ffmpeg -acodec copy does not copy all audio stream to the new container

Question

I wish i can find ffmpeg help here at stackexchange. I'd been re-encoding old videos to libx264 to save up some storage space, as I thought it should be working based on documentation seems failing to me. I'd been using the snippet below to re encode all files:

ffmpeg -i "$file" -y -acodec copy -vcodec libx264 -scodec copy -threads 12 -x264-params keyint=240:min-keyint=20 -profile:v baseline -level 3.0 "$output"

the -acodec copy i believed should be able to map all audio streams and just copy them all to the new container right? but I can't understand why all those dual audio videos are being re-encoded to a single audio video, the non-default audio stream was omitted/removed.

any idea how can I copy all codecs audio, subtitle, but only the vcodec to be re-encoded to libx264?

thanks!

Answer 1

https://trac.ffmpeg.org/wiki/How%20to%20use%20-map%20option#Example4

-map 0 would map all the streams, then keep them as it is then just state which codec to re-encode.

i should read more.