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576 lines
18 KiB
C
Executable File
576 lines
18 KiB
C
Executable File
/*
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* GIF decoder
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* Copyright (c) 2003 Fabrice Bellard
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* Copyright (c) 2006 Baptiste Coudurier
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* Copyright (c) 2012 Vitaliy E Sugrobov
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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 "libavutil/imgutils.h"
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#include "libavutil/opt.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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/* This value is intentionally set to "transparent white" color.
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* It is much better to have white background instead of black
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* when gif image converted to format which not support transparency.
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*/
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#define GIF_TRANSPARENT_COLOR 0x00ffffff
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typedef struct GifState {
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const AVClass *class;
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AVFrame *frame;
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int screen_width;
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int screen_height;
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int has_global_palette;
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int bits_per_pixel;
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uint32_t bg_color;
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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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/* intermediate buffer for storing color indices
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* obtained from lzw-encoded data stream */
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uint8_t *idx_line;
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int idx_line_size;
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/* after the frame is displayed, the disposal method is used */
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int gce_prev_disposal;
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int gce_disposal;
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/* rectangle describing area that must be disposed */
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int gce_l, gce_t, gce_w, gce_h;
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/* depending on disposal method we store either part of the image
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* drawn on the canvas or background color that
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* should be used upon disposal */
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uint32_t * stored_img;
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int stored_img_size;
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int stored_bg_color;
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GetByteContext gb;
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LZWState *lzw;
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/* aux buffers */
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uint32_t global_palette[256];
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uint32_t local_palette[256];
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AVCodecContext *avctx;
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int keyframe;
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int keyframe_ok;
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int trans_color; /**< color value that is used instead of transparent color */
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} GifState;
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static void gif_read_palette(GifState *s, uint32_t *pal, int nb)
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{
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int i;
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for (i = 0; i < nb; i++, pal++)
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*pal = (0xffu << 24) | bytestream2_get_be24u(&s->gb);
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}
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static void gif_fill(AVFrame *picture, uint32_t color)
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{
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uint32_t *p = (uint32_t *)picture->data[0];
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uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height;
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for (; p < p_end; p++)
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*p = color;
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}
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static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h)
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{
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const int linesize = picture->linesize[0] / sizeof(uint32_t);
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const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize;
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const uint32_t *pr, *pb = py + h * linesize;
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uint32_t *px;
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for (; py < pb; py += linesize) {
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px = (uint32_t *)py + l;
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pr = px + w;
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for (; px < pr; px++)
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*px = color;
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}
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}
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static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst,
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int linesize, int l, int t, int w, int h)
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{
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const int y_start = t * linesize;
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const uint32_t *src_px,
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*src_py = src + y_start,
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*dst_py = dst + y_start;
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const uint32_t *src_pb = src_py + h * linesize;
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uint32_t *dst_px;
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for (; src_py < src_pb; src_py += linesize, dst_py += linesize) {
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src_px = src_py + l;
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dst_px = (uint32_t *)dst_py + l;
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memcpy(dst_px, src_px, w * sizeof(uint32_t));
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}
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}
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static int gif_read_image(GifState *s, AVFrame *frame)
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{
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int left, top, width, height, bits_per_pixel, code_size, flags, pw;
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int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size, lzwed_len;
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uint32_t *ptr, *pal, *px, *pr, *ptr1;
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int ret;
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uint8_t *idx;
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/* At least 9 bytes of Image Descriptor. */
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if (bytestream2_get_bytes_left(&s->gb) < 9)
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return AVERROR_INVALIDDATA;
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left = bytestream2_get_le16u(&s->gb);
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top = bytestream2_get_le16u(&s->gb);
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width = bytestream2_get_le16u(&s->gb);
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height = bytestream2_get_le16u(&s->gb);
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flags = bytestream2_get_byteu(&s->gb);
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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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ff_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height);
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if (has_local_palette) {
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pal_size = 1 << bits_per_pixel;
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if (bytestream2_get_bytes_left(&s->gb) < pal_size * 3)
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return AVERROR_INVALIDDATA;
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gif_read_palette(s, s->local_palette, pal_size);
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pal = s->local_palette;
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} else {
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if (!s->has_global_palette) {
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av_log(s->avctx, AV_LOG_ERROR, "picture doesn't have either global or local palette.\n");
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return AVERROR_INVALIDDATA;
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}
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pal = s->global_palette;
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}
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if (s->keyframe) {
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if (s->transparent_color_index == -1 && s->has_global_palette) {
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/* transparency wasn't set before the first frame, fill with background color */
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gif_fill(frame, s->bg_color);
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} else {
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/* otherwise fill with transparent color.
