mirror of
https://git.videolan.org/git/ffmpeg.git
synced 2024-08-22 01:05:05 +02:00
180 lines
5.6 KiB
C
180 lines
5.6 KiB
C
/*
|
|
* GIF encoder.
|
|
* Copyright (c) 2000 Fabrice Bellard
|
|
* Copyright (c) 2002 Francois Revol
|
|
* Copyright (c) 2006 Baptiste Coudurier
|
|
*
|
|
* This file is part of Libav.
|
|
*
|
|
* Libav 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.
|
|
*
|
|
* Libav 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 Libav; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
/*
|
|
* First version by Francois Revol revol@free.fr
|
|
*
|
|
* Features and limitations:
|
|
* - currently no compression is performed,
|
|
* in fact the size of the data is 9/8 the size of the image in 8bpp
|
|
* - uses only a global standard palette
|
|
* - tested with IE 5.0, Opera for BeOS, NetPositive (BeOS), and Mozilla (BeOS).
|
|
*
|
|
* Reference documents:
|
|
* http://www.goice.co.jp/member/mo/formats/gif.html
|
|
* http://astronomy.swin.edu.au/pbourke/dataformats/gif/
|
|
* http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt
|
|
*
|
|
* this url claims to have an LZW algorithm not covered by Unisys patent:
|
|
* http://www.msg.net/utility/whirlgif/gifencod.html
|
|
* could help reduce the size of the files _a lot_...
|
|
* some sites mentions an RLE type compression also.
|
|
*/
|
|
|
|
#include "avcodec.h"
|
|
#include "bytestream.h"
|
|
#include "lzw.h"
|
|
|
|
/* The GIF format uses reversed order for bitstreams... */
|
|
/* at least they don't use PDP_ENDIAN :) */
|
|
#define BITSTREAM_WRITER_LE
|
|
|
|
#include "put_bits.h"
|
|
|
|
typedef struct {
|
|
AVFrame picture;
|
|
LZWState *lzw;
|
|
uint8_t *buf;
|
|
} GIFContext;
|
|
|
|
/* GIF header */
|
|
static int gif_image_write_header(AVCodecContext *avctx,
|
|
uint8_t **bytestream, uint32_t *palette)
|
|
{
|
|
int i;
|
|
unsigned int v;
|
|
|
|
bytestream_put_buffer(bytestream, "GIF", 3);
|
|
bytestream_put_buffer(bytestream, "89a", 3);
|
|
bytestream_put_le16(bytestream, avctx->width);
|
|
bytestream_put_le16(bytestream, avctx->height);
|
|
|
|
bytestream_put_byte(bytestream, 0xf7); /* flags: global clut, 256 entries */
|
|
bytestream_put_byte(bytestream, 0x1f); /* background color index */
|
|
bytestream_put_byte(bytestream, 0); /* aspect ratio */
|
|
|
|
/* the global palette */
|
|
for(i=0;i<256;i++) {
|
|
v = palette[i];
|
|
bytestream_put_be24(bytestream, v);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int gif_image_write_image(AVCodecContext *avctx,
|
|
uint8_t **bytestream, uint8_t *end,
|
|
const uint8_t *buf, int linesize)
|
|
{
|
|
GIFContext *s = avctx->priv_data;
|
|
int len = 0, height;
|
|
const uint8_t *ptr;
|
|
/* image block */
|
|
|
|
bytestream_put_byte(bytestream, 0x2c);
|
|
bytestream_put_le16(bytestream, 0);
|
|
bytestream_put_le16(bytestream, 0);
|
|
bytestream_put_le16(bytestream, avctx->width);
|
|
bytestream_put_le16(bytestream, avctx->height);
|
|
bytestream_put_byte(bytestream, 0x00); /* flags */
|
|
/* no local clut */
|
|
|
|
bytestream_put_byte(bytestream, 0x08);
|
|
|
|
ff_lzw_encode_init(s->lzw, s->buf, avctx->width*avctx->height,
|
|
12, FF_LZW_GIF, put_bits);
|
|
|
|
ptr = buf;
|
|
for (height = avctx->height; height--;) {
|
|
len += ff_lzw_encode(s->lzw, ptr, avctx->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 */
|
|
bytestream_put_byte(bytestream, 0x3b);
|
|
return 0;
|
|
}
|
|
|
|
static av_cold int gif_encode_init(AVCodecContext *avctx)
|
|
{
|
|
GIFContext *s = avctx->priv_data;
|
|
|
|
avctx->coded_frame = &s->picture;
|
|
s->lzw = av_mallocz(ff_lzw_encode_state_size);
|
|
if (!s->lzw)
|
|
return AVERROR(ENOMEM);
|
|
s->buf = av_malloc(avctx->width*avctx->height*2);
|
|
if (!s->buf)
|
|
return AVERROR(ENOMEM);
|
|
return 0;
|
|
}
|
|
|
|
/* better than nothing gif encoder */
|
|
static int gif_encode_frame(AVCodecContext *avctx, unsigned char *outbuf, int buf_size, void *data)
|
|
{
|
|
GIFContext *s = avctx->priv_data;
|
|
AVFrame *pict = data;
|
|
AVFrame *const p = (AVFrame *)&s->picture;
|
|
uint8_t *outbuf_ptr = outbuf;
|
|
uint8_t *end = outbuf + buf_size;
|
|
|
|
*p = *pict;
|
|
p->pict_type = AV_PICTURE_TYPE_I;
|
|
p->key_frame = 1;
|
|
gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]);
|
|
gif_image_write_image(avctx, &outbuf_ptr, end, pict->data[0], pict->linesize[0]);
|
|
return outbuf_ptr - outbuf;
|
|
}
|
|
|
|
static int gif_encode_close(AVCodecContext *avctx)
|
|
{
|
|
GIFContext *s = avctx->priv_data;
|
|
|
|
av_freep(&s->lzw);
|
|
av_freep(&s->buf);
|
|
return 0;
|
|
}
|
|
|
|
AVCodec ff_gif_encoder = {
|
|
.name = "gif",
|
|
.type = AVMEDIA_TYPE_VIDEO,
|
|
.id = CODEC_ID_GIF,
|
|
.priv_data_size = sizeof(GIFContext),
|
|
.init = gif_encode_init,
|
|
.encode = gif_encode_frame,
|
|
.close = gif_encode_close,
|
|
.pix_fmts= (const enum PixelFormat[]){PIX_FMT_RGB8, PIX_FMT_BGR8, PIX_FMT_RGB4_BYTE, PIX_FMT_BGR4_BYTE, PIX_FMT_GRAY8, PIX_FMT_PAL8, PIX_FMT_NONE},
|
|
.long_name= NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
|
|
};
|