[FFmpeg-user] ERROR in ffmpeg install on UBUNTU 14.04

[WY]

Dear ffmpeg users,

I am tring to install ffmpeg on UBUNTU 14.04, however could NOT install. 
The install process is the following:

#install PPA
sudo add-apt-repository ppa:mc3man/trusty-media

sudo apt-get update

W: GPG error: http://ppa.launchpad.net trusty Release: The following 
signatures couldn't be verified because the public key is not available: 
NO_PUBKEY 632D16BB0C713DA6


#install ffmpeg
sudo apt-get install ffmpeg

sudo ln -sf /opt/ffmpeg/bin/ffmpeg /usr/bin/ffmpeg

# check install
$ ffmpeg -codecs 2>&1 | grep PPM
DEV D  ppm             PPM (Portable PixelMap) image
$ rpm -qi ffmpeg

following info shows:

package ffmpeg is not installed


I am wondering if it is a correct way to install ffmpeg, pls anyone 
kindly indicate on this.

BTW, I could NOT find any search toolbar in user-archives, will it be 
modified?


Many thx,