Arch Linux

Can't reproduce on x86_64. Can you post the output of:
ldd -r /usr/lib/libavdevice.so.53

paste ldd /usr/bin/ffmpeg

ldd /usr/bin/ffmpeg
linux-gate.so.1 => (0xb778b000)
libavdevice.so.53 => /usr/lib/libavdevice.so.53 (0xb7763000)
libavfilter.so.2 => /usr/lib/libavfilter.so.2 (0xb76d8000)
libavformat.so.53 => /usr/lib/libavformat.so.53 (0xb75ab000)
libavcodec.so.53 => /usr/lib/libavcodec.so.53 (0xb68e7000)
libpostproc.so.52 => /usr/lib/libpostproc.so.52 (0xb68be000)
libswresample.so.0 => /usr/lib/libswresample.so.0 (0xb68b4000)
libswscale.so.2 => /usr/lib/libswscale.so.2 (0xb6861000)
libavutil.so.51 => /usr/lib/libavutil.so.51 (0xb683b000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb6820000)
libm.so.6 => /lib/libm.so.6 (0xb67f3000)
libc.so.6 => /lib/libc.so.6 (0xb6652000)
libX11.so.6 => /usr/lib/libX11.so.6 (0xb651c000)
libXext.so.6 => /usr/lib/libXext.so.6 (0xb650a000)
libXfixes.so.3 => /usr/lib/libXfixes.so.3 (0xb6505000)
libasound.so.2 => /usr/lib/libasound.so.2 (0xb6410000)
libSDL-1.2.so.0 => /usr/lib/libSDL-1.2.so.0 (0xb6374000)
libpulse-simple.so.0 => /usr/lib/libpulse-simple.so.0 (0xb636e000)
libpulse.so.0 => /usr/lib/libpulse.so.0 (0xb6320000)
librtmp.so.0 => /usr/lib/librtmp.so.0 (0xb6307000)
libz.so.1 => /usr/lib/libz.so.1 (0xb62f0000)
libbz2.so.1.0 => /lib/libbz2.so.1.0 (0xb62e0000)
libva.so.1 => /usr/lib/libva.so.1 (0xb62c8000)
libxvidcore.so.4 => /usr/lib/libxvidcore.so.4 (0xb61a9000)
libx264.so.120 => /usr/lib/libx264.so.120 (0xb6051000)
libvpx.so.1 => /usr/lib/libvpx.so.1 (0xb5fa9000)
libvorbisenc.so.2 => /usr/lib/libvorbisenc.so.2 (0xb5e33000)
libvorbis.so.0 => /usr/lib/libvorbis.so.0 (0xb5e0c000)
libtheoraenc.so.1 => /usr/lib/libtheoraenc.so.1 (0xb5dca000)
libtheoradec.so.1 => /usr/lib/libtheoradec.so.1 (0xb5dad000)
libspeex.so.1 => /usr/lib/libspeex.so.1 (0xb5d95000)
libschroedinger-1.0.so.0 => /usr/lib/libschroedinger-1.0.so.0 (0xb5cc7000)
libopenjpeg.so.1 => /usr/lib/libopenjpeg.so.1 (0xb5ca6000)
libopencore-amrwb.so.0 => /usr/lib/libopencore-amrwb.so.0 (0xb5c90000)
libopencore-amrnb.so.0 => /usr/lib/libopencore-amrnb.so.0 (0xb5c64000)
libmp3lame.so.0 => /usr/lib/libmp3lame.so.0 (0xb5bec000)
libgsm.so.1 => /usr/lib/libgsm.so.1 (0xb5be1000)
/lib/ld-linux.so.2 (0xb778c000)
libxcb.so.1 => /usr/lib/libxcb.so.1 (0xb5bc3000)
libdl.so.2 => /lib/libdl.so.2 (0xb5bbd000)
librt.so.1 => /lib/librt.so.1 (0xb5bb4000)
libpulsecommon-1.1.so => /usr/lib/libpulsecommon-1.1.so (0xb5b4d000)
libjson.so.0 => /usr/lib/libjson.so.0 (0xb5b44000)
libdbus-1.so.3 => /usr/lib/libdbus-1.so.3 (0xb5afa000)
libssl.so.1.0.0 => /usr/lib/libssl.so.1.0.0 (0xb5aa1000)
libcrypto.so.1.0.0 => /usr/lib/libcrypto.so.1.0.0 (0xb58fb000)
libogg.so.0 => /usr/lib/libogg.so.0 (0xb58f4000)
liborc-0.4.so.0 => /usr/lib/liborc-0.4.so.0 (0xb5864000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0xb577b000)
libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0xb575d000)
libXau.so.6 => /usr/lib/libXau.so.6 (0xb575a000)
libXdmcp.so.6 => /usr/lib/libXdmcp.so.6 (0xb5755000)
libsndfile.so.1 => /usr/lib/libsndfile.so.1 (0xb56e3000)
libasyncns.so.0 => /usr/lib/libasyncns.so.0 (0xb56de000)
libFLAC.so.8 => /usr/lib/libFLAC.so.8 (0xb568d000)
libnsl.so.1 => /lib/libnsl.so.1 (0xb5673000)
libresolv.so.2 => /lib/libresolv.so.2 (0xb565c000)



