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ffmpeg/libavcodec/gif.c

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/*
* Copyright (c) 2000 Fabrice Bellard
* Copyright (c) 2002 Francois Revol
* Copyright (c) 2006 Baptiste Coudurier
*
* first version by Francois Revol <revol@free.fr>
*
* 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
*/
/**
* @file
* GIF encoder
* @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
*/
#define BITSTREAM_WRITER_LE
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "lzw.h"
#include "gif.h"
#include "put_bits.h"
typedef struct GIFContext {
const AVClass *class;
LZWState *lzw;
uint8_t *buf;
int buf_size;
AVFrame *last_frame;
int flags;
uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
int palette_loaded;
int transparent_index;
uint8_t *pal_exdata;
uint8_t *tmpl; ///< temporary line buffer
} GIFContext;
enum {
GF_OFFSETTING = 1<<0,
GF_TRANSDIFF = 1<<1,
};
static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
{
int histogram[AVPALETTE_COUNT] = {0};
int x, y, i;
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++)
histogram[buf[x]]++;
buf += linesize;
}
for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
if (!histogram[i])
return i;
return -1;
}
static int gif_image_write_image(AVCodecContext *avctx,
uint8_t **bytestream, uint8_t *end,
const uint32_t *palette,
const uint8_t *buf, const int linesize,
AVPacket *pkt)
{
GIFContext *s = avctx->priv_data;
int len = 0, height = avctx->height, width = avctx->width, x, y;
int x_start = 0, y_start = 0, trans = s->transparent_index;
int honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame;
const uint8_t *ptr;
/* Crop image */
if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {
const uint8_t *ref = s->last_frame->data[0];
const int ref_linesize = s->last_frame->linesize[0];
int x_end = avctx->width - 1,
y_end = avctx->height - 1;
/* skip common lines */
while (y_start < y_end) {
if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
break;
y_start++;
}
while (y_end > y_start) {
if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
break;
y_end--;
}
height = y_end + 1 - y_start;
/* skip common columns */
while (x_start < x_end) {
int same_column = 1;
for (y = y_start; y <= y_end; y++) {
if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
same_column = 0;
break;
}
}
if (!same_column)
break;
x_start++;
}
while (x_end > x_start) {
int same_column = 1;
for (y = y_start; y <= y_end; y++) {
if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
same_column = 0;
break;
}
}
if (!same_column)
break;
x_end--;
}
width = x_end + 1 - x_start;
av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
width, height, x_start, y_start, avctx->width, avctx->height);
}
/* image block */
bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
bytestream_put_le16(bytestream, x_start);
bytestream_put_le16(bytestream, y_start);
bytestream_put_le16(bytestream, width);
bytestream_put_le16(bytestream, height);
if (!palette) {
bytestream_put_byte(bytestream, 0x00); /* flags */
} else {
unsigned i;
bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
for (i = 0; i < AVPALETTE_COUNT; i++) {
const uint32_t v = palette[i];
bytestream_put_be24(bytestream, v);
}
}
if (honor_transparency && trans < 0) {
trans = pick_palette_entry(buf + y_start*linesize + x_start,
linesize, width, height);
if (trans < 0) { // TODO, patch welcome
av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
} else {
uint8_t *pal_exdata = s->pal_exdata;
if (!pal_exdata)
pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
if (!pal_exdata)
return AVERROR(ENOMEM);
memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
}
}
if (trans < 0)
honor_transparency = 0;
bytestream_put_byte(bytestream, 0x08);
ff_lzw_encode_init(s->lzw, s->buf, s->buf_size,
12, FF_LZW_GIF, put_bits);
ptr = buf + y_start*linesize + x_start;
if (honor_transparency) {
const int ref_linesize = s->last_frame->linesize[0];
const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;
for (y = 0; y < height; y++) {
memcpy(s->tmpl, ptr, width);
for (x = 0; x < width; x++)
if (ref[x] == ptr[x])
