917)
Dolby Surround / Prologic / Prologic II (http://forum.doom9.org/showthread.php?s=&threadid=35209)

Real B-format recordings
Tremendous bittorrent-based resource for real ambisonic recordings. Note: these are not really "bootleg" recordings but rather they are personal B-format recordings shared by audio professionals. (http://www.ambisonicbootlegs.net/)

DirectX-based Ambisonic decoders
[/COLOR]Wigware Ambisonic Decoder (WAD) DirectX Filter by Dr. Bruce Wiggins for ITU 5.1 and traditional layouts. (http://sparg.derby.ac.uk/SPARG/Staff_BW.asp)

VST plugins
Wigware Ambisonic Decoder (WAD) VST plugins for 1st- and 2nd-order decoding by Dr. Bruce Wiggins for ITU 5.1 and traditional layouts. (http://sparg.derby.ac.uk/SPARG/Staff_BW.asp)
2-2-3 Center Channel Generator VST Plugin (http://forum.doom9.org/showthread.php?p=717448#post717448)
Circle Surround SRS VST in Bidule (http://forum.doom9.org/showthread.php?s=&postid=422169#post422169)
K-v-R : VST DX AU Supporting Open Standard Audio Plugins (http://www.kvr-vst.com/)
Commercial plugin SRS VST and link to an interesting French site (http://forum.doom9.org/showthread.php?s=&postid=518006#post518006)
Catt (http://forum.doom9.org/showthread.php?s=&postid=440053#post440053)

General Reading and Information
Barry Diament Audio articles (http://www.barrydiamentaudio.com/articles.htm)
Imperfect Sound Forever (http://www.stylusmagazine.com/articles/weekly_article/imperfect-sound-forever.htm)
Steve Hoffman web site forums (http://www.stevehoffman.tv/forums/)
Audio and Three-Dimensional Sound Links (http://www.users.dircon.co.uk/~wareing/3daudio.htm)
Expert Forums from Gig, EQ, Keyboard, Surround Professional & MusicPlayer (http://www.musicplayer.com/cgi-bin/ultimatebb.cgi?ubb=forum;f=16;DaysPrune=30)
You Are Surrounded (http://www.soundonsound.com/sos/Aug01/articles/surroundsound1.asp?session=dc8e17f)
Surround Sound: Exploration of Multichannel Audio (http://www.extremetech.com/article2/0,1558,12166,00.asp)
The Recording Academy's Producers & Engineers Wing Recommendations For Surround Sound Production (http://www.grammy.com/pe_wing/5_1_Rec.pdf)
AfterDawn.com: Forums: High resolution audio (http://forums.afterdawn.com/forum_view.cfm/90)
Hydrogenaudio Forums (http://www.hydrogenaudio.org/forums/index.php?act=idx)

Impulse Reponses
Noisevault (http://www.noisevault.com)

Scientific/engineering
Sursound mailing list (https://mail.music.vt.edu/mailman/listinfo/sursound.)
United States Patent: 5,594,800: Sound reproduction system having a matrix converter (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=5,594,800.WKU.&OS=PN/5,594,800&RS=PN/5,594,800.)
Third-Order Ambisonic Decoder BDec3 (http://www.york.ac.uk/inst/mustech/3d_audio/vst/bdec3_help.html)
First and Second Order Ambisonic Decoding Equations (http://www.muse.demon.co.uk/ref/speakers.html)
Conversion between UHJ and B-format (http://www.ramsete.com/aurora/conversion_between_uhj_and_b.htm/)

