libavcodec/xfacedec.c

   1 /*
   2  * Copyright (c) 1990 James Ashton - Sydney University
   3  * Copyright (c) 2012 Stefano Sabatini
   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
  22 /**
  23  * @file
  24  * X-Face decoder, based on libcompface, by James Ashton.
  25  */
  26
  27 #include "avcodec.h"
  28 #include "codec_internal.h"
  29 #include "decode.h"
  30 #include "xface.h"
  31
  32 static int pop_integer(BigInt *b, const ProbRange *pranges)
  33 {
  34     uint8_t r;
  35     int i;
  36
  37     /* extract the last byte into r, and shift right b by 8 bits */
  38     ff_big_div(b, 0, &r);
  39
  40     i = 0;
  41     while (r < pranges->offset || r >= pranges->range + pranges->offset) {
  42         pranges++;
  43         i++;
  44     }
  45     ff_big_mul(b, pranges->range);
  46     ff_big_add(b, r - pranges->offset);
  47     return i;
  48 }
  49
  50 static void pop_greys(BigInt *b, char *bitmap, int w, int h)
  51 {
  52     if (w > 3) {
  53         w /= 2;
  54         h /= 2;
  55         pop_greys(b, bitmap,                       w, h);
  56         pop_greys(b, bitmap + w,                   w, h);
  57         pop_greys(b, bitmap + XFACE_WIDTH * h,     w, h);
  58         pop_greys(b, bitmap + XFACE_WIDTH * h + w, w, h);
  59     } else {
  60         w = pop_integer(b, ff_xface_probranges_2x2);
  61         if (w & 1) bitmap[0]               = 1;
  62         if (w & 2) bitmap[1]               = 1;
  63         if (w & 4) bitmap[XFACE_WIDTH]     = 1;
  64         if (w & 8) bitmap[XFACE_WIDTH + 1] = 1;
  65     }
  66 }
  67
  68 static void decode_block(BigInt *b, char *bitmap, int w, int h, int level)
  69 {
  70     switch (pop_integer(b, &ff_xface_probranges_per_level[level][0])) {
  71     case XFACE_COLOR_WHITE:
  72         return;
  73     case XFACE_COLOR_BLACK:
  74         pop_greys(b, bitmap, w, h);
  75         return;
  76     default:
  77         w /= 2;
  78         h /= 2;
  79         level++;
  80         decode_block(b, bitmap,                       w, h, level);
  81         decode_block(b, bitmap + w,                   w, h, level);
  82         decode_block(b, bitmap + h * XFACE_WIDTH,     w, h, level);
  83         decode_block(b, bitmap + w + h * XFACE_WIDTH, w, h, level);
  84         return;
  85     }
  86 }
  87
  88 typedef struct XFaceContext {
  89     uint8_t bitmap[XFACE_PIXELS]; ///< image used internally for decoding
  90 } XFaceContext;
  91
  92 static av_cold int xface_decode_init(AVCodecContext *avctx)
  93 {
  94     if (avctx->width || avctx->height) {
  95         if (avctx->width != XFACE_WIDTH || avctx->height != XFACE_HEIGHT) {
  96             av_log(avctx, AV_LOG_ERROR,
  97                    "Size value %dx%d not supported, only accepts a size of %dx%d\n",
  98                    avctx->width, avctx->height, XFACE_WIDTH, XFACE_HEIGHT);
  99             return AVERROR(EINVAL);
 100         }
 101     }
 102
 103     avctx->width   = XFACE_WIDTH;
 104     avctx->height  = XFACE_HEIGHT;
 105     avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;
 106
 107     return 0;
 108 }
 109
 110 static int xface_decode_frame(AVCodecContext *avctx, AVFrame *frame,
 111                               int *got_frame, AVPacket *avpkt)
 112 {
 113     XFaceContext *xface = avctx->priv_data;
 114     int ret, i, j, k;
 115     uint8_t byte;
 116     BigInt b = {0};
 117     char *buf;
 118     int64_t c;
 119
 120     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 121         return ret;
 122
 123     for (i = 0, k = 0; i < avpkt->size && avpkt->data[i]; i++) {
 124         c = avpkt->data[i];
 125
 126         /* ignore invalid digits */
 127         if (c < XFACE_FIRST_PRINT || c > XFACE_LAST_PRINT)
 128             continue;
 129
 130         if (++k > XFACE_MAX_DIGITS) {
 131             av_log(avctx, AV_LOG_WARNING,
 132                    "Buffer is longer than expected, truncating at byte %d\n", i);
 133             break;
 134         }
 135         ff_big_mul(&b, XFACE_PRINTS);
 136         ff_big_add(&b, c - XFACE_FIRST_PRINT);
 137     }
 138
 139     /* decode image and put it in bitmap */
 140     memset(xface->bitmap, 0, XFACE_PIXELS);
 141     buf = xface->bitmap;
 142     decode_block(&b, buf,                         16, 16, 0);
 143     decode_block(&b, buf + 16,                    16, 16, 0);
 144     decode_block(&b, buf + 32,                    16, 16, 0);
 145     decode_block(&b, buf + XFACE_WIDTH * 16,      16, 16, 0);
 146     decode_block(&b, buf + XFACE_WIDTH * 16 + 16, 16, 16, 0);
 147     decode_block(&b, buf + XFACE_WIDTH * 16 + 32, 16, 16, 0);
 148     decode_block(&b, buf + XFACE_WIDTH * 32     , 16, 16, 0);
 149     decode_block(&b, buf + XFACE_WIDTH * 32 + 16, 16, 16, 0);
 150     decode_block(&b, buf + XFACE_WIDTH * 32 + 32, 16, 16, 0);
 151
 152     ff_xface_generate_face(xface->bitmap, xface->bitmap);
 153
 154     /* convert image from 1=black 0=white bitmap to MONOWHITE */
 155     buf = frame->data[0];
 156     for (i = 0, j = 0, k = 0, byte = 0; i < XFACE_PIXELS; i++) {
 157         byte += xface->bitmap[i];
 158         if (k == 7) {
 159             buf[j++] = byte;
 160             byte = k = 0;
 161         } else {
 162             k++;
 163             byte <<= 1;
 164         }
 165         if (j == XFACE_WIDTH/8) {
 166             j = 0;
 167             buf += frame->linesize[0];
 168         }
 169     }
 170
 171     *got_frame = 1;
 172
 173     return avpkt->size;
 174 }
 175
 176 const FFCodec ff_xface_decoder = {
 177     .p.name         = "xface",
 178     CODEC_LONG_NAME("X-face image"),
 179     .p.type         = AVMEDIA_TYPE_VIDEO,
 180     .p.id           = AV_CODEC_ID_XFACE,
 181     .p.capabilities = AV_CODEC_CAP_DR1,
 182     .priv_data_size = sizeof(XFaceContext),
 183     .init           = xface_decode_init,
 184     FF_CODEC_DECODE_CB(xface_decode_frame),
 185 };