Created attachment 172842 [details]
aac file that contains 2 audio channels then 6 then 2 then 6 (recorded with faac outputformat=1)

** steps to reproduce:

gst-launch-0.10 filesrc location=res.aac ! aacparse ! faad ! ffenc_ac3 ! filesink location=res.ac3

** Actual result:

Lot of errors when switching to 6 audio channels:

0:00:09.248382223 20569  0x8725130 ERROR                 ffmpeg gstffmpegcodecmap.c:122:gst_ff_channel_layout_to_gst: Number of channels is different (2 != 6)
0:00:09.250532238 20569  0x8725130 ERROR                 ffmpeg :0:: Bit allocation failed. Try increasing the bitrate.

But the recording pipeline does not stop.

Playing it with:

gst-launch-0.10 -v filesrc location=res.ac3 ! ac3parse ! a52dec ! audioconvert ! alsasink

You can hear the beginning of res.ac3 but you cannot hear when switching to 6 audio channels. 
But at least it seems to be detected (when switching from 2 to 6 channels: ac3parse0.GstPad:src: caps = audio/x-ac3, framed=(boolean)true, rate=(int)48000, channels=(int)6)

** Expected result:

You should be able to hear the whole audio stream from res.ac3

** Other infos:

- You can hear with aacparse: gst-launch-0.10 filesrc location=res.aac !
aacparse ! faad ! alsasink