pngenc.c 13 KB
Newer Older
1 2
/*
 * PNG image format
3
 * Copyright (c) 2003 Fabrice Bellard
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
 *
 * 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"
23
#include "dsputil.h"
24 25 26 27 28 29 30 31 32 33
#include "png.h"

/* TODO:
 * - add 2, 4 and 16 bit depth support
 */

#include <zlib.h>

//#define DEBUG

34 35 36
#define IOBUF_SIZE 4096

typedef struct PNGEncContext {
Loren Merritt's avatar
Loren Merritt committed
37 38
    DSPContext dsp;

39 40 41 42 43
    uint8_t *bytestream;
    uint8_t *bytestream_start;
    uint8_t *bytestream_end;
    AVFrame picture;

Loren Merritt's avatar
Loren Merritt committed
44 45
    int filter_type;

46 47 48 49
    z_stream zstream;
    uint8_t buf[IOBUF_SIZE];
} PNGEncContext;

50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87
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;
    }
}

Loren Merritt's avatar
Loren Merritt committed
88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160
static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
{
    int i;
    for(i = 0; i < w; i++) {
        int a, b, c, p, pa, pb, pc;

        a = src[i - bpp];
        b = top[i];
        c = top[i - bpp];

        p = b - c;
        pc = a - c;

        pa = abs(p);
        pb = abs(pc);
        pc = abs(p + pc);

        if (pa <= pb && pa <= pc)
            p = a;
        else if (pb <= pc)
            p = b;
        else
            p = c;
        dst[i] = src[i] - p;
    }
}

static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
                           uint8_t *src, uint8_t *top, int size, int bpp)
{
    int i;

    switch(filter_type) {
    case PNG_FILTER_VALUE_NONE:
        memcpy(dst, src, size);
        break;
    case PNG_FILTER_VALUE_SUB:
        dsp->diff_bytes(dst, src, src-bpp, size);
        memcpy(dst, src, bpp);
        break;
    case PNG_FILTER_VALUE_UP:
        dsp->diff_bytes(dst, src, top, size);
        break;
    case PNG_FILTER_VALUE_AVG:
        for(i = 0; i < bpp; i++)
            dst[i] = src[i] - (top[i] >> 1);
        for(; i < size; i++)
            dst[i] = src[i] - ((src[i-bpp] + top[i]) >> 1);
        break;
    case PNG_FILTER_VALUE_PAETH:
        for(i = 0; i < bpp; i++)
            dst[i] = src[i] - top[i];
        sub_png_paeth_prediction(dst+i, src+i, top+i, size-i, bpp);
        break;
    }
}

static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
                                  uint8_t *src, uint8_t *top, int size, int bpp)
{
    int pred = s->filter_type;
    assert(bpp || !pred);
    if(!top && pred)
        pred = PNG_FILTER_VALUE_SUB;
    if(pred == PNG_FILTER_VALUE_MIXED) {
        int i;
        int cost, bcost = INT_MAX;
        uint8_t *buf1 = dst, *buf2 = dst + size + 16;
        for(pred=0; pred<5; pred++) {
            png_filter_row(&s->dsp, buf1+1, pred, src, top, size, bpp);
            buf1[0] = pred;
            cost = 0;
            for(i=0; i<=size; i++)
Loren Merritt's avatar
Loren Merritt committed
161
                cost += abs((int8_t)buf1[i]);
Loren Merritt's avatar
Loren Merritt committed
162 163 164 165 166 167 168 169 170 171 172 173 174
            if(cost < bcost) {
                bcost = cost;
                FFSWAP(uint8_t*, buf1, buf2);
            }
        }
        return buf2;
    } else {
        png_filter_row(&s->dsp, dst+1, pred, src, top, size, bpp);
        dst[0] = pred;
        return dst;
    }
}

175 176 177 178 179 180 181 182 183 184
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);
185
    bytestream_put_be32(f, av_bswap32(tag));
186 187 188 189 190 191 192 193 194
    if (length > 0) {
        crc = crc32(crc, buf, length);
        memcpy(*f, buf, length);
        *f += length;
    }
    bytestream_put_be32(f, crc);
}

/* XXX: do filtering */
195
static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)
196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215
{
    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){
216
    PNGEncContext *s = avctx->priv_data;
217
    AVFrame *pict = data;
avcoder's avatar
avcoder committed
218
    AVFrame * const p= &s->picture;
219 220
    int bit_depth, color_type, y, len, row_size, ret, is_progressive;
    int bits_per_pixel, pass_row_size;
221
    int compression_level;
Loren Merritt's avatar
Loren Merritt committed
222 223 224 225
    uint8_t *ptr, *top;
    uint8_t *crow_base = NULL, *crow_buf, *crow;
    uint8_t *progressive_buf = NULL;
    uint8_t *top_buf = NULL;
226 227

