Increase volume in video using ffmpeg

A quick note on how to boost the audio stream in a video using the volume filter in ffmpeg

#;For newer versions of ffmpeg
ffmpeg -i input.mkv -filter:a "volume=4.0" output.mkv;
#For older versions of ffmpeg (we use multiples of 256)
ffmpeg -i input.mkv -vol 1024 -vcodec copy output.mkv;

Using the above command we were able to make the audio LOUDER!