500 lines
16 KiB
C
Executable file
500 lines
16 KiB
C
Executable file
/*
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* Copyright (c) 2000 Fabrice Bellard
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* Copyright (c) 2002 Francois Revol
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* Copyright (c) 2006 Baptiste Coudurier
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* Copyright (c) 2018 Bjorn Roche
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* Copyright (c) 2018 Paul B Mahol
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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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/**
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* @file
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* GIF encoder
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* @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
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*/
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#define BITSTREAM_WRITER_LE
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#include "libavutil/opt.h"
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#include "libavutil/imgutils.h"
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#include "avcodec.h"
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#include "bytestream.h"
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#include "internal.h"
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#include "lzw.h"
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#include "gif.h"
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#include "put_bits.h"
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#define DEFAULT_TRANSPARENCY_INDEX 0x1f
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typedef struct GIFContext {
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const AVClass *class;
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LZWState *lzw;
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uint8_t *buf;
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int buf_size;
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AVFrame *last_frame;
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int flags;
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int image;
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uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
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int palette_loaded;
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int transparent_index;
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uint8_t *tmpl; ///< temporary line buffer
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} GIFContext;
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enum {
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GF_OFFSETTING = 1<<0,
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GF_TRANSDIFF = 1<<1,
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};
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static int is_image_translucent(AVCodecContext *avctx,
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const uint8_t *buf, const int linesize)
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{
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GIFContext *s = avctx->priv_data;
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int trans = s->transparent_index;
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if (trans < 0)
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return 0;
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for (int y = 0; y < avctx->height; y++) {
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for (int x = 0; x < avctx->width; x++) {
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if (buf[x] == trans) {
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return 1;
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}
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}
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buf += linesize;
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}
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return 0;
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}
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static int get_palette_transparency_index(const uint32_t *palette)
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{
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int transparent_color_index = -1;
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unsigned i, smallest_alpha = 0xff;
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if (!palette)
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return -1;
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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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return smallest_alpha < 128 ? transparent_color_index : -1;
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}
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static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
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{
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int histogram[AVPALETTE_COUNT] = {0};
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int x, y, i;
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for (y = 0; y < h; y++) {
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for (x = 0; x < w; x++)
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histogram[buf[x]]++;
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buf += linesize;
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}
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for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
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if (!histogram[i])
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return i;
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return -1;
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}
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static void gif_crop_translucent(AVCodecContext *avctx,
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const uint8_t *buf, const int linesize,
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int *width, int *height,
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int *x_start, int *y_start)
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{
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GIFContext *s = avctx->priv_data;
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int trans = s->transparent_index;
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/* Crop image */
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if ((s->flags & GF_OFFSETTING) && trans >= 0) {
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const int w = avctx->width;
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const int h = avctx->height;
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int x_end = w - 1,
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y_end = h - 1;
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// crop top
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while (*y_start < y_end) {
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int is_trans = 1;
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for (int i = 0; i < w; i++) {
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if (buf[linesize * *y_start + i] != trans) {
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is_trans = 0;
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break;
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}
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}
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if (!is_trans)
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break;
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(*y_start)++;
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}
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// crop bottom
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while (y_end > *y_start) {
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int is_trans = 1;
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for (int i = 0; i < w; i++) {
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if (buf[linesize * y_end + i] != trans) {
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is_trans = 0;
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break;
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}
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}
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if (!is_trans)
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break;
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y_end--;
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}
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// crop left
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while (*x_start < x_end) {
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int is_trans = 1;
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for (int i = *y_start; i < y_end; i++) {
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if (buf[linesize * i + *x_start] != trans) {
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is_trans = 0;
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break;
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}
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}
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if (!is_trans)
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break;
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(*x_start)++;
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}
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// crop right
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while (x_end > *x_start) {
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int is_trans = 1;
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for (int i = *y_start; i < y_end; i++) {
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if (buf[linesize * i + x_end] != trans) {
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is_trans = 0;
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break;
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}
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}
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if (!is_trans)
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break;
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x_end--;
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}
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*height = y_end + 1 - *y_start;
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*width = x_end + 1 - *x_start;
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av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
