ffmpeg version git-2012-12-14-5c78a81 Copyright (c) 2000-2012 the FFmpeg developers
  built on Dec 23 2012 23:32:37 with gcc 4.4.5 (Debian 4.4.5-8)
  configuration: --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab --enable-libfreetype
  libavutil      52. 12.100 / 52. 12.100
  libavcodec     54. 79.102 / 54. 79.102
  libavformat    54. 49.102 / 54. 49.102
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 27.101 /  3. 27.101
  libswscale      2.  1.103 /  2.  1.103
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Input #0, flv, from 'pipe:':
  Metadata:
    encoder         : Lavf54.49.102
  Duration: 00:00:00.00, start: 0.017000, bitrate: N/A
    Stream #0:0: Video: h264 (High), yuv420p, 624x352 [SAR 1:1 DAR 39:22], 23.98 tbr, 1k tbn, 47.95 tbc
    Stream #0:1: Audio: mp3, 44100 Hz, stereo, s16p, 96 kb/s
Output #0, flv, to 'rtmp://...':
  Metadata:
    encoder         : Lavf54.49.102
    Stream #0:0: Video: h264 ([7][0][0][0] / 0x0007), yuv420p, 624x352 [SAR 1:1 DAR 39:22], q=2-31, 1k tbn, 1k tbc
    Stream #0:1: Audio: mp3 ([2][0][0][0] / 0x0002), 44100 Hz, stereo, 96 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
5rame=  161 fps= 24 q=-1.0 size=     270kB time=00:00:06.68 bitrate= 330.7kbits/s

=== NOW I KILLED PROCESS 1 AND PROCESS 3 (a new ffmpeg with pipes the stdout to stdin of process 2) SPAWNS ===

Failed to update header with correct duration.e=00:00:13.29 bitrate= 417.3kbits/s
[flv @ 0x32900a0] Failed to update header with correct filesize.
frame=  300 fps= 22 q=-1.0 Lsize=     703kB time=00:00:13.40 bitrate= 430.0kbits/s
video:379kB audio:310kB subtitle:0 global headers:0kB muxing overhead 2.070305%