/libavcodec/gifdec.c
http://github.com/FFmpeg/FFmpeg · C · 575 lines · 428 code · 89 blank · 58 comment · 84 complexity · 019bf211bee3919d9de286048a96b488 MD5 · raw file
- /*
- * GIF decoder
- * Copyright (c) 2003 Fabrice Bellard
- * Copyright (c) 2006 Baptiste Coudurier
- * Copyright (c) 2012 Vitaliy E Sugrobov
- *
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
- #include "libavutil/imgutils.h"
- #include "libavutil/opt.h"
- #include "avcodec.h"
- #include "bytestream.h"
- #include "internal.h"
- #include "lzw.h"
- #include "gif.h"
- /* This value is intentionally set to "transparent white" color.
- * It is much better to have white background instead of black
- * when gif image converted to format which not support transparency.
- */
- #define GIF_TRANSPARENT_COLOR 0x00ffffff
- typedef struct GifState {
- const AVClass *class;
- AVFrame *frame;
- int screen_width;
- int screen_height;
- int has_global_palette;
- int bits_per_pixel;
- uint32_t bg_color;
- int background_color_index;
- int transparent_color_index;
- int color_resolution;
- /* intermediate buffer for storing color indices
- * obtained from lzw-encoded data stream */
- uint8_t *idx_line;
- int idx_line_size;
- /* after the frame is displayed, the disposal method is used */
- int gce_prev_disposal;
- int gce_disposal;
- /* rectangle describing area that must be disposed */
- int gce_l, gce_t, gce_w, gce_h;
- /* depending on disposal method we store either part of the image
- * drawn on the canvas or background color that
- * should be used upon disposal */
- uint32_t * stored_img;
- int stored_img_size;
- int stored_bg_color;
- GetByteContext gb;
- LZWState *lzw;
- /* aux buffers */
- uint32_t global_palette[256];
- uint32_t local_palette[256];
- AVCodecContext *avctx;
- int keyframe;
- int keyframe_ok;
- int trans_color; /**< color value that is used instead of transparent color */
- } GifState;
- static void gif_read_palette(GifState *s, uint32_t *pal, int nb)
- {
- int i;
- for (i = 0; i < nb; i++, pal++)
- *pal = (0xffu << 24) | bytestream2_get_be24u(&s->gb);
- }
- static void gif_fill(AVFrame *picture, uint32_t color)
- {
- uint32_t *p = (uint32_t *)picture->data[0];
- uint32_t *p_end = p + (picture->linesize[0] / sizeof(uint32_t)) * picture->height;
- for (; p < p_end; p++)
- *p = color;
- }
- static void gif_fill_rect(AVFrame *picture, uint32_t color, int l, int t, int w, int h)
- {
- const int linesize = picture->linesize[0] / sizeof(uint32_t);
- const uint32_t *py = (uint32_t *)picture->data[0] + t * linesize;
- const uint32_t *pr, *pb = py + h * linesize;
- uint32_t *px;
- for (; py < pb; py += linesize) {
- px = (uint32_t *)py + l;
- pr = px + w;
- for (; px < pr; px++)
- *px = color;
- }
- }
- static void gif_copy_img_rect(const uint32_t *src, uint32_t *dst,
- int linesize, int l, int t, int w, int h)
- {
- const int y_start = t * linesize;
- const uint32_t *src_px,
- *src_py = src + y_start,
- *dst_py = dst + y_start;
- const uint32_t *src_pb = src_py + h * linesize;
- uint32_t *dst_px;
- for (; src_py < src_pb; src_py += linesize, dst_py += linesize) {
- src_px = src_py + l;
- dst_px = (uint32_t *)dst_py + l;
- memcpy(dst_px, src_px, w * sizeof(uint32_t));
- }
- }
