gifdec.c File Reference

#include "avformat.h"
#include "demux.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "avio_internal.h"
#include "internal.h"
#include "libavcodec/gif.h"

Go to the source code of this file.

Data Structures
struct	GIFDemuxContext

Macros
#define	GIF_PACKET_SIZE   1024
#define	GIF_DEFAULT_DELAY   10
	Major web browsers display gifs at ~10-15fps when rate is not explicitly set or have too low values. More...
#define	GIF_MIN_DELAY   2
	By default delay values less than this threshold considered to be invalid. More...

Functions
static int	gif_probe (const AVProbeData *p)
static int	resync (AVIOContext *pb)
static int	gif_skip_subblocks (AVIOContext *pb)
static int	gif_read_header (AVFormatContext *s)
static int	gif_read_packet (AVFormatContext *s, AVPacket *pkt)

Variables
static const AVOption	options []
static const AVClass	demuxer_class
const FFInputFormat	ff_gif_demuxer

Detailed Description

GIF demuxer.

Definition in file gifdec.c.

Macro Definition Documentation

GIF_PACKET_SIZE

#define GIF_PACKET_SIZE   1024

Definition at line 36 of file gifdec.c.

GIF_DEFAULT_DELAY

#define GIF_DEFAULT_DELAY   10

Major web browsers display gifs at ~10-15fps when rate is not explicitly set or have too low values.

We assume default rate to be 10. Default delay = 100hundredths of second / 10fps = 10hos per frame.

Definition at line 67 of file gifdec.c.

GIF_MIN_DELAY

#define GIF_MIN_DELAY   2

By default delay values less than this threshold considered to be invalid.

Definition at line 71 of file gifdec.c.

Function Documentation

gif_probe()

static int gif_probe ( const AVProbeData *  p )

static

Definition at line 73 of file gifdec.c.

resync()

static int resync ( AVIOContext *  pb )

static

Definition at line 86 of file gifdec.c.

Referenced by gif_read_header().

gif_skip_subblocks()

static int gif_skip_subblocks ( AVIOContext *  pb )

static

Definition at line 102 of file gifdec.c.

Referenced by gif_read_header().

gif_read_header()

static int gif_read_header ( AVFormatContext *  s )

static

Definition at line 114 of file gifdec.c.

gif_read_packet()

static int gif_read_packet ( AVFormatContext *  s, AVPacket *  pkt  )

static

Definition at line 244 of file gifdec.c.

Variable Documentation

options

const AVOption options[]

static

Initial value:

= {
    { "min_delay"    , "minimum valid delay between frames (in hundredths of second)", 0x42    , AV_OPT_TYPE_INT, {.i64 = GIF_MIN_DELAY}    , 0, 100 * 60, AV_OPT_FLAG_DECODING_PARAM },
    { "max_gif_delay", "maximum valid delay between frames (in hundredths of seconds)", 0x42   , AV_OPT_TYPE_INT, {.i64 = 65535}            , 0, 65535   , AV_OPT_FLAG_DECODING_PARAM },
    { "default_delay", "default delay between frames (in hundredths of second)"      , 0x42, AV_OPT_TYPE_INT, {.i64 = GIF_DEFAULT_DELAY}, 0, 100 * 60, AV_OPT_FLAG_DECODING_PARAM },
    { "ignore_loop"  , "ignore loop setting (netscape extension)"                    , 0x42  , AV_OPT_TYPE_BOOL,{.i64 = 1}                , 0,        1, AV_OPT_FLAG_DECODING_PARAM },
    { NULL },
}

Definition at line 269 of file gifdec.c.

demuxer_class

const AVClass demuxer_class

static

Initial value:

= {
    .class_name = "GIF demuxer",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
    .category   = AV_CLASS_CATEGORY_DEMUXER,
}

Definition at line 277 of file gifdec.c.

ff_gif_demuxer

const FFInputFormat ff_gif_demuxer

Initial value:

= {
    .p.name         = "gif",
    .p.long_name    = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"),
    .p.flags        = AVFMT_GENERIC_INDEX,
    .p.extensions   = "gif",
    .p.priv_class   = &demuxer_class,
    .priv_data_size = sizeof(GIFDemuxContext),
    .read_probe     = gif_probe,
    .read_header    = gif_read_header,
    .read_packet    = gif_read_packet,
}

Definition at line 285 of file gifdec.c.