libavcodec/bmv.c

   1 /*
   2  * Discworld II BMV video and audio decoder
   3  * Copyright (c) 2011 Konstantin Shishkov
   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 "libavutil/channel_layout.h"
  23 #include "avcodec.h"
  24 #include "bytestream.h"
  25 #include "internal.h"
  26
  27 enum BMVFlags{
  28     BMV_NOP = 0,
  29     BMV_END,
  30     BMV_DELTA,
  31     BMV_INTRA,
  32
  33     BMV_SCROLL  = 0x04,
  34     BMV_PALETTE = 0x08,
  35     BMV_COMMAND = 0x10,
  36     BMV_AUDIO   = 0x20,
  37     BMV_EXT     = 0x40,
  38     BMV_PRINT   = 0x80
  39 };
  40
  41 #define SCREEN_WIDE 640
  42 #define SCREEN_HIGH 429
  43
  44 typedef struct BMVDecContext {
  45     AVCodecContext *avctx;
  46     AVFrame pic;
  47
  48     uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
  49     uint32_t pal[256];
  50     const uint8_t *stream;
  51 } BMVDecContext;
  52
  53 #define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;
  54
  55 static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
  56 {
  57     unsigned val, saved_val = 0;
  58     int tmplen = src_len;
  59     const uint8_t *src, *source_end = source + src_len;
  60     uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
  61     uint8_t *dst, *dst_end;
  62     int len, mask;
  63     int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
  64     int read_two_nibbles, flag;
  65     int advance_mode;
  66     int mode = 0;
  67     int i;
  68
  69     if (src_len <= 0)
  70         return -1;
  71
  72     if (forward) {
  73         src = source;
  74         dst = frame;
  75         dst_end = frame_end;
  76     } else {
  77         src = source + src_len - 1;
  78         dst = frame_end - 1;
  79         dst_end = frame - 1;
  80     }
  81     for (;;) {
  82         int shift = 0;
  83         flag = 0;
  84
  85         /* The mode/len decoding is a bit strange:
  86          * values are coded as variable-length codes with nibble units,
  87          * code end is signalled by two top bits in the nibble being nonzero.
  88          * And since data is bytepacked and we read two nibbles at a time,
  89          * we may get a nibble belonging to the next code.
  90          * Hence this convoluted loop.
  91          */
  92         if (!mode || (tmplen == 4)) {
  93             if (src < source || src >= source_end)
  94                 return -1;
  95             val = *src;
  96             read_two_nibbles = 1;
  97         } else {
  98             val = saved_val;
  99             read_two_nibbles = 0;
 100         }
 101         if (!(val & 0xC)) {
 102             for (;;) {
 103                 if (!read_two_nibbles) {
 104                     if (src < source || src >= source_end)
 105                         return -1;
 106                     shift += 2;
 107                     val |= *src << shift;
 108                     if (*src & 0xC)
 109                         break;
 110                 }
 111                 // two upper bits of the nibble is zero,
 112                 // so shift top nibble value down into their place
 113                 read_two_nibbles = 0;
 114                 shift += 2;
 115                 mask = (1 << shift) - 1;
 116                 val = ((val >> 2) & ~mask) | (val & mask);
 117                 NEXT_BYTE(src);
 118                 if ((val & (0xC << shift))) {
 119                     flag = 1;
 120                     break;
 121                 }
 122             }
 123         } else if (mode) {
 124             flag = tmplen != 4;
 125         }
 126         if (flag) {
 127             tmplen = 4;
 128         } else {
 129             saved_val = val >> (4 + shift);
 130             tmplen = 0;
 131             val &= (1 << (shift + 4)) - 1;
 132             NEXT_BYTE(src);
 133         }
 134         advance_mode = val & 1;
 135         len = (val >> 1) - 1;
 136         mode += 1 + advance_mode;
 137         if (mode >= 4)
 138             mode -= 3;
 139         if (FFABS(dst_end - dst) < len)
 140             return -1;
 141         switch (mode) {
 142         case 1:
 143             if (forward) {
