How to convert an 5.1 AAC to 5.1 AC3?

[Jacoh]

Hi people! Got a movie with aac 5.1 audio, and want to convert it to AC3. But if I try to convert to WAV and then to AC3, I will loss the 5.1 channel won't I? there's someway to convert it without changing it to 2.0? thanks a lot!

[Skelsgard]

But if I try to convert to WAV and then to AC3, I will loss the 5.1 channel won't I?
Not at all. Use FAAD2 (the .exe, wich u can get from www.rarewares.com, along with the latest Menno GUI (the GUI is for convenience, but not mandatory)) to decode the file. The default settings will give u a 6-ch interleaved WAV file. All AAC profiles are decoded: LC/MAIN/LTP/HE.
Don´t know how much u know, so ask again for what u don´t know/understand if needed.
Then u encode to AC3:
BeSweet: load the 6-ch file into BeSweet (with Belight or BeSweet GUI, again cause it´s faster) and export it as 5.1 AC3. Upside: fast, free. Downside: is not one of the the best AC3 encoders, not much options.
FFDShow Audio: load the 6-ch WAV, and export it as AC3 (rendering within GraphEdit). Upside: fast, free. Downside: not much options. Don´t know about quality.
Soft Encode Dolby Digital: u need to strip the 6-ch WAV into 6 mono WAVs. Do that with Wavewizard (free, great options, excellent piece of software, no downsides anywhere) making sure that the exported WAVs are in WAV PCM format. Then load them into Soft Encode and encode. Upside: great quality (certified encoder). Downside: paid software, discontinued.
Surcode Dolby Digital: Downside: paid software (one of the programs that are NOT worth their pennies.)
Sony Vegas 6.0 AC-3 Encoder: load the 6 mono WAVs and encode. Upside: excellent quality (certified encoder), Dolby Surround EX options for 6.1 channels matrix encoding. Downside: paid software (but one of the programs that are worth every penny, a lot better than Premiere IMHO).

[Jacoh]

thanks mna! i already tried the faad, but when is decoding it appears (the channels will be reorganized) theni thought: Aff and if what should be in the center end going to the lsurround? thats why i didnt made it. i've been using scenarist and sonic foundry to encode ac3. if I split the wav into 6 diferent mono like u said, how can i know what is what there? thanks a lot man!

[Skelsgard]

Aff and if what should be in the center end going to the lsurround?
Don´t quite understand wath your saying but i´m assuming that u mean channel remapping. If u split the WAV, the wavewizard will asign a channel number to each, as in decoded_ch1.wav, decoded_ch2.wav and so on. To know what channels are wich (if remapping is being made in the faad decoding) just listen to and compare the source AAC with the splitted WAVs, and rename the WAVs accordingly, let´s say i.e. decoded_Center.wav, decoded_Left.wav (is more of a common sense thing).

[Dams]

Hi,

I've done similar actions with faad and besweet, and the correct order to give to besweet to obtain an AC3 file is (in a .mux file ) :

FL.wav
C.wav
FR.wav
SL.wav
SR.wav
LFE.wav

right !?

Cya

[Skelsgard]

Yes, that`s the standard order for AC3.

[Hans Ohlo]

Sony Vegas 6.0 AC-3 Encoder: load the 6 mono WAVs and encode. Upside: excellent quality (certified encoder), Dolby Surround EX options for 6.1 channels matrix encoding. Downside: paid software (but one of the programs that are worth every penny, a lot better than Premiere IMHO).could you please give a small step by step how to do this? i have vegas at work and have not seen how to get the streams in there properly.

i mean i get them into vegas and tell them which channel to map to, but after encoding the track sounds a lot dimmer. i read the ac3 encoding tutorial in here, but some parameters in the decoder a cant switch off (sourround and center mix level is always -3db). all other preprocessing options i turned off, because the source is also an ac3 stream.

[Skelsgard]

This are the track settings u need to ensure an output with equal volume as the source.
For Dolby Digital 5.1:
http://img164.imageshack.us/img164/2995/tracks7yo.jpg

For Dolby Digital Surround EX 5.1 (Matrix 6.1):
http://img164.imageshack.us/img164/439/tracksex4hn.jpg
Notice that the Rear Center (RC) channel has active both rear channels to enable sending the same audio info to each one of them, to be decoded afterwards by a Dolby EX decoder.

Notice that in the Surround Panner, ALL the tracks are mixed as "Balance (0dB Center)". It doesn´t matter to the output level that it says -6,0 on each speaker since that´s the default amount (and each speaker will be 0db compared to the center: i.e. if center is at 2dB and left is at 3dB, left will remain as 3dB cause the balance states that it will be 0dB of difference (3dB - 0dB = 3dB), if the balance is set to -6dB, then left woill be at -3dB (3dB - 6dB = -3dB)).
http://img164.imageshack.us/img164/2126/surroundpan5wv.jpg

Then render as Dolby Digital using this parameters:
For Dolby 5.1:
http://img156.imageshack.us/img156/7940/dolby015hr.jpg
http://img156.imageshack.us/img156/9743/dolby027sl.jpg
http://img164.imageshack.us/img164/8222/dolby035bn.jpg
The "Enable Extended Extended Bitstream" option is disabled, and so all the others in the Ex. Bitstream tab.

For Dolby Surround EX:
The "Enable Extended Extended Bitstream" option is enabled, as follows:
http://img156.imageshack.us/img156/7043/dolbyex011eg.jpg

(sourround and center mix level is always -3db)
You need to understand that these are DOWNMIXING parameters, not actual encoding. These parameters tell the decoder how much volume attenuation to apply to the center and surround channels when being mixed into the Lt/Rt stereo output (done by the decoder when 2ch output is selected in 5.1 systems, or by default in DVD players that only have 2ch output). They DO NOT affect when in 5.1: i.e. in 2ch, the C and SL and SR will be inside Lt/Rt at -3dB each, in 4-ch(2/2 quadraphonic) the Lt/Rt will have C at -3dB but the SL/SR will remain the same since they are not being mixed into Lt/Rt, in 3ch (3/0, Lt/Rt + C) the C is not mixed into Lt/Rt hence it remains untouched while SL and SR are mixed into Lt/Rt at -3 dB. In 5.1 there is NO DOWNMIXING, therefore the mix levels are not applied. Get it?. Same thing for the mix levels in the Extended bitstream information tab.

[enter]

I have a problem with Vegas 6. When I want to export to AC3 it opens something like an IE window for configuration, but everytime I get a Internet Explorer Script Error, Page could not be loaded correctly > so I'cant export to AC3. Is this a popular problem with an easy fix?

thx

[Skelsgard]

there´s a way to fix it:
- create a .txt file (i.e. vegasac3.txt)
- copy this lines and paste them into the .txt (all of them)
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Sony Media Software\AC-3 Encoder]

[HKEY_LOCAL_MACHINE\SOFTWARE\Sony Media Software\AC-3 Encoder\1.0]

[HKEY_LOCAL_MACHINE\SOFTWARE\Sony Media Software\AC-3 Encoder\1.0\License]
"AppGrade"="0x0040"
"CurrentKey"="paste key"

[HKEY_LOCAL_MACHINE\SOFTWARE\Sony Media Software\AC-3 Encoder\1.0\Metrics]
- replace "paste key" with your AC-3 Serial activation number (must be within doublequotes: i.e. "HJ-GT46T-4JDE-whatever").
- rename the .txt --> .reg (i.e. vegasac3.reg)
- open the .reg: it´ll prompt you to add the info into the Registry, or right-click --> Combine, then OK.
Done.