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* this is necessary since by default picture filled with 0x80808080. */
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gif_fill(frame, s->trans_color);
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}
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}
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/* verify that all the image is inside the screen dimensions */
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if (!width || width > s->screen_width) {
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av_log(s->avctx, AV_LOG_WARNING, "Invalid image width: %d, truncating.\n", width);
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width = s->screen_width;
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}
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if (left >= s->screen_width) {
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av_log(s->avctx, AV_LOG_ERROR, "Invalid left position: %d.\n", left);
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return AVERROR_INVALIDDATA;
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}
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if (!height || height > s->screen_height) {
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av_log(s->avctx, AV_LOG_WARNING, "Invalid image height: %d, truncating.\n", height);
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height = s->screen_height;
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}
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if (top >= s->screen_height) {
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av_log(s->avctx, AV_LOG_ERROR, "Invalid top position: %d.\n", top);
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return AVERROR_INVALIDDATA;
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}
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if (left + width > s->screen_width) {
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/* width must be kept around to avoid lzw vs line desync */
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pw = s->screen_width - left;
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av_log(s->avctx, AV_LOG_WARNING, "Image too wide by %d, truncating.\n",
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left + width - s->screen_width);
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} else {
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pw = width;
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}
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if (top + height > s->screen_height) {
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/* we don't care about the extra invisible lines */
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av_log(s->avctx, AV_LOG_WARNING, "Image too high by %d, truncating.\n",
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top + height - s->screen_height);
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height = s->screen_height - top;
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}
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/* process disposal method */
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if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
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gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
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} else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
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gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0],
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frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
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}
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s->gce_prev_disposal = s->gce_disposal;
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if (s->gce_disposal != GCE_DISPOSAL_NONE) {
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s->gce_l = left; s->gce_t = top;
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s->gce_w = pw; s->gce_h = height;
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if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
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if (s->transparent_color_index >= 0)
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s->stored_bg_color = s->trans_color;
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else
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s->stored_bg_color = s->bg_color;
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} else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
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av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height);
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if (!s->stored_img)
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return AVERROR(ENOMEM);
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gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img,
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frame->linesize[0] / sizeof(uint32_t), left, top, pw, height);
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}
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}
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/* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
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if (bytestream2_get_bytes_left(&s->gb) < 2)
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return AVERROR_INVALIDDATA;
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/* now get the image data */
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code_size = bytestream2_get_byteu(&s->gb);
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if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer,
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bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) {
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av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
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return ret;
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}
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/* read all the image */
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linesize = frame->linesize[0] / sizeof(uint32_t);
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ptr1 = (uint32_t *)frame->data[0] + top * linesize + left;
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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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int count = ff_lzw_decode(s->lzw, s->idx_line, width);
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if (count != width) {
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if (count)
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av_log(s->avctx, AV_LOG_ERROR, "LZW decode failed\n");
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goto decode_tail;
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}
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pr = ptr + pw;
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for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
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if (*idx != s->transparent_color_index)
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*px = pal[*idx];
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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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break;
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case 2:
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y1 += 4;
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ptr += linesize * 4;
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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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while (y1 >= height) {
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y1 = 4 >> pass;
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ptr = ptr1 + linesize * y1;
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pass++;
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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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decode_tail:
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/* read the garbage data until end marker is found */
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lzwed_len = ff_lzw_decode_tail(s->lzw);
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bytestream2_skipu(&s->gb, lzwed_len);
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/* Graphic Control Extension's scope is single frame.