 144                 if (dst - frame + SCREEN_WIDE < frame_off ||
 145                         dst - frame + SCREEN_WIDE + frame_off < 0 ||
 146                         frame_end - dst < frame_off + len ||
 147                         frame_end - dst < len)
 148                     return -1;
 149                 for (i = 0; i < len; i++)
 150                     dst[i] = dst[frame_off + i];
 151                 dst += len;
 152             } else {
 153                 dst -= len;
 154                 if (dst - frame + SCREEN_WIDE < frame_off ||
 155                         dst - frame + SCREEN_WIDE + frame_off < 0 ||
 156                         frame_end - dst < frame_off + len ||
 157                         frame_end - dst < len)
 158                     return -1;
 159                 for (i = len - 1; i >= 0; i--)
 160                     dst[i] = dst[frame_off + i];
 161             }
 162             break;
 163         case 2:
 164             if (forward) {
 165                 if (source + src_len - src < len)
 166                     return -1;
 167                 memcpy(dst, src, len);
 168                 dst += len;
 169                 src += len;
 170             } else {
 171                 if (src - source < len)
 172                     return -1;
 173                 dst -= len;
 174                 src -= len;
 175                 memcpy(dst, src, len);
 176             }
 177             break;
 178         case 3:
 179             val = forward ? dst[-1] : dst[1];
 180             if (forward) {
 181                 memset(dst, val, len);
 182                 dst += len;
 183             } else {
 184                 dst -= len;
 185                 memset(dst, val, len);
 186             }
 187             break;
 188         default:
 189             break;
 190         }
 191         if (dst == dst_end)
 192             return 0;
 193     }
 194     return 0;
 195 }
 196
 197 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *pkt)
 198 {
 199     BMVDecContext * const c = avctx->priv_data;
 200     int type, scr_off;
 201     int i, ret;
 202     uint8_t *srcptr, *outptr;
 203
 204     c->stream = pkt->data;
 205     type = bytestream_get_byte(&c->stream);
 206     if (type & BMV_AUDIO) {
 207         int blobs = bytestream_get_byte(&c->stream);
 208         if (pkt->size < blobs * 65 + 2) {
 209             av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
 210             return AVERROR_INVALIDDATA;
 211         }
 212         c->stream += blobs * 65;
 213     }
 214     if (type & BMV_COMMAND) {
 215         int command_size = (type & BMV_PRINT) ? 8 : 10;
 216         if (c->stream - pkt->data + command_size > pkt->size) {
 217             av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
 218             return AVERROR_INVALIDDATA;
 219         }
 220         c->stream += command_size;
 221     }
 222     if (type & BMV_PALETTE) {
 223         if (c->stream - pkt->data > pkt->size - 768) {
 224             av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
 225             return AVERROR_INVALIDDATA;
 226         }
 227         for (i = 0; i < 256; i++)
 228             c->pal[i] = bytestream_get_be24(&c->stream);
 229     }
 230     if (type & BMV_SCROLL) {
 231         if (c->stream - pkt->data > pkt->size - 2) {
 232             av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
 233             return AVERROR_INVALIDDATA;
 234         }
 235         scr_off = (int16_t)bytestream_get_le16(&c->stream);
 236     } else if ((type & BMV_INTRA) == BMV_INTRA) {
 237         scr_off = -640;
 238     } else {
 239         scr_off = 0;
 240     }
 241
 242     if (c->pic.data[0])
 243         avctx->release_buffer(avctx, &c->pic);
 244
 245     c->pic.reference = 3;
 246     if ((ret = ff_get_buffer(avctx, &c->pic)) < 0) {
 247         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 248         return ret;
 249     }
 250
 251     if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
 252         av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
 253         return AVERROR_INVALIDDATA;
 254     }
 255