- static int gif_read_image(GifState *s, AVFrame *frame)
- {
- int left, top, width, height, bits_per_pixel, code_size, flags, pw;
- int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size, lzwed_len;
- uint32_t *ptr, *pal, *px, *pr, *ptr1;
- int ret;
- uint8_t *idx;
- /* At least 9 bytes of Image Descriptor. */
- if (bytestream2_get_bytes_left(&s->gb) < 9)
- return AVERROR_INVALIDDATA;
- left = bytestream2_get_le16u(&s->gb);
- top = bytestream2_get_le16u(&s->gb);
- width = bytestream2_get_le16u(&s->gb);
- height = bytestream2_get_le16u(&s->gb);
- flags = bytestream2_get_byteu(&s->gb);
- is_interleaved = flags & 0x40;
- has_local_palette = flags & 0x80;
- bits_per_pixel = (flags & 0x07) + 1;
- ff_dlog(s->avctx, "image x=%d y=%d w=%d h=%d\n", left, top, width, height);
- if (has_local_palette) {
- pal_size = 1 << bits_per_pixel;
- if (bytestream2_get_bytes_left(&s->gb) < pal_size * 3)
- return AVERROR_INVALIDDATA;
- gif_read_palette(s, s->local_palette, pal_size);
- pal = s->local_palette;
- } else {
- if (!s->has_global_palette) {
- av_log(s->avctx, AV_LOG_ERROR, "picture doesn't have either global or local palette.\n");
- return AVERROR_INVALIDDATA;
- }
- pal = s->global_palette;
- }
- if (s->keyframe) {
- if (s->transparent_color_index == -1 && s->has_global_palette) {
- /* transparency wasn't set before the first frame, fill with background color */
- gif_fill(frame, s->bg_color);
- } else {
- /* otherwise fill with transparent color.
- * this is necessary since by default picture filled with 0x80808080. */
- gif_fill(frame, s->trans_color);
- }
- }
- /* verify that all the image is inside the screen dimensions */
- if (!width || width > s->screen_width) {
- av_log(s->avctx, AV_LOG_WARNING, "Invalid image width: %d, truncating.\n", width);
- width = s->screen_width;
- }
- if (left >= s->screen_width) {
- av_log(s->avctx, AV_LOG_ERROR, "Invalid left position: %d.\n", left);
- return AVERROR_INVALIDDATA;
- }
- if (!height || height > s->screen_height) {
- av_log(s->avctx, AV_LOG_WARNING, "Invalid image height: %d, truncating.\n", height);
- height = s->screen_height;
- }
- if (top >= s->screen_height) {
- av_log(s->avctx, AV_LOG_ERROR, "Invalid top position: %d.\n", top);
- return AVERROR_INVALIDDATA;
- }
- if (left + width > s->screen_width) {
- /* width must be kept around to avoid lzw vs line desync */
- pw = s->screen_width - left;
- av_log(s->avctx, AV_LOG_WARNING, "Image too wide by %d, truncating.\n",
- left + width - s->screen_width);
- } else {
- pw = width;
- }
- if (top + height > s->screen_height) {
- /* we don't care about the extra invisible lines */
- av_log(s->avctx, AV_LOG_WARNING, "Image too high by %d, truncating.\n",
- top + height - s->screen_height);
- height = s->screen_height - top;
- }
- /* process disposal method */
- if (s->gce_prev_disposal == GCE_DISPOSAL_BACKGROUND) {
- gif_fill_rect(frame, s->stored_bg_color, s->gce_l, s->gce_t, s->gce_w, s->gce_h);
- } else if (s->gce_prev_disposal == GCE_DISPOSAL_RESTORE) {
- gif_copy_img_rect(s->stored_img, (uint32_t *)frame->data[0],
- frame->linesize[0] / sizeof(uint32_t), s->gce_l, s->gce_t, s->gce_w, s->gce_h);
- }
- s->gce_prev_disposal = s->gce_disposal;
