What is the difference between AC3 and AC3_fixed?

Hello. :slight_smile:

I see in the options for the codec in the audio tab at the export menu has to AC3 listings. One says “AC3” and the other says “AC3fixed”.

Can someone tell me what the difference between the two is?


Both are audio codec formats available to use in Shotcut. The fixed version is most likely more efficient or less compressed, or some combination of the two. Or it could be that the original AC-3 version couldn’t be supported by some programs, but the fixed version could. I was able to play back videos exported with both of these formats in the default windows player and VLC. A quick test using both codecs with default settings for everything else really yields no noticeable difference in the audio quality. However I suspect that might change depending on what other audio export settings you use, such as sample rate, bit rate, and control. Sorry this isn’t more of a “clear” answer but it seems to me there isn’t a “clear” difference between them either.

floating point versus integer for the sample input. You should use the non-fixed one.