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FFmpeg/libavcodec/gif.c

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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"
#include "bitstream.h"
/* bitstream minipacket size */
#define GIF_CHUNKS 100
/* slows down the decoding (and some browsers don't like it) */
/* update on the 'some browsers don't like it issue from above: this was probably due to missing 'Data Sub-block Terminator' (byte 19) in the app_header */
#define GIF_ADD_APP_HEADER // required to enable looping of animated gif
typedef struct {
unsigned char r;
unsigned char g;
unsigned char b;
} rgb_triplet;
/* we use the standard 216 color palette */
/* this script was used to create the palette:
* for r in 00 33 66 99 cc ff; do for g in 00 33 66 99 cc ff; do echo -n " "; for b in 00 33 66 99 cc ff; do
* echo -n "{ 0x$r, 0x$g, 0x$b }, "; done; echo ""; done; done
*/
static const rgb_triplet gif_clut[216] = {
{ 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x33 }, { 0x00, 0x00, 0x66 }, { 0x00, 0x00, 0x99 }, { 0x00, 0x00, 0xcc }, { 0x00, 0x00, 0xff },
{ 0x00, 0x33, 0x00 }, { 0x00, 0x33, 0x33 }, { 0x00, 0x33, 0x66 }, { 0x00, 0x33, 0x99 }, { 0x00, 0x33, 0xcc }, { 0x00, 0x33, 0xff },
{ 0x00, 0x66, 0x00 }, { 0x00, 0x66, 0x33 }, { 0x00, 0x66, 0x66 }, { 0x00, 0x66, 0x99 }, { 0x00, 0x66, 0xcc }, { 0x00, 0x66, 0xff },
{ 0x00, 0x99, 0x00 }, { 0x00, 0x99, 0x33 }, { 0x00, 0x99, 0x66 }, { 0x00, 0x99, 0x99 }, { 0x00, 0x99, 0xcc }, { 0x00, 0x99, 0xff },
{ 0x00, 0xcc, 0x00 }, { 0x00, 0xcc, 0x33 }, { 0x00, 0xcc, 0x66 }, { 0x00, 0xcc, 0x99 }, { 0x00, 0xcc, 0xcc }, { 0x00, 0xcc, 0xff },
{ 0x00, 0xff, 0x00 }, { 0x00, 0xff, 0x33 }, { 0x00, 0xff, 0x66 }, { 0x00, 0xff, 0x99 }, { 0x00, 0xff, 0xcc }, { 0x00, 0xff, 0xff },
{ 0x33, 0x00, 0x00 }, { 0x33, 0x00, 0x33 }, { 0x33, 0x00, 0x66 }, { 0x33, 0x00, 0x99 }, { 0x33, 0x00, 0xcc }, { 0x33, 0x00, 0xff },
{ 0x33, 0x33, 0x00 }, { 0x33, 0x33, 0x33 }, { 0x33, 0x33, 0x66 }, { 0x33, 0x33, 0x99 }, { 0x33, 0x33, 0xcc }, { 0x33, 0x33, 0xff },
{ 0x33, 0x66, 0x00 }, { 0x33, 0x66, 0x33 }, { 0x33, 0x66, 0x66 }, { 0x33, 0x66, 0x99 }, { 0x33, 0x66, 0xcc }, { 0x33, 0x66, 0xff },
{ 0x33, 0x99, 0x00 }, { 0x33, 0x99, 0x33 }, { 0x33, 0x99, 0x66 }, { 0x33, 0x99, 0x99 }, { 0x33, 0x99, 0xcc }, { 0x33, 0x99, 0xff },
{ 0x33, 0xcc, 0x00 }, { 0x33, 0xcc, 0x33 }, { 0x33, 0xcc, 0x66 }, { 0x33, 0xcc, 0x99 }, { 0x33, 0xcc, 0xcc }, { 0x33, 0xcc, 0xff },
{ 0x33, 0xff, 0x00 }, { 0x33, 0xff, 0x33 }, { 0x33, 0xff, 0x66 }, { 0x33, 0xff, 0x99 }, { 0x33, 0xff, 0xcc }, { 0x33, 0xff, 0xff },
{ 0x66, 0x00, 0x00 }, { 0x66, 0x00, 0x33 }, { 0x66, 0x00, 0x66 }, { 0x66, 0x00, 0x99 }, { 0x66, 0x00, 0xcc }, { 0x66, 0x00, 0xff },
{ 0x66, 0x33, 0x00 }, { 0x66, 0x33, 0x33 }, { 0x66, 0x33, 0x66 }, { 0x66, 0x33, 0x99 }, { 0x66, 0x33, 0xcc }, { 0x66, 0x33, 0xff },
