Compile error with v4l2 in ffmpeg git master

[bermond]

I'm getting the following compile error with v4l2:

LD      ffplay_g
LD      ffmpeg_g
LD      ffprobe_g
LD      ffserver_g
libavdevice/libavdevice.a(v4l2.o): In function `device_open':
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_close'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_open'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_dup'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_ioctl'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_read'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_mmap'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_munmap'
libavdevice/libavdevice.a(v4l2.o): In function `v4l2_read_header':
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:840: undefined reference to `v4l2_log_file'
collect2: error: ld returned 1 exit status
make: *** [Makefile:107: ffplay_g] Error 1
make: *** Waiting for unfinished jobs....
libavdevice/libavdevice.a(v4l2.o): In function `device_open':
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_close'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_open'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_dup'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_ioctl'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_read'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_mmap'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_munmap'
libavdevice/libavdevice.a(v4l2.o): In function `v4l2_read_header':
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:840: undefined reference to `v4l2_log_file'
collect2: error: ld returned 1 exit status
make: *** [Makefile:107: ffprobe_g] Error 1
libavdevice/libavdevice.a(v4l2.o): In function `device_open':
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_close'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_open'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_dup'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_ioctl'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_read'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_mmap'
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:129: undefined reference to `v4l2_munmap'
libavdevice/libavdevice.a(v4l2.o): In function `v4l2_read_header':
/home/user/abs/ffmpeg-full-git/src/ffmpeg-full-git/libavdevice/v4l2.c:840: undefined reference to `v4l2_log_file'
collect2: error: ld returned 1 exit status
make: *** [Makefile:107: ffmpeg_g] Error 1

A git bisect shows that this is being caused by commit ​6dfcbd80ad446ff163b47f2bf432bbf706436ea8.

I can confirm that it was compiling fine until commit ​e4d5310a507d82656d670437c3a5f3b42b3fe060. This was the commit that I used in the git bisect good command.

How to reproduce:

$ git clone git://source.ffmpeg.org/ffmpeg.git
$ cd ffmpeg
$ ./configure --enable-libv4l2
$ make -j8

System information:
OS: Arch Linux x86_64
Compiler: gcc 7.2.0
glibc: 2.26
FFmpeg: git master
v4l2: 2.0.2

Relevant system-wide environmet variables:
CPPFLAGS="-D_FORTIFY_SOURCE=2"
CFLAGS="-march=native -O2 -pipe -fstack-protector-strong -fno-plt"
CXXFLAGS="-march=native -O2 -pipe -fstack-protector-strong -fno-plt"
LDFLAGS="-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now"

[James]

Can you test if the following change fixes it?

diff --git a/configure b/configure
index dfbc251bb2..9f95d58c6e 100755
--- a/configure
+++ b/configure
@@ -3116,7 +3116,7 @@ kmsgrab_indev_deps="libdrm"
 lavfi_indev_deps="avfilter"
 libcdio_indev_deps="libcdio"
 libdc1394_indev_deps="libdc1394"
-libv4l2_indev_deps="libv4l2"
+v4l2_indev_deps="libv4l2"
 openal_indev_deps="openal"
 opengl_outdev_deps="opengl"
 oss_indev_deps_any="soundcard_h sys_soundcard_h"

[bermond]

Replying to jamrial:

Can you test if the following change fixes it?

diff --git a/configure b/configure
index dfbc251bb2..9f95d58c6e 100755
--- a/configure
+++ b/configure
@@ -3116,7 +3116,7 @@ kmsgrab_indev_deps="libdrm"
 lavfi_indev_deps="avfilter"
 libcdio_indev_deps="libcdio"
 libdc1394_indev_deps="libdc1394"
-libv4l2_indev_deps="libv4l2"
+v4l2_indev_deps="libv4l2"
 openal_indev_deps="openal"
 opengl_outdev_deps="opengl"
 oss_indev_deps_any="soundcard_h sys_soundcard_h"

Hi. Thank you for the reply.

It compiles fine by applying this patch.

I can also confirm that my webcam input device is working as expected with -f video4linux2 -i /dev/video0.

[James]

Should be fixed in 734ed38931103c523c42333633a315a0ce1b5eb2. Thanks for the report and testing!

[bermond]

Replying to jamrial:

Should be fixed in 734ed38931103c523c42333633a315a0ce1b5eb2. Thanks for the report and testing!

I can confirm that this is fixed in the latest ffmpeg git master.

Thank for the reply and suppport. And also for the quick fix! :)