libavcodec/c93.c

   1 /*
   2  * Interplay C93 video decoder
   3  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
   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 #include "avcodec.h"
  23 #include "bytestream.h"
  24
  25 typedef struct {
  26     AVFrame pictures[2];
  27     int currentpic;
  28 } C93DecoderContext;
  29
  30 typedef enum {
  31     C93_8X8_FROM_PREV  = 0x02,
  32     C93_4X4_FROM_PREV  = 0x06,
  33     C93_4X4_FROM_CURR  = 0x07,
  34     C93_8X8_2COLOR     = 0x08,
  35     C93_4X4_2COLOR     = 0x0A,
  36     C93_4X4_4COLOR_GRP = 0x0B,
  37     C93_4X4_4COLOR     = 0x0D,
  38     C93_NOOP           = 0x0E,
  39     C93_8X8_INTRA      = 0x0F,
  40 } C93BlockType;
  41
  42 #define WIDTH   320
  43 #define HEIGHT  192
  44
  45 #define C93_HAS_PALETTE 0x01
  46 #define C93_FIRST_FRAME 0x02
  47
  48 static av_cold int decode_init(AVCodecContext *avctx)
  49 {
  50     avctx->pix_fmt = PIX_FMT_PAL8;
  51     return 0;
  52 }
  53
  54 static av_cold int decode_end(AVCodecContext *avctx)
  55 {
  56     C93DecoderContext * const c93 = avctx->priv_data;
  57
  58     if (c93->pictures[0].data[0])
  59         avctx->release_buffer(avctx, &c93->pictures[0]);
  60     if (c93->pictures[1].data[0])
  61         avctx->release_buffer(avctx, &c93->pictures[1]);
  62     return 0;
  63 }
  64
  65 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
  66         uint8_t *from, int offset, int height, int stride)
  67 {
  68     int i;
  69     int width = height;
  70     int from_x = offset % WIDTH;
  71     int from_y = offset / WIDTH;
  72     int overflow = from_x + width - WIDTH;
  73
  74     if (!from) {
  75         /* silently ignoring predictive blocks in first frame */
  76         return 0;
  77     }
  78
  79     if (from_y + height > HEIGHT) {
  80         av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
  81                offset);
  82         return -1;
  83     }
  84
  85     if (overflow > 0) {
  86         width -= overflow;
  87         for (i = 0; i < height; i++) {
  88             memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
  89         }
  90     }
  91
  92     for (i = 0; i < height; i++) {
  93         memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
  94     }
  95
  96     return 0;
  97 }
  98
  99 static inline void draw_n_color(uint8_t *out, int stride, int width,
 100          int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
 101 {
 102     int x, y;
 103     for (y = 0; y < height; y++) {
 104         if (grps)
 105             cols[0] = grps[3 * (y >> 1)];
 106         for (x = 0; x < width; x++) {
 107             if (grps)
 108                 cols[1]= grps[(x >> 1) + 1];
 109             out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
 110             col >>= bpp;
 111         }
 112     }
 113 }
 114
 115 static int decode_frame(AVCodecContext *avctx, void *data,
 116                             int *data_size, const uint8_t * buf, int buf_size)
 117 {
 118     C93DecoderContext * const c93 = avctx->priv_data;
 119     AVFrame * const newpic = &c93->pictures[c93->currentpic];
 120     AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
 121     AVFrame *picture = data;
 122     uint8_t *out;
 123     int stride, i, x, y, bt = 0;
 124
 125     c93->currentpic ^= 1;
 126
 127     newpic->reference = 1;
 128     newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
 129                          FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
 130     if (avctx->reget_buffer(avctx, newpic)) {
 131         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
 132         return -1;
 133     }
 134
 135     stride = newpic->linesize[0];
 136
 137     if (buf[0] & C93_FIRST_FRAME) {
 138         newpic->pict_type = FF_I_TYPE;
 139         newpic->key_frame = 1;
 140     } else {
 141         newpic->pict_type = FF_P_TYPE;
 142         newpic->key_frame = 0;
 143     }
 144
 145     if (*buf++ & C93_HAS_PALETTE) {
 146         uint32_t *palette = (uint32_t *) newpic->data[1];
