/*
* Animated GIF muxer
* Copyright (c) 2000 Fabrice Bellard
*
* first version by Francois Revol <revol@free.fr>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "internal.h"
#include "libavutil/avassert.h"
#include "libavutil/imgutils.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"
#include "libavcodec/bytestream.h"
#include "libavcodec/gif.h"
typedef struct GIFContext {
AVClass *class;
int loop;
int last_delay;
int duration;
int64_t last_pos;
int have_end;
AVPacket *prev_pkt;
} GIFContext;
static int gif_write_header(AVFormatContext *s)
{
if (s->nb_streams != 1 ||
s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ||
s->streams[0]->codecpar->codec_id != AV_CODEC_ID_GIF) {
av_log(s, AV_LOG_ERROR,
"GIF muxer supports only a single video GIF stream.\n");
return AVERROR(EINVAL);
}
avpriv_set_pts_info(s->streams[0], 64, 1, 100);
return 0;
}
static int gif_parse_packet(AVFormatContext *s, uint8_t *data, int size)
{
GetByteContext gb;
int x;
bytestream2_init(&gb, data, size);
while (bytestream2_get_bytes_left(&gb) > 0) {
x = bytestream2_get_byte(&gb);
if (x != GIF_EXTENSION_INTRODUCER)
return 0;
x = bytestream2_get_byte(&gb);
while (x != GIF_GCE_EXT_LABEL && bytestream2_get_bytes_left(&gb) > 0) {
int block_size = bytestream2_get_byte(&gb);
if (!block_size)
break;
bytestream2_skip(&gb, block_size);
}
if (x == GIF_GCE_EXT_LABEL)
return bytestream2_tell(&gb) + 2;
}
return 0;
}
static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new)
{
if (new && new->pts != AV_NOPTS_VALUE)
gif->duration = av_clip_uint16(new->pts - prev->pts);
else if (!new && gif->last_delay >= 0)
gif->duration = gif->last_delay;
return gif->duration;
}
static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt)
{
GIFContext *gif = s->priv_data;
AVIOContext *pb = s->pb;
AVPacket *pkt = gif->prev_pkt;
if (!gif->prev_pkt) {
gif->prev_pkt = av_packet_alloc();
if (!gif->prev_pkt)
return AVERROR(ENOMEM);
return av_packet_ref(gif->prev_pkt, new_pkt);
}
gif->last_pos = avio_tell(pb);
if (pkt->size > 0)
gif->have_end = pkt->data[pkt->size - 1] == GIF_TRAILER;
if (!gif->last_pos) {
int delay_pos;
int off = 13;
if (pkt->size < 13)
return AVERROR(EINVAL);
if (pkt->data[10] & 0x80)
off += 3 * (1 << ((pkt->data[10] & 0x07) + 1));
if (pkt->size < off + 2)
return AVERROR(EINVAL);
avio_write(pb, pkt->data, off);
if (pkt->data[off] == GIF_EXTENSION_INTRODUCER && pkt->data[off + 1] == 0xff)
off += 19;
if (pkt->size <= off)
return AVERROR(EINVAL);
/* "NETSCAPE EXTENSION" for looped animation GIF */
if (gif->loop >= 0) {
avio_w8(pb, GIF_EXTENSION_INTRODUCER); /* GIF Extension code */
avio_w8(pb, GIF_APP_EXT_LABEL); /* Application Extension Label */
avio_w8(pb, 0x0b); /* Length of Application Block */
avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
avio_w8(pb, 0x03); /* Length of Data Sub-Block */
avio_w8(pb, 0x01);
avio_wl16(pb, (uint16_t)gif->loop);
avio_w8(pb, 0x00); /* Data Sub-block Terminator */
}
delay_pos = gif_parse_packet(s, pkt->data + off, pkt->size - off);
if (delay_pos > 0 && delay_pos < pkt->size - off - 2) {
avio_write(pb, pkt->data + off, delay_pos);
avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
avio_write(pb, pkt->data + off + delay_pos + 2, pkt->size - off - delay_pos - 2);
} else {
avio_write(pb, pkt->data + off, pkt->size - off);
}
} else {
int delay_pos = gif_parse_packet(s, pkt->data, pkt->size);
if (delay_pos > 0 && delay_pos < pkt->size - 2) {
avio_write(pb, pkt->data, delay_pos);
avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
avio_write(pb, pkt->data + delay_pos + 2, pkt->size - delay_pos - 2);
} else {
avio_write(pb, pkt->data, pkt->size);
}
}
av_packet_unref(gif->prev_pkt);
if (new_pkt)
return av_packet_ref(gif->prev_pkt, new_pkt);
return 0;
}
static int gif_write_trailer(AVFormatContext *s)
{
GIFContext *gif = s->priv_data;
AVIOContext *pb = s->pb;
if (!gif->prev_pkt)
return AVERROR(EINVAL);
gif_write_packet(s, NULL);
if (!gif->have_end)
avio_w8(pb, GIF_TRAILER);
av_packet_free(&gif->prev_pkt);
return 0;
}
#define OFFSET(x) offsetof(GIFContext, x)
#define ENC AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
{ "loop", "Number of times to loop the output: -1 - no loop, 0 - infinite loop", OFFSET(loop),
AV_OPT_TYPE_INT, { .i64 = 0 }, -1, 65535, ENC },
{ "final_delay", "Force delay (in centiseconds) after the last frame", OFFSET(last_delay),
AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 65535, ENC },
{ NULL },
};
static const AVClass gif_muxer_class = {
.class_name = "GIF muxer",
.item_name = av_default_item_name,
.version = LIBAVUTIL_VERSION_INT,
.option = options,
};
AVOutputFormat ff_gif_muxer = {
.name = "gif",
.long_name = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"),
.mime_type = "image/gif",
.extensions = "gif",
.priv_data_size = sizeof(GIFContext),
.audio_codec = AV_CODEC_ID_NONE,
.video_codec = AV_CODEC_ID_GIF,
.write_header = gif_write_header,
.write_packet = gif_write_packet,
.write_trailer = gif_write_trailer,
.priv_class = &gif_muxer_class,
.flags = AVFMT_VARIABLE_FPS,
};