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FFmpeg/libavcodec/gif.c
Paul B Mahol faca28c264 avcodec: rewrite gif muxing and encoding
Now "-c copy" works.
Update FATE files.

Demuxer only split file into packets, no data is trimmed.
Encoder & muxer currently expect completely another format
where muxer writes stuff like disposal method which should
be really encoder job.
With this patch muxer only modifies delay between two packets.
Codec copy need to have same behavior between demuxer and
muxer to work correctly.

Fixes #6640.
2018-12-13 18:58:48 +01:00

380 lines
12 KiB
C

/*
* 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"
#define DEFAULT_TRANSPARENCY_INDEX 0x1f
typedef struct GIFContext {
const AVClass *class;
LZWState *lzw;
uint8_t *buf;
int buf_size;
int is_first_frame;
AVFrame *last_frame;
int flags;
uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
int palette_loaded;
int transparent_index;
uint8_t *tmpl; ///< temporary line buffer
} GIFContext;
enum {
GF_OFFSETTING = 1<<0,
GF_TRANSDIFF = 1<<1,
};
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 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 bcid = -1, honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette;
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);
}
if (s->is_first_frame) { /* GIF header */
const uint32_t *global_palette = palette ? palette : s->palette;
const AVRational sar = avctx->sample_aspect_ratio;
int64_t aspect = 0;
if (sar.num > 0 && sar.den > 0) {
aspect = sar.num * 64LL / sar.den - 15;
if (aspect < 0 || aspect > 255)
aspect = 0;
}
bytestream_put_buffer(bytestream, gif89a_sig, sizeof(gif89a_sig));
bytestream_put_le16(bytestream, avctx->width);
bytestream_put_le16(bytestream, avctx->height);
bcid = get_palette_transparency_index(global_palette);
bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid); /* background color index */
bytestream_put_byte(bytestream, aspect);
for (int i = 0; i < 256; i++) {
const uint32_t v = global_palette[i] & 0xffffff;
bytestream_put_be24(bytestream, v);
}
s->is_first_frame = 0;
}
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");
}
if (trans < 0)
honor_transparency = 0;
bcid = (honor_transparency && trans >= 0) ? trans : get_palette_transparency_index(palette);
/* graphic control extension */
bytestream_put_byte(bytestream, GIF_EXTENSION_INTRODUCER);
bytestream_put_byte(bytestream, GIF_GCE_EXT_LABEL);
bytestream_put_byte(bytestream, 0x04); /* block size */
bytestream_put_byte(bytestream, 1<<2 | (bcid >= 0));
bytestream_put_le16(bytestream, 5); // default delay
bytestream_put_byte(bytestream, bcid < 0 ? DEFAULT_TRANSPARENCY_INDEX : bcid);
bytestream_put_byte(bytestream, 0x00);
/* 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);
}
}
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);
}
s->transparent_index = -1;
s->is_first_frame = 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;
}
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) {
palette = (uint32_t*)pict->data[1];
if (!s->palette_loaded) {
memcpy(s->palette, palette, AVPALETTE_SIZE);
s->transparent_index = get_palette_transparency_index(palette);
s->palette_loaded = 1;
} 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,
};