{ 0x66, 0x66, 0x00 }, { 0x66, 0x66, 0x33 }, { 0x66, 0x66, 0x66 }, { 0x66, 0x66, 0x99 }, { 0x66, 0x66, 0xcc }, { 0x66, 0x66, 0xff },
{ 0x66, 0x99, 0x00 }, { 0x66, 0x99, 0x33 }, { 0x66, 0x99, 0x66 }, { 0x66, 0x99, 0x99 }, { 0x66, 0x99, 0xcc }, { 0x66, 0x99, 0xff },
{ 0x66, 0xcc, 0x00 }, { 0x66, 0xcc, 0x33 }, { 0x66, 0xcc, 0x66 }, { 0x66, 0xcc, 0x99 }, { 0x66, 0xcc, 0xcc }, { 0x66, 0xcc, 0xff },
{ 0x66, 0xff, 0x00 }, { 0x66, 0xff, 0x33 }, { 0x66, 0xff, 0x66 }, { 0x66, 0xff, 0x99 }, { 0x66, 0xff, 0xcc }, { 0x66, 0xff, 0xff },
{ 0x99, 0x00, 0x00 }, { 0x99, 0x00, 0x33 }, { 0x99, 0x00, 0x66 }, { 0x99, 0x00, 0x99 }, { 0x99, 0x00, 0xcc }, { 0x99, 0x00, 0xff },
{ 0x99, 0x33, 0x00 }, { 0x99, 0x33, 0x33 }, { 0x99, 0x33, 0x66 }, { 0x99, 0x33, 0x99 }, { 0x99, 0x33, 0xcc }, { 0x99, 0x33, 0xff },
{ 0x99, 0x66, 0x00 }, { 0x99, 0x66, 0x33 }, { 0x99, 0x66, 0x66 }, { 0x99, 0x66, 0x99 }, { 0x99, 0x66, 0xcc }, { 0x99, 0x66, 0xff },
{ 0x99, 0x99, 0x00 }, { 0x99, 0x99, 0x33 }, { 0x99, 0x99, 0x66 }, { 0x99, 0x99, 0x99 }, { 0x99, 0x99, 0xcc }, { 0x99, 0x99, 0xff },
{ 0x99, 0xcc, 0x00 }, { 0x99, 0xcc, 0x33 }, { 0x99, 0xcc, 0x66 }, { 0x99, 0xcc, 0x99 }, { 0x99, 0xcc, 0xcc }, { 0x99, 0xcc, 0xff },
{ 0x99, 0xff, 0x00 }, { 0x99, 0xff, 0x33 }, { 0x99, 0xff, 0x66 }, { 0x99, 0xff, 0x99 }, { 0x99, 0xff, 0xcc }, { 0x99, 0xff, 0xff },
{ 0xcc, 0x00, 0x00 }, { 0xcc, 0x00, 0x33 }, { 0xcc, 0x00, 0x66 }, { 0xcc, 0x00, 0x99 }, { 0xcc, 0x00, 0xcc }, { 0xcc, 0x00, 0xff },
{ 0xcc, 0x33, 0x00 }, { 0xcc, 0x33, 0x33 }, { 0xcc, 0x33, 0x66 }, { 0xcc, 0x33, 0x99 }, { 0xcc, 0x33, 0xcc }, { 0xcc, 0x33, 0xff },
{ 0xcc, 0x66, 0x00 }, { 0xcc, 0x66, 0x33 }, { 0xcc, 0x66, 0x66 }, { 0xcc, 0x66, 0x99 }, { 0xcc, 0x66, 0xcc }, { 0xcc, 0x66, 0xff },
{ 0xcc, 0x99, 0x00 }, { 0xcc, 0x99, 0x33 }, { 0xcc, 0x99, 0x66 }, { 0xcc, 0x99, 0x99 }, { 0xcc, 0x99, 0xcc }, { 0xcc, 0x99, 0xff },
{ 0xcc, 0xcc, 0x00 }, { 0xcc, 0xcc, 0x33 }, { 0xcc, 0xcc, 0x66 }, { 0xcc, 0xcc, 0x99 }, { 0xcc, 0xcc, 0xcc }, { 0xcc, 0xcc, 0xff },
{ 0xcc, 0xff, 0x00 }, { 0xcc, 0xff, 0x33 }, { 0xcc, 0xff, 0x66 }, { 0xcc, 0xff, 0x99 }, { 0xcc, 0xff, 0xcc }, { 0xcc, 0xff, 0xff },
{ 0xff, 0x00, 0x00 }, { 0xff, 0x00, 0x33 }, { 0xff, 0x00, 0x66 }, { 0xff, 0x00, 0x99 }, { 0xff, 0x00, 0xcc }, { 0xff, 0x00, 0xff },
{ 0xff, 0x33, 0x00 }, { 0xff, 0x33, 0x33 }, { 0xff, 0x33, 0x66 }, { 0xff, 0x33, 0x99 }, { 0xff, 0x33, 0xcc }, { 0xff, 0x33, 0xff },
{ 0xff, 0x66, 0x00 }, { 0xff, 0x66, 0x33 }, { 0xff, 0x66, 0x66 }, { 0xff, 0x66, 0x99 }, { 0xff, 0x66, 0xcc }, { 0xff, 0x66, 0xff },
{ 0xff, 0x99, 0x00 }, { 0xff, 0x99, 0x33 }, { 0xff, 0x99, 0x66 }, { 0xff, 0x99, 0x99 }, { 0xff, 0x99, 0xcc }, { 0xff, 0x99, 0xff },
{ 0xff, 0xcc, 0x00 }, { 0xff, 0xcc, 0x33 }, { 0xff, 0xcc, 0x66 }, { 0xff, 0xcc, 0x99 }, { 0xff, 0xcc, 0xcc }, { 0xff, 0xcc, 0xff },
