ffmpeg/avconv bitstream filter options

[Jon Davies]

I had a bug report relating to the ubuntu precise builds I've put
together, the relevant bit of which is as follows:

avconv version 0.8.1-4:0.8.1-0ubuntu1, Copyright (c) 2000-2011 the Libav
developers
 built on Mar 22 2012 05:29:10 with gcc 4.6.3
Input #0, aac, from
'/home/mark/Podcasts/Saturday_Drama/Saturday_Drama_-_Mountain_of_Light_b00sqgdw_default.partial.aac':
 Duration: 01:01:35.85, bitrate: 131 kb/s
   Stream #0.0: Audio: aac, 44100 Hz, stereo, s16, 131 kb/s
Unrecognized option 'absf'
Failed to set value 'aac_adtstoasc' for option 'absf'
INFO: Command exit code 1 (raw code = 256)

it appears that recent versions of both ffmpeg and avconv have changed
the options for applying bitstream filters  (see
http://ffmpeg.org/ffmpeg.html#toc-Bitstream-Filters).

For ubuntu precise, due out in a matter of days, I'm going to have to
change get_iplayer to support the new option formats, the question
that arises is whether we should
(a) change get_iplayer to support a more recent version of
ffmpeg/avconv universally and drag windows, mac and older linux users
into the new world, together with newer builds of the tools
(b) treat this as a special case for ubuntu precise for now
or
(c) make it possible to support both the old and new option formats
adding yet another option to get_iplayer to set this

any thoughts?
Jon