[FFmpeg-user] How can I determine behavior of the -to command?

[Grant Curtis]

I have two different videos. If I run the command:

$ ffmpeg -i [input] -c copy -to 10 [output]

on both videos, I will receive outputs of slightly different length. An
inspection of the frames reveals that, with one video, it'll stop on the
frame with the "best_effort_timestamp_time" of 10.04, and with the other
video, it'll stop on the frame with the timestamp of 9.96

What can I do to determine how the -to command will work with any given
video?

The two videos:

$ ffprobe  -hide_banner input1.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2018-03-14T22:10:26.000000Z
    encoder         : HandBrake 1.0.7 2017040900
  Duration: 00:00:33.02, start: 0.000000, bitrate: 2778 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,
smpte170m/bt470bg/bt709), 1920x1080 [SAR 1:1 DAR 16:9], 2653 kb/s, 25 fps,
25 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2018-03-14T22:10:26.000000Z
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
stereo, fltp, 159 kb/s (default)
    Metadata:
      creation_time   : 2018-03-14T22:10:26.000000Z
      handler_name    : Stereo

$ ffprobe  -hide_banner input2.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2018-02-17T02:19:35.000000Z
  Duration: 00:02:43.10, start: 0.000000, bitrate: 190 kb/s
    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 /
0x31637661), yuv420p, 320x240 [SAR 1:1 DAR 4:3], 116 kb/s, 25 fps, 25 tbr,
12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono,
fltp, 72 kb/s (default)
    Metadata:
      creation_time   : 2018-02-17T02:19:35.000000Z
      handler_name    : IsoMedia File Produced by Google, 5-11-2011