FFmpeg build with V4L2
I had the configure option --disable-indevs
and had missed the option --enable-indev=v4l2
. Adding the latter allows my build to access my webcam.
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Jon G
Updated on September 18, 2022Comments
-
Jon G over 1 year
I want to use ffmpeg to access my webcam. I tried:
ffmpeg -f v4l2 -i /dev/video0 output.mp4
but I am getting an error:
Unknown input format: 'v4l2'
Similarly with
video4linux2
instead ofv4l2
. I therefore assume my build of ffmpeg is missingv4l2
. I see that there is a configure option--enable-libv4l2
(https://ffmpeg.org/ffmpeg-all.html#video4linux2_002c-v4l2). I added this to my configuration, but running configure I get:ERROR: "libv4l2 not found using pkg-config"
How do I add this to my build? I am following the guide at https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu with some modifications to include specific decoders etc.
I understand that libv4l2 may come with the Ubuntu package
libv4l-dev
. Installing it with:sudo apt-get install libv4l-dev
doesn't seem to affect my issue though. I can see
/usr/lib/x86_64-linux-gnu/pkgconfig/libv4l2.pc
, which I guess is the file I need. Maybe I just need to point ffmpeg / pkg-config to it in the configure options? Something like:PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig:/usr/lib/x86_64-linux-gnu/pkgconfig" ./configure ...
? (Doesn't work). Modifying
--extra-cflags
or--extra-ldflags
to point to include / libs? Couldn't get that to work either. The FFmpeg build guide linked keeps all packages in a ffmpeg_build directory in my home folder. Should I installlibv4l-dev
there somehow?Tail of config.log:
END /tmp/ffconf.5wdQhyZ1.c gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 -I/home/jon/ffmpeg_build/include -std=c99 -fomit-frame-pointer -pthread -c -o /tmp/ffconf.LGU7tq3n.o /tmp/ffconf.5wdQhyZ1.c gcc -L/home/jon/ffmpeg_build/lib -Wl,--as-needed -Wl,-z,noexecstack -o /tmp/ffconf.Fhn6FivT /tmp/ffconf.LGU7tq3n.o -lv4l2 -lpthread -lv4lconvert -lrt -lm -ljpeg -lmp3lame -lfdk-aac -lm -lz -pthread /usr/bin/ld: cannot find -ljpeg collect2: error: ld returned 1 exit status ERROR: libv4l2 not found using pkg-config
Seems like it is missing a jpeg library:
sudo apt-get install libjpeg-dev
and it compiles OK, but I am returned to the original error of:
Unknown input format: 'v4l2'
On running the first command.