[FFmpeg-devel] [PATCH] v4l2: add libv4l2 support.
Clément Bœsch
ubitux at gmail.com
Sun Oct 30 13:11:54 CET 2011
On Sun, Oct 30, 2011 at 12:59:06PM +0100, Stefano Sabatini wrote:
> 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
>
Ah, ok thanks!
> > ---
> > 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.
>
Ah! I missed the library was LGPL, I just relied on the COPYING file, but
didn't see the COPYING.LIB, my bad. I'll fix that ASAP.
> > 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.
>
OK, will resend a patch soon, thanks for the review.
--
Clément B.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 490 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20111030/0b1d7f63/attachment.asc>
More information about the ffmpeg-devel
mailing list