Frame rate changing for no reason

[Elliott]

I have an MKV source at 23.98 fps. I simply rewrap it to MOV with stream copy, and the output is 24.39 fps, as identified by running ffmpeg again with that as the input. Both commands shown below:

$ ffmpeg -i /Scratch/Spears/Spears\ Munsil\ v2\ MKV/VIDEO\ CALIBRATION/002\ brightness.mkv -vcodec copy out.mov
ffmpeg version 3.0.git Copyright (c) 2000-2016 the FFmpeg developers

built with Apple LLVM version 7.0.2 (clang-700.1.81)
configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-avresample --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-libtheora --enable-libschroedinger --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libsoxr --enable-libspeex --enable-libass --enable-libbluray --enable-lzma --enable-gnutls --enable-fontconfig --enable-libfreetype --enable-libfribidi --disable-indev=jack --disable-outdev=xv --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --enable-vda --enable-audiotoolbox --enable-videotoolbox --arch=x86_64 --enable-yasm --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid --enable-nonfree --enable-libfdk-aac --enable-libfaac
libavutil 55. 28.100 / 55. 28.100
libavcodec 57. 51.100 / 57. 51.100
libavformat 57. 46.100 / 57. 46.100
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 50.100 / 6. 50.100
libavresample 3. 0. 0 / 3. 0. 0
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100

[h264 @ 0x7facfa008400] sps_id 1 out of range
[matroska,webm @ 0x7facf980a800] decoding for stream 0 failed
Input #0, matroska,webm, from '/Scratch/Spears/Spears Munsil v2 MKV/VIDEO CALIBRATION/002 brightness.mkv':

Metadata:

encoder : libmakemkv v1.10.4 (1.3.3/1.4.4) win(x64-release)
creation_time : 2017-02-17 04:27:15

Duration: 00:00:00.04, bitrate: 1719 kb/s

Stream #0:0(eng): Video: h264 (High), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc
Metadata:

stereo_mode : block_lr
BPS-eng : 1100292
DURATION-eng : 00:00:00.041708333
NUMBER_OF_FRAMES-eng: 1
NUMBER_OF_BYTES-eng: 5639
SOURCE_ID-eng : 001011
_STATISTICS_WRITING_APP-eng: MakeMKV v1.10.4 win(x64-release)
_STATISTICS_WRITING_DATE_UTC-eng: 2017-02-17 04:27:15
_STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES SOURCE_ID

Side data:

stereo3d: frame alternate

[mov @ 0x7facfa800600] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Output #0, mov, to 'out.mov':

Metadata:

encoder : Lavf57.46.100
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 23.98 fps, 23.98 tbr, 16k tbn, 1k tbc
Metadata:

stereo_mode : block_lr
BPS-eng : 1100292
DURATION-eng : 00:00:00.041708333
NUMBER_OF_FRAMES-eng: 1
NUMBER_OF_BYTES-eng: 5639
SOURCE_ID-eng : 001011
_STATISTICS_WRITING_APP-eng: MakeMKV v1.10.4 win(x64-release)
_STATISTICS_WRITING_DATE_UTC-eng: 2017-02-17 04:27:15
_STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES SOURCE_ID

Side data:

stereo3d: frame alternate

Stream mapping:

Stream #0:0 -> #0:0 (copy)

Press [q] to stop, ? for help
frame= 1 fps=0.0 q=-1.0 Lsize= 6kB time=00:00:00.00 bitrate=832761.9kbits/s speed=0.589x
video:6kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 16.297216%
$
$
$
$ ffmpeg -i out.mov
ffmpeg version 3.0.git Copyright (c) 2000-2016 the FFmpeg developers

built with Apple LLVM version 7.0.2 (clang-700.1.81)
configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-avresample --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-libtheora --enable-libschroedinger --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libsoxr --enable-libspeex --enable-libass --enable-libbluray --enable-lzma --enable-gnutls --enable-fontconfig --enable-libfreetype --enable-libfribidi --disable-indev=jack --disable-outdev=xv --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --enable-vda --enable-audiotoolbox --enable-videotoolbox --arch=x86_64 --enable-yasm --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid --enable-nonfree --enable-libfdk-aac --enable-libfaac
libavutil 55. 28.100 / 55. 28.100
libavcodec 57. 51.100 / 57. 51.100
libavformat 57. 46.100 / 57. 46.100
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 50.100 / 6. 50.100
libavresample 3. 0. 0 / 3. 0. 0
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100

[h264 @ 0x7fb653825400] sps_id 1 out of range
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out.mov':

Metadata:

major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf57.46.100

Duration: 00:00:00.04, start: 0.000000, bitrate: 1279 kb/s

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 1100 kb/s, 24.39 fps, 24.39 tbr, 16k tbn, 47.95 tbc (default)
Metadata:

handler_name : DataHandler

At least one output file must be specified

[Carl Eugen Hoyos]

How can a one-frame file have a frame-rate?

For future tickets: Please remember to test current FFmpeg git head before opening a ticket.