How do I Convert ac3 2 ch to ac3 5.1 ch

[imbatman]

I'm sure this has been asked a billion times before but, How do I Convert ac3 2 ch to ac3 5.1 ch
What software will I need.
Can anyone direct me to a tutorial or previous forum discussion.

[feenix]

You don't - simple as that. Absolutely no point whatsoever

[offline]

Offline's micro guide to producing AC3 5.1 from two channels

Q. Why convert two channel ac3 to 5.1?

a) To juice up the sound of an old movie
b) To add a bit of thump to a prologic or dolby surround 2.0 track
c) To mix music
d) Add effects to your home movie blockbuster

Q. How?

Software required:

Soft Encode - Dolby Digital 5.1
Audio editing software

1) Covert stereo ac3 file to to stereo .WAV using Headac3he or BeSweet.
2) Use audio editing software ( Adobe Audition, GoldWave ) to convert stereo .WAV to two mono .WAV (these will be your front left/right channels)
3) Use audio editing software to create centre, left rear surround, right rear surround and subwoofer mono .WAV tracks. Use mixing and filters to create best effect (ie band pass low filter for subwoofer.)
4) Use Soft Encode to blend the final 6 mono .WAV files to Dolby Digital 5.1

Note: You will not be making a true blue 5.1 track as you would need to
have access to the original 6 movie tracks BUT the result, if correctly done, produces a nice surround effect. Hint: reduce centre and rear surround channels by a few Db for the best effect.

If making a home movie, use Adobe Audition's multitrack & AVI feature which allows you to view the movie and edit the sound tracks at the same time.

[feenix]

offline,

OK - point taken, especially about home produced movies. Still can't believe it's worth the effort (and cost) for a commercial DVD back up (and NO I haven't tried it so I'm talking from theory not practice)

[andydd]

It certainly is worth it to make a 5.1 track from a 2.0, Ive done this with some films Ive recorded off TV and isnt as impressive as a thumping original 5.1 dvd soundtrack but its nice to have a bit of surround, also your subwoofer will come into play (if u have one).

[offline]

feenix,

Some on this forum (I would hope the majority) treat this whole deal as a hobby or an aid to their profession. While people can go too far in terms of cost and effort, it is a personal choice. For example, one of my favorite movies is an old French black & white classic. I bought the DVD and then re mastered the sound from scratch to DTS 6.1 Ex. The end result was perfection. Did I go overboard? Yep

[offline]

Hey andydd..

do you have prologic II ? If so how does that compare with
your home brewed 5.1 tracks? For TV sourced material I've just
run it under prologic and not bothered to touch the audio.

[alewisa]

Q. How?

Software required:

Soft Encode - Dolby Digital 5.1
Audio editing software

3) Use audio editing software to create centre, left rear surround, right rear surround and subwoofer mono .WAV tracks. ...
4) Use Soft Encode to blend the final 6 mono .WAV files to Dolby Digital 5.1

How does one "use editing software" to create these extra tracks?

Trying to think this through for myself...

At a guess, run the entire original .wav thru a filter to remove everything above a certain frequency to produce the LFE track (e.g. a high pass filter set to a low frequency.

At [another] guess, do the same but use a high and low pass filter to remove everything under and over the frequency range of the human voice (leaving, I dunno, everything between 40Khz and 60Khz for example).

Presumably one then does something with the mono left and mono right tracks to create the rear left and rear right tracks, but what? Remove the lowest frequency sounds (as they are in the LFE)?

Any help greatly appreciated!

[SallyDog]

I would suggest you check this out if you are really serious about making the conversion.


http://forum.doom9.org/showthread.php?s=&threadid=60137

[BJ_M]

I would suggest you check this out if you are really serious about making the conversion.


http://forum.doom9.org/showthread.php?s=&threadid=60137

maybe for home use -- wouldnt be used in a studio for sure except to play around with after work .. but he put a lot of time in his guide , nice job .. but there are far easier ways to do 2 to 6 channel conversions ..

but as mentioned -- its fairly pointless, if you want to hear 5.1 from your 2ch , most of the time your receiver can do a better job at fake surround

[alewisa]

But not if your authoring s/w requires ALL audio to be the same.... and in this case as the source film has a AC3 5.1 track, converting the .mpg title audio to AC3 results in a 2 channel track, and I suspect that it needs to be 5.1 too.... so there is a need for specific purposes.

[BJ_M]

get new authoring software --

but seriously, just put different types in thier own title set .. then you can mix all sorts of things including 4:3 and 16:9

[SallyDog]

.. but there are far easier ways to do 2 to 6 channel conversions ..

Please enlighten me

[BJ_M]

.. but there are far easier ways to do 2 to 6 channel conversions ..

Please enlighten me

you can do complete positional panning in both film and dvd mode in vegas - in real time ... just load your stereo track in 6 times ,

track 1 - select left channel
track 2 - select rightchannel
track 3 - select combine (center) -6db
track 4 - select left (left surround) -6dB
track 5 - select right (right surround) -6dB
track 6 - select both (LFE) +6dB

use panning tool and mix your hearts content -- add some reverb to rear channels. Roll off everything above 120Hz on LFE channel @ 24dB per oct.

there are also a whack of plug-ins that can add some quality (i suggest wave arts)

some plug ins

http://www.directxfiles.com/plugins.htm

[Skynet107]

This is such a stupid thing to do. If the original 2 channel sound had dolby surround matrixed into it (almost all do), by the time you were finished seperating and filtering the hell out of it, goodbye surround sound. It is a pointless project.

You will end up with a fake surround sound track, with no directional effects at all. Hasn't anyone noticed may TV shows have dolby surround? Give you any hints? TV is only 2 tracks.

[lordsmurf]

Pointless.

Good receivers can emulate 5.1 or higher from stereo sound if you're really juicing yourself to here audio all around.

But it's fake. It'll still be 2/0 ... just out of more speakers.

[BJ_M]

yes -- i said way up above its pointless -- most of the time -- but there times where I HAVE to do a full 5.1 from a 2channel mix and i dont have the orig. stubs ....

i WILL cut out various effects and re-position them and such and also recreate as much as possable the 3d sound field ...

[dmh13]

Since we are on this subject, I have a similar question.
How do I convert my Motorcycle in to a Car?
I have watched Monster Garage a couple of times and I believe I am ready.
There would be some good reasons in doing this, such as my motorcycle would never tip over. Any help would be great. Thank You.

[BJ_M]

that was already covered ...

that project rather failed also .. i think it was the one where they tried to use a 18 wheeler 7 liter engine and make a motorcycle with it ..

[muskgrave]

watch it dmh13...

I tried to make a funny like that once and some jerkface reported me..
can i say jerkface? is that allowed?

[BJ_M]

watch it dmh13...

I tried to make a funny like that once and some jerkface reported me..
can i say jerkface? is that allowed?

you don't have a card do you? -- don't sweat the little details ..

[mikesbytes]

I would of thought that the 5.1 could be used for home videos. The extra channels could be used for voice over, decreasing the chance of the Grandparents falling asleep while watching.

[choirislife923]

what i do for stereo to 5.1 is use graphedit, use cyberlink's audio decoder (anything but wav files) or effects (wav files) filter, turn it to 6-channel mode, pump up CEI (i dont like prologic II...sound produced sounds more artificial than it really is) to movie/music/onstage (depending on video), run it with a WAV Dest and File Writer filters.