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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 | }; |