v4l2.c File Reference

#include <stdatomic.h>
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "v4l2-common.h"
#include <dirent.h>

Go to the source code of this file.

Data Structures
struct	video_data
struct	buff_data

Macros
#define	V4L_ALLFORMATS   3
#define	V4L_RAWFORMATS   1
#define	V4L_COMPFORMATS   2
#define	V4L_TS_DEFAULT   0
	Return timestamps to the user exactly as returned by the kernel. More...
#define	V4L_TS_ABS   1
	Autodetect the kind of timestamps returned by the kernel and convert to absolute (wall clock) timestamps. More...
#define	V4L_TS_MONO2ABS   2
	Assume kernel timestamps are from the monotonic clock and convert to absolute timestamps. More...
#define	V4L_TS_CONVERT_READY   V4L_TS_DEFAULT
	Once the kind of timestamps returned by the kernel have been detected, the value of the timefilter (NULL or not) determines whether a conversion takes place. More...
#define	SET_WRAPPERS(prefix)
#define	v4l2_open   s->open_f
#define	v4l2_close   s->close_f
#define	v4l2_dup   s->dup_f
#define	v4l2_ioctl   s->ioctl_f
#define	v4l2_read   s->read_f
#define	v4l2_mmap   s->mmap_f
#define	v4l2_munmap   s->munmap_f
#define	OFFSET(x)   offsetof(struct video_data, x)
#define	DEC   AV_OPT_FLAG_DECODING_PARAM

Functions
static int	device_open (AVFormatContext *ctx, const char *device_path)
static int	device_init (AVFormatContext *ctx, int *width, int *height, uint32_t pixelformat)
static int	first_field (const struct video_data *s)
static void	list_formats (AVFormatContext *ctx, int type)
static void	list_standards (AVFormatContext *ctx)
static int	mmap_init (AVFormatContext *ctx)
static int	enqueue_buffer (struct video_data *s, struct v4l2_buffer *buf)
static void	mmap_release_buffer (void *opaque, uint8_t *data)
static int	init_convert_timestamp (AVFormatContext *ctx, int64_t ts)
static int	convert_timestamp (AVFormatContext *ctx, int64_t *ts)
static int	mmap_read_frame (AVFormatContext *ctx, AVPacket *pkt)
static int	mmap_start (AVFormatContext *ctx)
static void	mmap_close (struct video_data *s)
static int	v4l2_set_parameters (AVFormatContext *ctx)
static int	device_try_init (AVFormatContext *ctx, enum AVPixelFormat pix_fmt, int *width, int *height, uint32_t *desired_format, enum AVCodecID *codec_id)
static int	v4l2_read_probe (const AVProbeData *p)
static int	v4l2_read_header (AVFormatContext *ctx)
static int	v4l2_read_packet (AVFormatContext *ctx, AVPacket *pkt)
static int	v4l2_read_close (AVFormatContext *ctx)
static int	v4l2_is_v4l_dev (const char *name)
static int	v4l2_get_device_list (AVFormatContext *ctx, AVDeviceInfoList *device_list)

Variables
static const int	desired_video_buffers = 256
static const AVOption	options []
static const AVClass	v4l2_class
const AVInputFormat	ff_v4l2_demuxer

Detailed Description

Video4Linux2 grab interface

Part of this file is based on the V4L2 video capture example (http://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html)

Thanks to Michael Niedermayer for providing the mapping between V4L2_PIX_FMT_* and AV_PIX_FMT_*

Definition in file v4l2.c.

Macro Definition Documentation

V4L_ALLFORMATS

#define V4L_ALLFORMATS   3

Definition at line 46 of file v4l2.c.

V4L_RAWFORMATS

#define V4L_RAWFORMATS   1

Definition at line 47 of file v4l2.c.

V4L_COMPFORMATS

#define V4L_COMPFORMATS   2

Definition at line 48 of file v4l2.c.

V4L_TS_DEFAULT

#define V4L_TS_DEFAULT   0

Return timestamps to the user exactly as returned by the kernel.

Definition at line 53 of file v4l2.c.

V4L_TS_ABS

#define V4L_TS_ABS   1

Autodetect the kind of timestamps returned by the kernel and convert to absolute (wall clock) timestamps.

Definition at line 58 of file v4l2.c.

V4L_TS_MONO2ABS

#define V4L_TS_MONO2ABS   2

Assume kernel timestamps are from the monotonic clock and convert to absolute timestamps.

Definition at line 63 of file v4l2.c.

V4L_TS_CONVERT_READY

#define V4L_TS_CONVERT_READY   V4L_TS_DEFAULT

Once the kind of timestamps returned by the kernel have been detected, the value of the timefilter (NULL or not) determines whether a conversion takes place.

Definition at line 70 of file v4l2.c.