{ 0xff, 0xff, 0x00 }, { 0xff, 0xff, 0x33 }, { 0xff, 0xff, 0x66 }, { 0xff, 0xff, 0x99 }, { 0xff, 0xff, 0xcc }, { 0xff, 0xff, 0xff },
};
/* The GIF format uses reversed order for bitstreams... */
/* at least they don't use PDP_ENDIAN :) */
/* so we 'extend' PutBitContext. hmmm, OOP :) */
/* seems this thing changed slightly since I wrote it... */
#ifdef ALT_BITSTREAM_WRITER
# error no ALT_BITSTREAM_WRITER support for now
#endif
static void gif_put_bits_rev(PutBitContext *s, int n, unsigned int value)
{
unsigned int bit_buf;
int bit_cnt;
// printf("put_bits=%d %x\n", n, value);
assert(n == 32 || value < (1U << n));
bit_buf = s->bit_buf;
bit_cnt = 32 - s->bit_left; /* XXX:lazyness... was = s->bit_cnt; */
// printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
/* XXX: optimize */
if (n < (32-bit_cnt)) {
bit_buf |= value << (bit_cnt);
bit_cnt+=n;
} else {
bit_buf |= value << (bit_cnt);
bytestream_put_le32(&s->buf_ptr, bit_buf);
//printf("bitbuf = %08x\n", bit_buf);
if (s->buf_ptr >= s->buf_end)
abort();
// flush_buffer_rev(s);
bit_cnt=bit_cnt + n - 32;
if (bit_cnt == 0) {
bit_buf = 0;
} else {
bit_buf = value >> (n - bit_cnt);
}
}
s->bit_buf = bit_buf;
s->bit_left = 32 - bit_cnt;
}
/* pad the end of the output stream with zeros */
static void gif_flush_put_bits_rev(PutBitContext *s)
{
while (s->bit_left < 32) {
/* XXX: should test end of buffer */
*s->buf_ptr++=s->bit_buf & 0xff;
s->bit_buf>>=8;
s->bit_left+=8;
}
// flush_buffer_rev(s);
s->bit_left=32;
s->bit_buf=0;
}
/* !RevPutBitContext */
/* GIF header */
static int gif_image_write_header(uint8_t **bytestream,
int width, int height, int loop_count,
uint32_t *palette)
{
int i;
unsigned int v;
bytestream_put_buffer(bytestream, "GIF", 3);
bytestream_put_buffer(bytestream, "89a", 3);
bytestream_put_le16(bytestream, width);
bytestream_put_le16(bytestream, 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 */
if (!palette) {
bytestream_put_buffer(bytestream, (const unsigned char *)gif_clut, 216*3);
for(i=0;i<((256-216)*3);i++)
bytestream_put_byte(bytestream, 0);
} else {
for(i=0;i<256;i++) {
v = palette[i];
bytestream_put_be24(bytestream, v);
}
}
/* update: this is the 'NETSCAPE EXTENSION' that allows for looped animated gif
see http://members.aol.com/royalef/gifabout.htm#net-extension
byte 1 : 33 (hex 0x21) GIF Extension code
byte 2 : 255 (hex 0xFF) Application Extension Label
byte 3 : 11 (hex (0x0B) Length of Application Block
(eleven bytes of data to follow)
bytes 4 to 11 : "NETSCAPE"
bytes 12 to 14 : "2.0"
byte 15 : 3 (hex 0x03) Length of Data Sub-Block
(three bytes of data to follow)
byte 16 : 1 (hex 0x01)
bytes 17 to 18 : 0 to 65535, an unsigned integer in
lo-hi byte format. This indicate the
number of iterations the loop should
be executed.
