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 C93DecoderContext {
  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_end(AVCodecContext *avctx)
  50 {
  51     C93DecoderContext * const c93 = avctx->priv_data;
  52
  53     av_frame_free(&c93->pictures[0]);
  54     av_frame_free(&c93->pictures[1]);
  55
  56     return 0;
  57 }
  58
  59 static av_cold int decode_init(AVCodecContext *avctx)
  60 {
  61     C93DecoderContext *s = avctx->priv_data;
  62     avctx->pix_fmt = AV_PIX_FMT_PAL8;
  63
  64     s->pictures[0] = av_frame_alloc();
  65     s->pictures[1] = av_frame_alloc();
  66     if (!s->pictures[0] || !s->pictures[1]) {
  67         decode_end(avctx);
  68         return AVERROR(ENOMEM);
  69     }
  70
  71     return 0;
  72 }
  73
  74 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
  75         uint8_t *from, int offset, int height, int stride)
  76 {
  77     int i;
  78     int width = height;
  79     int from_x = offset % WIDTH;
  80     int from_y = offset / WIDTH;
  81     int overflow = from_x + width - WIDTH;
  82
  83     if (!from) {
  84         /* silently ignoring predictive blocks in first frame */
  85         return 0;
  86     }
  87
  88     if (from_y + height > HEIGHT) {
  89         av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
  90                offset);
  91         return AVERROR_INVALIDDATA;
  92     }
  93
  94     if (overflow > 0) {
  95         width -= overflow;
  96         for (i = 0; i < height; i++) {
  97             memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
  98         }
  99     }
 100
 101     for (i = 0; i < height; i++) {
 102         memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
 103     }
 104
 105     return 0;
 106 }
 107
 108 static inline void draw_n_color(uint8_t *out, int stride, int width,
 109          int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
 110 {
 111     int x, y;
 112     for (y = 0; y < height; y++) {
 113         if (grps)
 114             cols[0] = grps[3 * (y >> 1)];
 115         for (x = 0; x < width; x++) {
 116             if (grps)
 117                 cols[1]= grps[(x >> 1) + 1];
 118             out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
 119             col >>= bpp;
 120         }
 121     }
 122 }
 123
 124 static int decode_frame(AVCodecContext *avctx, void *data,
 125                         int *got_frame, AVPacket *avpkt)
 126 {
 127     const uint8_t *buf = avpkt->data;
 128     int buf_size = avpkt->size;
 129     C93DecoderContext * const c93 = avctx->priv_data;
 130     AVFrame * const newpic = c93->pictures[c93->currentpic];
 131     AVFrame * const oldpic = c93->pictures[c93->currentpic^1];
 132     GetByteContext gb;
 133     uint8_t *out;
 134     int stride, ret, i, x, y, b, bt = 0;
 135
 136     c93->currentpic ^= 1;
 137
 138     if ((ret = ff_reget_buffer(avctx, newpic)) < 0) {
 139         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
 140         return ret;
 141     }
 142
 143     stride = newpic->linesize[0];
 144
 145     bytestream2_init(&gb, buf, buf_size);
 146     b = bytestream2_get_byte(&gb);
 147     if (b & C93_FIRST_FRAME) {
 148         newpic->pict_type = AV_PICTURE_TYPE_I;
 149         newpic->key_frame = 1;
 150     } else {
 151         newpic->pict_type = AV_PICTURE_TYPE_P;
 152         newpic->key_frame = 0;
 153     }
 154
 155     for (y = 0; y < HEIGHT; y += 8) {
 156         out = newpic->data[0] + y * stride;
 157         for (x = 0; x < WIDTH; x += 8) {
 158             uint8_t *copy_from = oldpic->data[0];
 159             unsigned int offset, j;
 160             uint8_t cols[4], grps[4];
 161             C93BlockType block_type;
 162
 163             if (!bt)
 164                 bt = bytestream2_get_byte(&gb);
 165
 166             block_type= bt & 0x0F;
 167             switch (block_type) {
 168             case C93_8X8_FROM_PREV:
 169                 offset = bytestream2_get_le16(&gb);
 170                 if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
 171                     return ret;
 172                 break;
 173
 174             case C93_4X4_FROM_CURR:
 175                 copy_from = newpic->data[0];
 176             case C93_4X4_FROM_PREV:
 177                 for (j = 0; j < 8; j += 4) {
 178                     for (i = 0; i < 8; i += 4) {
 179                         offset = bytestream2_get_le16(&gb);
 180                         if ((ret = copy_block(avctx, &out[j*stride+i],
 181                                               copy_from, offset, 4, stride)) < 0)
 182                             return ret;
 183                     }
 184                 }
 185                 break;
 186
 187             case C93_8X8_2COLOR:
 188                 bytestream2_get_buffer(&gb, cols, 2);
 189                 for (i = 0; i < 8; i++) {
 190                     draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
 191                                      NULL, bytestream2_get_byte(&gb));
 192                 }
 193
 194                 break;
 195
 196             case C93_4X4_2COLOR:
 197             case C93_4X4_4COLOR:
 198             case C93_4X4_4COLOR_GRP:
 199                 for (j = 0; j < 8; j += 4) {
 200                     for (i = 0; i < 8; i += 4) {
 201                         if (block_type == C93_4X4_2COLOR) {
 202                             bytestream2_get_buffer(&gb, cols, 2);
 203                             draw_n_color(out + i + j*stride, stride, 4, 4,
 204                                     1, cols, NULL, bytestream2_get_le16(&gb));
 205                         } else if (block_type == C93_4X4_4COLOR) {
 206                             bytestream2_get_buffer(&gb, cols, 4);
 207                             draw_n_color(out + i + j*stride, stride, 4, 4,
 208                                     2, cols, NULL, bytestream2_get_le32(&gb));
 209                         } else {
 210                             bytestream2_get_buffer(&gb, grps, 4);
 211                             draw_n_color(out + i + j*stride, stride, 4, 4,
 212                                     1, cols, grps, bytestream2_get_le16(&gb));
 213                         }
 214                     }
 215                 }
 216                 break;
 217
 218             case C93_NOOP:
 219                 break;
 220
 221             case C93_8X8_INTRA:
 222                 for (j = 0; j < 8; j++)
 223                     bytestream2_get_buffer(&gb, out + j*stride, 8);
 224                 break;
 225
 226             default:
 227                 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
 228                        block_type, x, y);
 229                 return AVERROR_INVALIDDATA;
 230             }
 231             bt >>= 4;
 232             out += 8;
 233         }
 234     }
 235
 236     if (b & C93_HAS_PALETTE) {
 237         uint32_t *palette = (uint32_t *) newpic->data[1];
 238         for (i = 0; i < 256; i++) {
 239             palette[i] = bytestream2_get_be24(&gb);
 240         }
 241         newpic->palette_has_changed = 1;
 242     } else {
 243         if (oldpic->data[1])
 244             memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
 245     }
 246
 247     if ((ret = av_frame_ref(data, newpic)) < 0)
 248         return ret;
 249     *got_frame = 1;
 250
 251     return buf_size;
 252 }
 253
 254 AVCodec ff_c93_decoder = {
 255     .name           = "c93",
 256     .long_name      = NULL_IF_CONFIG_SMALL("Interplay C93"),
 257     .type           = AVMEDIA_TYPE_VIDEO,
 258     .id             = AV_CODEC_ID_C93,
 259     .priv_data_size = sizeof(C93DecoderContext),
 260     .init           = decode_init,
 261     .close          = decode_end,
 262     .decode         = decode_frame,
 263     .capabilities   = AV_CODEC_CAP_DR1,
 264     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 265 };