 256     memcpy(c->pic.data[1], c->pal, AVPALETTE_SIZE);
 257     c->pic.palette_has_changed = type & BMV_PALETTE;
 258
 259     outptr = c->pic.data[0];
 260     srcptr = c->frame;
 261
 262     for (i = 0; i < avctx->height; i++) {
 263         memcpy(outptr, srcptr, avctx->width);
 264         srcptr += avctx->width;
 265         outptr += c->pic.linesize[0];
 266     }
 267
 268     *data_size = sizeof(AVFrame);
 269     *(AVFrame*)data = c->pic;
 270
 271     /* always report that the buffer was completely consumed */
 272     return pkt->size;
 273 }
 274
 275 static av_cold int decode_init(AVCodecContext *avctx)
 276 {
 277     BMVDecContext * const c = avctx->priv_data;
 278
 279     c->avctx = avctx;
 280     avctx->pix_fmt = AV_PIX_FMT_PAL8;
 281
 282     c->frame = c->frame_base + 640;
 283
 284     return 0;
 285 }
 286
 287 static av_cold int decode_end(AVCodecContext *avctx)
 288 {
 289     BMVDecContext *c = avctx->priv_data;
 290
 291     if (c->pic.data[0])
 292         avctx->release_buffer(avctx, &c->pic);
 293
 294     return 0;
 295 }
 296
 297 typedef struct BMVAudioDecContext {
 298     AVFrame frame;
 299 } BMVAudioDecContext;
 300
 301 static const int bmv_aud_mults[16] = {
 302     16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
 303 };
 304
 305 static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
 306 {
 307     BMVAudioDecContext *c = avctx->priv_data;
 308
 309     avctx->channels       = 2;
 310     avctx->channel_layout = AV_CH_LAYOUT_STEREO;
 311     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
 312
 313     avcodec_get_frame_defaults(&c->frame);
 314     avctx->coded_frame = &c->frame;
 315
 316     return 0;
 317 }
 318
 319 static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
 320                                 int *got_frame_ptr, AVPacket *avpkt)
 321 {
 322     BMVAudioDecContext *c = avctx->priv_data;
 323     const uint8_t *buf = avpkt->data;
 324     int buf_size = avpkt->size;
 325     int blocks = 0, total_blocks, i;
 326     int ret;
 327     int16_t *output_samples;
 328     int scale[2];
 329
 330     total_blocks = *buf++;
 331     if (buf_size < total_blocks * 65 + 1) {
 332         av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
 333                total_blocks * 65 + 1, buf_size);
 334         return AVERROR_INVALIDDATA;
 335     }
 336
 337     /* get output buffer */
 338     c->frame.nb_samples = total_blocks * 32;
 339     if ((ret = ff_get_buffer(avctx, &c->frame)) < 0) {
 340         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 341         return ret;
 342     }
 343     output_samples = (int16_t *)c->frame.data[0];
 344
 345     for (blocks = 0; blocks < total_blocks; blocks++) {
 346         uint8_t code = *buf++;
 347         code = (code >> 1) | (code << 7);
 348         scale[0] = bmv_aud_mults[code & 0xF];
 349         scale[1] = bmv_aud_mults[code >> 4];
 350         for (i = 0; i < 32; i++) {
 351             *output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
 352             *output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
 353         }
 354     }
 355
 356     *got_frame_ptr   = 1;
 357     *(AVFrame *)data = c->frame;
 358
 359     return buf_size;
 360 }
 361
 362 AVCodec ff_bmv_video_decoder = {
 363     .name           = "bmv_video",
 364     .type           = AVMEDIA_TYPE_VIDEO,
 365     .id             = AV_CODEC_ID_BMV_VIDEO,
 366     .priv_data_size = sizeof(BMVDecContext),
 367     .init           = decode_init,
 368     .close          = decode_end,
 369     .decode         = decode_frame,
 370     .capabilities   = CODEC_CAP_DR1,
 371     .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
 372 };
 373
 374 AVCodec ff_bmv_audio_decoder = {
 375     .name           = "bmv_audio",
 376     .type           = AVMEDIA_TYPE_AUDIO,
 377     .id             = AV_CODEC_ID_BMV_AUDIO,
 378     .priv_data_size = sizeof(BMVAudioDecContext),
 379     .init           = bmv_aud_decode_init,
 380     .decode         = bmv_aud_decode_frame,
 381     .capabilities   = CODEC_CAP_DR1,
 382     .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
 383 };