0,0 → 1,544 |
/* |
* 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; |
/* LZW compatible decoder */ |
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; |
int is_interleaved, has_local_palette, y, pass, y1, linesize, pal_size; |
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; |
|
av_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 (left + width > s->screen_width || |
top + height > s->screen_height) |
return AVERROR_INVALIDDATA; |
if (width <= 0 || height <= 0) |
return AVERROR_INVALIDDATA; |
|
/* 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 = width; 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, width, 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++) { |
if (ff_lzw_decode(s->lzw, s->idx_line, width) == 0) |
goto decode_tail; |
|
pr = ptr + width; |
|
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; |
if (y1 >= height) { |
y1 = pass ? 2 : 4; |
ptr = ptr1 + linesize * y1; |
pass++; |
} |
break; |
case 2: |
y1 += 4; |
ptr += linesize * 4; |
if (y1 >= height) { |
y1 = 1; |
ptr = ptr1 + linesize; |
pass++; |
} |
break; |
case 3: |
y1 += 2; |
ptr += linesize * 2; |
break; |
} |
} else { |
ptr += linesize; |
} |
} |
|
decode_tail: |
/* read the garbage data until end marker is found */ |
ff_lzw_decode_tail(s->lzw); |
|
/* 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); |
|
av_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; |
|
av_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; |
av_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); |
|
av_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; |
} |
|
av_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)) { |
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); |
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_pts = avpkt->pts; |
s->frame->pkt_dts = avpkt->dts; |
av_frame_set_pkt_duration(s->frame, 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 = av_image_check_size(s->screen_width, s->screen_height, 0, avctx)) < 0) |
return ret; |
avcodec_set_dimensions(avctx, s->screen_width, s->screen_height); |
|
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) |
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 avpkt->size; |
} |
|
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 = CODEC_CAP_DR1, |
.priv_class = &decoder_class, |
}; |