The follow is my work flow, my mac has been installed ffmpeg, but when program checking not this.
please help me to analyse, where wrong.

localhost:mac app zhangzhang$ sudo port -u upgrade outdated
Error: No ports matched the given expression
localhost:mac app zhangzhang$ sudo port install kdenlive
---> Computing dependencies for kdenlive
Error: Dependency 'ffmpeg' not found.
To report a bug, follow the instructions in the guide:
http://guide.macports.org/#project.tickets
Error: Processing of port kdenlive failed
localhost:mac app zhangzhang$ ffmpeg
ffmpeg version 1.1.1 Copyright (c) 2000-2013 the FFmpeg developers
built on Jan 29 2013 16:01:44 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
configuration: --disable-yasm --prefix=/usr/ --enable-shared
libavutil 52. 13.100 / 52. 13.100
libavcodec 54. 86.100 / 54. 86.100
libavformat 54. 59.106 / 54. 59.106
libavdevice 54. 3.102 / 54. 3.102
libavfilter 3. 32.100 / 3. 32.100
libswscale 2. 1.103 / 2. 1.103
libswresample 0. 17.102 / 0. 17.102
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

Use -h to get full help or, even better, run 'man ffmpeg'
localhost:mac app zhangzhang$ sudo port install kdenlive
Password:
---> Computing dependencies for kdenlive
Error: Dependency 'ffmpeg' not found.
To report a bug, follow the instructions in the guide:
http://guide.macports.org/#project.tickets
Error: Processing of port kdenlive failed