bmv.c 11 KB
Newer Older
1 2 3 4
/*
 * Discworld II BMV video and audio decoder
 * Copyright (c) 2011 Konstantin Shishkov
 *
5
 * This file is part of FFmpeg.
6
 *
7
 * FFmpeg is free software; you can redistribute it and/or
8 9 10 11
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
12
 * FFmpeg is distributed in the hope that it will be useful,
13 14 15 16 17
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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 20 21
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

22
#include "libavutil/avassert.h"
23
#include "libavutil/channel_layout.h"
24 25
#include "avcodec.h"
#include "bytestream.h"
26
#include "internal.h"
27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

enum BMVFlags{
    BMV_NOP = 0,
    BMV_END,
    BMV_DELTA,
    BMV_INTRA,

    BMV_SCROLL  = 0x04,
    BMV_PALETTE = 0x08,
    BMV_COMMAND = 0x10,
    BMV_AUDIO   = 0x20,
    BMV_EXT     = 0x40,
    BMV_PRINT   = 0x80
};

#define SCREEN_WIDE 640
#define SCREEN_HIGH 429

typedef struct BMVDecContext {
    AVCodecContext *avctx;

    uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
    uint32_t pal[256];
    const uint8_t *stream;
} BMVDecContext;

#define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;

static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
{
57
    unsigned val, saved_val = 0;
58 59 60 61 62 63 64 65 66 67 68 69
    int tmplen = src_len;
    const uint8_t *src, *source_end = source + src_len;
    uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
    uint8_t *dst, *dst_end;
    int len, mask;
    int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
    int read_two_nibbles, flag;
    int advance_mode;
    int mode = 0;
    int i;

    if (src_len <= 0)
70
        return AVERROR_INVALIDDATA;
71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93

    if (forward) {
        src = source;
        dst = frame;
        dst_end = frame_end;
    } else {
        src = source + src_len - 1;
        dst = frame_end - 1;
        dst_end = frame - 1;
    }
    for (;;) {
        int shift = 0;
        flag = 0;

        /* The mode/len decoding is a bit strange:
         * values are coded as variable-length codes with nibble units,
         * code end is signalled by two top bits in the nibble being nonzero.
         * And since data is bytepacked and we read two nibbles at a time,
         * we may get a nibble belonging to the next code.
         * Hence this convoluted loop.
         */
        if (!mode || (tmplen == 4)) {
            if (src < source || src >= source_end)
94
                return AVERROR_INVALIDDATA;
95 96 97 98 99 100 101 102
            val = *src;
            read_two_nibbles = 1;
        } else {
            val = saved_val;
            read_two_nibbles = 0;
        }
        if (!(val & 0xC)) {
            for (;;) {
103 104
                if(shift>22)
                    return -1;
105 106
                if (!read_two_nibbles) {
                    if (src < source || src >= source_end)
107
                        return AVERROR_INVALIDDATA;
108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137
                    shift += 2;
                    val |= *src << shift;
                    if (*src & 0xC)
                        break;
                }
                // two upper bits of the nibble is zero,
                // so shift top nibble value down into their place
                read_two_nibbles = 0;
                shift += 2;
                mask = (1 << shift) - 1;
                val = ((val >> 2) & ~mask) | (val & mask);
                NEXT_BYTE(src);
                if ((val & (0xC << shift))) {
                    flag = 1;
                    break;
                }
            }
        } else if (mode) {
            flag = tmplen != 4;
        }
        if (flag) {
            tmplen = 4;
        } else {
            saved_val = val >> (4 + shift);
            tmplen = 0;
            val &= (1 << (shift + 4)) - 1;
            NEXT_BYTE(src);
        }
        advance_mode = val & 1;
        len = (val >> 1) - 1;
138
        av_assert0(len>0);
139 140 141
        mode += 1 + advance_mode;
        if (mode >= 4)
            mode -= 3;
142
        if (len <= 0 || FFABS(dst_end - dst) < len)
143
            return AVERROR_INVALIDDATA;
144 145 146 147
        switch (mode) {
        case 1:
            if (forward) {
                if (dst - frame + SCREEN_WIDE < frame_off ||
148 149 150
                        dst - frame + SCREEN_WIDE + frame_off < 0 ||
                        frame_end - dst < frame_off + len ||
                        frame_end - dst < len)
151
                    return AVERROR_INVALIDDATA;
152 153 154 155 156 157
                for (i = 0; i < len; i++)
                    dst[i] = dst[frame_off + i];
                dst += len;
            } else {
                dst -= len;
                if (dst - frame + SCREEN_WIDE < frame_off ||
158 159 160
                        dst - frame + SCREEN_WIDE + frame_off < 0 ||
                        frame_end - dst < frame_off + len ||
                        frame_end - dst < len)
161
                    return AVERROR_INVALIDDATA;
162 163 164 165 166 167 168
                for (i = len - 1; i >= 0; i--)
                    dst[i] = dst[frame_off + i];
            }
            break;
        case 2:
            if (forward) {
                if (source + src_len - src < len)
169
                    return AVERROR_INVALIDDATA;
170 171 172 173 174
                memcpy(dst, src, len);
                dst += len;
                src += len;
            } else {
                if (src - source < len)
175
                    return AVERROR_INVALIDDATA;
176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197
                dst -= len;
                src -= len;
                memcpy(dst, src, len);
            }
            break;
        case 3:
            val = forward ? dst[-1] : dst[1];
            if (forward) {
                memset(dst, val, len);
                dst += len;
            } else {
                dst -= len;
                memset(dst, val, len);
            }
            break;
        }
        if (dst == dst_end)
            return 0;
    }
    return 0;
}

