AC3 to Dolby Digital wav

[Richard Fairbanks]

Does anyone know how to convert an existing AC3 file (such as from A-Pack) into a Dolby Digital wav file? I would think that there would be a simple utility, shareware or freeware, but a couple hours googling hasn't uncovered one. Am I blind? Mac or PC is okay.

[Eric L]

Hey Richard,

You could give this a try. It's free. I have not used it, myself.

Also, if you have A-Pack 1.5, you can decode the ac3 to sdII files, and then use quicktime to convert those to wav. Not sure which is better, or if it matters since, the files are lossy anyway and audio quality is already compromised by the ac3 encoding process.

[Richard Fairbanks]

Thanks, Eric!!

Actually I found AC3Filter while I was googling. I can't tell if it does what I want to do, but my guess is that I would need to decode to audio then re-encode it to Dolby Digital wav. I would like to be able to do a simple conversion of AC3 files already existing into wav files, that can then be distributed and handled via S/PDIF or AES and fed into appropriate inputs of hardware decoders, or layback to videotape. I don't think A-pack does that, does it? I am not interested in decoding it to sound, rather I am looking for a way to output the data to video tape, or DAT, or whatever using Pro Tools. Does that make sense? SoundCode can make the type of file I want, so can a hardware Dolby encoder. I guess I could buy SoundCode and re-encode what I already have, but I was trying to find another way. Another workaround would be to burn DVDs and capture audio playback from the player's S/PDIF output but that just seems crazy-inefficient.

[minister]

i thought of a.pack because it will convert it from AC-3, but when you said Dolby Digital wav... what is Dolby Digital wav?

[TVPostSound]

http://besweet.notrace.dk/

[Eric L]

I can't tell if it does what I want to do, but my guess is that I would need to decode to audio then re-encode it to Dolby Digital wav.

Oops. I'm sorry, I did not read your request accurately. My bad. I kinda scanned over the Dolby Digital WAV part in my eagerness to help.

I don't think A-pack does that, does it?

No, you're right, it does not.

what is Dolby Digital wav? (from minister)

It is an actual wav file that contains the ac-3 data packets, which allows for the signal to be played and recorded by digibetas.(and possibly other digital devices?) If I remember correctly, the digibeta is put in "data" mode and the AES pair records the signal at full scale. Which is kinda freeky, because the clip lights are on all the time, and that is usually indicative of a major goof. The digibeta also must be in "cut" mode not "crossfade mode" or the bitstream gets all screwed up on insert edits.

But I digress, sorry about the hijack Richard. I think DIAFXMX has got you covered.

[Richard Fairbanks]

Thanks for the besweet link. Have you used it? I have seen a couple of references to it during my googles, mostly about how inconvenient the command line interface is. All user guide links I tried are currently broken and this line of text concerns me a bit:

ac3enc.dll creates (almost) useless ac3 streams. don't use it to encode things you care for. it's there only for test purposes.

I read that on a FAQ page. Maybe that is a wink-and-a-nod effort to avoid legal problems (ineffective though it may be), maybe it is just a hacked encoder. As with any freeware I am not excited about loading it (freeware often installs things you really do not want). Maybe I'll roll up my sleeves and try it, if I have to. As I said, I am not looking for a solution that requires decode to pcm data before making a Dolby Digital wav. I actually want to keep the properly encoded, and licensed, data I already have. In my head it seems very possible.

[TVPostSound]

Havent tried it yet, it's on my long "to do" list. I just remembered it, after seeing your post.
I also need to hijack my son's PC, as all my rigs are Macs!!!!

[pneyrinck]

I can think of two ways to do this.

The first solution uses the Neyrinck SoundCode For Dolby Digital plug-in:

1. Create a stereo track in Pro Tools.
2. Open the AudioSuite SoundCode Dolby Digital Decoder.
3. Set "decoding mode" to "data stream." Set "output stem format" to "stereo." Set "length" to "entire."
4. Place the cursor in the stereo track.
5. Choose your AC3 file with the "browse" control.
5. Click "Decode and Import." SoundCode will now import the AC3 stream into the stereo track, undecoded.
6. Use PT to export to a stereo interleaved 16-bit WAV file.

The second solution is less precise because you will have to do a bit of editing and requires the ability to author a DVD.
1. Burn the AC3 file into a DVD movie using a DVD authoring tool.
2. Play the DVD using a DVD player with its digital output connected to a Pro Tools input.
3. Record the data stream to a stereo track.
4. Edit the track to start at the first frame of AC3 data and end after the last frame of AC3 data
4. Export to a stereo interleaved 16-bit WAV file.

Paul Neyrinck
www.neyrinck.com

[Richard Fairbanks]

Ah, thank you Paul, that is what I want to do. I'm glad to know that SoundCode will do it, a definite timesaver for me! Your second solution is the brute force workaround I was trying to avoid. Now, you'll let me just "borrow" a copy of your plugin won't you?