What does this statement mean?

[SameSelf]

I ran across this on the web, and needless to say, it caught my attention. Can anyone provide further insight into this?

I use ffmpeg with the following parameters:
ffmpeg -i input -strict experimental -map 0:0 -map 0:1 -map 0:1 -c:v libx264 -preset placebo -crf 17 -c:a:0 aac -b:a:0 192k -c:a:1 ac3 -b:a:1 192k output

Now I know these aren't the best encoders on ffmpeg, but to get the best I would need to compile from source to get the best since they are part of the nonfree encoder set.

libx264 doesn't have the best encoders? would need to compile from the source to get the best? huh????

[sneaker]

He's probably talking about the aac audio. The aac encoders coming with e.g. zeranoe's builds have a bad reputation. If you compile with Fraunhofer aac encoder you will get better aac compression but the builds may not be distributed for licensing reasons depending on your local laws.

[SameSelf]

ahh, the audio encoder, of course. I was thinking, for a second, that there was some sort of special sauce in the x264 source code that one could only access if you compiled it yourself. Thanks.