Can't encode .aif and PCM audio

[Mr.Ash]

I can't encode any PCM 16bit stereo from a QT .mov to .ac3. I exported the audio to .aif but ffmpegX still can't encode it. The process windows says:

/movie.aif: Unknown format

or

Encoding started on Thu Jul 8 19:20:44 CEST 2004
Input #0, mov,mp4,m4a,3gp, from '/Volumes/Macintosh HD 2/TV/movie.mov':
Duration: 01:54:24.7, bitrate: 65833 kb/s
Stream #0.0: Video: mjpeg, 720x540, 24.96 fps
Stream #0.1: Audio: pcm_s16be, 48000 Hz, stereo, 1536 kb/s
Output #0, ac3, to '/Volumes/Macintosh HD 2/TV/movie.ac3':
Stream #0.0: Audio: ac3, 48000 Hz, 5:1, 448 kb/s
Stream mapping:
Stream #0.1 -> #0.0

[major]

Correct, aif input is not supported, it has to be wav.