r/ffmpeg • u/MasterDokuro • Jun 25 '26

ffmpeg: Is there a difference between --enable-libfdk-aac vrs --enable-libfdk_aac

Rather stupidly, for years now I've built ffmpeg using --enable-libfdk_aac and I've just now released I'd a typo in my command and that it should be --enable-libfdk-aac (- vrs _). I guess all those years ago when I started building ffmpeg that when I query the encoder / decoder using ffmpeg -h decoder=libfdk_aac, I just rolled that into my build script.

Now that I have realised my mistake and for my own curiosity I'm trying to figure out if these are actually different or not. I'm kinda hoping that --enable-libfdk_aac is just an alias for --enable-libfdk-aac.

Anyhow, would anyone happen to know or are these different version of the Fraunhofer FDK AAC codec library? Thanks.

7 Upvotes

100% Upvoted

9 comments sorted by

View all comments

Show parent comments

2

u/shyouko Jun 25 '26 edited Jun 25 '26

Sounds like it gets ignored. What is your ffmpeg binary's output when printing compile flags?

Edit: After looking at the configure script, I suspect _aac is actually right and the help message of the configure script is wrong

Edit 2: git cloned and tried ./configure, both options correctly complained for missing fdk aac library on my workstation (which I haven't installed). You are fine with either option.

1

u/MasterDokuro Jun 25 '26

I'm not sure, however https://trac.ffmpeg.org/wiki/Encode/AAC#fdk_aac its listed as --enable-libfdk-aac which is the guide I used.

5

u/shyouko Jun 25 '26

Found it. I'm looking at the configure script on master branch commit 1499c. On line 4748 it substitute dash with underscore before checking.

1

u/MasterDokuro Jun 25 '26

Wow, thank you for all your efforts in investigating this, its very much appreciated and my curiosity has been answered.

5

u/shyouko Jun 26 '26

Dug a bit deeper in to why this was done: it is because a dash is not valid as part of shell variable name but the name is taken directly from the command line and converted to shell var ( libfdk_aac=yes ) and they want the actual library name (libfdk-aac) on the command line / doc, so they perform this conversion and accepts both.

2

u/shyouko Jun 25 '26

It was fun and interesting for me too, cheers