mirror of https://git.videolan.org/git/ffmpeg.git
641 lines
17 KiB
C
641 lines
17 KiB
C
/*
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* GIF decoder
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* Copyright (c) 2003 Fabrice Bellard.
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*
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* This library 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 of the License, or (at your option) any later version.
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*
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* This library 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 this library; 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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int gif_write(ByteIOContext *pb, AVImageInfo *info);
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//#define DEBUG
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#define MAXBITS 12
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#define SIZTABLE (1<<MAXBITS)
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#define GCE_DISPOSAL_NONE 0
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#define GCE_DISPOSAL_INPLACE 1
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#define GCE_DISPOSAL_BACKGROUND 2
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#define GCE_DISPOSAL_RESTORE 3
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typedef struct GifState {
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int screen_width;
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int screen_height;
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int bits_per_pixel;
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int background_color_index;
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int transparent_color_index;
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int color_resolution;
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uint8_t *image_buf;
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int image_linesize;
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uint32_t *image_palette;
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int pix_fmt;
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/* after the frame is displayed, the disposal method is used */
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int gce_disposal;
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/* delay during which the frame is shown */
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int gce_delay;
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/* LZW compatible decoder */
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ByteIOContext *f;
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int eob_reached;
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uint8_t *pbuf, *ebuf;
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int bbits;
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unsigned int bbuf;
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int cursize; /* The current code size */
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int curmask;
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int codesize;
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int clear_code;
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int end_code;
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int newcodes; /* First available code */
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int top_slot; /* Highest code for current size */
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int slot; /* Last read code */
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int fc, oc;
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uint8_t *sp;
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uint8_t stack[SIZTABLE];
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uint8_t suffix[SIZTABLE];
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uint16_t prefix[SIZTABLE];
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/* aux buffers */
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uint8_t global_palette[256 * 3];
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uint8_t local_palette[256 * 3];
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uint8_t buf[256];
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} GifState;
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static const uint8_t gif87a_sig[6] = "GIF87a";
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static const uint8_t gif89a_sig[6] = "GIF89a";
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static const uint16_t mask[17] =
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{
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0x0000, 0x0001, 0x0003, 0x0007,
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0x000F, 0x001F, 0x003F, 0x007F,
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0x00FF, 0x01FF, 0x03FF, 0x07FF,
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0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF
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};
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/* Probe gif video format or gif image format. The current heuristic
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supposes the gif87a is always a single image. For gif89a, we
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consider it as a video only if a GCE extension is present in the
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first kilobyte. */
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static int gif_video_probe(AVProbeData * pd)
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{
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const uint8_t *p, *p_end;
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int bits_per_pixel, has_global_palette, ext_code, ext_len;
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int gce_flags, gce_disposal;
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if (pd->buf_size < 24 ||
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memcmp(pd->buf, gif89a_sig, 6) != 0)
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return 0;
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p_end = pd->buf + pd->buf_size;
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p = pd->buf + 6;
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bits_per_pixel = (p[4] & 0x07) + 1;
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has_global_palette = (p[4] & 0x80);
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p += 7;
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if (has_global_palette)
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p += (1 << bits_per_pixel) * 3;
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for(;;) {
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if (p >= p_end)
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return 0;
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if (*p != '!')
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break;
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p++;
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if (p >= p_end)
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return 0;
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ext_code = *p++;
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if (p >= p_end)
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return 0;
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ext_len = *p++;
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if (ext_code == 0xf9) {
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if (p >= p_end)
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return 0;
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/* if GCE extension found with gce_disposal != 0: it is
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likely to be an animation */
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gce_flags = *p++;
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gce_disposal = (gce_flags >> 2) & 0x7;
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if (gce_disposal != 0)
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return AVPROBE_SCORE_MAX;
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else
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return 0;
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}
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for(;;) {
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if (ext_len == 0)
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break;
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p += ext_len;
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if (p >= p_end)
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return 0;
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ext_len = *p++;
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}
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}
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return 0;
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}
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static int gif_image_probe(AVProbeData * pd)
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{
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if (pd->buf_size >= 24 &&
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(memcmp(pd->buf, gif87a_sig, 6) == 0 ||
