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 Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 #include "internal.h"
  25
  26 typedef struct {
  27     AVFrame pictures[2];
  28     int currentpic;
  29 } C93DecoderContext;
  30
  31 typedef enum {
  32     C93_8X8_FROM_PREV  = 0x02,
  33     C93_4X4_FROM_PREV  = 0x06,
  34     C93_4X4_FROM_CURR  = 0x07,
  35     C93_8X8_2COLOR     = 0x08,
  36     C93_4X4_2COLOR     = 0x0A,
  37     C93_4X4_4COLOR_GRP = 0x0B,
  38     C93_4X4_4COLOR     = 0x0D,
  39     C93_NOOP           = 0x0E,
  40     C93_8X8_INTRA      = 0x0F,
  41 } C93BlockType;
  42
  43 #define WIDTH   320
  44 #define HEIGHT  192
  45
  46 #define C93_HAS_PALETTE 0x01
  47 #define C93_FIRST_FRAME 0x02
  48
  49 static av_cold int decode_init(AVCodecContext *avctx)
  50 {
  51     avctx->pix_fmt = AV_PIX_FMT_PAL8;
  52     return 0;
  53 }
  54
  55 static av_cold int decode_end(AVCodecContext *avctx)
  56 {
  57     C93DecoderContext * const c93 = avctx->priv_data;
  58
  59     av_frame_unref(&c93->pictures[0]);
  60     av_frame_unref(&c93->pictures[1]);
  61
  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 AVERROR_INVALIDDATA;
  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 *got_frame, AVPacket *avpkt)
 117 {
 118     const uint8_t *buf = avpkt->data;
 119     int buf_size = avpkt->size;
 120     C93DecoderContext * const c93 = avctx->priv_data;
 121     AVFrame * const newpic = &c93->pictures[c93->currentpic];
 122     AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
 123     GetByteContext gb;
 124     uint8_t *out;
 125     int stride, ret, i, x, y, b, bt = 0;
 126
 127     c93->currentpic ^= 1;
 128
 129     if ((ret = ff_reget_buffer(avctx, newpic)) < 0) {
 130         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
 131         return ret;
 132     }
 133
 134     stride = newpic->linesize[0];
 135
 136     bytestream2_init(&gb, buf, buf_size);
 137     b = bytestream2_get_byte(&gb);
 138     if (b & C93_FIRST_FRAME) {
 139         newpic->pict_type = AV_PICTURE_TYPE_I;
 140         newpic->key_frame = 1;
 141     } else {
 142         newpic->pict_type = AV_PICTURE_TYPE_P;
 143         newpic->key_frame = 0;
 144     }
 145
 146     for (y = 0; y < HEIGHT; y += 8) {
 147         out = newpic->data[0] + y * stride;
 148         for (x = 0; x < WIDTH; x += 8) {
 149             uint8_t *copy_from = oldpic->data[0];
 150             unsigned int offset, j;
 151             uint8_t cols[4], grps[4];
 152             C93BlockType block_type;
 153
 154             if (!bt)
 155                 bt = bytestream2_get_byte(&gb);
 156
 157             block_type= bt & 0x0F;
 158             switch (block_type) {
 159             case C93_8X8_FROM_PREV:
 160                 offset = bytestream2_get_le16(&gb);
 161                 if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
 162                     return ret;
 163                 break;
 164
 165             case C93_4X4_FROM_CURR:
 166                 copy_from = newpic->data[0];
 167             case C93_4X4_FROM_PREV:
 168                 for (j = 0; j < 8; j += 4) {
 169                     for (i = 0; i < 8; i += 4) {
 170                         offset = bytestream2_get_le16(&gb);
 171                         if ((ret = copy_block(avctx, &out[j*stride+i],
 172                                               copy_from, offset, 4, stride)) < 0)
 173                             return ret;
 174                     }
 175                 }
 176                 break;
 177
 178             case C93_8X8_2COLOR:
 179                 bytestream2_get_buffer(&gb, cols, 2);
 180                 for (i = 0; i < 8; i++) {
 181                     draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
 182                                      NULL, bytestream2_get_byte(&gb));
 183                 }
 184
 185                 break;
 186
 187             case C93_4X4_2COLOR:
 188             case C93_4X4_4COLOR:
 189             case C93_4X4_4COLOR_GRP:
 190                 for (j = 0; j < 8; j += 4) {
 191                     for (i = 0; i < 8; i += 4) {
 192                         if (block_type == C93_4X4_2COLOR) {
 193                             bytestream2_get_buffer(&gb, cols, 2);
 194                             draw_n_color(out + i + j*stride, stride, 4, 4,
 195                                     1, cols, NULL, bytestream2_get_le16(&gb));
 196                         } else if (block_type == C93_4X4_4COLOR) {
 197                             bytestream2_get_buffer(&gb, cols, 4);
 198                             draw_n_color(out + i + j*stride, stride, 4, 4,
 199                                     2, cols, NULL, bytestream2_get_le32(&gb));
 200                         } else {
 201                             bytestream2_get_buffer(&gb, grps, 4);
 202                             draw_n_color(out + i + j*stride, stride, 4, 4,
 203                                     1, cols, grps, bytestream2_get_le16(&gb));
 204                         }
 205                     }
 206                 }
 207                 break;
 208
 209             case C93_NOOP:
 210                 break;
 211
 212             case C93_8X8_INTRA:
 213                 for (j = 0; j < 8; j++)
 214                     bytestream2_get_buffer(&gb, out + j*stride, 8);
 215                 break;
 216
 217             default:
 218                 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
 219                        block_type, x, y);
 220                 return AVERROR_INVALIDDATA;
 221             }
 222             bt >>= 4;
 223             out += 8;
 224         }
 225     }
 226
 227     if (b & C93_HAS_PALETTE) {
 228         uint32_t *palette = (uint32_t *) newpic->data[1];
 229         for (i = 0; i < 256; i++) {
 230             palette[i] = bytestream2_get_be24(&gb);
 231         }
 232         newpic->palette_has_changed = 1;
 233     } else {
 234         if (oldpic->data[1])
 235             memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
 236     }
 237
 238     if ((ret = av_frame_ref(data, newpic)) < 0)
 239         return ret;
 240     *got_frame = 1;
 241
 242     return buf_size;
 243 }
 244
 245 AVCodec ff_c93_decoder = {
 246     .name           = "c93",
 247     .type           = AVMEDIA_TYPE_VIDEO,
 248     .id             = AV_CODEC_ID_C93,
 249     .priv_data_size = sizeof(C93DecoderContext),
 250     .init           = decode_init,
 251     .close          = decode_end,
 252     .decode         = decode_frame,
 253     .capabilities   = CODEC_CAP_DR1,
 254     .long_name      = NULL_IF_CONFIG_SMALL("Interplay C93"),
 255 };