[FFmpeg-user] asetnsamples loses channel layout?

[Roger Pack]

Hello.
I noticed that:

ffmpeg.exe -filter_complex "amovie=mono.wav [l] ; amovie=mono.wav [r]
; [l] [r] amerge" -y yo.wav

works fine, but if I add "setnsamples" into each audio stream, I get
the following:

$ ffmpeg.exe -filter_complex "amovie=mono.wav [l] ; amovie=mono.wav
[r] ; [l] asetnsamples=n=1000 [l1]; [r] asetnsamples=n=1000 [r1]; [l1]
[r1] amerge" -y yo.wav
ffmpeg version N-44014-g8944206 Copyright (c) 2000-2012 the FFmpeg developers
  built on Aug 30 2012 13:43:43 with gcc 4.7.1 (GCC)
  configuration: --enable-memalign-hack --arch=x86 --enable-gpl
--enable-libx264 --enable-avisynth --enable-libxvid
--target-os=mingw32
--cross-prefix=/home/rogerdpack/dev/ffmpeg-windows-build-helpers/builds/mingw-w64-i686/bin/i686-w64-mingw32-
--pkg-config=pkg-config --enable-libmp3lame --enable-version3
--enable-libvo-aacenc --enable-libvpx --extra-libs=-lws2_32
--extra-libs=-lpthread --enable-zlib --extra-libs=-lwinmm
--extra-libs=-lgdi32 --enable-librtmp --enable-libvorbis
--enable-libtheora --enable-libspeex --enable-libopenjpeg
--enable-gnutls --enable-libgsm --enable-libfreetype
--disable-optimizations --enable-mmx --disable-postproc
--enable-runtime-cpudetect
  libavutil      51. 70.100 / 51. 70.100
  libavcodec     54. 54.100 / 54. 54.100
  libavformat    54. 25.104 / 54. 25.104
  libavdevice    54.  2.100 / 54.  2.100
  libavfilter     3. 14.100 /  3. 14.100
  libswscale      2.  1.101 /  2.  1.101
  libswresample   0. 15.100 /  0. 15.100
[wav @ 020B9E00] max_analyze_duration 5000000 reached at 5034667
[Parsed_amovie_0 @ 0037EA80] Channel layout is not set in output
stream 0, guessed channel layout is 'mono'
[wav @ 020BD480] max_analyze_duration 5000000 reached at 5034667
[Parsed_amovie_1 @ 020BD360] Channel layout is not set in output
stream 0, guessed channel layout is 'mono'
[Parsed_amerge_4 @ 020BD2E0] No channel layout for input 1

(early exit).
Anybody know if this is expected?
Thanks!
-r