1/*
2 * PNG image format
3 * Copyright (c) 2003 Fabrice Bellard
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21#include "avcodec.h"
22#include "bytestream.h"
23#include "dsputil.h"
24#include "png.h"
25
26/* TODO:
27 * - add 2, 4 and 16 bit depth support
28 */
29
30#include <zlib.h>
31
32//#define DEBUG
33
34#define IOBUF_SIZE 4096
35
36typedef struct PNGEncContext {
37    DSPContext dsp;
38
39    uint8_t *bytestream;
40    uint8_t *bytestream_start;
41    uint8_t *bytestream_end;
42    AVFrame picture;
43
44    int filter_type;
45
46    z_stream zstream;
47    uint8_t buf[IOBUF_SIZE];
48} PNGEncContext;
49
50static void png_get_interlaced_row(uint8_t *dst, int row_size,
51                                   int bits_per_pixel, int pass,
52                                   const uint8_t *src, int width)
53{
54    int x, mask, dst_x, j, b, bpp;
55    uint8_t *d;
56    const uint8_t *s;
57
58    mask = ff_png_pass_mask[pass];
59    switch(bits_per_pixel) {
60    case 1:
61        memset(dst, 0, row_size);
62        dst_x = 0;
63        for(x = 0; x < width; x++) {
64            j = (x & 7);
65            if ((mask << j) & 0x80) {
66                b = (src[x >> 3] >> (7 - j)) & 1;
67                dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
68                dst_x++;
69            }
70        }
71        break;
72    default:
73        bpp = bits_per_pixel >> 3;
74        d = dst;
75        s = src;
76        for(x = 0; x < width; x++) {
77            j = x & 7;
78            if ((mask << j) & 0x80) {
79                memcpy(d, s, bpp);
80                d += bpp;
81            }
82            s += bpp;
83        }
84        break;
85    }
86}
87
88static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
89{
90    int i;
91    for(i = 0; i < w; i++) {
92        int a, b, c, p, pa, pb, pc;
93
94        a = src[i - bpp];
95        b = top[i];
96        c = top[i - bpp];
97
98        p = b - c;
99        pc = a - c;
100
101        pa = abs(p);
102        pb = abs(pc);
103        pc = abs(p + pc);
104
105        if (pa <= pb && pa <= pc)
106            p = a;
107        else if (pb <= pc)
108            p = b;
109        else
110            p = c;
111        dst[i] = src[i] - p;
112    }
113}
114
115static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
116                           uint8_t *src, uint8_t *top, int size, int bpp)
117{
118    int i;
119
120    switch(filter_type) {
121    case PNG_FILTER_VALUE_NONE:
122        memcpy(dst, src, size);
123        break;
124    case PNG_FILTER_VALUE_SUB:
125        dsp->diff_bytes(dst, src, src-bpp, size);
126        memcpy(dst, src, bpp);
127        break;
128    case PNG_FILTER_VALUE_UP:
129        dsp->diff_bytes(dst, src, top, size);
130        break;
131    case PNG_FILTER_VALUE_AVG:
132        for(i = 0; i < bpp; i++)
133            dst[i] = src[i] - (top[i] >> 1);
134        for(; i < size; i++)
135            dst[i] = src[i] - ((src[i-bpp] + top[i]) >> 1);
136        break;
137    case PNG_FILTER_VALUE_PAETH:
138        for(i = 0; i < bpp; i++)
139            dst[i] = src[i] - top[i];
140        sub_png_paeth_prediction(dst+i, src+i, top+i, size-i, bpp);
141        break;
142    }
143}
144
145static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
146                                  uint8_t *src, uint8_t *top, int size, int bpp)
147{
148    int pred = s->filter_type;
149    assert(bpp || !pred);
150    if(!top && pred)
151        pred = PNG_FILTER_VALUE_SUB;
152    if(pred == PNG_FILTER_VALUE_MIXED) {
153        int i;
154        int cost, bcost = INT_MAX;
155        uint8_t *buf1 = dst, *buf2 = dst + size + 16;
156        for(pred=0; pred<5; pred++) {
157            png_filter_row(&s->dsp, buf1+1, pred, src, top, size, bpp);
158            buf1[0] = pred;
