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/*
* GIF encoder.
* Copyright (c) 2000 Fabrice Bellard
* Copyright (c) 2002 Francois Revol
* Copyright (c) 2006 Baptiste Coudurier
*
* 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
*/
/*
* 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"
/* The GIF format uses reversed order for bitstreams... */
/* at least they don't use PDP_ENDIAN :) */
#define BITSTREAM_WRITER_LE
#include "put_bits.h"
/* bitstream minipacket size */
#define GIF_CHUNKS 100
typedef struct {
AVFrame picture;
} 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,
const uint8_t *buf, int linesize)
{
PutBitContext p;
uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
int i, left, w;
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);
left= avctx->width * avctx->height;
init_put_bits(&p, buffer, 130);
/*
* the thing here is the bitstream is written as little packets, with a size byte before
* but it's still the same bitstream between packets (no flush !)
*/
ptr = buf;
w = avctx->width;
while(left>0) {
put_bits(&p, 9, 0x0100); /* clear code */
for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
put_bits(&p, 9, *ptr++);
if (--w == 0) {
w = avctx->width;
buf += linesize;
ptr = buf;
}
}
if(left<=GIF_CHUNKS) {
put_bits(&p, 9, 0x101); /* end of stream */
flush_put_bits(&p);
}
if(put_bits_ptr(&p) - p.buf > 0) {
bytestream_put_byte(bytestream, put_bits_ptr(&p) - p.buf); /* byte count of the packet */
bytestream_put_buffer(bytestream, p.buf, put_bits_ptr(&p) - p.buf); /* the actual buffer */
p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
}
left-=GIF_CHUNKS;
}
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;
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;
*p = *pict;
p->pict_type = FF_I_TYPE;
p->key_frame = 1;
gif_image_write_header(avctx, &outbuf_ptr, (uint32_t *)pict->data[1]);
gif_image_write_image(avctx, &outbuf_ptr, pict->data[0], pict->linesize[0]);
return outbuf_ptr - outbuf;
}
AVCodec gif_encoder = {
"gif",
CODEC_TYPE_VIDEO,
CODEC_ID_GIF,
sizeof(GIFContext),
gif_encode_init,
gif_encode_frame,
NULL, //encode_end,
.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)"),
};
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