FFmpeg: libavcodec/pngenc.c Source File

00001 /*
00002  * PNG image format
00003  * Copyright (c) 2003 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include "avcodec.h"
00022 #include "bytestream.h"
00023 #include "dsputil.h"
00024 #include "png.h"
00025 
00026 /* TODO:
00027  * - add 2, 4 and 16 bit depth support
00028  */
00029 
00030 #include <zlib.h>
00031 
00032 //#define DEBUG
00033 
00034 #define IOBUF_SIZE 4096
00035 
00036 typedef struct PNGEncContext {
00037     DSPContext dsp;
00038 
00039     uint8_t *bytestream;
00040     uint8_t *bytestream_start;
00041     uint8_t *bytestream_end;
00042     AVFrame picture;
00043 
00044     int filter_type;
00045 
00046     z_stream zstream;
00047     uint8_t buf[IOBUF_SIZE];
00048 } PNGEncContext;
00049 
00050 static void png_get_interlaced_row(uint8_t *dst, int row_size,
00051                                    int bits_per_pixel, int pass,
00052                                    const uint8_t *src, int width)
00053 {
00054     int x, mask, dst_x, j, b, bpp;
00055     uint8_t *d;
00056     const uint8_t *s;
00057 
00058     mask = ff_png_pass_mask[pass];
00059     switch(bits_per_pixel) {
00060     case 1:
00061         memset(dst, 0, row_size);
00062         dst_x = 0;
00063         for(x = 0; x < width; x++) {
00064             j = (x & 7);
00065             if ((mask << j) & 0x80) {
00066                 b = (src[x >> 3] >> (7 - j)) & 1;
00067                 dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
00068                 dst_x++;
00069             }
00070         }
00071         break;
00072     default:
00073         bpp = bits_per_pixel >> 3;
00074         d = dst;
00075         s = src;
00076         for(x = 0; x < width; x++) {
00077             j = x & 7;
00078             if ((mask << j) & 0x80) {
00079                 memcpy(d, s, bpp);
00080                 d += bpp;
00081             }
00082             s += bpp;
00083         }
00084         break;
00085     }
00086 }
00087 
00088 static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
00089 {
00090     int i;
00091     for(i = 0; i < w; i++) {
00092         int a, b, c, p, pa, pb, pc;
00093 
00094         a = src[i - bpp];
00095         b = top[i];
00096         c = top[i - bpp];
00097 
00098         p = b - c;
00099         pc = a - c;
00100 
00101         pa = abs(p);
00102         pb = abs(pc);
00103         pc = abs(p + pc);
00104 
00105         if (pa <= pb && pa <= pc)
00106             p = a;
00107         else if (pb <= pc)
00108             p = b;
00109         else
00110             p = c;
00111         dst[i] = src[i] - p;
00112     }
00113 }
00114 
00115 static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
00116                            uint8_t *src, uint8_t *top, int size, int bpp)
00117 {
00118     int i;
00119 
00120     switch(filter_type) {
00121     case PNG_FILTER_VALUE_NONE:
00122         memcpy(dst, src, size);
00123         break;
00124     case PNG_FILTER_VALUE_SUB:
00125         dsp->diff_bytes(dst, src, src-bpp, size);
00126         memcpy(dst, src, bpp);
00127         break;
00128     case PNG_FILTER_VALUE_UP:
00129         dsp->diff_bytes(dst, src, top, size);
00130         break;
00131     case PNG_FILTER_VALUE_AVG:
00132         for(i = 0; i < bpp; i++)
00133             dst[i] = src[i] - (top[i] >> 1);
00134         for(; i < size; i++)
00135             dst[i] = src[i] - ((src[i-bpp] + top[i]) >> 1);
00136         break;
00137     case PNG_FILTER_VALUE_PAETH:
00138         for(i = 0; i < bpp; i++)
00139             dst[i] = src[i] - top[i];
00140         sub_png_paeth_prediction(dst+i, src+i, top+i, size-i, bpp);
00141         break;
00142     }
00143 }
00144 
00145 static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
