help needed to add 6ch audio to my ffmpeg command

[raebie2]

I am not clued about ffmpeg at all but looking at different threads i did manage to make a command line to convert my files. I was hoping someone could help me add 6ch audio in my command line this is my command

ffmpeg -i input.mkv -vcodec libx264 -vf "scale=1920:1080:flags=lanczos, format=yuv420p" -preset slow -crf 21.5 -c:a ac3 -b:a 256k output.mkv

help would be very appreciated thanks

[cholla]

This should work added to your code:

ffmpeg -i input.mkv -vcodec libx264 -vf "scale=1920:1080:flags=lanczos, format=yuv420p" -preset slow -crf 21.5 -c:a ac3 -b:a 256k -ac 6 output.mkv

I have never used a decimal for the -crf . I would use 21 or 22 for close to what you are trying.

[raebie2]

Thank you very much for the help it worked great. The decimal i use to get the exact size i want .1 to .9 i find it helps probably just me though lol