How can I quickly determine positions in a video? For example, I have a video file and it looks like this.
I want to crop the video and get the part in the black box as a new video using ffmpeg. But first I need to get the upper left corner position of the black box and its width and height. How can I do this easily? Right now this is what I did. First I use ffprobe to get the actual video size:
I:\tutorial\Juggling - Step By Step [4 Vols]>ffprobe "Juggling - Step by Step (2 of 4) [VHS-Rip].avi"
ffprobe version N-103679-g7bbad32d5a-20210918 Copyright (c) 2007-2021 the FFmpeg developers
built with gcc 10-win32 (GCC) 20210408
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 --disable-debug --disable-w32threads --enable-pthreads --enable-iconv --enable-libxml2 --enable-zlib --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-libvorbis --enable-opencl --enable-libvmaf --enable-vulkan --disable-libxcb --disable-xlib --enable-amf --enable-libaom --enable-avisynth --enable-libdav1d --enable-libdavs2 --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libglslang --enable-libgme --enable-libass --enable-libbluray --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvpx --enable-libwebp --enable-lv2 --enable-libmfx --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --disable-vaapi --enable-libvidstab --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-ldexeflags= --extra-libs=-lgomp --extra-version=20210918
libavutil 57. 5.101 / 57. 5.101
libavcodec 59. 7.103 / 59. 7.103
libavformat 59. 5.100 / 59. 5.100
libavdevice 59. 0.101 / 59. 0.101
libavfilter 8. 9.100 / 8. 9.100
libswscale 6. 1.100 / 6. 1.100
libswresample 4. 0.100 / 4. 0.100
libpostproc 56. 0.100 / 56. 0.100
Input #0, avi, from 'Juggling - Step by Step (2 of 4) [VHS-Rip].avi':
Metadata:
software : VirtualDubMod 1.5.4.1 (build 2178/release)
Duration: 00:33:09.92, start: 0.000000, bitrate: 1266 kb/s
Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 448x336 [SAR 1:1 DAR 4:3], 1116 kb/s, 25 fps, 25 tbr, 25 tbn
Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, fltp, 137 kb/s
I:\tutorial\Juggling - Step By Step [4 Vols]>
As you can see, this video is 448x336. Now I manually set my video player window size to 448x336.
Then I use a tool called Golden Section, which is used to draw rectangles on the screen. I make it overlay over the video player like this:
And I take a screenshot and paste into mspaint.
Then I use Golden Section again to measure the black box position and size in mspaint.
Here as you can see, the upper left point of the black box is (130, 96). I can get the width & height of the black box using the same method.
As you can see, this process is way too complex! Is there an easier way? Thanks.