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*width, *height, *x_start, *y_start, avctx->width, avctx->height);
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}
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}
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static void gif_crop_opaque(AVCodecContext *avctx,
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const uint32_t *palette,
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const uint8_t *buf, const int linesize,
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int *width, int *height, int *x_start, int *y_start)
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{
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GIFContext *s = avctx->priv_data;
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/* Crop image */
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if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {
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const uint8_t *ref = s->last_frame->data[0];
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const int ref_linesize = s->last_frame->linesize[0];
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int x_end = avctx->width - 1,
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y_end = avctx->height - 1;
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/* skip common lines */
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while (*y_start < y_end) {
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if (memcmp(ref + *y_start*ref_linesize, buf + *y_start*linesize, *width))
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break;
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(*y_start)++;
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}
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while (y_end > *y_start) {
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if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, *width))
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break;
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y_end--;
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}
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*height = y_end + 1 - *y_start;
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/* skip common columns */
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while (*x_start < x_end) {
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int same_column = 1;
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for (int y = *y_start; y <= y_end; y++) {
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if (ref[y*ref_linesize + *x_start] != buf[y*linesize + *x_start]) {
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same_column = 0;
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break;
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}
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}
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if (!same_column)
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break;
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(*x_start)++;
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}
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while (x_end > *x_start) {
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int same_column = 1;
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for (int y = *y_start; y <= y_end; y++) {
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if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
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same_column = 0;
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break;
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}
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}
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if (!same_column)
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break;
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x_end--;
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}
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*width = x_end + 1 - *x_start;
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av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
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*width, *height, *x_start, *y_start, avctx->width, avctx->height);
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}
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}
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static int gif_image_write_image(AVCodecContext *avctx,
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uint8_t **bytestream, uint8_t *end,
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const uint32_t *palette,
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const uint8_t *buf, const int linesize,
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AVPacket *pkt)
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{
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GIFContext *s = avctx->priv_data;
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int disposal, len = 0, height = avctx->height, width = avctx->width, x, y;
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int x_start = 0, y_start = 0, trans = s->transparent_index;
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int bcid = -1, honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette;
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const uint8_t *ptr;
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if (!s->image && avctx->frame_number && is_image_translucent(avctx, buf, linesize)) {
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gif_crop_translucent(avctx, buf, linesize, &width, &height, &x_start, &y_start);
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honor_transparency = 0;
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disposal = GCE_DISPOSAL_BACKGROUND;
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} else {
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gif_crop_opaque(avctx, palette, buf, linesize, &width, &height, &x_start, &y_start);
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disposal = GCE_DISPOSAL_INPLACE;
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}
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if (s->image || !avctx->frame_number) { /* GIF header */
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const uint32_t *global_palette = palette ? palette : s->palette;
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const AVRational sar = avctx->sample_aspect_ratio;
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int64_t aspect = 0;
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if (sar.num > 0 && sar.den > 0) {
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aspect = sar.num * 64LL / sar.den - 15;
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if (aspect < 0 || aspect > 255)
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aspect = 0;
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}
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bytestream_put_buffer(bytestream, gif89a_sig, sizeof(gif89a_sig));
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bytestream_put_le16(bytestream, avctx->width);
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bytestream_put_le16(bytestream, avctx->height);
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bcid = get_palette_transparency_index(global_palette);
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bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
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bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid); /* background color index */
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bytestream_put_byte(bytestream, aspect);
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for (int i = 0; i < 256; i++) {
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const uint32_t v = global_palette[i] & 0xffffff;
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bytestream_put_be24(bytestream, v);
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}
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}
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if (honor_transparency && trans < 0) {
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trans = pick_palette_entry(buf + y_start*linesize + x_start,
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linesize, width, height);
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if (trans < 0) // TODO, patch welcome
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av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
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}
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if (trans < 0)
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honor_transparency = 0;
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bcid = honor_transparency || disposal == GCE_DISPOSAL_BACKGROUND ? trans : get_palette_transparency_index(palette);
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/* graphic control extension */
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bytestream_put_byte(bytestream, GIF_EXTENSION_INTRODUCER);
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bytestream_put_byte(bytestream, GIF_GCE_EXT_LABEL);
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bytestream_put_byte(bytestream, 0x04); /* block size */
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bytestream_put_byte(bytestream, disposal<<2 | (bcid >= 0));
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bytestream_put_le16(bytestream, 5); // default delay
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bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid);
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bytestream_put_byte(bytestream, 0x00);
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/* image block */
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bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
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bytestream_put_le16(bytestream, x_start);
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bytestream_put_le16(bytestream, y_start);
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bytestream_put_le16(bytestream, width);
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bytestream_put_le16(bytestream, height);
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if (!palette) {
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bytestream_put_byte(bytestream, 0x00); /* flags */
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} else {
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unsigned i;
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bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
