View Full Version : ac3 question


Jonathan Grant
September 5th, 2006, 03:39 PM
I'm not that familiar with ac3. I know it allows you to do surround sound, but is there an advantage over 24bit wav when only doing stereo? The film I'm working on is stereo and not surround. Should I bother with trying export in ac3?

The audio has been cleaned up and edited in pro-tools, exported as a 24 bit wav file, then imported to sony vegas to match with the video. Would exporting it in ac3 format be any different than exporting it in 24bit wav?

Peter Jefferson
September 5th, 2006, 06:05 PM
I'm not that familiar with ac3. I know it allows you to do surround sound,
((surround sound wow factor is only one element)

but is there an advantage over 24bit wav when only doing stereo?

((if this si for DVD, then 24bit isnt an option...16bit@ 48khz is the DVD standard, whether it be wav or ac3 or dts ))

The film I'm working on is stereo and not surround. Should I bother with trying export in ac3?
((a 192kbps ac3 stereo file ill give you the full 20khz bandwidth of audio. much like a surround sound 5.1 encoded file at 448kbps. to the naked ear the differnce will not be noticable, however the end file you will have will be MUCH smaller than PCM wav, in turn allowing you to have a higher bitrate for your image))

The audio has been cleaned up and edited in pro-tools, exported as a 24 bit wav file, ((u sure about that?? How was it recorded? Scaling up and interplating the bitrate really makes no differece if the source material is recorded as 16bit... ))

then imported to sony vegas to match with the video. Would exporting it in ac3 format be any different than exporting it in 24bit wav?

((for DVD, yo udont have a choice. it MUST be 16bit... either pcm or ac3 or even mpg audio <which DVDArchitect doesnt support by the way>

good luck with it

Eric Darling
September 5th, 2006, 06:50 PM
AC3 format is compressed, whereas WAV isn't. So, you'll save a ton of room, and you'll also leave more total muxed bitrate percentage available for video - possibly leading to a better quality product. But perhaps the best side-effect of converting your sound tracks to AC3 format is that it will greatly improve the chances that your DVD will be more compatible with more DVD playing devices.

Make sure your settings are appropriate for DVD video - depending on what tools you're using for the encode, this can be more or less challenging.

Jonathan Grant
September 8th, 2006, 04:49 AM
Thanks guys. Is there a program out there that just converts wav files to ac3? I don't think the version of Vegas has an ac3 encoder.

Eric Darling
September 8th, 2006, 06:15 AM
http://www.dekorte.com/projects/shareware/SoundConverter/

Emre Safak
September 8th, 2006, 07:27 AM
Vegas does have an AC3 encoder; you just need to install DVD Architect. Go to Render As from the File menu. What are you making your DVDs with?

Jonathan Grant
September 11th, 2006, 06:02 PM
Is there a program for PC?

Emre Safak
September 11th, 2006, 06:47 PM
Vegas is a PC application. Do you mean free?

Jonathan Grant
September 12th, 2006, 01:29 PM
Sorry, no I meant stand-alone. I am doing the sound editing and don't have Vegas and all that.

Emre Safak
September 12th, 2006, 02:09 PM
Try this (http://www.doom9.org/index.html?/belight-ac3toac3.htm) free, stand-alone encoder. While the guide is written for AC3 to AC3, you can use it for converting any common audio format to AC3.

Derek Prestegard
September 17th, 2006, 09:42 PM
yes yes yes! doom9! :)

There are some decent free AC3 encoders, but the payware is generally a lot better. Dolby charges too much for their IP licenses...

About your 24 bit master..

Make sure the sources were recorded in 24 bit. If they weren't, then re-export the project into a 16 bit wav. 24 bit is a waste of space in that case.

DVD standard supports PCM, MP2, AC3, and DTS. Some players won't play all of these formats, but they all HAVE to play AC3. So AC3 is always a safe route. It also has the advantage of dynamic range compression (assuming the decoder can make use of this metadata), and dialogue normalization. AC3 is awesome :) In general I would always reccommend it for the reasons other people have stated!

-Derek Prestegard