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FFmpeg/swfenc.c
Fabrice Bellard 9aeeeb63f7 Initial revision 
Originally committed as revision 2 to svn://svn.ffmpeg.org/ffmpeg/trunk
2000-12-20 00:02:47 +00:00

348 lines
8.8 KiB
C
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/*
* Flash Compatible Streaming Format
* Copyright (c) 2000 Gerard Lantau.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <stdio.h>
#include <netinet/in.h>
#include <string.h>
#include "mpegenc.h"
#include <assert.h>
/* should have a generic way to indicate probable size */
#define DUMMY_FILE_SIZE (100 * 1024 * 1024)
#define DUMMY_DURATION 600 /* in seconds */
#define TAG_END 0
#define TAG_SHOWFRAME 1
#define TAG_DEFINESHAPE 2
#define TAG_FREECHARACTER 3
#define TAG_PLACEOBJECT 4
#define TAG_REMOVEOBJECT 5
#define TAG_JPEG2 21
#define TAG_LONG 0x100
/* flags for shape definition */
#define FLAG_MOVETO 0x01
#define FLAG_SETFILL0 0x02
#define FLAG_SETFILL1 0x04
/* character id used */
#define BITMAP_ID 0
#define SHAPE_ID 1
typedef struct {
long long duration_pos;
long long tag_pos;
int tag;
} SWFContext;
static void put_swf_tag(AVFormatContext *s, int tag)
{
SWFContext *swf = s->priv_data;
PutByteContext *pb = &s->pb;
swf->tag_pos = put_pos(pb);
swf->tag = tag;
/* reserve some room for the tag */
if (tag & TAG_LONG) {
put_le16(pb, 0);
put_le32(pb, 0);
} else {
put_le16(pb, 0);
}
}
static void put_swf_end_tag(AVFormatContext *s)
{
SWFContext *swf = s->priv_data;
PutByteContext *pb = &s->pb;
long long pos;
int tag_len, tag;
pos = put_pos(pb);
tag_len = pos - swf->tag_pos - 2;
tag = swf->tag;
put_seek(pb, swf->tag_pos, SEEK_SET);
if (tag & TAG_LONG) {
tag &= ~TAG_LONG;
put_le16(pb, (tag << 6) | 0x3f);
put_le32(pb, tag_len - 4);
} else {
assert(tag_len < 0x3f);
put_le16(pb, (tag << 6) | tag_len);
}
put_seek(pb, pos, SEEK_SET);
}
static inline void max_nbits(int *nbits_ptr, int val)
{
int n;
if (val == 0)
return;
val = abs(val);
n = 1;
while (val != 0) {
n++;
val >>= 1;
}
if (n > *nbits_ptr)
*nbits_ptr = n;
}
static void put_swf_rect(PutByteContext *pb,
int xmin, int xmax, int ymin, int ymax)
{
PutBitContext p;
UINT8 buf[256];
int nbits, mask;
init_put_bits(&p, buf, sizeof(buf), NULL, NULL);
nbits = 0;
max_nbits(&nbits, xmin);
max_nbits(&nbits, xmax);
max_nbits(&nbits, ymin);
max_nbits(&nbits, ymax);
mask = (1 << nbits) - 1;
/* rectangle info */
put_bits(&p, 5, nbits);
put_bits(&p, nbits, xmin & mask);
put_bits(&p, nbits, xmax & mask);
put_bits(&p, nbits, ymin & mask);
put_bits(&p, nbits, ymax & mask);
flush_put_bits(&p);
put_buffer(pb, buf, p.buf_ptr - p.buf);
}
static void put_swf_line_edge(PutBitContext *pb, int dx, int dy)
{
int nbits, mask;
put_bits(pb, 1, 1); /* edge */
put_bits(pb, 1, 1); /* line select */
nbits = 2;
max_nbits(&nbits, dx);
max_nbits(&nbits, dy);
mask = (1 << nbits) - 1;
put_bits(pb, 4, nbits - 2); /* 16 bits precision */
if (dx == 0) {
put_bits(pb, 1, 0);
put_bits(pb, 1, 1);
put_bits(pb, nbits, dy & mask);
} else if (dy == 0) {
put_bits(pb, 1, 0);
put_bits(pb, 1, 0);
put_bits(pb, nbits, dx & mask);
} else {
put_bits(pb, 1, 1);
put_bits(pb, nbits, dx & mask);
put_bits(pb, nbits, dy & mask);
}
}
#define FRAC_BITS 16
/* put matrix (not size optimized */
static void put_swf_matrix(PutByteContext *pb,
int a, int b, int c, int d, int tx, int ty)
{
PutBitContext p;
UINT8 buf[256];
init_put_bits(&p, buf, sizeof(buf), NULL, NULL);
put_bits(&p, 1, 1); /* a, d present */
put_bits(&p, 5, 20); /* nb bits */
put_bits(&p, 20, a);
put_bits(&p, 20, d);
put_bits(&p, 1, 1); /* b, c present */
put_bits(&p, 5, 20); /* nb bits */
put_bits(&p, 20, c);
put_bits(&p, 20, b);
put_bits(&p, 5, 20); /* nb bits */
put_bits(&p, 20, tx);
