1/* 2 * Kega Game Video (KGV1) decoder 3 * Copyright (c) 2010 Daniel Verkamp 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/** 23 * @file 24 * Kega Game Video decoder 25 */ 26 27#include "libavutil/intreadwrite.h" 28#include "libavutil/imgutils.h" 29#include "avcodec.h" 30 31typedef struct { 32 AVCodecContext *avctx; 33 AVFrame prev, cur; 34} KgvContext; 35 36static void decode_flush(AVCodecContext *avctx) 37{ 38 KgvContext * const c = avctx->priv_data; 39 40 if (c->prev.data[0]) 41 avctx->release_buffer(avctx, &c->prev); 42} 43 44static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) 45{ 46 const uint8_t *buf = avpkt->data; 47 const uint8_t *buf_end = buf + avpkt->size; 48 KgvContext * const c = avctx->priv_data; 49 int offsets[8]; 50 uint16_t *out, *prev; 51 int outcnt = 0, maxcnt; 52 int w, h, i, res; 53 54 if (avpkt->size < 2) 55 return -1; 56 57 w = (buf[0] + 1) * 8; 58 h = (buf[1] + 1) * 8; 59 buf += 2; 60 61 if (av_image_check_size(w, h, 0, avctx)) 62 return -1; 63 64 if (w != avctx->width || h != avctx->height) { 65 if (c->prev.data[0]) 66 avctx->release_buffer(avctx, &c->prev); 67 avcodec_set_dimensions(avctx, w, h); 68 } 69 70 maxcnt = w * h; 71 72 c->cur.reference = 3; 73 if ((res = avctx->get_buffer(avctx, &c->cur)) < 0) 74 return res; 75 out = (uint16_t *) c->cur.data[0]; 76 if (c->prev.data[0]) { 77 prev = (uint16_t *) c->prev.data[0]; 78 } else { 79 prev = NULL; 80 } 81 82 for (i = 0; i < 8; i++) 83 offsets[i] = -1; 84 85 while (outcnt < maxcnt && buf_end - 2 > buf) { 86 int code = AV_RL16(buf); 87 buf += 2; 88 89 if (!(code & 0x8000)) { 90 out[outcnt++] = code; // rgb555 pixel coded directly 91 } else { 92 int count; 93 int inp_off; 94 uint16_t *inp; 95 96 if ((code & 0x6000) == 0x6000) { 97 // copy from previous frame 98 int oidx = (code >> 10) & 7; 99 int start; 100 101 count = (code & 0x3FF) + 3; 102 103 if (offsets[oidx] < 0) { 104 if (buf_end - 3 < buf) 105 break; 106 offsets[oidx] = AV_RL24(buf); 107 buf += 3; 108 } 109 110 start = (outcnt + offsets[oidx]) % maxcnt; 111 112 if (maxcnt - start < count) 113 break; 114 115 if (!prev) { 116 av_log(avctx, AV_LOG_ERROR, 117 "Frame reference does not exist\n"); 118 break; 119 } 120 121 inp = prev; 122 inp_off = start; 123 } else { 124 // copy from earlier in this frame 125 int offset = (code & 0x1FFF) + 1; 126 127 if (!(code & 0x6000)) { 128 count = 2; 129 } else if ((code & 0x6000) == 0x2000) { 130 count = 3; 131 } else { 132 if (buf_end - 1 < buf) 133 break; 134 count = 4 + *buf++; 135 } 136 137 if (outcnt < offset) 138 break; 139 140 inp = out; 141 inp_off = outcnt - offset; 142 } 143 144 if (maxcnt - outcnt < count) 145 break; 146 147 for (i = inp_off; i < count + inp_off; i++) { 148 out[outcnt++] = inp[i]; 149 } 150 } 151 } 152 153 if (outcnt - maxcnt) 154 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); 155 156 *data_size = sizeof(AVFrame); 157 *(AVFrame*)data = c->cur; 158 159 if (c->prev.data[0]) 160 avctx->release_buffer(avctx, &c->prev); 161 FFSWAP(AVFrame, c->cur, c->prev); 162 163 return avpkt->size; 164} 165 166static av_cold int decode_init(AVCodecContext *avctx) 167{ 168 KgvContext * const c = avctx->priv_data; 169 170 c->avctx = avctx; 171 avctx->pix_fmt = PIX_FMT_RGB555; 172 avctx->flags |= CODEC_FLAG_EMU_EDGE; 173 174 return 0; 175} 176 177static av_cold int decode_end(AVCodecContext *avctx) 178{ 179 decode_flush(avctx); 180 return 0; 181} 182 183AVCodec ff_kgv1_decoder = { 184 .name = "kgv1", 185 .type = AVMEDIA_TYPE_VIDEO, 186 .id = CODEC_ID_KGV1, 187 .priv_data_size = sizeof(KgvContext), 188 .init = decode_init, 189 .close = decode_end, 190 .decode = decode_frame, 191 .flush = decode_flush, 192 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"), 193}; 194