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* Remove its influence. */
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s->transparent_color_index = -1;
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s->gce_disposal = GCE_DISPOSAL_NONE;
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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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int ext_code, ext_len, gce_flags, gce_transparent_index;
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/* There must be at least 2 bytes:
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* 1 for extension label and 1 for extension length. */
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if (bytestream2_get_bytes_left(&s->gb) < 2)
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return AVERROR_INVALIDDATA;
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ext_code = bytestream2_get_byteu(&s->gb);
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ext_len = bytestream2_get_byteu(&s->gb);
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ff_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
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switch(ext_code) {
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case GIF_GCE_EXT_LABEL:
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if (ext_len != 4)
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goto discard_ext;
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/* We need at least 5 bytes more: 4 is for extension body
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* and 1 for next block size. */
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if (bytestream2_get_bytes_left(&s->gb) < 5)
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return AVERROR_INVALIDDATA;
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gce_flags = bytestream2_get_byteu(&s->gb);
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bytestream2_skipu(&s->gb, 2); // delay during which the frame is shown
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gce_transparent_index = bytestream2_get_byteu(&s->gb);
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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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ff_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
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gce_flags,
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s->transparent_color_index, s->gce_disposal);
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if (s->gce_disposal > 3) {
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s->gce_disposal = GCE_DISPOSAL_NONE;
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ff_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
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}
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ext_len = bytestream2_get_byteu(&s->gb);
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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) {
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/* There must be at least ext_len bytes and 1 for next block size byte. */
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if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1)
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return AVERROR_INVALIDDATA;
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bytestream2_skipu(&s->gb, ext_len);
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ext_len = bytestream2_get_byteu(&s->gb);
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ff_dlog(s->avctx, "ext_len1=%d\n", ext_len);
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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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uint8_t sig[6];
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int v, n;
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int background_color_index;
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if (bytestream2_get_bytes_left(&s->gb) < 13)
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return AVERROR_INVALIDDATA;
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/* read gif signature */
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bytestream2_get_bufferu(&s->gb, sig, 6);
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if (memcmp(sig, gif87a_sig, 6) &&
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memcmp(sig, gif89a_sig, 6))
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return AVERROR_INVALIDDATA;
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/* read screen header */
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s->transparent_color_index = -1;
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s->screen_width = bytestream2_get_le16u(&s->gb);
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s->screen_height = bytestream2_get_le16u(&s->gb);
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v = bytestream2_get_byteu(&s->gb);
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s->color_resolution = ((v & 0x70) >> 4) + 1;
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s->has_global_palette = (v & 0x80);
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s->bits_per_pixel = (v & 0x07) + 1;
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background_color_index = bytestream2_get_byteu(&s->gb);
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n = bytestream2_get_byteu(&s->gb);
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if (n) {
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s->avctx->sample_aspect_ratio.num = n + 15;
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s->avctx->sample_aspect_ratio.den = 64;
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}
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ff_dlog(s->avctx, "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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s->has_global_palette);
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if (s->has_global_palette) {
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s->background_color_index = background_color_index;
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n = 1 << s->bits_per_pixel;
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if (bytestream2_get_bytes_left(&s->gb) < n * 3)
