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 25typedef struct { 26 AVFrame pictures[2]; 27 int currentpic; 28} C93DecoderContext; 29 30typedef 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 48static av_cold int decode_init(AVCodecContext *avctx) 49{ 50 avctx->pix_fmt = PIX_FMT_PAL8; 51 return 0; 52} 53 54static 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 65static 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 99static 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 115static 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 243AVCodec 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}; 255