bytes 19 : 0 (hex 0x00) a Data Sub-block Terminator
*/
/* application extension header */
#ifdef GIF_ADD_APP_HEADER
if (loop_count >= 0 && loop_count <= 65535) {
bytestream_put_byte(bytestream, 0x21);
bytestream_put_byte(bytestream, 0xff);
bytestream_put_byte(bytestream, 0x0b);
bytestream_put_buffer(bytestream, "NETSCAPE2.0", 11); // bytes 4 to 14
bytestream_put_byte(bytestream, 0x03); // byte 15
bytestream_put_byte(bytestream, 0x01); // byte 16
bytestream_put_le16(bytestream, (uint16_t)loop_count);
bytestream_put_byte(bytestream, 0x00); // byte 19
}
#endif
return 0;
}
/* this is maybe slow, but allows for extensions */
static inline unsigned char gif_clut_index(uint8_t r, uint8_t g, uint8_t b)
{
return ((((r)/47)%6)*6*6+(((g)/47)%6)*6+(((b)/47)%6));
}
static int gif_image_write_image(uint8_t **bytestream,
int x1, int y1, int width, int height,
const uint8_t *buf, int linesize, int pix_fmt)
{
PutBitContext p;
uint8_t buffer[200]; /* 100 * 9 / 8 = 113 */
int i, left, w, v;
const uint8_t *ptr;
/* image block */
bytestream_put_byte(bytestream, 0x2c);
bytestream_put_le16(bytestream, x1);
bytestream_put_le16(bytestream, y1);
bytestream_put_le16(bytestream, width);
bytestream_put_le16(bytestream, height);
bytestream_put_byte(bytestream, 0x00); /* flags */
/* no local clut */
bytestream_put_byte(bytestream, 0x08);
left= width * 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 = width;
while(left>0) {
gif_put_bits_rev(&p, 9, 0x0100); /* clear code */
for(i=(left<GIF_CHUNKS)?left:GIF_CHUNKS;i;i--) {
if (pix_fmt == PIX_FMT_RGB24) {
v = gif_clut_index(ptr[0], ptr[1], ptr[2]);
ptr+=3;
} else {
v = *ptr++;
}
gif_put_bits_rev(&p, 9, v);
if (--w == 0) {
w = width;
buf += linesize;
ptr = buf;
}
}
if(left<=GIF_CHUNKS) {
gif_put_bits_rev(&p, 9, 0x101); /* end of stream */
gif_flush_put_bits_rev(&p);
}
if(pbBufPtr(&p) - p.buf > 0) {
bytestream_put_byte(bytestream, pbBufPtr(&p) - p.buf); /* byte count of the packet */
bytestream_put_buffer(bytestream, p.buf, pbBufPtr(&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;
}
typedef struct {
int64_t time, file_time;
uint8_t buffer[100]; /* data chunks */
AVFrame picture;
} GIFContext;
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(&outbuf_ptr, avctx->width, avctx->height, -1, (uint32_t *)pict->data[1]);
gif_image_write_image(&outbuf_ptr, 0, 0, avctx->width, avctx->height, pict->data[0], pict->linesize[0], PIX_FMT_PAL8);
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= (enum PixelFormat[]){PIX_FMT_PAL8, PIX_FMT_NONE},
.long_name= "GIF (Graphics Interchange Format)",
};