- if (s->gce_disposal != GCE_DISPOSAL_NONE) {
- s->gce_l = left; s->gce_t = top;
- s->gce_w = pw; s->gce_h = height;
- if (s->gce_disposal == GCE_DISPOSAL_BACKGROUND) {
- if (s->transparent_color_index >= 0)
- s->stored_bg_color = s->trans_color;
- else
- s->stored_bg_color = s->bg_color;
- } else if (s->gce_disposal == GCE_DISPOSAL_RESTORE) {
- av_fast_malloc(&s->stored_img, &s->stored_img_size, frame->linesize[0] * frame->height);
- if (!s->stored_img)
- return AVERROR(ENOMEM);
- gif_copy_img_rect((uint32_t *)frame->data[0], s->stored_img,
- frame->linesize[0] / sizeof(uint32_t), left, top, pw, height);
- }
- }
- /* Expect at least 2 bytes: 1 for lzw code size and 1 for block size. */
- if (bytestream2_get_bytes_left(&s->gb) < 2)
- return AVERROR_INVALIDDATA;
- /* now get the image data */
- code_size = bytestream2_get_byteu(&s->gb);
- if ((ret = ff_lzw_decode_init(s->lzw, code_size, s->gb.buffer,
- bytestream2_get_bytes_left(&s->gb), FF_LZW_GIF)) < 0) {
- av_log(s->avctx, AV_LOG_ERROR, "LZW init failed\n");
- return ret;
- }
- /* read all the image */
- linesize = frame->linesize[0] / sizeof(uint32_t);
- ptr1 = (uint32_t *)frame->data[0] + top * linesize + left;
- ptr = ptr1;
- pass = 0;
- y1 = 0;
- for (y = 0; y < height; y++) {
- int count = ff_lzw_decode(s->lzw, s->idx_line, width);
- if (count != width) {
- if (count)
- av_log(s->avctx, AV_LOG_ERROR, "LZW decode failed\n");
- goto decode_tail;
- }
- pr = ptr + pw;
- for (px = ptr, idx = s->idx_line; px < pr; px++, idx++) {
- if (*idx != s->transparent_color_index)
- *px = pal[*idx];
- }
- if (is_interleaved) {
- switch(pass) {
- default:
- case 0:
- case 1:
- y1 += 8;
- ptr += linesize * 8;
- break;
- case 2:
- y1 += 4;
- ptr += linesize * 4;
- break;
- case 3:
- y1 += 2;
- ptr += linesize * 2;
- break;
- }
- while (y1 >= height) {
- y1 = 4 >> pass;
- ptr = ptr1 + linesize * y1;
- pass++;
- }
- } else {
- ptr += linesize;
- }
- }
- decode_tail:
- /* read the garbage data until end marker is found */
- lzwed_len = ff_lzw_decode_tail(s->lzw);
- bytestream2_skipu(&s->gb, lzwed_len);
- /* Graphic Control Extension's scope is single frame.
- * Remove its influence. */
- s->transparent_color_index = -1;
- s->gce_disposal = GCE_DISPOSAL_NONE;
- return 0;
- }
- static int gif_read_extension(GifState *s)
- {
- int ext_code, ext_len, gce_flags, gce_transparent_index;
- /* There must be at least 2 bytes:
- * 1 for extension label and 1 for extension length. */
- if (bytestream2_get_bytes_left(&s->gb) < 2)
- return AVERROR_INVALIDDATA;
- ext_code = bytestream2_get_byteu(&s->gb);
- ext_len = bytestream2_get_byteu(&s->gb);
- ff_dlog(s->avctx, "ext_code=0x%x len=%d\n", ext_code, ext_len);
- switch(ext_code) {
- case GIF_GCE_EXT_LABEL:
- if (ext_len != 4)
- goto discard_ext;
- /* We need at least 5 bytes more: 4 is for extension body
- * and 1 for next block size. */
- if (bytestream2_get_bytes_left(&s->gb) < 5)
- return AVERROR_INVALIDDATA;
- gce_flags = bytestream2_get_byteu(&s->gb);
- bytestream2_skipu(&s->gb, 2); // delay during which the frame is shown
- gce_transparent_index = bytestream2_get_byteu(&s->gb);
- if (gce_flags & 0x01)
- s->transparent_color_index = gce_transparent_index;
- else
- s->transparent_color_index = -1;
