AC3Machine is a front-end that automates the AC3 encoding process. It uses BeSweet in order to transcode AC3/MP2/MP3 to a regular AC3 file or an AC3 WAV for Dolby Digital audio CDs. The AC3 encoder being used is ac3enc which is part of the ffmpeg project.

Once you've started AC3Machine, configure the location of BeSweet.exe and the input file. The output file will be automatically set.

Then configure the downmix options. These are essentially the same settings as in the Azid/BeSweet GUI. If you have a 5.1ch AC3 source which you want to downconvert to a 2 channel AC3 check LFE To LR Channels and set it to -3db, and in all other cases leave this option unchecked. Also don't check the other 3 options.

Then the overall settings:

Channels mode sets the resulting output format. Surround means you get a 2ch Dolby Surround encoded AC3 file which is the default. Stereo would only give you a stereo file and 5.1 would result in a 6 channel AC3 (which of course only works if the input is also 5.1 channel). AC3-WAV will create an AC3 WAV file that you can used to create a DolbyDigital audio CD (just burn the WAV as a regular CD and hook up the digital output of your CD player to your AC3 capable receiver).

Dynamic Compression would reduce the dynamic range of the output file but here it's not really needed - you don't want to tamper with the dynamics or your transcoded file will suddently behave much different from the original. The same applies to the rest of the options.

Leave Set Delay to checked so you won't have to tamper with offsets when adding the AC3 to your DVD projects (or AVIs).

Change framerate is only necessary if you want to convert a PAL movie to NTSC (25000 -> 23976) or NTSC to PAL (23976 -> 25000).

Last but not least let's configure the AC3 bitrate.

Set whatever bitrate you see fit. Going below 224kbit/s for a 5.1ch AC3 doesn't make much sense and going above the input bitrate doesn't make any sense either.

Once you're all set press the "Give me AC3!" button to start transcoding. If you get a runtime error you most likely haven't properly configured the path to BeSweet.exe or you need to download the latest release of msvbvm60.dll. Don't forget to check Output to Logfile.. it will help you in case you're having any problems (basically you can't expect any help in the forum if you can't supply that file.. it helps us determine what could've gone wrong).