    *p = *pict;
228
    p->pict_type= AV_PICTURE_TYPE_I;
229 230 231 232 233 234 235 236
    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) {
237 238 239 240 241 242 243 244
    case PIX_FMT_RGBA64BE:
        bit_depth = 16;
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
        break;
    case PIX_FMT_RGB48BE:
        bit_depth = 16;
        color_type = PNG_COLOR_TYPE_RGB;
        break;
245
    case PIX_FMT_RGBA:
246 247 248 249 250 251 252
        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;
253 254 255 256
    case PIX_FMT_GRAY16BE:
        bit_depth = 16;
        color_type = PNG_COLOR_TYPE_GRAY;
        break;
257 258 259 260
    case PIX_FMT_GRAY8:
        bit_depth = 8;
        color_type = PNG_COLOR_TYPE_GRAY;
        break;
261 262 263 264
    case PIX_FMT_GRAY8A:
        bit_depth = 8;
        color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
        break;
265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281
    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;
282 283 284 285
    compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT ?
                            Z_DEFAULT_COMPRESSION :
                            av_clip(avctx->compression_level, 0, 9);
    ret = deflateInit2(&s->zstream, compression_level,
286 287 288
                       Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
    if (ret != Z_OK)
        return -1;
Loren Merritt's avatar
Loren Merritt committed
289 290
    crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
    if (!crow_base)
291
        goto fail;
Loren Merritt's avatar
Loren Merritt committed
292
    crow_buf = crow_base + 15; // pixel data should be aligned, but there's a control byte before it
293
    if (is_progressive) {
Loren Merritt's avatar
Loren Merritt committed
294 295 296 297
        progressive_buf = av_malloc(row_size + 1);
        if (!progressive_buf)
            goto fail;
    }
298
    if (is_progressive) {
Loren Merritt's avatar
Loren Merritt committed
299 300
        top_buf = av_malloc(row_size + 1);
        if (!top_buf)
301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331
            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;
332
            if (alpha != 0xff)
333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353
                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) {
        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) {
Loren Merritt's avatar
Loren Merritt committed
354
                top = NULL;
355 356 357
                for(y = 0; y < avctx->height; y++) {
                    if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
                        ptr = p->data[0] + y * p->linesize[0];
Loren Merritt's avatar
Loren Merritt committed
358 359
                        FFSWAP(uint8_t*, progressive_buf, top_buf);
                        png_get_interlaced_row(progressive_buf, pass_row_size,
360
                                               bits_per_pixel, pass,
Loren Merritt's avatar
Loren Merritt committed
361 362 363 364
                                               ptr, avctx->width);
                        crow = png_choose_filter(s, crow_buf, progressive_buf, top, pass_row_size, bits_per_pixel>>3);
                        png_write_row(s, crow, pass_row_size + 1);
                        top = progressive_buf;
365 366 367 368 369
                    }
                }
            }
        }
    } else {
Loren Merritt's avatar
Loren Merritt committed
370
        top = NULL;
371 372
        for(y = 0; y < avctx->height; y++) {
            ptr = p->data[0] + y * p->linesize[0];
Loren Merritt's avatar
Loren Merritt committed
373 374 375
            crow = png_choose_filter(s, crow_buf, ptr, top, row_size, bits_per_pixel>>3);
            png_write_row(s, crow, row_size + 1);
            top = ptr;
376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397
        }
    }
    /* 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:
Loren Merritt's avatar
Loren Merritt committed
398 399 400
    av_free(crow_base);
    av_free(progressive_buf);
    av_free(top_buf);
401 402 403 404 405 406 407
    deflateEnd(&s->zstream);
    return ret;
 fail:
    ret = -1;
    goto the_end;
}

408
static av_cold int png_enc_init(AVCodecContext *avctx){
409 410
    PNGEncContext *s = avctx->priv_data;

avcoder's avatar
avcoder committed
411 412
    avcodec_get_frame_defaults(&s->picture);
    avctx->coded_frame= &s->picture;
Loren Merritt's avatar
Loren Merritt committed
413 414 415 416 417
    dsputil_init(&s->dsp, avctx);

    s->filter_type = av_clip(avctx->prediction_method, PNG_FILTER_VALUE_NONE, PNG_FILTER_VALUE_MIXED);
    if(avctx->pix_fmt == PIX_FMT_MONOBLACK)
        s->filter_type = PNG_FILTER_VALUE_NONE;
418 419 420 421

    return 0;
}

422
AVCodec ff_png_encoder = {
423 424 425 426 427 428
    .name           = "png",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_PNG,
    .priv_data_size = sizeof(PNGEncContext),
    .init           = png_enc_init,
    .encode         = encode_frame,
429 430 431 432 433 434
    .pix_fmts= (const enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGBA,
                                          PIX_FMT_RGB48BE, PIX_FMT_RGBA64BE,
                                          PIX_FMT_PAL8,
                                          PIX_FMT_GRAY8, PIX_FMT_GRAY8A,
                                          PIX_FMT_GRAY16BE,
                                          PIX_FMT_MONOBLACK, PIX_FMT_NONE},
435
    .long_name= NULL_IF_CONFIG_SMALL("PNG image"),
436
};