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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static int gif_image_write_header(AVIOContext *pb, int width, int height,
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int loop_count, uint32_t *palette)
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{
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int i;
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avio_write(pb, "GIF", 3);
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avio_write(pb, "89a", 3);
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avio_wl16(pb, width);
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avio_wl16(pb, height);
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if (palette) {
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avio_w8(pb, 0xf7); /* flags: global clut, 256 entries */
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avio_w8(pb, 0x1f); /* background color index */
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avio_w8(pb, 0); /* aspect ratio */
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for (i = 0; i < 256; i++) {
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const uint32_t v = palette[i] & 0xffffff;
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avio_wb24(pb, v);
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}
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} else {
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avio_w8(pb, 0); /* flags */
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avio_w8(pb, 0); /* background color index */
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avio_w8(pb, 0); /* aspect ratio */
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}
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/* "NETSCAPE EXTENSION" for looped animation GIF */
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avio_w8(pb, 0x21); /* GIF Extension code */
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avio_w8(pb, 0xff); /* 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)loop_count);
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avio_w8(pb, 0x00); /* Data Sub-block Terminator */
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return 0;
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}
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typedef struct {
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AVClass *class; /** Class for private options. */
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int loop;
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int last_delay;
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AVPacket *prev_pkt;
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int duration;
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} GIFContext;
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static int gif_write_header(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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AVCodecContext *video_enc;
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int width, height;
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uint32_t palette[AVPALETTE_COUNT];
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if (s->nb_streams != 1 ||
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s->streams[0]->codec->codec_type != AVMEDIA_TYPE_VIDEO ||
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s->streams[0]->codec->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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video_enc = s->streams[0]->codec;
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width = video_enc->width;
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height = video_enc->height;
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avpriv_set_pts_info(s->streams[0], 64, 1, 100);
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if (avpriv_set_systematic_pal2(palette, video_enc->pix_fmt) < 0) {
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av_assert0(video_enc->pix_fmt == AV_PIX_FMT_PAL8);
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gif_image_write_header(pb, width, height, gif->loop, NULL);
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} else {
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gif_image_write_header(pb, width, height, gif->loop, palette);
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}
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avio_flush(s->pb);
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return 0;
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}
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static int flush_packet(AVFormatContext *s, AVPacket *new)
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{
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GIFContext *gif = s->priv_data;
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int size;
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AVIOContext *pb = s->pb;
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uint8_t flags = 0x4, transparent_color_index = 0x1f;
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const uint32_t *palette;
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AVPacket *pkt = gif->prev_pkt;
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if (!pkt)
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return 0;
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/* Mark one colour as transparent if the input palette contains at least
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* one colour that is more than 50% transparent. */
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palette = (uint32_t*)av_packet_get_side_data(pkt, AV_PKT_DATA_PALETTE, &size);
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if (palette && size != AVPALETTE_SIZE) {
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av_log(s, AV_LOG_ERROR, "Invalid palette extradata\n");
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return AVERROR_INVALIDDATA;
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}
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if (palette) {
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unsigned i, smallest_alpha = 0xff;
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for (i = 0; i < AVPALETTE_COUNT; i++) {
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const uint32_t v = palette[i];
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if (v >> 24 < smallest_alpha) {
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smallest_alpha = v >> 24;
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transparent_color_index = i;
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}
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}
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if (smallest_alpha < 128)
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flags |= 0x1; /* Transparent Color Flag */
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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 - gif->prev_pkt->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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/* graphic control extension block */
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avio_w8(pb, 0x21);
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avio_w8(pb, 0xf9);
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avio_w8(pb, 0x04); /* block size */
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avio_w8(pb, flags);
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avio_wl16(pb, gif->duration);
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avio_w8(pb, transparent_color_index);
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avio_w8(pb, 0x00);
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avio_write(pb, pkt->data, pkt->size);
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av_free_packet(gif->prev_pkt);
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if (new)
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av_copy_packet(gif->prev_pkt, new);
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return 0;
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}
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static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
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{
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GIFContext *gif = s->priv_data;
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if (!gif->prev_pkt) {
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gif->prev_pkt = av_malloc(sizeof(*gif->prev_pkt));
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if (!gif->prev_pkt)
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return AVERROR(ENOMEM);
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return av_copy_packet(gif->prev_pkt, pkt);
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}
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return flush_packet(s, pkt);
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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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flush_packet(s, NULL);
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av_freep(&gif->prev_pkt);
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avio_w8(pb, 0x3b);
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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.", OFFSET(loop),
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AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 65535, ENC },
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{ "final_delay", "Force delay (in ms) 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("GIF Animation"),
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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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