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return AVERROR_INVALIDDATA;
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gif_read_palette(s, s->global_palette, n);
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s->bg_color = s->global_palette[s->background_color_index];
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} else
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s->background_color_index = -1;
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return 0;
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}
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static int gif_parse_next_image(GifState *s, AVFrame *frame)
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{
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while (bytestream2_get_bytes_left(&s->gb) > 0) {
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int code = bytestream2_get_byte(&s->gb);
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int ret;
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av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
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switch (code) {
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case GIF_IMAGE_SEPARATOR:
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return gif_read_image(s, frame);
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case GIF_EXTENSION_INTRODUCER:
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if ((ret = gif_read_extension(s)) < 0)
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return ret;
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break;
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case GIF_TRAILER:
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/* end of image */
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return AVERROR_EOF;
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default:
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/* erroneous block label */
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return AVERROR_INVALIDDATA;
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}
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}
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return AVERROR_EOF;
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}
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static av_cold int gif_decode_init(AVCodecContext *avctx)
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{
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GifState *s = avctx->priv_data;
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s->avctx = avctx;
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avctx->pix_fmt = AV_PIX_FMT_RGB32;
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s->frame = av_frame_alloc();
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if (!s->frame)
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return AVERROR(ENOMEM);
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ff_lzw_decode_open(&s->lzw);
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if (!s->lzw)
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return AVERROR(ENOMEM);
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return 0;
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}
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static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
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{
|
|
GifState *s = avctx->priv_data;
|
|
int ret;
|
|
|
|
bytestream2_init(&s->gb, avpkt->data, avpkt->size);
|
|
|
|
s->frame->pts = avpkt->pts;
|
|
#if FF_API_PKT_PTS
|
|
FF_DISABLE_DEPRECATION_WARNINGS
|
|
s->frame->pkt_pts = avpkt->pts;
|
|
FF_ENABLE_DEPRECATION_WARNINGS
|
|
#endif
|
|
s->frame->pkt_dts = avpkt->dts;
|
|
s->frame->pkt_duration = avpkt->duration;
|
|
|
|
if (avpkt->size >= 6) {
|
|
s->keyframe = memcmp(avpkt->data, gif87a_sig, 6) == 0 ||
|
|
memcmp(avpkt->data, gif89a_sig, 6) == 0;
|
|
} else {
|
|
s->keyframe = 0;
|
|
}
|
|
|
|
if (s->keyframe) {
|
|
s->keyframe_ok = 0;
|
|
s->gce_prev_disposal = GCE_DISPOSAL_NONE;
|
|
if ((ret = gif_read_header1(s)) < 0)
|
|
return ret;
|
|
|
|
if ((ret = ff_set_dimensions(avctx, s->screen_width, s->screen_height)) < 0)
|
|
return ret;
|
|
|
|
av_frame_unref(s->frame);
|
|
if ((ret = ff_get_buffer(avctx, s->frame, 0)) < 0)
|
|
return ret;
|
|
|
|
av_fast_malloc(&s->idx_line, &s->idx_line_size, s->screen_width);
|
|
if (!s->idx_line)
|
|
return AVERROR(ENOMEM);
|
|
|
|
s->frame->pict_type = AV_PICTURE_TYPE_I;
|
|
s->frame->key_frame = 1;
|
|
s->keyframe_ok = 1;
|
|
} else {
|
|
if (!s->keyframe_ok) {
|
|
av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n");
|
|
return AVERROR_INVALIDDATA;
|
|
}
|
|
|
|
if ((ret = ff_reget_buffer(avctx, s->frame, 0)) < 0)
|
|
return ret;
|
|
|
|
s->frame->pict_type = AV_PICTURE_TYPE_P;
|
|
s->frame->key_frame = 0;
|
|
}
|
|
|
|
ret = gif_parse_next_image(s, s->frame);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if ((ret = av_frame_ref(data, s->frame)) < 0)
|
|
return ret;
|
|
*got_frame = 1;
|
|
|
|
return bytestream2_tell(&s->gb);
|
|
}
|
|
|
|
static av_cold int gif_decode_close(AVCodecContext *avctx)
|
|
{
|
|
GifState *s = avctx->priv_data;
|
|
|
|
ff_lzw_decode_close(&s->lzw);
|
|
av_frame_free(&s->frame);
|
|
av_freep(&s->idx_line);
|
|
av_freep(&s->stored_img);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const AVOption options[] = {
|
|
{ "trans_color", "color value (ARGB) that is used instead of transparent color",
|
|
offsetof(GifState, trans_color), AV_OPT_TYPE_INT,
|
|
{.i64 = GIF_TRANSPARENT_COLOR}, 0, 0xffffffff,
|
|
AV_OPT_FLAG_DECODING_PARAM|AV_OPT_FLAG_VIDEO_PARAM },
|
|
{ NULL },
|
|
};
|
|
|
|
static const AVClass decoder_class = {
|
|
.class_name = "gif decoder",
|
|
.item_name = av_default_item_name,
|
|
.option = options,
|
|
.version = LIBAVUTIL_VERSION_INT,
|
|
.category = AV_CLASS_CATEGORY_DECODER,
|
|
};
|
|
|
|
AVCodec ff_gif_decoder = {
|
|
.name = "gif",
|
|
.long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
|
|
.type = AVMEDIA_TYPE_VIDEO,
|
|
.id = AV_CODEC_ID_GIF,
|
|
.priv_data_size = sizeof(GifState),
|
|
.init = gif_decode_init,
|
|
.close = gif_decode_close,
|
|
.decode = gif_decode_frame,
|
|
.capabilities = AV_CODEC_CAP_DR1,
|
|
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE |
|
|
FF_CODEC_CAP_INIT_CLEANUP,
|
|
.priv_class = &decoder_class,
|
|
};
|