c93.c 7.55 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
/*
 * Interplay C93 video decoder
 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * 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.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * 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
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

#include "avcodec.h"
#include "bytestream.h"

typedef struct {
    AVFrame pictures[2];
    int currentpic;
} C93DecoderContext;

typedef enum {
    C93_8X8_FROM_PREV  = 0x02,
    C93_4X4_FROM_PREV  = 0x06,
    C93_4X4_FROM_CURR  = 0x07,
    C93_8X8_2COLOR     = 0x08,
    C93_4X4_2COLOR     = 0x0A,
    C93_4X4_4COLOR_GRP = 0x0B,
    C93_4X4_4COLOR     = 0x0D,
    C93_NOOP           = 0x0E,
    C93_8X8_INTRA      = 0x0F,
} C93BlockType;

#define WIDTH   320
#define HEIGHT  192

#define C93_HAS_PALETTE 0x01
#define C93_FIRST_FRAME 0x02

49
static int decode_init(AVCodecContext *avctx)
50 51 52 53 54
{
    avctx->pix_fmt = PIX_FMT_PAL8;
    return 0;
}

55
static int decode_end(AVCodecContext *avctx)
56 57 58 59 60 61 62 63 64 65
{
    C93DecoderContext * const c93 = avctx->priv_data;

    if (c93->pictures[0].data[0])
        avctx->release_buffer(avctx, &c93->pictures[0]);
    if (c93->pictures[1].data[0])
        avctx->release_buffer(avctx, &c93->pictures[1]);
    return 0;
}

66
static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
        uint8_t *from, int offset, int height, int stride)
{
    int i;
    int width = height;
    int from_x = offset % WIDTH;
    int from_y = offset / WIDTH;
    int overflow = from_x + width - WIDTH;

    if (!from) {
        /* silently ignoring predictive blocks in first frame */
        return 0;
    }

    if (from_y + height > HEIGHT) {
        av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
               offset);
        return -1;
    }

    if (overflow > 0) {
        width -= overflow;
        for (i = 0; i < height; i++) {
            memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
        }
    }

    for (i = 0; i < height; i++) {
        memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
    }

    return 0;
}

100
static inline void draw_n_color(uint8_t *out, int stride, int width,
101 102 103 104 105 106 107 108 109 110 111 112 113 114 115
         int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
{
    int x, y;
    for (y = 0; y < height; y++) {
        if (grps)
            cols[0] = grps[3 * (y >> 1)];
        for (x = 0; x < width; x++) {
            if (grps)
                cols[1]= grps[(x >> 1) + 1];
            out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
            col >>= bpp;
        }
    }
}

116
static int decode_frame(AVCodecContext *avctx, void *data,
117 118 119 120 121 122 123
                            int *data_size, uint8_t * buf, int buf_size)
{
    C93DecoderContext * const c93 = avctx->priv_data;
    AVFrame * const newpic = &c93->pictures[c93->currentpic];
    AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
    AVFrame *picture = data;
    uint8_t *out;
Michael Niedermayer's avatar
Michael Niedermayer committed
124
    int stride, i, x, y, bt = 0;
125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162

    c93->currentpic ^= 1;

    newpic->reference = 1;
    newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
                         FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
    if (avctx->reget_buffer(avctx, newpic)) {
        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
        return -1;
    }

    stride = newpic->linesize[0];

    if (buf[0] & C93_FIRST_FRAME) {
        newpic->pict_type = FF_I_TYPE;
        newpic->key_frame = 1;
    } else {
        newpic->pict_type = FF_P_TYPE;
        newpic->key_frame = 0;
    }

    if (*buf++ & C93_HAS_PALETTE) {
        uint32_t *palette = (uint32_t *) newpic->data[1];
        uint8_t *palbuf = buf + buf_size - 768 - 1;
        for (i = 0; i < 256; i++) {
            palette[i] = bytestream_get_be24(&palbuf);
        }
    } else {
        if (oldpic->data[1])
            memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
    }

    for (y = 0; y < HEIGHT; y += 8) {
        out = newpic->data[0] + y * stride;
        for (x = 0; x < WIDTH; x += 8) {
            uint8_t *copy_from = oldpic->data[0];
            unsigned int offset, j;
            uint8_t cols[4], grps[4];
Michael Niedermayer's avatar
Michael Niedermayer committed
163
            C93BlockType block_type;
164 165 166 167

            if (!bt)
                bt = *buf++;

Michael Niedermayer's avatar
Michael Niedermayer committed
168 169
            block_type= bt & 0x0F;
            switch (block_type) {
170 171
            case C93_8X8_FROM_PREV:
                offset = bytestream_get_le16(&buf);
172
                if (copy_block(avctx, out, copy_from, offset, 8, stride))
173 174 175 176 177 178 179 180 181
                    return -1;
                break;

            case C93_4X4_FROM_CURR:
                copy_from = newpic->data[0];
            case C93_4X4_FROM_PREV:
                for (j = 0; j < 8; j += 4) {
                    for (i = 0; i < 8; i += 4) {
                        offset = bytestream_get_le16(&buf);
182
                        if (copy_block(avctx, &out[j*stride+i],
183 184 185 186 187 188 189 190 191
                                           copy_from, offset, 4, stride))
                            return -1;
                    }
                }
                break;

            case C93_8X8_2COLOR:
                bytestream_get_buffer(&buf, cols, 2);
                for (i = 0; i < 8; i++) {
192
                    draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
193 194 195 196 197 198 199 200 201 202
                                     NULL, *buf++);
                }

                break;

            case C93_4X4_2COLOR:
            case C93_4X4_4COLOR:
            case C93_4X4_4COLOR_GRP:
                for (j = 0; j < 8; j += 4) {
                    for (i = 0; i < 8; i += 4) {
Michael Niedermayer's avatar
Michael Niedermayer committed
203
                        if (block_type == C93_4X4_2COLOR) {
204
                            bytestream_get_buffer(&buf, cols, 2);
205
                            draw_n_color(out + i + j*stride, stride, 4, 4,
206
                                    1, cols, NULL, bytestream_get_le16(&buf));
Michael Niedermayer's avatar
Michael Niedermayer committed
207
                        } else if (block_type == C93_4X4_4COLOR) {
208
                            bytestream_get_buffer(&buf, cols, 4);
209
                            draw_n_color(out + i + j*stride, stride, 4, 4,
210 211 212
                                    2, cols, NULL, bytestream_get_le32(&buf));
                        } else {
                            bytestream_get_buffer(&buf, grps, 4);
213
                            draw_n_color(out + i + j*stride, stride, 4, 4,
214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229
                                    1, cols, grps, bytestream_get_le16(&buf));
                        }
                    }
                }
                break;

            case C93_NOOP:
                break;

            case C93_8X8_INTRA:
                for (j = 0; j < 8; j++)
                    bytestream_get_buffer(&buf, out + j*stride, 8);
                break;

            default:
                av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
Michael Niedermayer's avatar
Michael Niedermayer committed
230
                       block_type, x, y);
231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248
                return -1;
            }
            bt >>= 4;
            out += 8;
        }
    }

    *picture = *newpic;
    *data_size = sizeof(AVFrame);

    return buf_size;
}

AVCodec c93_decoder = {
    "c93",
    CODEC_TYPE_VIDEO,
    CODEC_ID_C93,
    sizeof(C93DecoderContext),
249
    decode_init,
250
    NULL,
251 252
    decode_end,
    decode_frame,
253 254
    CODEC_CAP_DR1,
};