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memcmp(pd->buf, gif89a_sig, 6) == 0))
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return AVPROBE_SCORE_MAX - 1;
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else
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return 0;
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}
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static void GLZWDecodeInit(GifState * s, int csize)
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{
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/* read buffer */
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s->eob_reached = 0;
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s->pbuf = s->buf;
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s->ebuf = s->buf;
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s->bbuf = 0;
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s->bbits = 0;
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/* decoder */
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s->codesize = csize;
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s->cursize = s->codesize + 1;
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s->curmask = mask[s->cursize];
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s->top_slot = 1 << s->cursize;
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s->clear_code = 1 << s->codesize;
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s->end_code = s->clear_code + 1;
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s->slot = s->newcodes = s->clear_code + 2;
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s->oc = s->fc = 0;
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s->sp = s->stack;
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}
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/* XXX: optimize */
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static inline int GetCode(GifState * s)
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{
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int c, sizbuf;
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uint8_t *ptr;
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while (s->bbits < s->cursize) {
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ptr = s->pbuf;
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if (ptr >= s->ebuf) {
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if (!s->eob_reached) {
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sizbuf = get_byte(s->f);
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s->ebuf = s->buf + sizbuf;
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s->pbuf = s->buf;
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if (sizbuf > 0) {
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get_buffer(s->f, s->buf, sizbuf);
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} else {
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s->eob_reached = 1;
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}
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}
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ptr = s->pbuf;
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}
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s->bbuf |= ptr[0] << s->bbits;
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ptr++;
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s->pbuf = ptr;
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s->bbits += 8;
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}
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c = s->bbuf & s->curmask;
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s->bbuf >>= s->cursize;
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s->bbits -= s->cursize;
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return c;
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}
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/* NOTE: the algorithm here is inspired from the LZW GIF decoder
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written by Steven A. Bennett in 1987. */
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/* return the number of byte decoded */
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static int GLZWDecode(GifState * s, uint8_t * buf, int len)
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{
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int l, c, code, oc, fc;
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uint8_t *sp;
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if (s->end_code < 0)
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return 0;
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l = len;
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sp = s->sp;
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oc = s->oc;
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fc = s->fc;
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while (sp > s->stack) {
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*buf++ = *(--sp);
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if ((--l) == 0)
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goto the_end;
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}
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for (;;) {
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c = GetCode(s);
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if (c == s->end_code) {
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s->end_code = -1;
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break;
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} else if (c == s->clear_code) {
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s->cursize = s->codesize + 1;
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s->curmask = mask[s->cursize];
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s->slot = s->newcodes;
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s->top_slot = 1 << s->cursize;
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while ((c = GetCode(s)) == s->clear_code);
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if (c == s->end_code) {
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s->end_code = -1;
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break;
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}
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/* test error */
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if (c >= s->slot)
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c = 0;
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fc = oc = c;
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*buf++ = c;
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if ((--l) == 0)
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break;
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} else {
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code = c;
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if (code >= s->slot) {
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*sp++ = fc;
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code = oc;
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}
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while (code >= s->newcodes) {
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*sp++ = s->suffix[code];
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code = s->prefix[code];
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}
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*sp++ = code;
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if (s->slot < s->top_slot) {
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s->suffix[s->slot] = fc = code;
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s->prefix[s->slot++] = oc;
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oc = c;
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}
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if (s->slot >= s->top_slot) {
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if (s->cursize < MAXBITS) {
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s->top_slot <<= 1;
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s->curmask = mask[++s->cursize];
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}
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}
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while (sp > s->stack) {
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*buf++ = *(--sp);
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if ((--l) == 0)
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goto the_end;
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}
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}
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}
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the_end:
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s->sp = sp;
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s->oc = oc;
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s->fc = fc;
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return len - l;
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}
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static int gif_read_image(GifState *s)
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{
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ByteIOContext *f = s->f;
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int left, top, width, height, bits_per_pixel, code_size, flags;
