AC3

[james_stewart]

I downloaded a Divx movie with 128kb 64/ch stereo audio. I extracted the audio to wave and then converted it to AC3 with AC3machine. I noticed a 400mb difference in size from from the wave file, the AC3 file is much smaller. Can someone tell me why, and is there any quality loss or is there a quality increase? Why do people recommend turning your wave files to AC3 files? Does the video conversion in Tmpgenc remain the same even when you're using AC3 audio?

[Perro Grande]

AC3 is a compressed format, while WAV is not. In my experience, the resultant AC3 file is about 1/4th the size of the starting WAV file.

Quality/Loss depends largely on what bitrate you select when converting to AC3. Likewise, the more times an audio file is converted to and from lossy compression methods (like MP3 and AC3) the worse the quality will be. There will certainly not be an increase in quality going to AC3 format. The best you can hope for is minimal degradation of quality.

I usually always compress my audio, unless I'm working on a project sufficiently small as to not notice the difference or there is a specific quality requirement.

[james_stewart]

The conversion that I did was exactly the same 128kb as the original avi file. the wave file was 1.1gb the AC3 file was 611mb. When you use the Bitrate calculator does it take a wave file into account?