00146                                   uint8_t *src, uint8_t *top, int size, int bpp)
00147 {
00148     int pred = s->filter_type;
00149     assert(bpp || !pred);
00150     if(!top && pred)
00151         pred = PNG_FILTER_VALUE_SUB;
00152     if(pred == PNG_FILTER_VALUE_MIXED) {
00153         int i;
00154         int cost, bcost = INT_MAX;
00155         uint8_t *buf1 = dst, *buf2 = dst + size + 16;
00156         for(pred=0; pred<5; pred++) {
00157             png_filter_row(&s->dsp, buf1+1, pred, src, top, size, bpp);
00158             buf1[0] = pred;
00159             cost = 0;
00160             for(i=0; i<=size; i++)
00161                 cost += abs((int8_t)buf1[i]);
00162             if(cost < bcost) {
00163                 bcost = cost;
00164                 FFSWAP(uint8_t*, buf1, buf2);
00165             }
00166         }
00167         return buf2;
00168     } else {
00169         png_filter_row(&s->dsp, dst+1, pred, src, top, size, bpp);
00170         dst[0] = pred;
00171         return dst;
00172     }
00173 }
00174 
00175 static void convert_from_rgb32(uint8_t *dst, const uint8_t *src, int width)
00176 {
00177     uint8_t *d;
00178     int j;
00179     unsigned int v;
00180 
00181     d = dst;
00182     for(j = 0; j < width; j++) {
00183         v = ((const uint32_t *)src)[j];
00184         d[0] = v >> 16;
00185         d[1] = v >> 8;
00186         d[2] = v;
00187         d[3] = v >> 24;
00188         d += 4;
00189     }
00190 }
00191 
00192 static void png_write_chunk(uint8_t **f, uint32_t tag,
00193                             const uint8_t *buf, int length)
00194 {
00195     uint32_t crc;
00196     uint8_t tagbuf[4];
00197 
00198     bytestream_put_be32(f, length);
00199     crc = crc32(0, Z_NULL, 0);
00200     AV_WL32(tagbuf, tag);
00201     crc = crc32(crc, tagbuf, 4);
00202     bytestream_put_be32(f, bswap_32(tag));
00203     if (length > 0) {
00204         crc = crc32(crc, buf, length);
00205         memcpy(*f, buf, length);
00206         *f += length;
00207     }
00208     bytestream_put_be32(f, crc);
00209 }
00210 
00211 /* XXX: do filtering */
00212 static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)
00213 {
00214     int ret;
00215 
00216     s->zstream.avail_in = size;
00217     s->zstream.next_in = (uint8_t *)data;
00218     while (s->zstream.avail_in > 0) {
00219         ret = deflate(&s->zstream, Z_NO_FLUSH);
00220         if (ret != Z_OK)
00221             return -1;
00222         if (s->zstream.avail_out == 0) {
00223             if(s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
00224                 png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
00225             s->zstream.avail_out = IOBUF_SIZE;
00226             s->zstream.next_out = s->buf;
00227         }
00228     }
00229     return 0;
00230 }
00231 
00232 static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int buf_size, void *data){
00233     PNGEncContext *s = avctx->priv_data;
00234     AVFrame *pict = data;
00235     AVFrame * const p= &s->picture;
00236     int bit_depth, color_type, y, len, row_size, ret, is_progressive;
00237     int bits_per_pixel, pass_row_size;
00238     int compression_level;
00239     uint8_t *ptr, *top;
00240     uint8_t *crow_base = NULL, *crow_buf, *crow;
00241     uint8_t *progressive_buf = NULL;
00242     uint8_t *rgba_buf = NULL;
00243     uint8_t *top_buf = NULL;
00244 
00245     *p = *pict;
00246     p->pict_type= FF_I_TYPE;
00247     p->key_frame= 1;
00248 
00249     s->bytestream_start=
00250     s->bytestream= buf;
00251     s->bytestream_end= buf+buf_size;
00252 
00253     is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
00254     switch(avctx->pix_fmt) {
00255     case PIX_FMT_RGB32:
00256         bit_depth = 8;
00257         color_type = PNG_COLOR_TYPE_RGB_ALPHA;
00258         break;
00259     case PIX_FMT_RGB24:
00260         bit_depth = 8;
00261         color_type = PNG_COLOR_TYPE_RGB;
00262         break;
00263     case PIX_FMT_GRAY8:
00264         bit_depth = 8;
00265         color_type = PNG_COLOR_TYPE_GRAY;
00266         break;
00267     case PIX_FMT_MONOBLACK:
00268         bit_depth = 1;
00269         color_type = PNG_COLOR_TYPE_GRAY;
00270         break;
00271     case PIX_FMT_PAL8:
00272         bit_depth = 8;
00273         color_type = PNG_COLOR_TYPE_PALETTE;
00274         break;
00275     default:
00276         return -1;
00277     }
00278     bits_per_pixel = ff_png_get_nb_channels(color_type) * bit_depth;
00279     row_size = (avctx->width * bits_per_pixel + 7) >> 3;
00280 
00281     s->zstream.zalloc = ff_png_zalloc;
00282     s->zstream.zfree = ff_png_zfree;
00283     s->zstream.opaque = NULL;
00284     compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT ?
00285                             Z_DEFAULT_COMPRESSION :
00286                             av_clip(avctx->compression_level, 0, 9);
00287     ret = deflateInit2(&s->zstream, compression_level,
00288                        Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
00289     if (ret != Z_OK)
00290         return -1;
00291     crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
00292     if (!crow_base)
00293         goto fail;
00294     crow_buf = crow_base + 15; // pixel data should be aligned, but there's a control byte before it
00295     if (is_progressive) {
00296         progressive_buf = av_malloc(row_size + 1);
00297         if (!progressive_buf)
00298             goto fail;
00299     }
00300     if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00301         rgba_buf = av_malloc(row_size + 1);
00302         if (!rgba_buf)
00303             goto fail;
00304     }
00305     if (is_progressive || color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00306         top_buf = av_malloc(row_size + 1);
00307         if (!top_buf)
00308             goto fail;
00309     }
00310 
00311     /* write png header */
00312     memcpy(s->bytestream, ff_pngsig, 8);
00313     s->bytestream += 8;
00314 
00315     AV_WB32(s->buf, avctx->width);
00316     AV_WB32(s->buf + 4, avctx->height);
00317     s->buf[8] = bit_depth;
00318     s->buf[9] = color_type;
00319     s->buf[10] = 0; /* compression type */
00320     s->buf[11] = 0; /* filter type */
00321     s->buf[12] = is_progressive; /* interlace type */
00322 
00323     png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
00324 
00325     /* put the palette if needed */
00326     if (color_type == PNG_COLOR_TYPE_PALETTE) {
00327         int has_alpha, alpha, i;
00328         unsigned int v;
00329         uint32_t *palette;
00330         uint8_t *alpha_ptr;
00331 
00332         palette = (uint32_t *)p->data[1];
00333         ptr = s->buf;
00334         alpha_ptr = s->buf + 256 * 3;
00335         has_alpha = 0;
00336         for(i = 0; i < 256; i++) {
00337             v = palette[i];
00338             alpha = v >> 24;
00339             if (alpha && alpha != 0xff)
00340                 has_alpha = 1;
00341             *alpha_ptr++ = alpha;
00342             bytestream_put_be24(&ptr, v);
00343         }
00344         png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
00345         if (has_alpha) {
00346             png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
00347         }
00348     }
00349 
00350     /* now put each row */
00351     s->zstream.avail_out = IOBUF_SIZE;
00352     s->zstream.next_out = s->buf;
00353     if (is_progressive) {
00354         int pass;
00355 
00356         for(pass = 0; pass < NB_PASSES; pass++) {
00357             /* NOTE: a pass is completely omited if no pixels would be
00358                output */
00359             pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
