title: Recording RTP VP8 packets with FFMPEG with named pipe
body: <p>I'm developing a <code>WebRTC</code> video session recorder, in a gateway developed in C++, where I only have access to individual <code>RTP</code> packets.</p>
  
  <p>When a session starts, I create two threads one that initializes a named pipe and an other that starts <code>FFMPEG</code> to fetch data from that pipe and store it in a matroska file, with the command: </p>
  
  <pre><code>ffmpeg -i \\.\pipe\screenRec -f matroska D:\djhfifj.mkv
  </code></pre>
  
  <p>Whenever I receive an <code>RTP</code> packet I send it through the pipe to <code>FFMPEG</code>. Although all communication is working fine, <code>FFMPEG</code> does not seem to be recognizing the <code>RTP</code> packet:</p>
  
  <pre><code>ffmpeg version N-73633-gdfc5858 Copyright (c) 2000-2015 the FFmpeg developers
    built with gcc 4.9.2 (GCC)
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib
    libavutil      54. 28.100 / 54. 28.100
    libavcodec     56. 47.100 / 56. 47.100
    libavformat    56. 40.100 / 56. 40.100
    libavdevice    56.  4.100 / 56.  4.100
    libavfilter     5. 21.100 /  5. 21.100
    libswscale      3.  1.101 /  3.  1.101
    libswresample   1.  2.100 /  1.  2.100
    libpostproc    53.  3.100 / 53.  3.100
  [aac @ 031b3fc0] Format aac detected only with low score of 1, misdetection possible!
  [aac @ 031bd820] More than one AAC RDB per ADTS frame is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
  [aac @ 031bd820] channel element 3.13 is not allocated
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (26) exceeds limit (9).
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (60) exceeds limit (44).
  [aac @ 031bd820] Number of bands (6) exceeds limit (4).
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (30) exceeds limit (23).
  [aac @ 031bd820] Sample rate index in program config element does not match the sample rate index configured by the container.
  [aac @ 031bd820] Inconsistent channel configuration.
  [aac @ 031bd820] get_buffer() failed
  [aac @ 031bd820] Assuming an incorrectly encoded 7.1 channel layout instead of a spec-compliant 7.1(wide) layout, use -strict 1 to decode according to the specification instead.
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (16) exceeds limit (11).
  [aac @ 031bd820] Dependent coupling is not supported together with LTP
      Last message repeated 9 times
  [aac @ 031bd820] channel element 3.5 is not allocated
  [aac @ 031bd820] channel element 3.13 is not allocated
  [aac @ 031bd820] channel element 3.3 is not allocated
  [aac @ 031bd820] Number of bands (16) exceeds limit (14).
  [aac @ 031bd820] channel element 3.10 is not allocated
  [aac @ 031bd820] channel element 3.2 is not allocated
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of scalefactor bands in group (61) exceeds limit (43).
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (29) exceeds limit (13).
  [aac @ 031bd820] Sample rate index in program config element does not match the sample rate index configured by the container.
  [aac @ 031bd820] Inconsistent channel configuration.
  [aac @ 031bd820] get_buffer() failed
  [aac @ 031bd820] channel element 0.7 is not allocated
  [aac @ 031bd820] Number of bands (24) exceeds limit (15).
  [aac @ 031bd820] channel element 1.1 is not allocated
  [aac @ 031bd820] channel element 2.0 is not allocated
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of scalefactor bands in group (62) exceeds limit (41).
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (15) exceeds limit (13).
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (23) exceeds limit (2).
  [aac @ 031bd820] channel element 1.4 is not allocated
  [aac @ 031bd820] Assuming an incorrectly encoded 7.1 channel layout instead of a spec-compliant 7.1(wide) layout, use -strict 1 to decode according to the specification instead.
  [aac @ 031bd820] channel element 1.2 is not allocated
  [aac @ 031bd820] channel element 1.8 is not allocated
  [aac @ 031bd820] channel element 3.7 is not allocated
  [aac @ 031bd820] channel element 2.9 is not allocated
  [aac @ 031bd820] channel element 3.8 is not allocated
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of scalefactor bands in group (48) exceeds limit (43).
  [aac @ 031bd820] channel element 3.8 is not allocated
  [aac @ 031bd820] channel element 2.13 is not allocated
  [aac @ 031bd820] channel element 3.4 is not allocated
  [aac @ 031bd820] Dependent coupling is not supported together with LTP
      Last message repeated 13 times
  [aac @ 031bd820] channel element 2.14 is not allocated
  [aac @ 031bd820] SBR was found before the first channel element.
  [aac @ 031bd820] Sample rate index in program config element does not match the sample rate index configured by the container.
  [aac @ 031bd820] Inconsistent channel configuration.
  [aac @ 031bd820] get_buffer() failed
  [aac @ 031bd820] Number of bands (6) exceeds limit (5).
  [aac @ 031bd820] channel element 3.0 is not allocated
  [aac @ 031bd820] channel element 1.5 is not allocated
  [aac @ 031bd820] channel element 1.13 is not allocated
  [aac @ 031bd820] channel element 1.7 is not allocated
  [aac @ 031bd820] channel element 2.0 is not allocated
  [aac @ 031bd820] Dependent coupling is not supported together with LTP
      Last message repeated 13 times
  [aac @ 031bd820] channel element 3.0 is not allocated
  [aac @ 031bd820] Assuming an incorrectly encoded 7.1 channel layout instead of a spec-compliant 7.1(wide) layout, use -strict 1 to decode according to the specification instead.
  [aac @ 031bd820] SBR was found before the first channel element.
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (31) exceeds limit (30).
  [aac @ 031bd820] channel element 1.12 is not allocated
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] Number of bands (29) exceeds limit (10).
  [aac @ 031bd820] channel element 3.2 is not allocated
  [aac @ 031bd820] channel element 3.15 is not allocated
  [aac @ 031bd820] channel element 1.5 is not allocated
  [aac @ 031bd820] channel element 2.7 is not allocated
  [aac @ 031bd820] channel element 1.9 is not allocated
  [aac @ 031bd820] Number of bands (54) exceeds limit (34).
  [aac @ 031bd820] channel element 1.6 is not allocated
  [aac @ 031bd820] channel element 1.2 is not allocated
  [aac @ 031bd820] channel element 3.7 is not allocated
  [aac @ 031bd820] Reserved bit set.
  [aac @ 031bd820] ms_present = 3 is reserved.
  [aac @ 031b3fc0] decoding for stream 0 failed
  [aac @ 031b3fc0] Could not find codec parameters for stream 0 (Audio: aac (LTP), 4.0, fltp, 1506 kb/s): unspecified sample rate
  Consider increasing the value for the 'analyzeduration' and 'probesize' options
  \\.\pipe\screenRec96: could not find codec parameters
  Input #0, aac, from '\\.\pipe\screenRec96':
    Duration: N/A, bitrate: 1506 kb/s
      Stream #0:0: Audio: aac (LTP), 4.0, fltp, 1506 kb/s
  [abuffer @ 0435cd00] Value inf for parameter 'time_base' out of range [0 - 2.14748e+009]
      Last message repeated 3 times
  [abuffer @ 0435cd00] Error setting option time_base to value 1/0.
  [graph 0 input from stream 0:0 @ 0319afe0] Error applying options to the filter.
  Error opening filters!
  </code></pre>
  
  <p>Is it possible to make <code>FFMPEG</code> understand that the packet sent is <code>RTP</code> with <code>VP8</code>?</p>