SET_WRAPPERS

#define SET_WRAPPERS

(

prefix

)

Value:

    do {       \
    s->open_f   = prefix ## open;       \
    s->close_f  = prefix ## close;      \
    s->dup_f    = prefix ## dup;        \
    s->ioctl_f  = prefix ## ioctl;      \
    s->read_f   = prefix ## read;       \
    s->mmap_f   = prefix ## mmap;       \
    s->munmap_f = prefix ## munmap;     \
} while (0)

v4l2_open

#define v4l2_open   s->open_f

v4l2_close

#define v4l2_close   s->close_f

v4l2_dup

#define v4l2_dup   s->dup_f

v4l2_ioctl

#define v4l2_ioctl   s->ioctl_f

v4l2_read

#define v4l2_read   s->read_f

v4l2_mmap

#define v4l2_mmap   s->mmap_f

v4l2_munmap

#define v4l2_munmap   s->munmap_f

OFFSET

#define OFFSET

(

x

)

offsetof(struct video_data, x)

Definition at line 1090 of file v4l2.c.

DEC

#define DEC   AV_OPT_FLAG_DECODING_PARAM

Definition at line 1091 of file v4l2.c.

Function Documentation

device_open()

static int device_open ( AVFormatContext *  ctx, const char *  device_path  )

static

Definition at line 115 of file v4l2.c.

Referenced by v4l2_get_device_list(), and v4l2_read_header().

device_init()

static int device_init ( AVFormatContext *  ctx, int *  width, int *  height, uint32_t  pixelformat  )

static

Definition at line 194 of file v4l2.c.

Referenced by device_try_init().

first_field()

static int first_field ( const struct video_data *  s )

static

Definition at line 236 of file v4l2.c.

Referenced by dnxhd_decode_frame(), dnxhd_decode_header(), dnxhd_encode_picture(), ff_draw_horiz_band(), and v4l2_read_header().

list_formats()

static void list_formats ( AVFormatContext *  ctx, int  type  )

static

Definition at line 277 of file v4l2.c.

Referenced by v4l2_read_header().

list_standards()

static void list_standards ( AVFormatContext *  ctx )

static

Definition at line 315 of file v4l2.c.

Referenced by v4l2_read_header().

mmap_init()

static int mmap_init ( AVFormatContext *  ctx )

static

Definition at line 339 of file v4l2.c.

Referenced by v4l2_read_header().

enqueue_buffer()

static int enqueue_buffer ( struct video_data *  s, struct v4l2_buffer *  buf  )

static

Definition at line 405 of file v4l2.c.

Referenced by mmap_read_frame(), and mmap_release_buffer().

mmap_release_buffer()

static void mmap_release_buffer ( void *  opaque, uint8_t *  data  )

static

Definition at line 419 of file v4l2.c.

Referenced by mmap_read_frame().

init_convert_timestamp()

static int init_convert_timestamp ( AVFormatContext *  ctx, int64_t  ts  )

static

Definition at line 440 of file v4l2.c.

Referenced by convert_timestamp().

convert_timestamp()

static int convert_timestamp ( AVFormatContext *  ctx, int64_t *  ts  )

static

Definition at line 473 of file v4l2.c.

Referenced by mmap_read_frame().

mmap_read_frame()

static int mmap_read_frame ( AVFormatContext *  ctx, AVPacket *  pkt  )

static

Definition at line 494 of file v4l2.c.

Referenced by v4l2_read_packet().

mmap_start()

static int mmap_start ( AVFormatContext *  ctx )

static

Definition at line 600 of file v4l2.c.

Referenced by v4l2_read_header().

mmap_close()

static void mmap_close ( struct video_data *  s )

static

Definition at line 633 of file v4l2.c.

Referenced by v4l2_read_close().

v4l2_set_parameters()

static int v4l2_set_parameters ( AVFormatContext *  ctx )

static

Definition at line 650 of file v4l2.c.

Referenced by v4l2_read_header().

device_try_init()

static int device_try_init ( AVFormatContext *  ctx, enum AVPixelFormat  pix_fmt, int *  width, int *  height, uint32_t *  desired_format, enum AVCodecID *  codec_id  )

static

Definition at line 768 of file v4l2.c.

Referenced by v4l2_read_header().

v4l2_read_probe()

static int v4l2_read_probe ( const AVProbeData *  p )

static

Definition at line 821 of file v4l2.c.

v4l2_read_header()

static int v4l2_read_header ( AVFormatContext *  ctx )

static

Definition at line 828 of file v4l2.c.

v4l2_read_packet()

static int v4l2_read_packet ( AVFormatContext *  ctx, AVPacket *  pkt  )

static

Definition at line 984 of file v4l2.c.

v4l2_read_close()

static int v4l2_read_close ( AVFormatContext *  ctx )

static

Definition at line 995 of file v4l2.c.

v4l2_is_v4l_dev()

static int v4l2_is_v4l_dev ( const char *  name )

static

Definition at line 1009 of file v4l2.c.

