Muxing with ffmpeg -> vfr, why?

[Selur]

using:

ffmpeg -y  -i "E:\Temp\18_17_42_2410_04.264" -vcodec copy -map 0:0 -bsf:v h264_mp4toannexb -vtag avc1 -metadata encoding_tool="Hybrid 2019.11.22.1"  -aspect 181818:100000 -r 60 "E:\Output\ffmpeg.mp4"

MediaInfo shows:

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4.1
Format settings                          : CABAC / 3 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 3 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 17 s 158 ms
Bit rate                                 : 1 500 kb/s
Width                                    : 640 pixels
Height                                   : 352 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Frame rate                               : 59.940 (59940/1000) FPS
Minimum frame rate                       : 25.016 FPS
Maximum frame rate                       : 60.000 FPS
Original frame rate                      : 60.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.111
Stream size                              : 3.04 MiB (100%)
Writing library                          : x264 core 158 r2988 7817004
Encoding settings                        : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x111 / me=hex / subme=5 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=0 / threads=11 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=1 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=1500 / ratetol=1.0 / qcomp=0.50 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=62500 / vbv_bufsize=78125 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:0.00
Color range                              : Limited
Matrix coefficients                      : BT.470 Sys

When using MP4Box instead,

MP4Box -add "E:\Temp\18_17_42_2410_04.264"#video:fps=60:name="" -brand avc1 -itags tool="Hybrid 2019.11.22.1" -tmp "E:\Temp" -new "E:\Output\18_17_22_8410__08.mp4"

MediaInfo reports:

Frame rate mode                          : Constant
Frame rate                               : 60.000 FPS

Am I missing something obvious?

--
Here are the x264 calls I used for the encoding:
1st pass:

x264 --preset veryfast --pass 1 --bitrate 1500 --profile high --level 4.1 --bframes 0 --sync-lookahead 24 --qcomp 0.5 --rc-lookahead 40 --qpmax 81 --aq-mode 0 --sar 1:1 --non-deterministic --range tv --stats "E:\Temp\test_18_17_22_8410_03.stats" --demuxer y4m  --input-range tv --fps 60/1 --output-depth 8 --output NUL -

2nd pass:

x264 --preset veryfast --pass 2 --bitrate 1500 --profile high --level 4.1 --ref 3 --bframes 0 --sync-lookahead 24 --qcomp 0.5 --rc-lookahead 40 --qpmax 81 --partitions i4x4,p8x8,b8x8 --no-fast-pskip --subme 5 --aq-mode 0 --vbv-maxrate 62500 --vbv-bufsize 78125 --sar 1:1 --non-deterministic --range tv --colormatrix bt470bg --stats "E:\Temp\test_18_17_22_8410_03.stats" --demuxer y4m  --input-range tv --fps 60/1 --output-depth 8 --output "E:\Temp\18_17_22_8410_04.264" -

Cu Selur

[Selur]

Okay, found a workaround, by specifying the frame rate also before the input.

Cu Selur