Distorted sound after converting to mpg

[Colin Law]

Hi

I am just learning about get-iplayer and have succeeded in downloading
programs to mp4 files.  In order to show them on my tv (which will
only read mpg) I am attempting to convert to mpg using ffmpeg, using
the command line
ffmpeg -i program.mp4 -target pal-dvd program.mpg
Unfortunately the audio produced is hiss, slightly modified by the
underlying audio track.  The video is fine.

If instead I use -target pal-vcd the sound is ok but I get lower quality video.

I googled and searched the mail archives but did not find anything.

Any help would be much appreciated.

Colin