AC3 to MP2/MP3 transcoding
In order to get the best possible quality in this process and without having to create any temporary files or rely on complicated DirectShow Filter operations there can be only 2 solutions to the problem: BeSweet and HeadAC3he.
The two programs offer the same basic functionality: Decode AC3 using azid while also supporting WAV, MP2 and MP3 input, normalize and boost the volume of the input files, downsample using ssrc, encode to MP3 using lame, mp2 using mp2enc and encode to Ogg Vorbis. Furthermore they both support 6ch WAV output and Dolby Surround 2 downmix. Each program also has its own specialties: BeSweet is also used for AAC encoding using AACMachine, it can output AIFF files required for MPEG-2 multichannel audio creation, it can create AC3 files using ac3enc, it allows you to adjust the length of the audio for TV format conversions, supports MP3 and Vorbis post gain which means the AC3 has only to be decoded once to find the optimal gain, VOB input, has a built-in equalizer, can append silence at the end of a track, and supports some of lame's special switches. HeadAC3he on the other hand has a special float mode that will also result in only decoding the AC3 once to find the optimal gain but requires a lot of HD space and a fast I/O subsystem to really make this feature count - but it is more accurate than MP3 post gain - it supports 4 channel downmix for Ogg Vorbis, it allows you to set a priority for the decoding process so that you can still work normally on your PC, you can pause the process and the program is a regular GUI program but can also be launched via command line parameters and using an ini file to configure it whereas BeSweet is a pure commandline program and needs a GUI if you don't want to launch it from the commandline (though that GUI also allows you to set a process priority).
Now make your pick:
This document was last updated on 07/25/02