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FFmpeg/libavformat/gif.c
Roman Shaposhnik f5fc28d23c * fixing a buffer overrun in gif.c 
Originally committed as revision 3363 to svn://svn.ffmpeg.org/ffmpeg/trunk
2004-07-28 21:56:59 +00:00

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/*
* Animated GIF encoder
* Copyright (c) 2000 Fabrice Bellard.
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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 "avformat.h"
/* bitstream minipacket size */
#define GIF_CHUNKS 100
/* slows down the decoding (and some browsers doesn't like it) */
/* #define GIF_ADD_APP_HEADER */
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;
#ifdef STATS
st_out_bit_counts[st_current_index] += n;
#endif
// 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);
*s->buf_ptr = bit_buf & 0xff;
s->buf_ptr[1] = (bit_buf >> 8) & 0xff;
s->buf_ptr[2] = (bit_buf >> 16) & 0xff;
s->buf_ptr[3] = (bit_buf >> 24) & 0xff;
//printf("bitbuf = %08x\n", bit_buf);
s->buf_ptr+=4;
if (s->buf_ptr >= s->buf_end)
puts("bit buffer overflow !!"); // should never happen ! who got rid of the callback ???
// 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(ByteIOContext *pb,
int width, int height, uint32_t *palette)
{
int i;
unsigned int v;
put_tag(pb, "GIF");
put_tag(pb, "89a");
put_le16(pb, width);
put_le16(pb, height);
put_byte(pb, 0xf7); /* flags: global clut, 256 entries */
put_byte(pb, 0x1f); /* background color index */
put_byte(pb, 0); /* aspect ratio */
/* the global palette */
if (!palette) {
put_buffer(pb, (unsigned char *)gif_clut, 216*3);
for(i=0;i<((256-216)*3);i++)
put_byte(pb, 0);
} else {
for(i=0;i<256;i++) {
v = palette[i];
put_byte(pb, (v >> 16) & 0xff);
put_byte(pb, (v >> 8) & 0xff);
put_byte(pb, (v) & 0xff);
}
}
/* application extension header */
/* XXX: not really sure what to put in here... */
#ifdef GIF_ADD_APP_HEADER
put_byte(pb, 0x21);
put_byte(pb, 0xff);
put_byte(pb, 0x0b);
put_tag(pb, "NETSCAPE2.0");
put_byte(pb, 0x03);
put_byte(pb, 0x01);
put_byte(pb, 0x00);
put_byte(pb, 0x00);
#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(ByteIOContext *pb,
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 */
put_byte(pb, 0x2c);
put_le16(pb, x1);
put_le16(pb, y1);
put_le16(pb, width);
put_le16(pb, height);
put_byte(pb, 0x00); /* flags */
/* no local clut */
put_byte(pb, 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) {
put_byte(pb, pbBufPtr(&p) - p.buf); /* byte count of the packet */
put_buffer(pb, p.buf, pbBufPtr(&p) - p.buf); /* the actual buffer */
p.buf_ptr = p.buf; /* dequeue the bytes off the bitstream */
}
left-=GIF_CHUNKS;
}
put_byte(pb, 0x00); /* end of image block */
return 0;
}
typedef struct {
int64_t time, file_time;
uint8_t buffer[100]; /* data chunks */
} GIFContext;
static int gif_write_header(AVFormatContext *s)
{
GIFContext *gif = s->priv_data;
ByteIOContext *pb = &s->pb;
AVCodecContext *enc, *video_enc;
int i, width, height/*, rate*/;
/* XXX: do we reject audio streams or just ignore them ?
if(s->nb_streams > 1)
return -1;
*/
gif->time = 0;
gif->file_time = 0;
video_enc = NULL;
for(i=0;i<s->nb_streams;i++) {
enc = &s->streams[i]->codec;
if (enc->codec_type != CODEC_TYPE_AUDIO)
video_enc = enc;
}
if (!video_enc) {
av_free(gif);
return -1;
} else {
width = video_enc->width;
height = video_enc->height;
// rate = video_enc->frame_rate;
}
/* XXX: is it allowed ? seems to work so far... */
video_enc->pix_fmt = PIX_FMT_RGB24;
gif_image_write_header(pb, width, height, NULL);
put_flush_packet(&s->pb);
return 0;
}
static int gif_write_video(AVFormatContext *s,
AVCodecContext *enc, const uint8_t *buf, int size)
{
ByteIOContext *pb = &s->pb;
GIFContext *gif = s->priv_data;
int jiffies;
int64_t delay;
/* graphic control extension block */
put_byte(pb, 0x21);
put_byte(pb, 0xf9);
put_byte(pb, 0x04); /* block size */
put_byte(pb, 0x04); /* flags */
/* 1 jiffy is 1/70 s */
/* the delay_time field indicates the number of jiffies - 1 */
delay = gif->file_time - gif->time;
/* XXX: should use delay, in order to be more accurate */
/* instead of using the same rounded value each time */
/* XXX: don't even remember if I really use it for now */
jiffies = (70*enc->frame_rate_base/enc->frame_rate) - 1;
put_le16(pb, jiffies);
put_byte(pb, 0x1f); /* transparent color index */
put_byte(pb, 0x00);
gif_image_write_image(pb, 0, 0, enc->width, enc->height,
buf, enc->width * 3, PIX_FMT_RGB24);
put_flush_packet(&s->pb);
return 0;
}
static int gif_write_packet(AVFormatContext *s, AVPacket *pkt)
{
AVCodecContext *codec = &s->streams[pkt->stream_index]->codec;
if (codec->codec_type == CODEC_TYPE_AUDIO)
return 0; /* just ignore audio */
else
return gif_write_video(s, codec, pkt->data, pkt->size);
}
static int gif_write_trailer(AVFormatContext *s)
{
ByteIOContext *pb = &s->pb;
put_byte(pb, 0x3b);
put_flush_packet(&s->pb);
return 0;
}
/* better than nothing gif image writer */
int gif_write(ByteIOContext *pb, AVImageInfo *info)
{
gif_image_write_header(pb, info->width, info->height,
(uint32_t *)info->pict.data[1]);
gif_image_write_image(pb, 0, 0, info->width, info->height,
info->pict.data[0], info->pict.linesize[0],
PIX_FMT_PAL8);
put_byte(pb, 0x3b);
put_flush_packet(pb);
return 0;
}
static AVOutputFormat gif_oformat = {
"gif",
"GIF Animation",
"image/gif",
"gif",
sizeof(GIFContext),
CODEC_ID_NONE,
CODEC_ID_RAWVIDEO,
gif_write_header,
gif_write_packet,
gif_write_trailer,
};
extern AVInputFormat gif_iformat;
int gif_init(void)
{
av_register_output_format(&gif_oformat);
av_register_input_format(&gif_iformat);
return 0;
}
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