Broken audio timestamps with Hikvision recording

[Carl Eugen Hoyos]

​http://ffmpeg.org/pipermail/ffmpeg-user/2017-December/038232.html
A two-minute sample was uploaded, video works correctly, audio has completely broken timestamps (plays for exactly two minutes).

$ ffmpeg -i 1.mp4 -vn -f null -
ffmpeg version N-89467-g0e52602 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 6.3.0 (GCC)
  configuration: --enable-gpl
  libavutil      56.  5.100 / 56.  5.100
  libavcodec     58.  6.103 / 58.  6.103
  libavformat    58.  3.100 / 58.  3.100
  libavdevice    58.  0.100 / 58.  0.100
  libavfilter     7.  7.100 /  7.  7.100
  libswscale      5.  0.101 /  5.  0.101
  libswresample   3.  0.101 /  3.  0.101
  libpostproc    55.  0.100 / 55.  0.100
Input #0, mpeg, from '1.mp4':
  Duration: 02:07:57.93, start: 789.820800, bitrate: 9 kb/s
    Stream #0:0[0x1e0]: Video: h264 (Baseline), yuv420p(progressive), 1920x1080, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x1c0]: Audio: pcm_mulaw, 8000 Hz, mono, s16, 64 kb/s
Stream mapping:
  Stream #0:1 -> #0:0 (pcm_mulaw (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
  Metadata:
    encoder         : Lavf58.3.100
    Stream #0:0: Audio: pcm_s16le, 8000 Hz, mono, s16, 128 kb/s
    Metadata:
      encoder         : Lavc58.6.103 pcm_s16le
size=N/A time=02:07:57.92 bitrate=N/A speed=2.33e+05x
video:0kB audio:1875kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

[Carl Eugen Hoyos]

​http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket6910/

[Carl Eugen Hoyos]

There is some indication that the sample is actually broken:
​http://ffmpeg.org/pipermail/ffmpeg-user/2018-January/038642.html