ffmpeg with overlay and -ss cause the second layer to start on the wrong frame

[jsteinkamp]

::start on frame 11 end 15 -ss start in seconds 11-1 / 30 = 0.33333333333333333333333333333333
set sf=0.33333333333333333333333333333333
ffmpeg -y -framerate 30 -i %st% -ss %sf% -framerate 30 -i %st% -ss %sf% -frames 5 -filter_complex [0:v][1:v]overlay %codec% -start_number 11 %output%

::FFMPEG READOUT
ffmpeg version git-2017-12-18-3f88744 Copyright (c) 2000-2017 the FFmpeg developers

built with gcc 7.2.0 (GCC)
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-amf --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
libavutil 56. 6.100 / 56. 6.100
libavcodec 58. 8.100 / 58. 8.100
libavformat 58. 3.100 / 58. 3.100
libavdevice 58. 0.100 / 58. 0.100
libavfilter 7. 7.100 / 7. 7.100
libswscale 5. 0.101 / 5. 0.101
libswresample 3. 0.101 / 3. 0.101
libpostproc 55. 0.100 / 55. 0.100

Input #0, image2, from 'i\numbers.%04d.tif':

Duration: 00:00:00.50, start: 0.000000, bitrate: N/A

Stream #0:0: Video: tiff, rgba, 400x100 [SAR 1:4 DAR 1:1], 30 fps, 30 tbr, 30 tbn, 30 tbc

Input #1, image2, from 'i\numbers.%04d.tif':

Duration: 00:00:00.50, start: 0.000000, bitrate: N/A

Stream #1:0: Video: tiff, rgba, 400x100 [SAR 1:4 DAR 1:1], 30 fps, 30 tbr, 30 tbn, 30 tbc

Stream mapping:

Stream #0:0 (tiff) -> overlay:main
Stream #1:0 (tiff) -> overlay:overlay
overlay -> Stream #0:0 (tiff)

Press [q] to stop, ? for help
Output #0, image2, to 'test1\t.%04d.tif':

Metadata:

encoder : Lavf58.3.100
Stream #0:0: Video: tiff, rgba, 400x100 [SAR 1:4 DAR 1:1], q=2-31, 200 kb/s, 30 fps, 30 tbn, 30 tbc (default)
Metadata:

encoder : Lavc58.8.100 tiff

frame= 5 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.16 bitrate=N/A speed=5.73x
video:55kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

[Elon Musk]

Correct command:

ffmpeg -y -framerate 30 -i numbers.00%02d.tif -ss 0.33333333333333333 -start_number 11 -framerate 30 -i numbers.00%02d.tif -ss 0.3333333333333333333 -frames 5 -lavfi overlay -c:v rawvideo

Command you provided is incorrect, -start number 11 is ignored if set in position you gave.