Referenced by v4l2_get_device_list().

v4l2_get_device_list()

static int v4l2_get_device_list ( AVFormatContext *  ctx, AVDeviceInfoList *  device_list  )

static

Definition at line 1017 of file v4l2.c.

Variable Documentation

desired_video_buffers

const int desired_video_buffers = 256

static

Definition at line 44 of file v4l2.c.

Referenced by mmap_init().

options

const AVOption options[]

static

Initial value:

= {
    { "standard",     "set TV standard, used only by analog frame grabber",       OFFSET(standard),     AV_OPT_TYPE_STRING, {.str = NULL }, 0, 0,       DEC },
    { "channel",      "set TV channel, used only by frame grabber",               OFFSET(channel),      AV_OPT_TYPE_INT,    {.i64 = -1 },  -1, INT_MAX, DEC },
    { "video_size",   "set frame size",                                           OFFSET(width),        AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL},  0, 0,   DEC },
    { "pixel_format", "set preferred pixel format",                               OFFSET(pixel_format), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       DEC },
    { "input_format", "set preferred pixel format (for raw video) or codec name", OFFSET(pixel_format), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       DEC },
    { "framerate",    "set frame rate",                                           OFFSET(framerate),    AV_OPT_TYPE_STRING, {.str = NULL},  0, 0,       DEC },
 
    { "list_formats", "list available formats and exit",                          OFFSET(list_format),  AV_OPT_TYPE_INT,    {.i64 = 0 },  0, INT_MAX, DEC, "list_formats" },
    { "all",          "show all available formats",                               OFFSET(list_format),  AV_OPT_TYPE_CONST,  {.i64 = V4L_ALLFORMATS  },    0, INT_MAX, DEC, "list_formats" },
    { "raw",          "show only non-compressed formats",                         OFFSET(list_format),  AV_OPT_TYPE_CONST,  {.i64 = V4L_RAWFORMATS  },    0, INT_MAX, DEC, "list_formats" },
    { "compressed",   "show only compressed formats",                             OFFSET(list_format),  AV_OPT_TYPE_CONST,  {.i64 = V4L_COMPFORMATS },    0, INT_MAX, DEC, "list_formats" },
 
    { "list_standards", "list supported standards and exit",                      OFFSET(list_standard), AV_OPT_TYPE_INT,   {.i64 = 0 },  0, 1, DEC, "list_standards" },
    { "all",            "show all supported standards",                           OFFSET(list_standard), AV_OPT_TYPE_CONST, {.i64 = 1 },  0, 0, DEC, "list_standards" },
 
    { "timestamps",   "set type of timestamps for grabbed frames",                OFFSET(ts_mode),      AV_OPT_TYPE_INT,    {.i64 = 0 }, 0, 2, DEC, "timestamps" },
    { "ts",           "set type of timestamps for grabbed frames",                OFFSET(ts_mode),      AV_OPT_TYPE_INT,    {.i64 = 0 }, 0, 2, DEC, "timestamps" },
    { "default",      "use timestamps from the kernel",                           OFFSET(ts_mode),      AV_OPT_TYPE_CONST,  {.i64 = V4L_TS_DEFAULT  }, 0, 2, DEC, "timestamps" },
    { "abs",          "use absolute timestamps (wall clock)",                     OFFSET(ts_mode),      AV_OPT_TYPE_CONST,  {.i64 = V4L_TS_ABS      }, 0, 2, DEC, "timestamps" },
    { "mono2abs",     "force conversion from monotonic to absolute timestamps",   OFFSET(ts_mode),      AV_OPT_TYPE_CONST,  {.i64 = V4L_TS_MONO2ABS }, 0, 2, DEC, "timestamps" },
    { "use_libv4l2",  "use libv4l2 (v4l-utils) conversion functions",             OFFSET(use_libv4l2),  AV_OPT_TYPE_BOOL,   {.i64 = 0}, 0, 1, DEC },
    { NULL },
}

Definition at line 1093 of file v4l2.c.

v4l2_class

const AVClass v4l2_class

static

Initial value:

= {
    .class_name = "V4L2 indev",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
    .category   = AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
}

Definition at line 1118 of file v4l2.c.

ff_v4l2_demuxer

const AVInputFormat ff_v4l2_demuxer

Initial value:

= {
    .name           = "video4linux2,v4l2",
    .long_name      = NULL_IF_CONFIG_SMALL("Video4Linux2 device grab"),
    .priv_data_size = sizeof(struct video_data),
    .read_probe     = v4l2_read_probe,
    .read_header    = v4l2_read_header,
    .read_packet    = v4l2_read_packet,
    .read_close     = v4l2_read_close,
    .get_device_list = v4l2_get_device_list,
    .flags          = AVFMT_NOFILE,
    .priv_class     = &v4l2_class,
}

Definition at line 1126 of file v4l2.c.