s->tmpl[x] = trans;
len += ff_lzw_encode(s->lzw, s->tmpl, width);
ptr += linesize;
ref += ref_linesize;
}
} else {
for (y = 0; y < height; y++) {
len += ff_lzw_encode(s->lzw, ptr, width);
ptr += linesize;
}
}
len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
ptr = s->buf;
while (len > 0) {
int size = FFMIN(255, len);
bytestream_put_byte(bytestream, size);
if (end - *bytestream < size)
return -1;
bytestream_put_buffer(bytestream, ptr, size);
ptr += size;
len -= size;
}
bytestream_put_byte(bytestream, 0x00); /* end of image block */
return 0;
}
static av_cold int gif_encode_init(AVCodecContext *avctx)
{
GIFContext *s = avctx->priv_data;
if (avctx->width > 65535 || avctx->height > 65535) {
av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
return AVERROR(EINVAL);
}
#if FF_API_CODED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
avctx->coded_frame->key_frame = 1;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
s->transparent_index = -1;
s->lzw = av_mallocz(ff_lzw_encode_state_size);
s->buf_size = avctx->width*avctx->height*2 + 1000;
s->buf = av_malloc(s->buf_size);
s->tmpl = av_malloc(avctx->width);
if (!s->tmpl || !s->buf || !s->lzw)
return AVERROR(ENOMEM);
if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
return 0;
}
/* FIXME: duplicated with lavc */
static int get_palette_transparency_index(const uint32_t *palette)
{
int transparent_color_index = -1;
unsigned i, smallest_alpha = 0xff;
if (!palette)
return -1;
for (i = 0; i < AVPALETTE_COUNT; i++) {
const uint32_t v = palette[i];
if (v >> 24 < smallest_alpha) {
smallest_alpha = v >> 24;
transparent_color_index = i;
}
}
return smallest_alpha < 128 ? transparent_color_index : -1;
}
static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
const AVFrame *pict, int *got_packet)
{
GIFContext *s = avctx->priv_data;
uint8_t *outbuf_ptr, *end;
const uint32_t *palette = NULL;
int ret;
if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)
return ret;
outbuf_ptr = pkt->data;
end = pkt->data + pkt->size;
if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
if (!pal_exdata)
return AVERROR(ENOMEM);
memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
palette = (uint32_t*)pict->data[1];
s->pal_exdata = pal_exdata;
/* The first palette with PAL8 will be used as generic palette by the
* muxer so we don't need to write it locally in the packet. We store
* it as a reference here in case it changes later. */
if (!s->palette_loaded) {
memcpy(s->palette, palette, AVPALETTE_SIZE);
s->transparent_index = get_palette_transparency_index(palette);
s->palette_loaded = 1;
palette = NULL;
} else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
palette = NULL;
}
}
gif_image_write_image(avctx, &outbuf_ptr, end, palette,
pict->data[0], pict->linesize[0], pkt);
if (!s->last_frame) {
s->last_frame = av_frame_alloc();
if (!s->last_frame)
return AVERROR(ENOMEM);
}
av_frame_unref(s->last_frame);
ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
if (ret < 0)
return ret;
pkt->size = outbuf_ptr - pkt->data;
pkt->flags |= AV_PKT_FLAG_KEY;
*got_packet = 1;
return 0;
}
static int gif_encode_close(AVCodecContext *avctx)
{
GIFContext *s = avctx->priv_data;
av_freep(&s->lzw);
av_freep(&s->buf);
s->buf_size = 0;
av_frame_free(&s->last_frame);
av_freep(&s->tmpl);
return 0;
}
#define OFFSET(x) offsetof(GIFContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
static const AVOption gif_options[] = {
{ "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
{ "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
{ "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
{ NULL }
};
static const AVClass gif_class = {
.class_name = "GIF encoder",
.item_name = av_default_item_name,
.option = gif_options,
.version = LIBAVUTIL_VERSION_INT,
};
AVCodec ff_gif_encoder = {
.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(GIFContext),
.init = gif_encode_init,
.encode2 = gif_encode_frame,
.close = gif_encode_close,
.pix_fmts = (const enum AVPixelFormat[]){
AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
},
.priv_class = &gif_class,
};
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