159            cost = 0;
160            for(i=0; i<=size; i++)
161                cost += abs((int8_t)buf1[i]);
162            if(cost < bcost) {
163                bcost = cost;
164                FFSWAP(uint8_t*, buf1, buf2);
165            }
166        }
167        return buf2;
168    } else {
169        png_filter_row(&s->dsp, dst+1, pred, src, top, size, bpp);
170        dst[0] = pred;
171        return dst;
172    }
173}
174
175static void convert_from_rgb32(uint8_t *dst, const uint8_t *src, int width)
176{
177    uint8_t *d;
178    int j;
179    unsigned int v;
180
181    d = dst;
182    for(j = 0; j < width; j++) {
183        v = ((const uint32_t *)src)[j];
184        d[0] = v >> 16;
185        d[1] = v >> 8;
186        d[2] = v;
187        d[3] = v >> 24;
188        d += 4;
189    }
190}
191
192static void png_write_chunk(uint8_t **f, uint32_t tag,
193                            const uint8_t *buf, int length)
194{
195    uint32_t crc;
196    uint8_t tagbuf[4];
197
198    bytestream_put_be32(f, length);
199    crc = crc32(0, Z_NULL, 0);
200    AV_WL32(tagbuf, tag);
201    crc = crc32(crc, tagbuf, 4);
202    bytestream_put_be32(f, bswap_32(tag));
203    if (length > 0) {
204        crc = crc32(crc, buf, length);
205        memcpy(*f, buf, length);
206        *f += length;
207    }
208    bytestream_put_be32(f, crc);
209}
210
211/* XXX: do filtering */
212static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)
213{
214    int ret;
215
216    s->zstream.avail_in = size;
217    s->zstream.next_in = (uint8_t *)data;
218    while (s->zstream.avail_in > 0) {
219        ret = deflate(&s->zstream, Z_NO_FLUSH);
220        if (ret != Z_OK)
221            return -1;
222        if (s->zstream.avail_out == 0) {
223            if(s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
224                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
225            s->zstream.avail_out = IOBUF_SIZE;
226            s->zstream.next_out = s->buf;
227        }
228    }
229    return 0;
230}
231
232static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size, void *data){
233    PNGEncContext *s = avctx->priv_data;
234    AVFrame *pict = data;
235    AVFrame * const p= &s->picture;
236    int bit_depth, color_type, y, len, row_size, ret, is_progressive;
237    int bits_per_pixel, pass_row_size;
238    int compression_level;
239    uint8_t *ptr, *top;
240    uint8_t *crow_base = NULL, *crow_buf, *crow;
241    uint8_t *progressive_buf = NULL;
242    uint8_t *rgba_buf = NULL;
243    uint8_t *top_buf = NULL;
244
245    *p = *pict;
246    p->pict_type= FF_I_TYPE;
247    p->key_frame= 1;
248
249    s->bytestream_start=
250    s->bytestream= buf;
251    s->bytestream_end= buf+buf_size;
252
253    is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
254    switch(avctx->pix_fmt) {
255    case PIX_FMT_RGB32:
256        bit_depth = 8;
257        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
258        break;
259    case PIX_FMT_RGB24:
260        bit_depth = 8;
261        color_type = PNG_COLOR_TYPE_RGB;
262        break;
263    case PIX_FMT_GRAY8:
264        bit_depth = 8;
265        color_type = PNG_COLOR_TYPE_GRAY;
266        break;
267    case PIX_FMT_MONOBLACK:
268        bit_depth = 1;
269        color_type = PNG_COLOR_TYPE_GRAY;
270        break;
271    case PIX_FMT_PAL8:
272        bit_depth = 8;
273        color_type = PNG_COLOR_TYPE_PALETTE;
274        break;
275    default:
276        return -1;
277    }
278    bits_per_pixel = ff_png_get_nb_channels(color_type) * bit_depth;
279    row_size = (avctx->width * bits_per_pixel + 7) >> 3;
280
281    s->zstream.zalloc = ff_png_zalloc;
282    s->zstream.zfree = ff_png_zfree;
283    s->zstream.opaque = NULL;
284    compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT ?