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int is_interleaved, has_local_palette, y, x, pass, y1, linesize, n, i;
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uint8_t *ptr, *line, *d, *spal, *palette, *sptr, *ptr1;
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left = get_le16(f);
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top = get_le16(f);
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width = get_le16(f);
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height = get_le16(f);
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flags = get_byte(f);
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is_interleaved = flags & 0x40;
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has_local_palette = flags & 0x80;
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bits_per_pixel = (flags & 0x07) + 1;
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#ifdef DEBUG
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printf("gif: image x=%d y=%d w=%d h=%d\n", left, top, width, height);
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#endif
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if (has_local_palette) {
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get_buffer(f, s->local_palette, 3 * (1 << bits_per_pixel));
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palette = s->local_palette;
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} else {
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palette = s->global_palette;
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bits_per_pixel = s->bits_per_pixel;
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}
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/* verify that all the image is inside the screen dimensions */
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if (left + width > s->screen_width ||
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top + height > s->screen_height)
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return -EINVAL;
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/* build the palette */
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if (s->pix_fmt == PIX_FMT_RGB24) {
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line = av_malloc(width);
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if (!line)
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return -ENOMEM;
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} else {
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n = (1 << bits_per_pixel);
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spal = palette;
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for(i = 0; i < n; i++) {
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s->image_palette[i] = (0xff << 24) |
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(spal[0] << 16) | (spal[1] << 8) | (spal[2]);
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spal += 3;
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}
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for(; i < 256; i++)
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s->image_palette[i] = (0xff << 24);
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/* handle transparency */
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if (s->transparent_color_index >= 0)
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s->image_palette[s->transparent_color_index] = 0;
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line = NULL;
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}
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/* now get the image data */
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s->f = f;
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code_size = get_byte(f);
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GLZWDecodeInit(s, code_size);
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/* read all the image */
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linesize = s->image_linesize;
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ptr1 = s->image_buf + top * linesize + (left * 3);
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ptr = ptr1;
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pass = 0;
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y1 = 0;
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for (y = 0; y < height; y++) {
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if (s->pix_fmt == PIX_FMT_RGB24) {
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/* transcode to RGB24 */
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GLZWDecode(s, line, width);
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d = ptr;
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sptr = line;
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for(x = 0; x < width; x++) {
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spal = palette + sptr[0] * 3;
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d[0] = spal[0];
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d[1] = spal[1];
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d[2] = spal[2];
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d += 3;
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sptr++;
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}
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} else {
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GLZWDecode(s, ptr, width);
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}
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if (is_interleaved) {
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switch(pass) {
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default:
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case 0:
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case 1:
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y1 += 8;
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ptr += linesize * 8;
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if (y1 >= height) {
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y1 = 4;
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if (pass == 0)
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ptr = ptr1 + linesize * 4;
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else
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ptr = ptr1 + linesize * 2;
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pass++;
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}
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break;
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case 2:
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y1 += 4;
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ptr += linesize * 4;
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if (y1 >= height) {
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y1 = 1;
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ptr = ptr1 + linesize;
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pass++;
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}
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break;
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case 3:
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y1 += 2;
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ptr += linesize * 2;
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break;
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}
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} else {
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ptr += linesize;
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}
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}
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av_free(line);
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/* read the garbage data until end marker is found */
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while (!s->eob_reached)
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GetCode(s);
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return 0;
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}
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static int gif_read_extension(GifState *s)
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{
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ByteIOContext *f = s->f;
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int ext_code, ext_len, i, gce_flags, gce_transparent_index;
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/* extension */
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ext_code = get_byte(f);
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ext_len = get_byte(f);
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#ifdef DEBUG
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printf("gif: ext_code=0x%x len=%d\n", ext_code, ext_len);
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#endif
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switch(ext_code) {
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case 0xf9:
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if (ext_len != 4)
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goto discard_ext;
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s->transparent_color_index = -1;
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gce_flags = get_byte(f);
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s->gce_delay = get_le16(f);
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gce_transparent_index = get_byte(f);
