Command (PS == Windows PowerShell):
PS D:\> ffmpeg -f dshow -show_video_device_dialog True -video_device_save some_profile.txt -i 'video=MicrosoftR LifeCam Studio(TM)'
FFmpeg Header:
ffmpeg version git-2020-06-04-7f81785 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 9.3.1 (GCC) 20200523
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --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-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
libavutil 56. 49.100 / 56. 49.100
libavcodec 58. 90.100 / 58. 90.100
libavformat 58. 44.100 / 58. 44.100
libavdevice 58. 9.103 / 58. 9.103
libavfilter 7. 84.100 / 7. 84.100
libswscale 5. 6.101 / 5. 6.101
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
Error after OK/Cancel/Close in camera settings dialog (empty file was created). Also tried without dialog - the same problem:
[dshow @ 0715de40] Query for IPersistStream failed.
video=Microsoft® LifeCam Studio(TM): I/O error
I assume that problem at the camera side, but I don't exclude my blindness (didn’t find any examples of saving settings or required command options in the documentation).
Perhaps there is another way to save / load webcamera properties?
Ability to save/load properties for DirectShow objects representing webcameras is optional. Having said that, "Query... failed." and "I/O error" is not exactly an error. It is non-fatal error, that is. There is no problem at the camera side.
Webcamera driver implementation might have its own internal persistence, such as, for example, when you change some property like contrast setting it might be stored and be used further for all application consuming the camera.