Software
Plogue Bidule - modular audio software that offers endless possibilities for connections, routings, etc. Truly an amazing program. (http://www.plogue.com)
WaveWizard - excellent soundfile utility that simplifies many tasks (http://forum.doom9.org/showthread.php?p=662555#post662555)
Tranzcode+ TranzGUI - effective decoding/splitting tool for multichannel WAV and DTS/DTSWAV files (http://forum.doom9.org/showthread.php?p=648990#post648990)
BeLight - new up-to-date GUI for BeSweet (http://forum.doom9.org/showthread.php?p=571527#post571527)
ASIO4ALL - ASIO Driver for WDM soundcards (http://michael.tippach.bei.t-online.de/asio4all/install.html)
KX Project - Free ASIO driver for most Soundblaster Live! and Audigy soundcards (http://www.kxproject.com)
ASIO2KS - ASIO driver for WDM soundcards (http://www.asio2ks.de/)
If you have any other good links to surround articles, information, software, etc., feel free to post them here or send them to UrsaMtl (http://forum.doom9.org/member.php?s=&action=getinfo&userid=56838) in a PM for inclusion in a list here.

[ursamtl]

UPDATE NOTICE

This message is to let all forum readers know that this thread has been updated as follows:

January 16, 2007 Added GUIDE: WaveLab 5 - Stereo to 6.1 (V.I Suite) (http://forum.doom9.org/showthread.php?p=936460#post936460) by Elektra999 (http://forum.doom9.org/member.php?u=103285) to the guide list.
This message will be deleted and a new one posted the next time an update is carried out. Previous update notices will be removed.

[oscarjunk25]

looks good were did you find that at ? or were did you look that up at ?

[Priyatam]

thanx

[amsudeen]

it easy way from nero wave editor nero v7.XXX.
just call any mp3 or wav file.
edit/ covert sample/ select 48000 and 5.1 channel.
save file ac3 format thats all.

shartaj2000@hotmail.com

[daphy]

Hiho,

if you need the old VSt-Plugins collection mentioned in my old guide and the other stuff from Needfulthings take a look here (http://forum.doom9.org/showthread.php?p=1095135#post1095135) :rolleyes:


CYA
Daphy

[Jenyok]

Maybe somebody knows...
.
Where could I find algorithm "A real time audio upmixing method from stereo to 7.1 channel audio" ?
Discription of this algorithm in text and graphics.
.
Thanks.
.

[sebus]

Not free. You can buy it here (http://link.springer.com/chapter/10.1007%2F978-3-642-17604-3_18)

First 2 pages are here:


http://link.springer.com/static-content/lookinside/131/chp%253A10.1007%252F978-3-642-17604-3_18/000.png
http://link.springer.com/static-content/lookinside/131/chp%253A10.1007%252F978-3-642-17604-3_18/001.png


You might be interested in PhD Thesis ~ Single sided (5.9 MB PDF) - JAR-Lab.com (www.jar-lab.com/papers/PhD/Usher_PhD.pdf)

[Chainmax]

My apologies for the thread necro, but does anyone know if there is a method to use Harman Kardon's Logic 7 for upsampling to x.1?

[HaydenField000]

Can someone please advice if it's possible to accomplish the above using Nero? If yes, please suggest which version of Nero shall be required... thanks a lot in advance!

[FranceBB]

@HaydenField000... it's possible to convert stereo to surround 5.1 via avisynth, using these filters (try them and choose one according to the results on your source):

UpAction() #action movies only
UpDialog() #dialogues mainly
UpGerzen()
UpFarina()
UpMultisonic()
UpSoundOnSound()

Once you have a 5.1 converted track, you'll just have to encode it using your favourite encoder, for instance, NeroAAC.

Sample script:



video=colorbars(width = 704, height = 396, pixel_type = "yv12")

audio=DirectShowSource("audio2.0.something")
#using WAVSource for .wav audio files is reccomend
#you can use FFAudioSource as well

audioDub(video, audio)

UpDialog() #it converts to 5.1



Please note that upmix it's not like a real 5.1 audio track, due to potential unexpected behaviours, 'cause it uses filters to detect frequencies and create channels, so you might have a light echo in FL and FR channels during dialogues, when they are supposed to be mute in a real 5.1 track etc.
Unfortunately, there is no magic and I really wanted to upmix audio tracks back in the days, but in most cases it's not worth it and it's better to just make a Loudness correction (Normalization, EQ etc).