[Libav-user] Why ffmpeg is writing to stderr instead of stdout?

[satya gowtham kudupudi]

$ ffmpeg -f v4l2 -r 15 -s 40x30 -i /dev/video0 -f flv rtmp://
192.168.2.125:25333/venkat/test0
ffmpeg version git-2013-07-17-a0b7e73 Copyright (c) 2000-2013 the FFmpeg
developers
  built on Jul 17 2013 17:20:26 with gcc 4.7 (Ubuntu/Linaro 4.7.3-1ubuntu1)
  configuration: --prefix=/usr/local/ffmpeg_build
--extra-cflags=-I/usr/local/ffmpeg_build/include
--extra-ldflags=-L/usr/local/ffmpeg_build/lib --bindir=/usr/local/bin
--extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac
--enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis
--enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
  libavutil      52. 40.100 / 52. 40.100
  libavcodec     55. 18.102 / 55. 18.102
  libavformat    55. 12.102 / 55. 12.102
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 81.101 /  3. 81.101
  libswscale      2.  4.100 /  2.  4.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
[video4linux2,v4l2 @ 0xf0ce40] The V4L2 driver changed the video from 40x30
to 160x120
Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 8718.480573, bitrate: 4608 kb/s
    Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 160x120,
4608 kb/s, 15 fps, 15 tbr, 1000k tbn, 1000k tbc
[tcp @ 0xf0cd40] Connection to tcp://192.168.2.125:25333 failed: No route
to host
[rtmp @ 0xf0e060] Cannot open connection tcp://192.168.2.125:25333
rtmp://192.168.2.125:25333/venkat/test0: No route to host

I am making system call to above command and i want to extract only error
message but unfortunately ffmpeg is writing non error messages to stderr.
-- 
*Gowtham*
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