Overview

Transcoding audio, and trying to make it "perfect" can be a pain in the ass. When it comes to audio it's easy to go overboard, and try useless procedures that really just degrade the audio quality. I'm mostly referring to normalizing audio. Seriously, don't bother just use your converter, and turn the volume up, or down, and save yourself a whole lot of theory, and useless forum talk.

Section 1 - What steps to take

To figure out what applies to you read below

1. ac3 file extracted using virtualdubmod - run ac3fix on it, then skip to the next section
2. ac3 file extracted using something else - run ac3fix on it just to be sure it's not corrupt, then skip to next section
3. wav file extracted from virtualdubmod - read this section
4. any format other then the above - read this section

Section 2 - Converting any format to Wav

If you have a wav file you can skip this bit. To convert an audio file to ac3 we must first convert the audio file to a wav file. To do this load up foobar2000. I'm pretty sure this is a free program, and is awesome for converting odd file formats to wav format. If you have a file format that you have never seen before, or can't play you will need to download a filter for it. Formats that will require filters include AAC, OGG, AC3. Once you can play the audio file in foobar you will be able to convert it.

Now we are going to setup the options, so that when we decode our audio to wav format there is no clipping.

Go to Components -> DiskWriter settings. Aside from the output directory make sure all your settings are identical to the ones in the picture below

Now we need to setup a dsp. To do this go to your Playback -> DSP Manager settings. Now add the Advanced Limiter dsp to the list. Always make sure the Advanced Limiter dsp is at the bottom of the list. The reason we need to use this dsp is because it helps to remove, or reduce clipping from your extracted audio. If you have experience dealing with MP3 files I'm sure your familar with mp3gain which is a program that can change the gain on an mp3 file to eliminate clipping. The advanced limiter sort of works like that, it removes the clipping caused by decoding your audio file to wav.

After you have done that save your settings, and follow these steps to convert your audio

1. Playlist -> add files
2. select all your audio files
3. press (crtl + a) to select all
4. right click on the files
5. convert -> run conversion

This takes care of the first part of converting to ac3. You should know have a whole bunch of wav files ready for converting to ac3. For this next section you will need to go download BeSweet and the GUI for it, and ac3machine. BeSweet is a program that acts as an interface to a wide variety of programs in our case this would be ac3machine.

Section 3 - Converting Wav -> AC3

For this next section you will need the following programs.

• BeSweet 1.5bv29 with GUI
• The AC3Machine v0.41

Make sure you find the GUI for BeSweet, it helps a lot. To install BeSweet just extract it to a directory, and throw the GUI file in the same directory. To install ac3machine just put the file in the same directory as BeSweet. To load it up double-click the BeSweet GUI icon.

At first glance BeSweets interface can be intimidating, but once you get use to it, it's not that bad. I'll provide lots of pics to help get things moving fast.

We first need to setup out options for ac3 encoding. Click on the input folder (top left). A new window should now open up. In this window click on VOB/AC3/LST on the left side under BeSweet.exe. Once you have done this select wav from the listbox on the top right under where it says Enter File Name. Click Ok.

In your main screen it should display wav -> to some format under the batch mode button. If not you need to go back and fix it until wav shows up first. No click on the BeSweet button and where it says AC3Enc select ac3 from the listbox. Under batch mode your button should now display wav -> ac3.

Now just click on the AC3/OGG/PCM, and change your bitrate to 256, and leave the other options as is.

Now that all our options are setup, we are going to use batch mode, so we don't have to load up the files one at a time. To use batch mode I suggest that you first go to windows explorer, and open up you directory with all your audio files, and select them all. Now make BeSweet the active window, and move it down, so that the batch mode button is level with your start menu. Once you have donw that click the batch mode button, and move the other two windows down just enough so you can see some of your selected audio files. Now move your mouse over then selected files and click and drag them in to the batch mode window.

Your list should now be filled with the audio you selected. You are now ready to encode your wav files to ac3 files. Just click the BeSweet's list -> Multiple WAVS button. It should take around 5 - 10 minutes to complete. If all goes well the transcoding process looks like the pic below.

After BeSweet has finished converting to ac3 you will have fully complient ac3 files ready to be muxed together with your video, but before you skip to the next section I highly recommmend that your run all your ac3 files through ac3 fix just to be certain they are not corrupt.

Section 4 - Using ac3fix

To be a 100% sure your ac3 file is good run it through ac3fix just to be on the safe side. I just make a batch file and run them all through that, only takes a few minutes to setup. To setup your batch file use the example below as a reference. Also make sure that your batch file is in the same directory as the ac3fix.exe file.

In the above example the first part ac3fix refers to the command (just like DOS). The next part refers to our input file (file that needs fixing). The next part refers to our renamed output file, so we can differentiate between the two files.

The audio portion is done, you now have high quality Dolby Digital 2/0 (depending on your settings) ac3 files that are fully DVD complient, and compatable with all DVD players that you know will work :)

>> Part 6. Trimming