mirror of
https://git.videolan.org/git/ffmpeg.git
synced 2024-08-28 20:26:14 +02:00
220 lines
6.6 KiB
C
220 lines
6.6 KiB
C
/*
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* Animated GIF muxer
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* Copyright (c) 2000 Fabrice Bellard
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*
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* first version by Francois Revol <revol@free.fr>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avformat.h"
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#include "internal.h"
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#include "libavutil/avassert.h"
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#include "libavutil/imgutils.h"
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#include "libavutil/log.h"
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#include "libavutil/opt.h"
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#include "libavcodec/bytestream.h"
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#include "libavcodec/gif.h"
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typedef struct GIFContext {
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AVClass *class;
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int loop;
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int last_delay;
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int duration;
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int64_t last_pos;
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int have_end;
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AVPacket *prev_pkt;
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} GIFContext;
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static int gif_write_header(AVFormatContext *s)
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{
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if (s->nb_streams != 1 ||
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s->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_VIDEO ||
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s->streams[0]->codecpar->codec_id != AV_CODEC_ID_GIF) {
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av_log(s, AV_LOG_ERROR,
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"GIF muxer supports only a single video GIF stream.\n");
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return AVERROR(EINVAL);
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}
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avpriv_set_pts_info(s->streams[0], 64, 1, 100);
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return 0;
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}
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static int gif_parse_packet(AVFormatContext *s, uint8_t *data, int size)
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{
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GetByteContext gb;
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int x;
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bytestream2_init(&gb, data, size);
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while (bytestream2_get_bytes_left(&gb) > 0) {
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x = bytestream2_get_byte(&gb);
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if (x != GIF_EXTENSION_INTRODUCER)
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return 0;
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x = bytestream2_get_byte(&gb);
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while (x != GIF_GCE_EXT_LABEL && bytestream2_get_bytes_left(&gb) > 0) {
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int block_size = bytestream2_get_byte(&gb);
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if (!block_size)
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break;
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bytestream2_skip(&gb, block_size);
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}
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if (x == GIF_GCE_EXT_LABEL)
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return bytestream2_tell(&gb) + 2;
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}
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return 0;
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}
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static int gif_get_delay(GIFContext *gif, AVPacket *prev, AVPacket *new)
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{
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if (new && new->pts != AV_NOPTS_VALUE)
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gif->duration = av_clip_uint16(new->pts - prev->pts);
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else if (!new && gif->last_delay >= 0)
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gif->duration = gif->last_delay;
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return gif->duration;
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}
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static int gif_write_packet(AVFormatContext *s, AVPacket *new_pkt)
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{
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GIFContext *gif = s->priv_data;
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AVIOContext *pb = s->pb;
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AVPacket *pkt = gif->prev_pkt;
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if (!gif->prev_pkt) {
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gif->prev_pkt = av_packet_alloc();
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if (!gif->prev_pkt)
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return AVERROR(ENOMEM);
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return av_packet_ref(gif->prev_pkt, new_pkt);
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}
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gif->last_pos = avio_tell(pb);
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if (pkt->size > 0)
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gif->have_end = pkt->data[pkt->size - 1] == GIF_TRAILER;
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if (!gif->last_pos) {
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int delay_pos;
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int off = 13;
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if (pkt->size < 13)
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return AVERROR(EINVAL);
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if (pkt->data[10] & 0x80)
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off += 3 * (1 << ((pkt->data[10] & 0x07) + 1));
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if (pkt->size < off + 2)
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return AVERROR(EINVAL);
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avio_write(pb, pkt->data, off);
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if (pkt->data[off] == GIF_EXTENSION_INTRODUCER && pkt->data[off + 1] == 0xff)
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off += 19;
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if (pkt->size <= off)
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return AVERROR(EINVAL);
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/* "NETSCAPE EXTENSION" for looped animation GIF */
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if (gif->loop >= 0) {
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avio_w8(pb, GIF_EXTENSION_INTRODUCER); /* GIF Extension code */
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avio_w8(pb, GIF_APP_EXT_LABEL); /* Application Extension Label */
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avio_w8(pb, 0x0b); /* Length of Application Block */
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avio_write(pb, "NETSCAPE2.0", sizeof("NETSCAPE2.0") - 1);
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avio_w8(pb, 0x03); /* Length of Data Sub-Block */
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avio_w8(pb, 0x01);
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avio_wl16(pb, (uint16_t)gif->loop);
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avio_w8(pb, 0x00); /* Data Sub-block Terminator */
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}
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delay_pos = gif_parse_packet(s, pkt->data + off, pkt->size - off);
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if (delay_pos > 0 && delay_pos < pkt->size - off - 2) {
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avio_write(pb, pkt->data + off, delay_pos);
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avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
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avio_write(pb, pkt->data + off + delay_pos + 2, pkt->size - off - delay_pos - 2);
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} else {
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avio_write(pb, pkt->data + off, pkt->size - off);
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}
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} else {
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int delay_pos = gif_parse_packet(s, pkt->data, pkt->size);
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if (delay_pos > 0 && delay_pos < pkt->size - 2) {
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avio_write(pb, pkt->data, delay_pos);
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avio_wl16(pb, gif_get_delay(gif, pkt, new_pkt));
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avio_write(pb, pkt->data + delay_pos + 2, pkt->size - delay_pos - 2);
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} else {
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avio_write(pb, pkt->data, pkt->size);
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}
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}
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av_packet_unref(gif->prev_pkt);
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if (new_pkt)
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return av_packet_ref(gif->prev_pkt, new_pkt);
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return 0;
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}
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static int gif_write_trailer(AVFormatContext *s)
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{
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GIFContext *gif = s->priv_data;
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AVIOContext *pb = s->pb;
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if (!gif->prev_pkt)
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return AVERROR(EINVAL);
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gif_write_packet(s, NULL);
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if (!gif->have_end)
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avio_w8(pb, GIF_TRAILER);
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av_packet_free(&gif->prev_pkt);
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return 0;
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}
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#define OFFSET(x) offsetof(GIFContext, x)
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#define ENC AV_OPT_FLAG_ENCODING_PARAM
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static const AVOption options[] = {
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{ "loop", "Number of times to loop the output: -1 - no loop, 0 - infinite loop", OFFSET(loop),
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AV_OPT_TYPE_INT, { .i64 = 0 }, -1, 65535, ENC },
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{ "final_delay", "Force delay (in centiseconds) after the last frame", OFFSET(last_delay),
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AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 65535, ENC },
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{ NULL },
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};
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static const AVClass gif_muxer_class = {
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.class_name = "GIF muxer",
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.item_name = av_default_item_name,
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.version = LIBAVUTIL_VERSION_INT,
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.option = options,
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};
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AVOutputFormat ff_gif_muxer = {
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.name = "gif",
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.long_name = NULL_IF_CONFIG_SMALL("CompuServe Graphics Interchange Format (GIF)"),
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.mime_type = "image/gif",
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.extensions = "gif",
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.priv_data_size = sizeof(GIFContext),
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.audio_codec = AV_CODEC_ID_NONE,
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.video_codec = AV_CODEC_ID_GIF,
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.write_header = gif_write_header,
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.write_packet = gif_write_packet,
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.write_trailer = gif_write_trailer,
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.priv_class = &gif_muxer_class,
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.flags = AVFMT_VARIABLE_FPS,
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};
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