- s->gce_disposal = (gce_flags >> 2) & 0x7;
- ff_dlog(s->avctx, "gce_flags=%x tcolor=%d disposal=%d\n",
- gce_flags,
- s->transparent_color_index, s->gce_disposal);
- if (s->gce_disposal > 3) {
- s->gce_disposal = GCE_DISPOSAL_NONE;
- ff_dlog(s->avctx, "invalid value in gce_disposal (%d). Using default value of 0.\n", ext_len);
- }
- ext_len = bytestream2_get_byteu(&s->gb);
- break;
- }
- /* NOTE: many extension blocks can come after */
- discard_ext:
- while (ext_len) {
- /* There must be at least ext_len bytes and 1 for next block size byte. */
- if (bytestream2_get_bytes_left(&s->gb) < ext_len + 1)
- return AVERROR_INVALIDDATA;
- bytestream2_skipu(&s->gb, ext_len);
- ext_len = bytestream2_get_byteu(&s->gb);
- ff_dlog(s->avctx, "ext_len1=%d\n", ext_len);
- }
- return 0;
- }
- static int gif_read_header1(GifState *s)
- {
- uint8_t sig[6];
- int v, n;
- int background_color_index;
- if (bytestream2_get_bytes_left(&s->gb) < 13)
- return AVERROR_INVALIDDATA;
- /* read gif signature */
- bytestream2_get_bufferu(&s->gb, sig, 6);
- if (memcmp(sig, gif87a_sig, 6) &&
- memcmp(sig, gif89a_sig, 6))
- return AVERROR_INVALIDDATA;
- /* read screen header */
- s->transparent_color_index = -1;
- s->screen_width = bytestream2_get_le16u(&s->gb);
- s->screen_height = bytestream2_get_le16u(&s->gb);
- v = bytestream2_get_byteu(&s->gb);
- s->color_resolution = ((v & 0x70) >> 4) + 1;
- s->has_global_palette = (v & 0x80);
- s->bits_per_pixel = (v & 0x07) + 1;
- background_color_index = bytestream2_get_byteu(&s->gb);
- n = bytestream2_get_byteu(&s->gb);
- if (n) {
- s->avctx->sample_aspect_ratio.num = n + 15;
- s->avctx->sample_aspect_ratio.den = 64;
- }
- ff_dlog(s->avctx, "screen_w=%d screen_h=%d bpp=%d global_palette=%d\n",
- s->screen_width, s->screen_height, s->bits_per_pixel,
- s->has_global_palette);
- if (s->has_global_palette) {
- s->background_color_index = background_color_index;
- n = 1 << s->bits_per_pixel;
- if (bytestream2_get_bytes_left(&s->gb) < n * 3)
- return AVERROR_INVALIDDATA;
- gif_read_palette(s, s->global_palette, n);
- s->bg_color = s->global_palette[s->background_color_index];
- } else
- s->background_color_index = -1;
- return 0;
- }
- static int gif_parse_next_image(GifState *s, AVFrame *frame)
- {
- while (bytestream2_get_bytes_left(&s->gb) > 0) {
- int code = bytestream2_get_byte(&s->gb);
- int ret;
- av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
- switch (code) {
- case GIF_IMAGE_SEPARATOR:
- return gif_read_image(s, frame);
- case GIF_EXTENSION_INTRODUCER:
- if ((ret = gif_read_extension(s)) < 0)
- return ret;
- break;
- case GIF_TRAILER:
- /* end of image */
- return AVERROR_EOF;
- default:
- /* erroneous block label */
- return AVERROR_INVALIDDATA;
- }
- }
- return AVERROR_EOF;
- }
- static av_cold int gif_decode_init(AVCodecContext *avctx)
- {
- GifState *s = avctx->priv_data;
- s->avctx = avctx;
- avctx->pix_fmt = AV_PIX_FMT_RGB32;
- s->frame = av_frame_alloc();
- if (!s->frame)
- return AVERROR(ENOMEM);
- ff_lzw_decode_open(&s->lzw);
- if (!s->lzw)
- return AVERROR(ENOMEM);
- return 0;
- }
- static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
- {
- 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,
- };