Infinite loop in do_video_out

[tsmith]

How to reproduce:

% ffmpeg -f ivf -i <test_case> -an out.mp4

ffmpeg version N-77454-ge42e0b1 Copyright (c) 2000-2015 the FFmpeg developers
  built with Ubuntu clang version 3.7.1-svn253742-1~exp1 (branches/release_37) (based on LLVM 3.7.1)
  configuration: --cc=clang --cxx=clang++ --disable-libxcb --disable-xlib --disable-logging --disable-ffprobe --disable-ffplay --disable-sdl --disable-ffserver --disable-doc --disable-pthreads --disable-network --disable-d3d11va --disable-dxva2 --disable-vaapi --disable-vda --disable-vdpau --disable-stripping --disable-runtime-cpudetect --disable-optimizations --disable-pic
  libavutil      55. 11.100 / 55. 11.100
  libavcodec     57. 20.100 / 57. 20.100
  libavformat    57. 20.100 / 57. 20.100
  libavdevice    57.  0.100 / 57.  0.100
  libavfilter     6. 21.101 /  6. 21.101
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101

built on Linux x86_46

[Carl Eugen Hoyos]

$ ffmpeg -f ivf -i hanging.ivf out.mp4
ffmpeg version N-77567-g29e6606 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      55. 11.100 / 55. 11.100
  libavcodec     57. 20.100 / 57. 20.100
  libavformat    57. 21.100 / 57. 21.100
  libavdevice    57.  0.100 / 57.  0.100
  libavfilter     6. 22.100 /  6. 22.100
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Truncating packet of size 170197058 to 105
Input #0, ivf, from 'hanging.ivf':
  Duration: 17:25:43.20, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: vp9 (Profile 0) (VP90 / 0x30395056), yuv420p(tv), 320x432, 133.70 tbr, 133.70 tbn, 133.70 tbc
Output #0, mp4, to 'out.mp4':
  Metadata:
    encoder         : Lavf57.21.100
    Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 320x432, q=2-31, 200 kb/s, 133.70 fps, 59228 tbn, 133.70 tbc
    Metadata:
      encoder         : Lavc57.20.100 mpeg4
    Side data:
      unknown side data type 10 (24 bytes)
Stream mapping:
  Stream #0:0 -> #0:0 (vp9 (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
Input stream #0:0 frame changed from size:320x432 fmt:yuv420p to size:395x511 fmt:yuv420p
frame=720768 fps=5301 q=2.0 size=  165648kB time=01:29:51.03 bitrate= 251.7kbits/s dup=720766 drop=0 speed=39.6x
video:162597kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.876789%