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ffmpeg/libavcodec/pngenc.c

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/*
* PNG image format
* Copyright (c) 2003 Fabrice Bellard.
*
* 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
*/
#include "avcodec.h"
#include "bytestream.h"
#include "png.h"
/* TODO:
* - add 2, 4 and 16 bit depth support
* - use filters when generating a png (better compression)
*/
#include <zlib.h>
//#define DEBUG
#define IOBUF_SIZE 4096
typedef struct PNGEncContext {
uint8_t *bytestream;
uint8_t *bytestream_start;
uint8_t *bytestream_end;
AVFrame picture;
z_stream zstream;
uint8_t buf[IOBUF_SIZE];
} PNGEncContext;
static void png_get_interlaced_row(uint8_t *dst, int row_size,
int bits_per_pixel, int pass,
const uint8_t *src, int width)
{
int x, mask, dst_x, j, b, bpp;
uint8_t *d;
const uint8_t *s;
mask = ff_png_pass_mask[pass];
switch(bits_per_pixel) {
case 1:
memset(dst, 0, row_size);
dst_x = 0;
for(x = 0; x < width; x++) {
j = (x & 7);
if ((mask << j) & 0x80) {
b = (src[x >> 3] >> (7 - j)) & 1;
dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
dst_x++;
}
}
break;
default:
bpp = bits_per_pixel >> 3;
d = dst;
s = src;
for(x = 0; x < width; x++) {
j = x & 7;
if ((mask << j) & 0x80) {
memcpy(d, s, bpp);
d += bpp;
}
s += bpp;
}
break;
}
}
static void convert_from_rgb32(uint8_t *dst, const uint8_t *src, int width)
{
uint8_t *d;
int j;
unsigned int v;
d = dst;
for(j = 0; j < width; j++) {
v = ((const uint32_t *)src)[j];
d[0] = v >> 16;
d[1] = v >> 8;
d[2] = v;
d[3] = v >> 24;
d += 4;
}
}
static void png_write_chunk(uint8_t **f, uint32_t tag,
const uint8_t *buf, int length)
{
uint32_t crc;
uint8_t tagbuf[4];
bytestream_put_be32(f, length);
crc = crc32(0, Z_NULL, 0);
AV_WL32(tagbuf, tag);
crc = crc32(crc, tagbuf, 4);
bytestream_put_be32(f, bswap_32(tag));
if (length > 0) {
crc = crc32(crc, buf, length);
memcpy(*f, buf, length);
*f += length;
}
bytestream_put_be32(f, crc);
}
/* XXX: do filtering */
static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)
{
int ret;
s->zstream.avail_in = size;
s->zstream.next_in = (uint8_t *)data;
while (s->zstream.avail_in > 0) {
ret = deflate(&s->zstream, Z_NO_FLUSH);
if (ret != Z_OK)
return -1;
if (s->zstream.avail_out == 0) {
if(s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
s->zstream.avail_out = IOBUF_SIZE;
s->zstream.next_out = s->buf;
}
}
return 0;
}
static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size, void *data){
PNGEncContext *s = avctx->priv_data;
AVFrame *pict = data;
AVFrame * const p= (AVFrame*)&s->picture;
int bit_depth, color_type, y, len, row_size, ret, is_progressive;
int bits_per_pixel, pass_row_size;
uint8_t *ptr;
uint8_t *crow_buf = NULL;
uint8_t *tmp_buf = NULL;
*p = *pict;
p->pict_type= FF_I_TYPE;
p->key_frame= 1;
s->bytestream_start=
s->bytestream= buf;
s->bytestream_end= buf+buf_size;
is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
switch(avctx->pix_fmt) {
case PIX_FMT_RGB32:
bit_depth = 8;
color_type = PNG_COLOR_TYPE_RGB_ALPHA;
break;
case PIX_FMT_RGB24:
bit_depth = 8;
color_type = PNG_COLOR_TYPE_RGB;
break;
case PIX_FMT_GRAY8:
bit_depth = 8;
color_type = PNG_COLOR_TYPE_GRAY;
break;
case PIX_FMT_MONOBLACK:
bit_depth = 1;
color_type = PNG_COLOR_TYPE_GRAY;
break;
case PIX_FMT_PAL8:
bit_depth = 8;
color_type = PNG_COLOR_TYPE_PALETTE;
break;
default:
return -1;
}
bits_per_pixel = ff_png_get_nb_channels(color_type) * bit_depth;
row_size = (avctx->width * bits_per_pixel + 7) >> 3;
