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, 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 AVFrame *picture = data; 124 uint8_t *out; 125 int stride, i, x, y, bt = 0; 126 127 c93->currentpic ^= 1; 128 129 newpic->reference = 1; 130 newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | 131 FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE; 132 if (avctx->reget_buffer(avctx, newpic)) { 133 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n"); 134 return -1; 135 } 136 137 stride = newpic->linesize[0]; 138 139 if (buf[0] & C93_FIRST_FRAME) { 140 newpic->pict_type = FF_I_TYPE; 141 newpic->key_frame = 1; 142 } else { 143 newpic->pict_type = FF_P_TYPE; 144 newpic->key_frame = 0; 145 } 146 147 if (*buf++ & C93_HAS_PALETTE) { 148 uint32_t *palette = (uint32_t *) newpic->data[1]; 149 const uint8_t *palbuf = buf + buf_size - 768 - 1; 150 for (i = 0; i < 256; i++) { 151 palette[i] = bytestream_get_be24(&palbuf); 152 } 153 } else { 154 if (oldpic->data[1]) 155 memcpy(newpic->data[1], oldpic->data[1], 256 * 4); 156 } 157 158 for (y = 0; y < HEIGHT; y += 8) { 159 out = newpic->data[0] + y * stride; 160 for (x = 0; x < WIDTH; x += 8) { 161 uint8_t *copy_from = oldpic->data[0]; 162 unsigned int offset, j; 163 uint8_t cols[4], grps[4]; 164 C93BlockType block_type; 165 166 if (!bt) 167 bt = *buf++; 168 169 block_type= bt & 0x0F; 170 switch (block_type) { 171 case C93_8X8_FROM_PREV: 172 offset = bytestream_get_le16(&buf); 173 if (copy_block(avctx, out, copy_from, offset, 8, stride)) 174 return -1; 175 break; 176 177 case C93_4X4_FROM_CURR: 178 copy_from = newpic->data[0]; 179 case C93_4X4_FROM_PREV: 180 for (j = 0; j < 8; j += 4) { 181 for (i = 0; i < 8; i += 4) { 182 offset = bytestream_get_le16(&buf); 183 if (copy_block(avctx, &out[j*stride+i], 184 copy_from, offset, 4, stride)) 185 return -1; 186 } 187 } 188 break; 189 190 case C93_8X8_2COLOR: 191 bytestream_get_buffer(&buf, cols, 2); 192 for (i = 0; i < 8; i++) { 193 draw_n_color(out + i*stride, stride, 8, 1, 1, cols, 194 NULL, *buf++); 195 } 196 197 break; 198 199 case C93_4X4_2COLOR: 200 case C93_4X4_4COLOR: 201 case C93_4X4_4COLOR_GRP: 202 for (j = 0; j < 8; j += 4) { 203 for (i = 0; i < 8; i += 4) { 204 if (block_type == C93_4X4_2COLOR) { 205 bytestream_get_buffer(&buf, cols, 2); 206 draw_n_color(out + i + j*stride, stride, 4, 4, 207 1, cols, NULL, bytestream_get_le16(&buf)); 208 } else if (block_type == C93_4X4_4COLOR) { 209 bytestream_get_buffer(&buf, cols, 4); 210 draw_n_color(out + i + j*stride, stride, 4, 4, 211 2, cols, NULL, bytestream_get_le32(&buf)); 212 } else { 213 bytestream_get_buffer(&buf, grps, 4); 214 draw_n_color(out + i + j*stride, stride, 4, 4, 215 1, cols, grps, bytestream_get_le16(&buf)); 216 } 217 } 218 } 219 break; 220 221 case C93_NOOP: 222 break; 223 224 case C93_8X8_INTRA: 225 for (j = 0; j < 8; j++) 226 bytestream_get_buffer(&buf, out + j*stride, 8); 227 break; 228 229 default: 230 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n", 231 block_type, x, y); 232 return -1; 233 } 234 bt >>= 4; 235 out += 8; 236 } 237 } 238 239 *picture = *newpic; 240 *data_size = sizeof(AVFrame); 241 242 return buf_size; 243} 244 245AVCodec c93_decoder = { 246 "c93", 247 AVMEDIA_TYPE_VIDEO, 248 CODEC_ID_C93, 249 sizeof(C93DecoderContext), 250 decode_init, 251 NULL, 252 decode_end, 253 decode_frame, 254 CODEC_CAP_DR1, 255 .long_name = NULL_IF_CONFIG_SMALL("Interplay C93"), 256}; 257