put_bits(&p, 20, ty);
flush_put_bits(&p);
put_buffer(pb, buf, p.buf_ptr - p.buf);
}
static int swf_write_header(AVFormatContext *s)
{
SWFContext *swf;
PutByteContext *pb = &s->pb;
AVEncodeContext *enc = s->video_enc;
PutBitContext p;
UINT8 buf1[256];
swf = malloc(sizeof(SWFContext));
if (!swf)
return -1;
s->priv_data = swf;
put_tag(pb, "FWS");
put_byte(pb, 3); /* version (should use 4 for mpeg audio support) */
put_le32(pb, DUMMY_FILE_SIZE); /* dummy size
(will be patched if not streamed) */
put_swf_rect(pb, 0, enc->width, 0, enc->height);
put_le16(pb, enc->rate << 8); /* frame rate */
swf->duration_pos = put_pos(pb);
put_le16(pb, DUMMY_DURATION * enc->rate); /* frame count */
/* define a shape with the jpeg inside */
put_swf_tag(s, TAG_DEFINESHAPE);
put_le16(pb, SHAPE_ID); /* ID of shape */
/* bounding rectangle */
put_swf_rect(pb, 0, enc->width, 0, enc->height);
/* style info */
put_byte(pb, 1); /* one fill style */
put_byte(pb, 0x41); /* clipped bitmap fill */
put_le16(pb, BITMAP_ID); /* bitmap ID */
/* position of the bitmap */
put_swf_matrix(pb, (int)(1.0 * (1 << FRAC_BITS)), 0,
0, (int)(1.0 * (1 << FRAC_BITS)), 0, 0);
put_byte(pb, 0); /* no line style */
/* shape drawing */
init_put_bits(&p, buf1, sizeof(buf1), NULL, NULL);
put_bits(&p, 4, 1); /* one fill bit */
put_bits(&p, 4, 0); /* zero line bit */
put_bits(&p, 1, 0); /* not an edge */
put_bits(&p, 5, FLAG_MOVETO | FLAG_SETFILL0);
put_bits(&p, 5, 1); /* nbits */
put_bits(&p, 1, 0); /* X */
put_bits(&p, 1, 0); /* Y */
put_bits(&p, 1, 1); /* set fill style 1 */
/* draw the rectangle ! */
put_swf_line_edge(&p, enc->width, 0);
put_swf_line_edge(&p, 0, enc->height);
put_swf_line_edge(&p, -enc->width, 0);
put_swf_line_edge(&p, 0, -enc->height);
/* end of shape */
put_bits(&p, 1, 0); /* not an edge */
put_bits(&p, 5, 0);
flush_put_bits(&p);
put_buffer(pb, buf1, p.buf_ptr - p.buf);
put_swf_end_tag(s);
put_flush_packet(&s->pb);
return 0;
}
static int swf_write_video(AVFormatContext *s, UINT8 *buf, int size)
{
PutByteContext *pb = &s->pb;
AVEncodeContext *enc = s->video_enc;
static int tag_id = 0;
if (enc->frame_number > 1) {
/* remove the shape */
put_swf_tag(s, TAG_REMOVEOBJECT);
put_le16(pb, SHAPE_ID); /* shape ID */
put_le16(pb, 1); /* depth */
put_swf_end_tag(s);
/* free the bitmap */
put_swf_tag(s, TAG_FREECHARACTER);
put_le16(pb, BITMAP_ID);
put_swf_end_tag(s);
}
put_swf_tag(s, TAG_JPEG2 | TAG_LONG);
put_le16(pb, tag_id); /* ID of the image */
/* a dummy jpeg header seems to be required */
put_byte(pb, 0xff);
put_byte(pb, 0xd8);
put_byte(pb, 0xff);
put_byte(pb, 0xd9);
/* write the jpeg image */
put_buffer(pb, buf, size);
put_swf_end_tag(s);
/* draw the shape */
put_swf_tag(s, TAG_PLACEOBJECT);
put_le16(pb, SHAPE_ID); /* shape ID */
put_le16(pb, 1); /* depth */
put_swf_matrix(pb, 1 << FRAC_BITS, 0, 0, 1 << FRAC_BITS, 0, 0);
put_swf_end_tag(s);
/* output the frame */
put_swf_tag(s, TAG_SHOWFRAME);
put_swf_end_tag(s);
put_flush_packet(&s->pb);
return 0;
}
static int swf_write_trailer(AVFormatContext *s)
{
SWFContext *swf = s->priv_data;
PutByteContext *pb = &s->pb;
int file_size;
AVEncodeContext *enc = s->video_enc;
put_swf_tag(s, TAG_END);
put_swf_end_tag(s);
put_flush_packet(&s->pb);
/* patch file size and number of frames if not streamed */
if (!s->is_streamed) {
file_size = put_pos(pb);
put_seek(pb, 4, SEEK_SET);
put_le32(pb, file_size);
put_seek(pb, swf->duration_pos, SEEK_SET);
put_le16(pb, enc->frame_number);
}
free(swf);
return 0;
}
AVFormat swf_format = {
"swf",
"Flash format",
"application/x-shockwave-flash",
"swf",
CODEC_ID_NONE,
CODEC_ID_MJPEG,
swf_write_header,
NULL,
swf_write_video,
swf_write_trailer,
};
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