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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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bytestream_put_be24(bytestream, v);
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}
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}
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bytestream_put_byte(bytestream, 0x08);
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ff_lzw_encode_init(s->lzw, s->buf, s->buf_size,
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12, FF_LZW_GIF, put_bits);
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ptr = buf + y_start*linesize + x_start;
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if (honor_transparency) {
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const int ref_linesize = s->last_frame->linesize[0];
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const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;
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for (y = 0; y < height; y++) {
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memcpy(s->tmpl, ptr, width);
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for (x = 0; x < width; x++)
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if (ref[x] == ptr[x])
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s->tmpl[x] = trans;
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len += ff_lzw_encode(s->lzw, s->tmpl, width);
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ptr += linesize;
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ref += ref_linesize;
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}
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} else {
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for (y = 0; y < height; y++) {
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len += ff_lzw_encode(s->lzw, ptr, width);
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ptr += linesize;
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}
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}
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len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
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ptr = s->buf;
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while (len > 0) {
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int size = FFMIN(255, len);
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bytestream_put_byte(bytestream, size);
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if (end - *bytestream < size)
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return -1;
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bytestream_put_buffer(bytestream, ptr, size);
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ptr += size;
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len -= size;
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}
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bytestream_put_byte(bytestream, 0x00); /* end of image block */
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return 0;
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}
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static av_cold int gif_encode_init(AVCodecContext *avctx)
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{
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GIFContext *s = avctx->priv_data;
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if (avctx->width > 65535 || avctx->height > 65535) {
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av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
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return AVERROR(EINVAL);
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}
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s->transparent_index = -1;
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s->lzw = av_mallocz(ff_lzw_encode_state_size);
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s->buf_size = avctx->width*avctx->height*2 + 1000;
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s->buf = av_malloc(s->buf_size);
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s->tmpl = av_malloc(avctx->width);
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if (!s->tmpl || !s->buf || !s->lzw)
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return AVERROR(ENOMEM);
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if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
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av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
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return 0;
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}
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static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
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const AVFrame *pict, int *got_packet)
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{
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GIFContext *s = avctx->priv_data;
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uint8_t *outbuf_ptr, *end;
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const uint32_t *palette = NULL;
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int ret;
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if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)
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return ret;
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outbuf_ptr = pkt->data;
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end = pkt->data + pkt->size;
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if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
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palette = (uint32_t*)pict->data[1];
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if (!s->palette_loaded) {
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memcpy(s->palette, palette, AVPALETTE_SIZE);
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s->transparent_index = get_palette_transparency_index(palette);
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s->palette_loaded = 1;
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} else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
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palette = NULL;
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}
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}
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gif_image_write_image(avctx, &outbuf_ptr, end, palette,
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pict->data[0], pict->linesize[0], pkt);
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if (!s->last_frame && !s->image) {
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s->last_frame = av_frame_alloc();
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if (!s->last_frame)
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return AVERROR(ENOMEM);
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}
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if (!s->image) {
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av_frame_unref(s->last_frame);
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ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
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if (ret < 0)
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return ret;
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}
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pkt->size = outbuf_ptr - pkt->data;
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if (s->image || !avctx->frame_number)
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pkt->flags |= AV_PKT_FLAG_KEY;
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*got_packet = 1;
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return 0;
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}
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static int gif_encode_close(AVCodecContext *avctx)
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{
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GIFContext *s = avctx->priv_data;
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av_freep(&s->lzw);
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av_freep(&s->buf);
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s->buf_size = 0;
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av_frame_free(&s->last_frame);
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av_freep(&s->tmpl);
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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 FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
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static const AVOption gif_options[] = {
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{ "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
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{ "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
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{ "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
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{ "gifimage", "enable encoding only images per frame", OFFSET(image), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
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{ NULL }
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};
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static const AVClass gif_class = {
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.class_name = "GIF encoder",
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.item_name = av_default_item_name,
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.option = gif_options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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|
|
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AVCodec ff_gif_encoder = {
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.name = "gif",
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.long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
|
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.type = AVMEDIA_TYPE_VIDEO,
|
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.id = AV_CODEC_ID_GIF,
|
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.priv_data_size = sizeof(GIFContext),
|
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.init = gif_encode_init,
|
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.encode2 = gif_encode_frame,
|
|
.close = gif_encode_close,
|
|
.pix_fmts = (const enum AVPixelFormat[]){
|
|
AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
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AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
|
|
},
|
|
.priv_class = &gif_class,
|
|
};
|