Encoding to -f null is broken

[Carl Eugen Hoyos]

Encoding to -f null sometimes fails since af1761f7b5b1b72197dc40934953b775c2d951cc

$ ffmpeg -i fate-suite/svq3/Vertical400kbit.sorenson3.mov -f null -
ffmpeg version N-87628-g148c8e8 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 6.3.0 (GCC)
  configuration: --enable-gpl
  libavutil      55. 77.101 / 55. 77.101
  libavcodec     57.106.104 / 57.106.104
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57.  9.101 / 57.  9.101
  libavfilter     6.106.100 /  6.106.100
  libswscale      4.  7.103 /  4.  7.103
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
Guessed Channel Layout for Input Stream #0.1 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'fate-suite/svq3/Vertical400kbit.sorenson3.mov':
  Metadata:
    creation_time   : 2001-03-20T16:17:18.000000Z
    title           : Vertical Online SV3 Demo
    title-eng       : Vertical Online SV3 Demo
    artist          : Logan Kelsey
    artist-eng      : Logan Kelsey
    copyright       : © Vertical Online 2001
    copyright-eng   : © Vertical Online 2001
    encoder         : Sorenson Video 3
    encoder-eng     : Sorenson Video 3
  Duration: 00:00:43.58, start: 0.000000, bitrate: 580 kb/s
    Stream #0:0(eng): Video: svq3 (SVQ3 / 0x33515653), yuvj420p(pc), 320x240, 391 kb/s, 30.02 fps, 30 tbr, 600 tbn, 600 tbc (default)
    Metadata:
      creation_time   : 2001-03-20T16:17:18.000000Z
      handler_name    : Apple Alias Data Handler
      encoder         : Sorenson Video 3
    Stream #0:1(eng): Audio: adpcm_ima_qt (ima4 / 0x34616D69), 44100 Hz, mono, s16p, 176 kb/s (default)
    Metadata:
      creation_time   : 2001-03-20T16:17:18.000000Z
      handler_name    : Apple Alias Data Handler
Stream mapping:
  Stream #0:0 -> #0:0 (svq3 (native) -> wrapped_avframe (native))
  Stream #0:1 -> #0:1 (adpcm_ima_qt (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
[adpcm_ima_qt @ 0x28dc980] Multiple frames in a packet.
Too many packets buffered for output stream 0:1.
Conversion failed!

[ponpon]

To cehoyos
Plesea see #6472. The error of this ticket don't happen by a delete of #6472. Do #6375 and #6472 have a relationship to this ticket?
Thank you,

[Carl Eugen Hoyos]

Duplicate of ticket #6375, #6472.