 147         const uint8_t *palbuf = buf + buf_size - 768 - 1;
 148         for (i = 0; i < 256; i++) {
 149             palette[i] = bytestream_get_be24(&palbuf);
 150         }
 151     } else {
 152         if (oldpic->data[1])
 153             memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
 154     }
 155
 156     for (y = 0; y < HEIGHT; y += 8) {
 157         out = newpic->data[0] + y * stride;
 158         for (x = 0; x < WIDTH; x += 8) {
 159             uint8_t *copy_from = oldpic->data[0];
 160             unsigned int offset, j;
 161             uint8_t cols[4], grps[4];
 162             C93BlockType block_type;
 163
 164             if (!bt)
 165                 bt = *buf++;
 166
 167             block_type= bt & 0x0F;
 168             switch (block_type) {
 169             case C93_8X8_FROM_PREV:
 170                 offset = bytestream_get_le16(&buf);
 171                 if (copy_block(avctx, out, copy_from, offset, 8, stride))
 172                     return -1;
 173                 break;
 174
 175             case C93_4X4_FROM_CURR:
 176                 copy_from = newpic->data[0];
 177             case C93_4X4_FROM_PREV:
 178                 for (j = 0; j < 8; j += 4) {
 179                     for (i = 0; i < 8; i += 4) {
 180                         offset = bytestream_get_le16(&buf);
 181                         if (copy_block(avctx, &out[j*stride+i],
 182                                            copy_from, offset, 4, stride))
 183                             return -1;
 184                     }
 185                 }
 186                 break;
 187
 188             case C93_8X8_2COLOR:
 189                 bytestream_get_buffer(&buf, cols, 2);
 190                 for (i = 0; i < 8; i++) {
 191                     draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
 192                                      NULL, *buf++);
 193                 }
 194
 195                 break;
 196
 197             case C93_4X4_2COLOR:
 198             case C93_4X4_4COLOR:
 199             case C93_4X4_4COLOR_GRP:
 200                 for (j = 0; j < 8; j += 4) {
 201                     for (i = 0; i < 8; i += 4) {
 202                         if (block_type == C93_4X4_2COLOR) {
 203                             bytestream_get_buffer(&buf, cols, 2);
 204                             draw_n_color(out + i + j*stride, stride, 4, 4,
 205                                     1, cols, NULL, bytestream_get_le16(&buf));
 206                         } else if (block_type == C93_4X4_4COLOR) {
 207                             bytestream_get_buffer(&buf, cols, 4);
 208                             draw_n_color(out + i + j*stride, stride, 4, 4,
 209                                     2, cols, NULL, bytestream_get_le32(&buf));
 210                         } else {
 211                             bytestream_get_buffer(&buf, grps, 4);
 212                             draw_n_color(out + i + j*stride, stride, 4, 4,
 213                                     1, cols, grps, bytestream_get_le16(&buf));
 214                         }
 215                     }
 216                 }
 217                 break;
 218
 219             case C93_NOOP:
 220                 break;
 221
 222             case C93_8X8_INTRA:
 223                 for (j = 0; j < 8; j++)
 224                     bytestream_get_buffer(&buf, out + j*stride, 8);
 225                 break;
 226
 227             default:
 228                 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
 229                        block_type, x, y);
 230                 return -1;
 231             }
 232             bt >>= 4;
 233             out += 8;
 234         }
 235     }
 236
 237     *picture = *newpic;
 238     *data_size = sizeof(AVFrame);
 239
 240     return buf_size;
 241 }
 242
 243 AVCodec c93_decoder = {
 244     "c93",
 245     CODEC_TYPE_VIDEO,
 246     CODEC_ID_C93,
 247     sizeof(C93DecoderContext),
 248     decode_init,
 249     NULL,
 250     decode_end,
 251     decode_frame,
 252     CODEC_CAP_DR1,
 253     .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
 254 };