ffmpeg and ac3 ?

[Dieter]

FreeBSD 7.0 release  amd64

I compiled ffmpeg from ports.  Input is mpeg2 transport stream
from OTA ATSC/8VSB.  Output is DV.

My old non-ports ffmpeg reports the input as

Stream #0.2[0x34]: Audio: ac3, 48000 Hz, stereo, 384 kb/s
or
Stream #0.2[0x34]: Audio: ac3, 48000 Hz, 5:1, 448 kb/s
or similar.

Ffmpeg from ports says:

Stream #0.1[0x44], 1/90000: Audio: liba52, 48000 Hz, stereo, 192 kb/s

output is:

old:  Stream #0.1: Audio: pcm_s16le, 48000 Hz, stereo, 1536 kb/s
new:  Stream #0.1, 1/90000: Audio: pcm_s16le, 48000 Hz, stereo, 1536 kb/s

Audio was ok with the old version.  I don't recall haviing to jump through
any hoops to get audio working before.  Problem is, with the new ports version,
the output is silent.  No error messages, just silence.

Adding "-acodec ac3" gives "unknown codec".

There is a libavcodec/ac3dec.c ac3 decoder, but it doesn't appear to
be used.  Turning on ENABLE_AC3_DECODER in config.h doesn't build.

Didn't find anything with google.

What is the secret?