AC3 to stereo aiff

[audio_pete]

In the past I have used mac3dec to convert ac3 file to stereo aiff file.
Am trying to find a substitute.

Does not work on upgraded setup Early 2009 mac mini intel
rosetta translator does not work for all PPC apps.

Actually the mac3dec part seems to work
just did not realize it was really a link to sound converter.
it is the sound converter that is "missing"
soundconverter apparently lives happily on as linux but that's not me.

Audacity with attached library can open ac3 files
I got as far as saving as a mono file.

wikipedia has a complicated filter to translate ac3 to stereo
which may be in the attached library but ....

am I missing the easy answer or is the answer no?
Audacity does not do ac3 to stereo aiff.

[Trebor]

... Audacity does not do ac3 to stereo aiff.

Me no speak Mac , but If AIFF is not shown on the drop down menu shown below ( when exporting audio from Audacity) ...

save in AIFF format option in Audacity in Windows.gif (23.77 KiB) Viewed 1915 times

Then I think you need to install something called FFmpeg into Audacity to be able to export any audio from Audacity in the AIFF format ...http://manual.audacityteam.org/o/man/fa ... Library.3F[/u]


[ IIRC AIFF is native to Audacity : you shouldn't have to install FFmpeg to export in that format ]

[audio_pete]

Thanks for you time.

Already installed library and split AC3 file into 5 tracks.

Did not see any easy way to combine into 2 stereo tracks and export as air.

Will look again but am not holding my breath.

Maybe FFmpeg does this but looks pretty scary to me.
The box does not come over so well, but it is how to demux? the 5 into Left Total and Right Total

The Dolby Stereo Matrix is straightforward: the four original channels: Left (L), Center (C), Right (R), and Surround (S), are combined into two,
known as Left-total (LT) and Right-total (RT) by this formula:

Dolby Stereo Mix Left Right Center Surround
Left Total 1 0 frac {1}{sqrt 2} +j frac {1}{sqrt 2}
Right Total 0 1 frac {1}{sqrt 2} -j frac {1}{sqrt 2}

where j = 90° phase-shift

[steve]

Did not see any easy way to combine into 2 stereo tracks and export as air.

I presume that you mean "as AIFF"?

Maybe FFmpeg does this but looks pretty scary to me.

You don't need FFmpeg to export AIFF (mono or stereo).

When you Export from Audacity, all tracks that are not muted are mixed down to a single file.
If all of the tracks are "mono" tracks, then the exported file will be mono.
If any of the tracks are stereo, or set to "Left Channel" or "Right Channel" or panned left or right, the the Exported file will be stereo.

To set a mono track to "Left Channel" or "Right Channel", use the track dropdown menu: http://manual.audacityteam.org/o/man/tr ... _menu.html
To combine two mono tracks into a stereo track, use "Make Stereo Track" (also in the track dropdown menu).
To "pan" a track left or right, use the track "Pan Slider": http://manual.audacityteam.org/o/man/au ... s.html#pan

When you have the tracks and channels as you want them, export from Audacity and select AIFF as the export format.

[Trebor]

Already installed library and split AC3 file into 5 tracks.
Did not see any easy way to combine into 2 stereo tracks ...

I think the magic word is "downmix" ...

https://www.google.com/search?q=downmixing+stereo+5.1+convert+site:forum.audacityteam.org

[ I've not downmixed 5.1 to stereo , DVDdoug may be your man for that job ]

I'm sure I've seen plugins to do that , e.g.
2.102 Surround matrix encoder (surroundEncoder, 1401)
but I've never used that myself.

[audio_pete]

Already installed library and split AC3 file into 5 tracks.
Did not see any easy way to combine into 2 stereo tracks ...

I think the magic word is "downmix" ...

https://www.google.com/search?q=downmixing+stereo+5.1+convert+site:forum.audacityteam.org

[ I've not downmixed 5.1 to stereo , DVDdoug may be your man for that job ]

I'm sure I've seen plugins to do that , e.g.
2.102 Surround matrix encoder (surroundEncoder, 1401)
but I've never used that myself.

Yeah, this is the wiki info I was looking for audio mixing

Stereo downmixes / fold-downs[edit]
Left total /Right total (Lt/Rt)[edit]
Lt/Rt is a downmix suitable for decoding with a Dolby Pro Logic decoder to obtain 5.1 channels again. Lt/Rt is also suitable for stereophonic sound playback on a hi-fi or on headphones as it is.

Lt = L + -3dB*C + -3dB*(-Ls -Rs)

Rt = R + -3dB*C + -3dB*(Ls + Rs)

(where Ls and Rs are phase shifted 90°)[7]

Have no idea what mac3dec did, total black box
open ac3 file save as stereo aiff.

For all I know it may have just saved "L" and "R" whatever the heck that means.

Now that it does not work on intel, do know it used sound converter which seems to still be available in the linux world.
Rosetta can not / will not run sound converter.

I have my ppc setup , I can go back
but was hoping I could do something with Audacity

[audio_pete]

here is as far as I get when exporting as apple aiff

"Your tracks will be mixed down to a single mono channel in the exported file"

On the other hand,
the choices on FFmpeg export are beyond bewildering.

There are formats: "aiff" is one
12 codecs and
10 general options

nothing that says stereo aiff you dummy ; )

[steve]

"Your tracks will be mixed down to a single mono channel in the exported file"

That's because all of your tracks are mono.
In my previous post I described how to create a stereo mix down.

On the other hand,
the choices on FFmpeg export are beyond bewildering.

As I wrote previously, you don't need to use FFmpeg to export AIFF files.

[audio_pete]

"Your tracks will be mixed down to a single mono channel in the exported file"

That's because all of your tracks are mono.
In my previous post I described how to create a stereo mix down.

On the other hand,
the choices on FFmpeg export are beyond bewildering.

As I wrote previously, you don't need to use FFmpeg to export AIFF files.

Ok can see that can make tracks left channel or right channel
I am looking at 6 tracks
5 make sound, 1 does not seem to be able to be played by my computer.
(its solo is very quiet)

Any idea which track goes where?
Is it
left
right
center
unplayable
left "highlight"
right "highlight"

You do need FFmpeg to open the AC3 file.

I am not trying to do anything fancy.
I used mac3dec to make a copy of the Buffy singing episode for my iPod. : )

[kozikowski]

I am not trying to do anything fancy

Yes, you are. You happen to have a program line-up that makes it look easy. In addition to the obvious L and R, you have dialog almost always in the Center (separate track), low frequency effects (rumble and boom) and Dial Norm which is the automatic volume control that allows the system to simulate the real sound of thunder and jets taking off. All that is or can be hiding in a surround AC3 performance and must be untangled for a stereo mixdown.

My fuzzy memory is that nobody tries to re-use the surround tracks. I could be corrected.

Koz