00360             if (pass_row_size > 0) {
00361                 top = NULL;
00362                 for(y = 0; y < avctx->height; y++) {
00363                     if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
00364                         ptr = p->data[0] + y * p->linesize[0];
00365                         FFSWAP(uint8_t*, progressive_buf, top_buf);
00366                         if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00367                             convert_from_rgb32(rgba_buf, ptr, avctx->width);
00368                             ptr = rgba_buf;
00369                         }
00370                         png_get_interlaced_row(progressive_buf, pass_row_size,
00371                                                bits_per_pixel, pass,
00372                                                ptr, avctx->width);
00373                         crow = png_choose_filter(s, crow_buf, progressive_buf, top, pass_row_size, bits_per_pixel>>3);
00374                         png_write_row(s, crow, pass_row_size + 1);
00375                         top = progressive_buf;
00376                     }
00377                 }
00378             }
00379         }
00380     } else {
00381         top = NULL;
00382         for(y = 0; y < avctx->height; y++) {
00383             ptr = p->data[0] + y * p->linesize[0];
00384             if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
00385                 FFSWAP(uint8_t*, rgba_buf, top_buf);
00386                 convert_from_rgb32(rgba_buf, ptr, avctx->width);
00387                 ptr = rgba_buf;
00388             }
00389             crow = png_choose_filter(s, crow_buf, ptr, top, row_size, bits_per_pixel>>3);
00390             png_write_row(s, crow, row_size + 1);
00391             top = ptr;
00392         }
00393     }
00394     /* compress last bytes */
00395     for(;;) {
00396         ret = deflate(&s->zstream, Z_FINISH);
00397         if (ret == Z_OK || ret == Z_STREAM_END) {
00398             len = IOBUF_SIZE - s->zstream.avail_out;
00399             if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
00400                 png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
00401             }
00402             s->zstream.avail_out = IOBUF_SIZE;
00403             s->zstream.next_out = s->buf;
00404             if (ret == Z_STREAM_END)
00405                 break;
00406         } else {
00407             goto fail;
00408         }
00409     }
00410     png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
00411 
00412     ret = s->bytestream - s->bytestream_start;
00413  the_end:
00414     av_free(crow_base);
00415     av_free(progressive_buf);
00416     av_free(rgba_buf);
00417     av_free(top_buf);
00418     deflateEnd(&s->zstream);
00419     return ret;
00420  fail:
00421     ret = -1;
00422     goto the_end;
00423 }
00424 
00425 static av_cold int png_enc_init(AVCodecContext *avctx){
00426     PNGEncContext *s = avctx->priv_data;
00427 
00428     avcodec_get_frame_defaults(&s->picture);
00429     avctx->coded_frame= &s->picture;
00430     dsputil_init(&s->dsp, avctx);
00431 
00432     s->filter_type = av_clip(avctx->prediction_method, PNG_FILTER_VALUE_NONE, PNG_FILTER_VALUE_MIXED);
00433     if(avctx->pix_fmt == PIX_FMT_MONOBLACK)
00434         s->filter_type = PNG_FILTER_VALUE_NONE;
00435 
00436     return 0;
00437 }
00438 
00439 AVCodec png_encoder = {
00440     "png",
00441     CODEC_TYPE_VIDEO,
00442     CODEC_ID_PNG,
00443     sizeof(PNGEncContext),
00444     png_enc_init,
00445     encode_frame,
00446     NULL, //encode_end,
00447     .pix_fmts= (enum PixelFormat[]){PIX_FMT_RGB24, PIX_FMT_RGB32, PIX_FMT_PAL8, PIX_FMT_GRAY8, PIX_FMT_MONOBLACK, PIX_FMT_NONE},
00448     .long_name= NULL_IF_CONFIG_SMALL("PNG image"),
00449 };