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if (gce_flags & 0x01)
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s->transparent_color_index = gce_transparent_index;
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else
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s->transparent_color_index = -1;
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s->gce_disposal = (gce_flags >> 2) & 0x7;
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#ifdef DEBUG
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printf("gif: gce_flags=%x delay=%d tcolor=%d disposal=%d\n",
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gce_flags, s->gce_delay,
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s->transparent_color_index, s->gce_disposal);
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#endif
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ext_len = get_byte(f);
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break;
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}
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/* NOTE: many extension blocks can come after */
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discard_ext:
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while (ext_len != 0) {
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for (i = 0; i < ext_len; i++)
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get_byte(f);
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ext_len = get_byte(f);
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#ifdef DEBUG
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printf("gif: ext_len1=%d\n", ext_len);
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#endif
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}
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return 0;
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}
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static int gif_read_header1(GifState *s)
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{
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ByteIOContext *f = s->f;
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uint8_t sig[6];
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int ret, v, n;
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int has_global_palette;
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/* read gif signature */
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ret = get_buffer(f, sig, 6);
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if (ret != 6)
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return -1;
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if (memcmp(sig, gif87a_sig, 6) != 0 &&
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memcmp(sig, gif89a_sig, 6) != 0)
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return -1;
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/* read screen header */
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s->transparent_color_index = -1;
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s->screen_width = get_le16(f);
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s->screen_height = get_le16(f);
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if( (unsigned)s->screen_width > 32767
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|| (unsigned)s->screen_height > 32767){
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av_log(NULL, AV_LOG_ERROR, "picture size too large\n");
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return -1;
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}
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v = get_byte(f);
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s->color_resolution = ((v & 0x70) >> 4) + 1;
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has_global_palette = (v & 0x80);
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s->bits_per_pixel = (v & 0x07) + 1;
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s->background_color_index = get_byte(f);
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get_byte(f); /* ignored */
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#ifdef DEBUG
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printf("gif: screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
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s->screen_width, s->screen_height, s->bits_per_pixel,
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has_global_palette);
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#endif
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if (has_global_palette) {
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n = 1 << s->bits_per_pixel;
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get_buffer(f, s->global_palette, n * 3);
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}
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return 0;
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}
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static int gif_parse_next_image(GifState *s)
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{
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ByteIOContext *f = s->f;
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int ret, code;
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for (;;) {
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code = url_fgetc(f);
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#ifdef DEBUG
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printf("gif: code=%02x '%c'\n", code, code);
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#endif
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switch (code) {
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case ',':
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if (gif_read_image(s) < 0)
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return AVERROR_IO;
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ret = 0;
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goto the_end;
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case ';':
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/* end of image */
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ret = AVERROR_IO;
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goto the_end;
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case '!':
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if (gif_read_extension(s) < 0)
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return AVERROR_IO;
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break;
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case EOF:
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default:
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|
/* error or errneous EOF */
|
|
ret = AVERROR_IO;
|
|
goto the_end;
|
|
}
|
|
}
|
|
the_end:
|
|
return ret;
|
|
}
|
|
|
|
static int gif_read_header(AVFormatContext * s1,
|
|
AVFormatParameters * ap)
|
|
{
|
|
GifState *s = s1->priv_data;
|
|
ByteIOContext *f = &s1->pb;
|
|
AVStream *st;
|
|
|
|
s->f = f;
|
|
if (gif_read_header1(s) < 0)
|
|
return -1;
|
|
|
|
/* allocate image buffer */
|
|
s->image_linesize = s->screen_width * 3;
|
|
s->image_buf = av_malloc(s->screen_height * s->image_linesize);
|
|
if (!s->image_buf)
|
|
return -ENOMEM;
|
|
s->pix_fmt = PIX_FMT_RGB24;
|
|
/* now we are ready: build format streams */
|
|
st = av_new_stream(s1, 0);
|
|
if (!st)
|
|
return -1;
|
|
|
|
st->codec->codec_type = CODEC_TYPE_VIDEO;
|
|
st->codec->codec_id = CODEC_ID_RAWVIDEO;
|
|
st->codec->time_base.den = 5;
|
|
st->codec->time_base.num = 1;
|
|
/* XXX: check if screen size is always valid */
|
|
st->codec->width = s->screen_width;
|
|
st->codec->height = s->screen_height;
|
|
st->codec->pix_fmt = PIX_FMT_RGB24;
|
|
return 0;
|
|
}
|
|
|
|
static int gif_read_packet(AVFormatContext * s1,
|
|
AVPacket * pkt)
|
|
{
|
|
GifState *s = s1->priv_data;
|
|
int ret;
|
|
|
|
ret = gif_parse_next_image(s);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* XXX: avoid copying */
|
|
if (av_new_packet(pkt, s->screen_width * s->screen_height * 3)) {
|
|
return AVERROR_IO;
|
|
}
|
|
pkt->stream_index = 0;
|
|
memcpy(pkt->data, s->image_buf, s->screen_width * s->screen_height * 3);
|
|
return 0;
|
|
}
|
|
|
|
static int gif_read_close(AVFormatContext *s1)
|
|
{
|
|
GifState *s = s1->priv_data;
|
|
av_free(s->image_buf);
|
|
return 0;
|
|
}
|
|
|
|
/* read gif as image */
|
|
static int gif_read(ByteIOContext *f,
|
|
int (*alloc_cb)(void *opaque, AVImageInfo *info), void *opaque)
|
|
{
|
|
GifState s1, *s = &s1;
|
|
AVImageInfo info1, *info = &info1;
|
|
int ret;
|
|
|
|
memset(s, 0, sizeof(GifState));
|
|
s->f = f;
|
|
if (gif_read_header1(s) < 0)
|
|
return -1;
|
|
info->width = s->screen_width;
|
|
info->height = s->screen_height;
|
|
info->pix_fmt = PIX_FMT_PAL8;
|
|
ret = alloc_cb(opaque, info);
|
|
if (ret)
|
|
return ret;
|
|
s->image_buf = info->pict.data[0];
|
|
s->image_linesize = info->pict.linesize[0];
|
|
s->image_palette = (uint32_t *)info->pict.data[1];
|
|
|
|
if (gif_parse_next_image(s) < 0)
|
|
return -1;
|
|
return 0;
|
|
}
|
|
|
|
AVInputFormat gif_iformat =
|
|
{
|
|
"gif",
|
|
"gif format",
|
|
sizeof(GifState),
|
|
gif_video_probe,
|
|
gif_read_header,
|
|
gif_read_packet,
|
|
gif_read_close,
|
|
};
|
|
|
|
AVImageFormat gif_image_format = {
|
|
"gif",
|
|
"gif",
|
|
gif_image_probe,
|
|
gif_read,
|
|
(1 << PIX_FMT_PAL8),
|
|
gif_write,
|
|
};
|