[FFmpeg-devel] [PATCH] v4l2: add libv4l2 support.
Stefano Sabatini
stefasab at gmail.com
Sun Oct 30 12:59:06 CET 2011
On date Sunday 2011-10-30 03:57:41 +0100, Clément Bœsch encoded:
> ---
> Here is a patch to support old webcams with exotic colorspaces or insane
> drivers using userland libv4l2 (see for instance
> http://hansdegoede.livejournal.com/3636.html).
>
> It seems to work with my personnal crazy webcam, but more tests are welcome.
>
> I wanted to make the support optional at runtime, but it raises at least one
> issue: the context has to be transmitted to all subfunctions, which is not
> easily possible in some cases such as mmap_release_buffer() callback. So ATM,
> if you build FFmpeg with --enable-libv4l2, then deal with it, you have to use
> it...
>
> Also, I noticed the gpl dependency is not strict by default: I needed to add
> the "die_license..." stuff to force --enable-gpl. Is it a wanted behaviour?
> What is the "gpl" dependency for in that case?
If you have dependencies on a given symbol, if one of the dependency
symbol is not enabled the symbol is silently not enabled as well. If
you want to force a fail in this case, you need to rely on the ad-hoc
die_licence() mechanism.
See also:
http://thread.gmane.org/gmane.comp.video.libav.devel/586
> ---
> configure | 6 ++++
> libavdevice/v4l2.c | 78 ++++++++++++++++++++++++++++++++++------------------
> 2 files changed, 57 insertions(+), 27 deletions(-)
>
> diff --git a/configure b/configure
> index a1106a1..700cc97 100755
> --- a/configure
> +++ b/configure
> @@ -186,6 +186,7 @@ External library support:
> --enable-libstagefright-h264 enable H.264 decoding via libstagefright [no]
> --enable-libtheora enable Theora encoding via libtheora [no]
> --enable-libutvideo enable Ut Video decoding via libutvideo [no]
> + --enable-libv4l2 enable libv4l2/v4l-utils [no]
> --enable-libvo-aacenc enable AAC encoding via libvo-aacenc [no]
> --enable-libvo-amrwbenc enable AMR-WB encoding via libvo-amrwbenc [no]
> --enable-libvorbis enable Vorbis encoding via libvorbis,
> @@ -1021,6 +1022,7 @@ CONFIG_LIST="
> libstagefright_h264
> libtheora
> libutvideo
> + libv4l2
> libvo_aacenc
> libvo_amrwbenc
> libvorbis
> @@ -1564,6 +1566,7 @@ jack_indev_deps="jack_jack_h sem_timedwait"
> lavfi_indev_deps="avfilter"
> libcdio_indev_deps="libcdio"
> libdc1394_indev_deps="libdc1394"
> +libv4l2_indev_deps="libv4l2 gpl"
> openal_indev_deps="openal"
> oss_indev_deps_any="soundcard_h sys_soundcard_h"
> oss_outdev_deps_any="soundcard_h sys_soundcard_h"
> @@ -2697,6 +2700,7 @@ die_license_disabled gpl libx264
> die_license_disabled gpl libxavs
> die_license_disabled gpl libxvid
> die_license_disabled gpl x11grab
> +die_license_disabled gpl libv4l2
Why GPL? The libvl2 library itself is LGPL, or are you GPL-ing the code of
*this* patch? In this case I think it should be done differently
(like adding a symbol --enable-libvl2-v4l2 and setting:
libv4l2_v4l2_deps="libv4l2 gpl"
) but I'd consider this overkill and I'd rather try to keep it LGPL.
> die_license_disabled nonfree libaacplus
> die_license_disabled nonfree libfaac
> @@ -3042,6 +3046,7 @@ enabled libstagefright_h264 && require_cpp libstagefright_h264 "binder/ProcessS
> media/stagefright/OMXClient.h media/stagefright/OMXCodec.h" android::OMXClient -lstagefright -lmedia -lutils -lbinder
> enabled libtheora && require libtheora theora/theoraenc.h th_info_init -ltheoraenc -ltheoradec -logg
> enabled libutvideo && require_cpp utvideo "stdint.h stdlib.h utvideo/utvideo.h utvideo/Codec.h" 'CCodec*' -lutvideo -lstdc++
> +enabled libv4l2 && require_pkg_config libv4l2 libv4l2.h v4l2_ioctl
> enabled libvo_aacenc && require libvo_aacenc vo-aacenc/voAAC.h voGetAACEncAPI -lvo-aacenc
> enabled libvo_amrwbenc && require libvo_amrwbenc vo-amrwbenc/enc_if.h E_IF_init -lvo-amrwbenc
> enabled libvorbis && require libvorbis vorbis/vorbisenc.h vorbis_info_init -lvorbisenc -lvorbis -logg
> @@ -3370,6 +3375,7 @@ echo "libspeex enabled ${libspeex-no}"
> echo "libstagefright-h264 enabled ${libstagefright_h264-no}"
> echo "libtheora enabled ${libtheora-no}"
> echo "libutvideo enabled ${libutvideo-no}"
> +echo "libv4l2 enabled ${libv4l2-no}"
> echo "libvo-aacenc support ${libvo_aacenc-no}"
> echo "libvo-amrwbenc support ${libvo_amrwbenc-no}"
> echo "libvorbis enabled ${libvorbis-no}"
> diff --git a/libavdevice/v4l2.c b/libavdevice/v4l2.c
> index 9e26b2d..e1631ba 100644
> --- a/libavdevice/v4l2.c
> +++ b/libavdevice/v4l2.c
> @@ -52,6 +52,18 @@
> #include "libavutil/parseutils.h"
> #include "libavutil/pixdesc.h"
>
> +#if CONFIG_LIBV4L2
> +#include <libv4l2.h>
> +#else
> +#define v4l2_open open
> +#define v4l2_close close
> +#define v4l2_dup dup
> +#define v4l2_ioctl ioctl
> +#define v4l2_read read
> +#define v4l2_mmap mmap
> +#define v4l2_munmap munmap
> +#endif
> +
> static const int desired_video_buffers = 256;
>
> enum io_method {
> @@ -113,36 +125,48 @@ static int device_open(AVFormatContext *ctx, uint32_t *capabilities)
> {
> struct v4l2_capability cap;
> int fd;
> +#if CONFIG_LIBV4L2
> + int fd_libv4l;
> +#endif
> int res, err;
> int flags = O_RDWR;
>
> if (ctx->flags & AVFMT_FLAG_NONBLOCK) {
> flags |= O_NONBLOCK;
> }
> - fd = open(ctx->filename, flags, 0);
> + fd = v4l2_open(ctx->filename, flags, 0);
> if (fd < 0) {
> av_log(ctx, AV_LOG_ERROR, "Cannot open video device %s : %s\n",
> ctx->filename, strerror(errno));
> return AVERROR(errno);
> }
> +#if CONFIG_LIBV4L2
> + fd_libv4l = v4l2_fd_open(fd, 0);
> + if (fd < 0) {
> + av_log(ctx, AV_LOG_ERROR, "Cannot open video device with libv4l neither %s : %s\n",
> + ctx->filename, strerror(errno));
> + return AVERROR(errno);
err = AVERROR(errno);
av_log(...)
return err;
is safer, as av_log() may change the value of errno.
> + }
> + fd = fd_libv4l;
> +#endif
Also av_strerror() should be preferred, or this has a slight
chance the get bogus data in multi-threaded apps.
[...]
--
FFmpeg = Fundamentalist & Fanciful Mean Practical Explosive Gangster
More information about the ffmpeg-devel
mailing list