285                            Z_DEFAULT_COMPRESSION :
286                            av_clip(avctx->compression_level, 0, 9);
287    ret = deflateInit2(&s->zstream, compression_level,
288                       Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
289    if (ret != Z_OK)
290        return -1;
291    crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
292    if (!crow_base)
293        goto fail;
294    crow_buf = crow_base + 15; // pixel data should be aligned, but there's a control byte before it
295    if (is_progressive) {
296        progressive_buf = av_malloc(row_size + 1);
297        if (!progressive_buf)
298            goto fail;
299    }
300    if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
301        rgba_buf = av_malloc(row_size + 1);
302        if (!rgba_buf)
303            goto fail;
304    }
305    if (is_progressive || color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
306        top_buf = av_malloc(row_size + 1);
307        if (!top_buf)
308            goto fail;
309    }
310
311    /* write png header */
312    memcpy(s->bytestream, ff_pngsig, 8);
313    s->bytestream += 8;
314
315    AV_WB32(s->buf, avctx->width);
316    AV_WB32(s->buf + 4, avctx->height);
317    s->buf[8] = bit_depth;
318    s->buf[9] = color_type;
319    s->buf[10] = 0; /* compression type */
320    s->buf[11] = 0; /* filter type */
321    s->buf[12] = is_progressive; /* interlace type */
322
323    png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
324
325    /* put the palette if needed */
326    if (color_type == PNG_COLOR_TYPE_PALETTE) {
327        int has_alpha, alpha, i;
328        unsigned int v;
329        uint32_t *palette;
330        uint8_t *alpha_ptr;
331
332        palette = (uint32_t *)p->data[1];
333        ptr = s->buf;
334        alpha_ptr = s->buf + 256 * 3;
335        has_alpha = 0;
336        for(i = 0; i < 256; i++) {
337            v = palette[i];
338            alpha = v >> 24;
339            if (alpha && alpha != 0xff)
340                has_alpha = 1;
341            *alpha_ptr++ = alpha;
342            bytestream_put_be24(&ptr, v);
343        }
344        png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
345        if (has_alpha) {
346            png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
347        }
348    }
349
350    /* now put each row */
351    s->zstream.avail_out = IOBUF_SIZE;
352    s->zstream.next_out = s->buf;
353    if (is_progressive) {
354        int pass;
355
356        for(pass = 0; pass < NB_PASSES; pass++) {
357            /* NOTE: a pass is completely omited if no pixels would be
358               output */
359            pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
360            if (pass_row_size > 0) {
361                top = NULL;
362                for(y = 0; y < avctx->height; y++) {
363                    if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
364                        ptr = p->data[0] + y * p->linesize[0];
365                        FFSWAP(uint8_t*, progressive_buf, top_buf);
366                        if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
367                            convert_from_rgb32(rgba_buf, ptr, avctx->width);
368                            ptr = rgba_buf;
369                        }
370                        png_get_interlaced_row(progressive_buf, pass_row_size,
371                                               bits_per_pixel, pass,
372                                               ptr, avctx->width);
373                        crow = png_choose_filter(s, crow_buf, progressive_buf, top, pass_row_size, bits_per_pixel>>3);
374                        png_write_row(s, crow, pass_row_size + 1);
375                        top = progressive_buf;
376                    }
377                }
378            }
379        }
380    } else {
381        top = NULL;
382        for(y = 0; y < avctx->height; y++) {
383            ptr = p->data[0] + y * p->linesize[0];
384            if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
385                FFSWAP(uint8_t*, rgba_buf, top_buf);
386                convert_from_rgb32(rgba_buf, ptr, avctx->width);
387                ptr = rgba_buf;
388            }
389            crow = png_choose_filter(s, crow_buf, ptr, top, row_size, bits_per_pixel>>3);
390            png_write_row(s, crow, row_size + 1);
391            top = ptr;
392        }
393    }
394    /* compress last bytes */
395    for(;;) {
396        ret = deflate(&s->zstream, Z_FINISH);
397        if (ret == Z_OK || ret == Z_STREAM_END) {
398            len = IOBUF_SIZE - s->zstream.avail_out;
399            if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
400                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
401            }
402            s->zstream.avail_out = IOBUF_SIZE;
403            s->zstream.next_out = s->buf;
404            if (ret == Z_STREAM_END)
405                break;
406        } else {
407            goto fail;
408        }
409    }
410    png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
411
412    ret = s->bytestream - s->bytestream_start;
413 the_end:
414    av_free(crow_base);
415    av_free(progressive_buf);
416    av_free(rgba_buf);
417    av_free(top_buf);
418    deflateEnd(&s->zstream);
419    return ret;
420 fail:
421    ret = -1;
422    goto the_end;
423}
424
425static av_cold int png_enc_init(AVCodecContext *avctx){
426    PNGEncContext *s = avctx->priv_data;
427
428    avcodec_get_frame_defaults(&s->picture);
429    avctx->coded_frame= &s->picture;
430    dsputil_init(&s->dsp, avctx);
431
432    s->filter_type = av_clip(avctx->prediction_method, PNG_FILTER_VALUE_NONE, PNG_FILTER_VALUE_MIXED);
433    if(avctx->pix_fmt == PIX_FMT_MONOBLACK)
434        s->filter_type = PNG_FILTER_VALUE_NONE;
435
436    return 0;
437}
438
439AVCodec png_encoder = {
440    "png",
441    CODEC_TYPE_VIDEO,
442    CODEC_ID_PNG,
443    sizeof(PNGEncContext),
444    png_enc_init,
445    encode_frame,
446    NULL, //encode_end,
447    .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGB32, PIX_FMT_PAL8, PIX_FMT_GRAY8, PIX_FMT_MONOBLACK, PIX_FMT_NONE},
448    .long_name= NULL_IF_CONFIG_SMALL("PNG image"),
449};
450