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FFmpeg/libavcodec/gifdec.c
Andreas Rheinhardt a247ac640d avcodec: Constify AVCodecs
Given that the AVCodec.next pointer has now been removed, most of the
AVCodecs are not modified at all any more and can therefore be made
const (as this patch does); the only exceptions are the very few codecs
for external libraries that have a init_static_data callback.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
2021-04-27 10:43:15 -03:00

571 lines
18 KiB
C

/*
* 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;
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,
};
const 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,
};