Option -brand does nothing

[Ulf Zibis]

Summary of the bug: I used option "-brand" to manually set the major brand name, but here is what I got
How to reproduce:

$ ~/Projects/ffmpeg/dev_2/ffmpeg -i MVI_1324.MOV -c:a copy -profile:v baseline -level 4.1 -colorspace smpte170m -color_primaries bt709 -color_trc bt709 -refs 1 -g 15 -map_metadata 0 -brand "qt  CAEP" MVI_1324_smpte170m_git.mov
ffmpeg version N-96935-g34d7c8d942 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --enable-libx264 --enable-gpl
  libavutil      56. 42.100 / 56. 42.100
  libavcodec     58. 75.100 / 58. 75.100
  libavformat    58. 41.100 / 58. 41.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.100 /  7. 77.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'MVI_1324.MOV':
  Metadata:
    major_brand     : qt
    minor_version   : 537331968
    compatible_brands: qt  CAEP
    creation_time   : 2020-02-05T20:17:27.000000Z
  Duration: 00:00:29.10, start: 0.000000, bitrate: 23351 kb/s
    Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuvj420p(pc, smpte170m/bt709/bt709), 1280x720, 23228 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 2020-02-05T20:17:27.000000Z
    Stream #0:1(eng): Audio: pcm_u8 (raw  / 0x20776172), 12000 Hz, mono, u8, 96 kb/s (default)
    Metadata:
      creation_time   : 2020-02-05T20:17:27.000000Z
File 'MVI_1324_smpte170m_git.mov' already exists. Overwrite? [y/N] y
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[libx264 @ 0x56147f6a2900] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x56147f6a2900] profile Constrained Baseline, level 4.1
[libx264 @ 0x56147f6a2900] 264 - core 152 r2854 e9a5903 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=15 keyint_min=1 scenecut=40 intra_refresh=0 rc_lookahead=15 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mov, to 'MVI_1324_smpte170m_git.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 537331968
    compatible_brands: qt  CAEP
    creation_time   : 2020-02-05T20:17:27.000000Z
    encoder         : Lavf58.41.100
    Stream #0:0(eng): Video: h264 (libx264) (avc1 / 0x31637661), yuvj420p(pc, smpte170m/bt709/bt709), 1280x720, q=-1--1, 29.97 fps, 30k tbn, 29.97 tbc (default)
    Metadata:
      creation_time   : 2020-02-05T20:17:27.000000Z
      encoder         : Lavc58.75.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1(eng): Audio: pcm_u8 (raw  / 0x20776172), 12000 Hz, mono, u8, 96 kb/s (default)
    Metadata:
      creation_time   : 2020-02-05T20:17:27.000000Z
frame=  872 fps= 14 q=-1.0 Lsize=   22995kB time=00:00:29.06 bitrate=6481.7kbits/s speed=0.478x
video:22641kB audio:341kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.056903%
[libx264 @ 0x56147f6a2900] frame I:63    Avg QP:23.08  size: 54602
[libx264 @ 0x56147f6a2900] frame P:809   Avg QP:25.80  size: 24405
[libx264 @ 0x56147f6a2900] mb I  I16..4: 34.0%  0.0% 66.0%
[libx264 @ 0x56147f6a2900] mb P  I16..4: 12.9%  0.0%  6.3% P16..4: 46.8% 17.8%  3.9%  0.0%  0.0%    skip:12.3%
[libx264 @ 0x56147f6a2900] coded y,uvDC,uvAC intra: 40.8% 45.3% 6.7% inter: 32.6% 30.1% 0.2%
[libx264 @ 0x56147f6a2900] i16 v,h,dc,p: 28% 31% 21% 20%
[libx264 @ 0x56147f6a2900] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 13% 42% 17%  4%  4%  3%  7%  2%  8%
[libx264 @ 0x56147f6a2900] i8c dc,h,v,p: 66% 18% 14%  2%
[libx264 @ 0x56147f6a2900] kb/s:6374.39

$ ~/Projects/ffmpeg/dev_2/ffprobe MVI_1324_smpte170m_git.mov
ffprobe version N-96935-g34d7c8d942 Copyright (c) 2007-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --enable-libx264 --enable-gpl
  libavutil      56. 42.100 / 56. 42.100
  libavcodec     58. 75.100 / 58. 75.100
  libavformat    58. 41.100 / 58. 41.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.100 /  7. 77.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'MVI_1324_smpte170m_git.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 512
    compatible_brands: qt
    creation_time   : 2020-02-05T20:17:27.000000Z
    encoder         : Lavf58.41.100
  Duration: 00:00:29.10, start: 0.000000, bitrate: 6474 kb/s
    Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuvj420p(pc, smpte170m/bt709/bt709), 1280x720, 6374 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
    Metadata:
      creation_time   : 2020-02-05T20:17:27.000000Z
      handler_name    : VideoHandler
      encoder         : Lavc58.75.100 libx264
    Stream #0:1(eng): Audio: pcm_u8 (raw  / 0x20776172), 12000 Hz, mono, u8, 96 kb/s (default)
    Metadata:
      creation_time   : 2020-02-05T20:17:27.000000Z
      handler_name    : SoundHandler

[Carl Eugen Hoyos]

Only the first four characters are written.