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| 1 | +/* |
| 2 | + * Kega Game Video (KGV1) decoder |
| 3 | + * Copyright (c) 2010 Daniel Verkamp |
| 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 | +/** |
| 23 | + * @file libavcodec/kgv1dec.c |
| 24 | + * Kega Game Video decoder |
| 25 | + */ |
| 26 | + |
| 27 | +#include "libavutil/intreadwrite.h" |
| 28 | +#include "avcodec.h" |
| 29 | + |
| 30 | +typedef struct { |
| 31 | + AVCodecContext *avctx; |
| 32 | + AVFrame pic; |
| 33 | + uint16_t *prev, *cur; |
| 34 | +} KgvContext; |
| 35 | + |
| 36 | +static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) |
| 37 | +{ |
| 38 | + const uint8_t *buf = avpkt->data; |
| 39 | + const uint8_t *buf_end = buf + avpkt->size; |
| 40 | + KgvContext * const c = avctx->priv_data; |
| 41 | + int offsets[7]; |
| 42 | + uint16_t *out, *prev; |
| 43 | + int outcnt = 0, maxcnt; |
| 44 | + int w, h, i; |
| 45 | + |
| 46 | + if (avpkt->size < 2) |
| 47 | + return -1; |
| 48 | + |
| 49 | + w = (buf[0] + 1) * 8; |
| 50 | + h = (buf[1] + 1) * 8; |
| 51 | + buf += 2; |
| 52 | + |
| 53 | + if (avcodec_check_dimensions(avctx, w, h)) |
| 54 | + return -1; |
| 55 | + |
| 56 | + if (w != avctx->width || h != avctx->height) |
| 57 | + avcodec_set_dimensions(avctx, w, h); |
| 58 | + |
| 59 | + maxcnt = w * h; |
| 60 | + |
| 61 | + out = av_realloc(c->cur, w * h * 2); |
| 62 | + if (!out) |
| 63 | + return -1; |
| 64 | + c->cur = out; |
| 65 | + |
| 66 | + prev = av_realloc(c->prev, w * h * 2); |
| 67 | + if (!prev) |
| 68 | + return -1; |
| 69 | + c->prev = prev; |
| 70 | + |
| 71 | + for (i = 0; i < 7; i++) |
| 72 | + offsets[i] = -1; |
| 73 | + |
| 74 | + while (outcnt < maxcnt && buf_end - 2 > buf) { |
| 75 | + int code = AV_RL16(buf); |
| 76 | + buf += 2; |
| 77 | + |
| 78 | + if (!(code & 0x8000)) { |
| 79 | + out[outcnt++] = code; // rgb555 pixel coded directly |
| 80 | + } else { |
| 81 | + int count; |
| 82 | + uint16_t *inp; |
| 83 | + |
| 84 | + if ((code & 0x6000) == 0x6000) { |
| 85 | + // copy from previous frame |
| 86 | + int oidx = (code >> 10) & 7; |
| 87 | + int start; |
| 88 | + |
| 89 | + count = (code & 0x3FF) + 3; |
| 90 | + |
| 91 | + if (offsets[oidx] < 0) { |
| 92 | + if (buf_end - 3 < buf) |
| 93 | + break; |
| 94 | + offsets[oidx] = AV_RL24(buf); |
| 95 | + buf += 3; |
| 96 | + } |
| 97 | + |
| 98 | + start = (outcnt + offsets[oidx]) % maxcnt; |
| 99 | + |
| 100 | + if (maxcnt - start < count) |
| 101 | + break; |
| 102 | + |
| 103 | + inp = prev + start; |
| 104 | + } else { |
| 105 | + // copy from earlier in this frame |
| 106 | + int offset = (code & 0x1FFF) + 1; |
| 107 | + |
| 108 | + if (!(code & 0x6000)) { |
| 109 | + count = 2; |
| 110 | + } else if ((code & 0x6000) == 0x2000) { |
| 111 | + count = 3; |
| 112 | + } else { |
| 113 | + if (buf_end - 1 < buf) |
| 114 | + break; |
| 115 | + count = 4 + *buf++; |
| 116 | + } |
| 117 | + |
| 118 | + if (outcnt < offset) |
| 119 | + break; |
| 120 | + |
| 121 | + inp = out + outcnt - offset; |
| 122 | + } |
| 123 | + |
| 124 | + if (maxcnt - outcnt < count) |
| 125 | + break; |
| 126 | + |
| 127 | + for (i = 0; i < count; i++) |
| 128 | + out[outcnt++] = inp[i]; |
| 129 | + } |
| 130 | + } |
| 131 | + |
| 132 | + if (outcnt - maxcnt) |
| 133 | + av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); |
| 134 | + |
| 135 | + c->pic.data[0] = (uint8_t *)c->cur; |
| 136 | + c->pic.linesize[0] = w * 2; |
| 137 | + |
| 138 | + *data_size = sizeof(AVFrame); |
| 139 | + *(AVFrame*)data = c->pic; |
| 140 | + |
| 141 | + FFSWAP(uint16_t *, c->cur, c->prev); |
| 142 | + |
| 143 | + return avpkt->size; |
| 144 | +} |
| 145 | + |
| 146 | +static av_cold int decode_init(AVCodecContext *avctx) |
| 147 | +{ |
| 148 | + KgvContext * const c = avctx->priv_data; |
| 149 | + |
| 150 | + c->avctx = avctx; |
| 151 | + avctx->pix_fmt = PIX_FMT_RGB555; |
| 152 | + |
| 153 | + return 0; |
| 154 | +} |
| 155 | + |
| 156 | +static av_cold int decode_end(AVCodecContext *avctx) |
| 157 | +{ |
| 158 | + KgvContext * const c = avctx->priv_data; |
| 159 | + |
| 160 | + av_freep(&c->cur); |
| 161 | + av_freep(&c->prev); |
| 162 | + |
| 163 | + return 0; |
| 164 | +} |
| 165 | + |
| 166 | +AVCodec kgv1_decoder = { |
| 167 | + "kgv1", |
| 168 | + CODEC_TYPE_VIDEO, |
| 169 | + CODEC_ID_KGV1, |
| 170 | + sizeof(KgvContext), |
| 171 | + decode_init, |
| 172 | + NULL, |
| 173 | + decode_end, |
| 174 | + decode_frame, |
| 175 | + .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"), |
| 176 | +}; |