198 199
static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                        AVPacket *pkt)
200 201
{
    BMVDecContext * const c = avctx->priv_data;
202
    AVFrame *frame = data;
203
    int type, scr_off;
204
    int i, ret;
205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230
    uint8_t *srcptr, *outptr;

    c->stream = pkt->data;
    type = bytestream_get_byte(&c->stream);
    if (type & BMV_AUDIO) {
        int blobs = bytestream_get_byte(&c->stream);
        if (pkt->size < blobs * 65 + 2) {
            av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
            return AVERROR_INVALIDDATA;
        }
        c->stream += blobs * 65;
    }
    if (type & BMV_COMMAND) {
        int command_size = (type & BMV_PRINT) ? 8 : 10;
        if (c->stream - pkt->data + command_size > pkt->size) {
            av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
            return AVERROR_INVALIDDATA;
        }
        c->stream += command_size;
    }
    if (type & BMV_PALETTE) {
        if (c->stream - pkt->data > pkt->size - 768) {
            av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
            return AVERROR_INVALIDDATA;
        }
        for (i = 0; i < 256; i++)
231
            c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream);
232 233 234 235 236 237 238 239 240 241 242 243 244
    }
    if (type & BMV_SCROLL) {
        if (c->stream - pkt->data > pkt->size - 2) {
            av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
            return AVERROR_INVALIDDATA;
        }
        scr_off = (int16_t)bytestream_get_le16(&c->stream);
    } else if ((type & BMV_INTRA) == BMV_INTRA) {
        scr_off = -640;
    } else {
        scr_off = 0;
    }

245
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
246 247
        return ret;

248 249 250 251 252
    if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
        av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
        return AVERROR_INVALIDDATA;
    }

253 254
    memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
    frame->palette_has_changed = type & BMV_PALETTE;
255

256
    outptr = frame->data[0];
257 258 259 260 261
    srcptr = c->frame;

    for (i = 0; i < avctx->height; i++) {
        memcpy(outptr, srcptr, avctx->width);
        srcptr += avctx->width;
262
        outptr += frame->linesize[0];
263 264
    }

265
    *got_frame = 1;
266 267 268 269 270 271 272 273 274 275

    /* always report that the buffer was completely consumed */
    return pkt->size;
}

static av_cold int decode_init(AVCodecContext *avctx)
{
    BMVDecContext * const c = avctx->priv_data;

    c->avctx = avctx;
276
    avctx->pix_fmt = AV_PIX_FMT_PAL8;
277

278 279 280 281 282
    if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) {
        av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height);
        return AVERROR_INVALIDDATA;
    }

283 284 285 286 287 288 289 290 291 292 293
    c->frame = c->frame_base + 640;

    return 0;
}

static const int bmv_aud_mults[16] = {
    16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
};

static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
{
294 295 296
    avctx->channels       = 2;
    avctx->channel_layout = AV_CH_LAYOUT_STEREO;
    avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
297 298 299 300

    return 0;
}

301 302
static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
                                int *got_frame_ptr, AVPacket *avpkt)
303
{
304
    AVFrame *frame     = data;
305 306 307
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    int blocks = 0, total_blocks, i;
308 309
    int ret;
    int16_t *output_samples;
310 311 312 313 314 315 316 317
    int scale[2];

    total_blocks = *buf++;
    if (buf_size < total_blocks * 65 + 1) {
        av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
               total_blocks * 65 + 1, buf_size);
        return AVERROR_INVALIDDATA;
    }
318 319

    /* get output buffer */
320
    frame->nb_samples = total_blocks * 32;
321
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
322
        return ret;
323
    output_samples = (int16_t *)frame->data[0];
324 325 326 327 328 329 330 331 332 333 334 335

    for (blocks = 0; blocks < total_blocks; blocks++) {
        uint8_t code = *buf++;
        code = (code >> 1) | (code << 7);
        scale[0] = bmv_aud_mults[code & 0xF];
        scale[1] = bmv_aud_mults[code >> 4];
        for (i = 0; i < 32; i++) {
            *output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
            *output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
        }
    }

336
    *got_frame_ptr = 1;
337

338 339 340 341 342
    return buf_size;
}

AVCodec ff_bmv_video_decoder = {
    .name           = "bmv_video",
343
    .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
344
    .type           = AVMEDIA_TYPE_VIDEO,
345
    .id             = AV_CODEC_ID_BMV_VIDEO,
346 347 348
    .priv_data_size = sizeof(BMVDecContext),
    .init           = decode_init,
    .decode         = decode_frame,
Paul B Mahol's avatar
Paul B Mahol committed
349
    .capabilities   = CODEC_CAP_DR1,
350 351 352 353
};

AVCodec ff_bmv_audio_decoder = {
    .name           = "bmv_audio",
354
    .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
355
    .type           = AVMEDIA_TYPE_AUDIO,
356
    .id             = AV_CODEC_ID_BMV_AUDIO,
357 358
    .init           = bmv_aud_decode_init,
    .decode         = bmv_aud_decode_frame,
359
    .capabilities   = CODEC_CAP_DR1,
360
};