s->zstream.zalloc = ff_png_zalloc;
s->zstream.zfree = ff_png_zfree;
s->zstream.opaque = NULL;
ret = deflateInit2(&s->zstream, Z_DEFAULT_COMPRESSION,
Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
if (ret != Z_OK)
return -1;
crow_buf = av_malloc(row_size + 1);
if (!crow_buf)
goto fail;
if (is_progressive) {
tmp_buf = av_malloc(row_size + 1);
if (!tmp_buf)
goto fail;
}
/* write png header */
memcpy(s->bytestream, ff_pngsig, 8);
s->bytestream += 8;
AV_WB32(s->buf, avctx->width);
AV_WB32(s->buf + 4, avctx->height);
s->buf[8] = bit_depth;
s->buf[9] = color_type;
s->buf[10] = 0; /* compression type */
s->buf[11] = 0; /* filter type */
s->buf[12] = is_progressive; /* interlace type */
png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
/* put the palette if needed */
if (color_type == PNG_COLOR_TYPE_PALETTE) {
int has_alpha, alpha, i;
unsigned int v;
uint32_t *palette;
uint8_t *alpha_ptr;
palette = (uint32_t *)p->data[1];
ptr = s->buf;
alpha_ptr = s->buf + 256 * 3;
has_alpha = 0;
for(i = 0; i < 256; i++) {
v = palette[i];
alpha = v >> 24;
if (alpha && alpha != 0xff)
has_alpha = 1;
*alpha_ptr++ = alpha;
bytestream_put_be24(&ptr, v);
}
png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
if (has_alpha) {
png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
}
}
/* now put each row */
s->zstream.avail_out = IOBUF_SIZE;
s->zstream.next_out = s->buf;
if (is_progressive) {
uint8_t *ptr1;
int pass;
for(pass = 0; pass < NB_PASSES; pass++) {
/* NOTE: a pass is completely omited if no pixels would be
output */
pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
if (pass_row_size > 0) {
for(y = 0; y < avctx->height; y++) {
if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
ptr = p->data[0] + y * p->linesize[0];
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
convert_from_rgb32(tmp_buf, ptr, avctx->width);
ptr1 = tmp_buf;
} else {
ptr1 = ptr;
}
png_get_interlaced_row(crow_buf + 1, pass_row_size,
bits_per_pixel, pass,
ptr1, avctx->width);
crow_buf[0] = PNG_FILTER_VALUE_NONE;
png_write_row(s, crow_buf, pass_row_size + 1);
}
}
}
}
} else {
for(y = 0; y < avctx->height; y++) {
ptr = p->data[0] + y * p->linesize[0];
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
convert_from_rgb32(crow_buf + 1, ptr, avctx->width);
else
memcpy(crow_buf + 1, ptr, row_size);
crow_buf[0] = PNG_FILTER_VALUE_NONE;
png_write_row(s, crow_buf, row_size + 1);
}
}
/* compress last bytes */
for(;;) {
ret = deflate(&s->zstream, Z_FINISH);
if (ret == Z_OK || ret == Z_STREAM_END) {
len = IOBUF_SIZE - s->zstream.avail_out;
if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
}
s->zstream.avail_out = IOBUF_SIZE;
s->zstream.next_out = s->buf;
if (ret == Z_STREAM_END)
break;
} else {
goto fail;
}
}
png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
ret = s->bytestream - s->bytestream_start;
the_end:
av_free(crow_buf);
av_free(tmp_buf);
deflateEnd(&s->zstream);
return ret;
fail:
ret = -1;
goto the_end;
}
static int png_enc_init(AVCodecContext *avctx){
PNGEncContext *s = avctx->priv_data;
avcodec_get_frame_defaults((AVFrame*)&s->picture);
avctx->coded_frame= (AVFrame*)&s->picture;
return 0;
}
AVCodec png_encoder = {
"png",
CODEC_TYPE_VIDEO,
CODEC_ID_PNG,
sizeof(PNGEncContext),
png_enc_init,
encode_frame,
NULL, //encode_end,
.pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGB32, PIX_FMT_PAL8, PIX_FMT_GRAY8, PIX_FMT_MONOBLACK, -1},
};
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