ldd -r /usr/lib/libavdevice.so.53
linux-gate.so.1 => (0xb7701000)
libavfilter.so.2 => /usr/lib/libavfilter.so.2 (0xb764e000)
libavformat.so.53 => /usr/lib/libavformat.so.53 (0xb7521000)
libavcodec.so.53 => /usr/lib/libavcodec.so.53 (0xb685d000)
libavutil.so.51 => /usr/lib/libavutil.so.51 (0xb6837000)
libX11.so.6 => /usr/lib/libX11.so.6 (0xb6700000)
libXext.so.6 => /usr/lib/libXext.so.6 (0xb66ee000)
libXfixes.so.3 => /usr/lib/libXfixes.so.3 (0xb66e9000)
libasound.so.2 => /usr/lib/libasound.so.2 (0xb65f4000)
libSDL-1.2.so.0 => /usr/lib/libSDL-1.2.so.0 (0xb6558000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb653d000)
libpulse-simple.so.0 => /usr/lib/libpulse-simple.so.0 (0xb6537000)
libpulse.so.0 => /usr/lib/libpulse.so.0 (0xb64e9000)
libm.so.6 => /lib/libm.so.6 (0xb64bd000)
libc.so.6 => /lib/libc.so.6 (0xb631c000)
libswresample.so.0 => /usr/lib/libswresample.so.0 (0xb6312000)
libswscale.so.2 => /usr/lib/libswscale.so.2 (0xb62be000)
librtmp.so.0 => /usr/lib/librtmp.so.0 (0xb62a5000)
libz.so.1 => /usr/lib/libz.so.1 (0xb628e000)
libbz2.so.1.0 => /lib/libbz2.so.1.0 (0xb627e000)
libva.so.1 => /usr/lib/libva.so.1 (0xb6267000)
libxvidcore.so.4 => /usr/lib/libxvidcore.so.4 (0xb6148000)
libx264.so.120 => /usr/lib/libx264.so.120 (0xb5fef000)
libvpx.so.1 => /usr/lib/libvpx.so.1 (0xb5f47000)
libvorbisenc.so.2 => /usr/lib/libvorbisenc.so.2 (0xb5dd1000)
libvorbis.so.0 => /usr/lib/libvorbis.so.0 (0xb5dab000)
libtheoraenc.so.1 => /usr/lib/libtheoraenc.so.1 (0xb5d69000)
libtheoradec.so.1 => /usr/lib/libtheoradec.so.1 (0xb5d4b000)
libspeex.so.1 => /usr/lib/libspeex.so.1 (0xb5d33000)
libschroedinger-1.0.so.0 => /usr/lib/libschroedinger-1.0.so.0 (0xb5c65000)
libopenjpeg.so.1 => /usr/lib/libopenjpeg.so.1 (0xb5c44000)
libopencore-amrwb.so.0 => /usr/lib/libopencore-amrwb.so.0 (0xb5c2f000)
libopencore-amrnb.so.0 => /usr/lib/libopencore-amrnb.so.0 (0xb5c03000)
libmp3lame.so.0 => /usr/lib/libmp3lame.so.0 (0xb5b8a000)
libgsm.so.1 => /usr/lib/libgsm.so.1 (0xb5b7f000)
libxcb.so.1 => /usr/lib/libxcb.so.1 (0xb5b61000)
libdl.so.2 => /lib/libdl.so.2 (0xb5b5c000)
librt.so.1 => /lib/librt.so.1 (0xb5b53000)
/lib/ld-linux.so.2 (0xb7702000)
libpulsecommon-1.1.so => /usr/lib/libpulsecommon-1.1.so (0xb5aeb000)
libjson.so.0 => /usr/lib/libjson.so.0 (0xb5ae2000)
libdbus-1.so.3 => /usr/lib/libdbus-1.so.3 (0xb5a98000)
libssl.so.1.0.0 => /usr/lib/libssl.so.1.0.0 (0xb5a40000)
libcrypto.so.1.0.0 => /usr/lib/libcrypto.so.1.0.0 (0xb589a000)
libogg.so.0 => /usr/lib/libogg.so.0 (0xb5892000)
liborc-0.4.so.0 => /usr/lib/liborc-0.4.so.0 (0xb5802000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0xb5719000)
libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0xb56fc000)
libXau.so.6 => /usr/lib/libXau.so.6 (0xb56f9000)
libXdmcp.so.6 => /usr/lib/libXdmcp.so.6 (0xb56f3000)
libsndfile.so.1 => /usr/lib/libsndfile.so.1 (0xb5681000)
libasyncns.so.0 => /usr/lib/libasyncns.so.0 (0xb567c000)
libFLAC.so.8 => /usr/lib/libFLAC.so.8 (0xb562c000)
libnsl.so.1 => /lib/libnsl.so.1 (0xb5612000)
libresolv.so.2 => /lib/libresolv.so.2 (0xb55fa000)
undefined symbol: _XGetRequest (/usr/lib/libavdevice.so.53)

Sounds like _XGetREquest -> libxi, so what is your version of libxi?
Also pacman -Syyu should be usefull.

Thanks Jelle,

I've performed a full system upgrade and now ffmpeg works correctly!