Libav
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00001 /* 00002 * Kega Game Video (KGV1) decoder 00003 * Copyright (c) 2010 Daniel Verkamp 00004 * 00005 * This file is part of FFmpeg. 00006 * 00007 * FFmpeg is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * FFmpeg is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with FFmpeg; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00027 #include "libavutil/intreadwrite.h" 00028 #include "avcodec.h" 00029 00030 typedef struct { 00031 AVCodecContext *avctx; 00032 AVFrame pic; 00033 uint16_t *prev, *cur; 00034 } KgvContext; 00035 00036 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) 00037 { 00038 const uint8_t *buf = avpkt->data; 00039 const uint8_t *buf_end = buf + avpkt->size; 00040 KgvContext * const c = avctx->priv_data; 00041 int offsets[7]; 00042 uint16_t *out, *prev; 00043 int outcnt = 0, maxcnt; 00044 int w, h, i; 00045 00046 if (avpkt->size < 2) 00047 return -1; 00048 00049 w = (buf[0] + 1) * 8; 00050 h = (buf[1] + 1) * 8; 00051 buf += 2; 00052 00053 if (avcodec_check_dimensions(avctx, w, h)) 00054 return -1; 00055 00056 if (w != avctx->width || h != avctx->height) 00057 avcodec_set_dimensions(avctx, w, h); 00058 00059 maxcnt = w * h; 00060 00061 out = av_realloc(c->cur, w * h * 2); 00062 if (!out) 00063 return -1; 00064 c->cur = out; 00065 00066 prev = av_realloc(c->prev, w * h * 2); 00067 if (!prev) 00068 return -1; 00069 c->prev = prev; 00070 00071 for (i = 0; i < 7; i++) 00072 offsets[i] = -1; 00073 00074 while (outcnt < maxcnt && buf_end - 2 > buf) { 00075 int code = AV_RL16(buf); 00076 buf += 2; 00077 00078 if (!(code & 0x8000)) { 00079 out[outcnt++] = code; // rgb555 pixel coded directly 00080 } else { 00081 int count; 00082 uint16_t *inp; 00083 00084 if ((code & 0x6000) == 0x6000) { 00085 // copy from previous frame 00086 int oidx = (code >> 10) & 7; 00087 int start; 00088 00089 count = (code & 0x3FF) + 3; 00090 00091 if (offsets[oidx] < 0) { 00092 if (buf_end - 3 < buf) 00093 break; 00094 offsets[oidx] = AV_RL24(buf); 00095 buf += 3; 00096 } 00097 00098 start = (outcnt + offsets[oidx]) % maxcnt; 00099 00100 if (maxcnt - start < count) 00101 break; 00102 00103 inp = prev + start; 00104 } else { 00105 // copy from earlier in this frame 00106 int offset = (code & 0x1FFF) + 1; 00107 00108 if (!(code & 0x6000)) { 00109 count = 2; 00110 } else if ((code & 0x6000) == 0x2000) { 00111 count = 3; 00112 } else { 00113 if (buf_end - 1 < buf) 00114 break; 00115 count = 4 + *buf++; 00116 } 00117 00118 if (outcnt < offset) 00119 break; 00120 00121 inp = out + outcnt - offset; 00122 } 00123 00124 if (maxcnt - outcnt < count) 00125 break; 00126 00127 for (i = 0; i < count; i++) 00128 out[outcnt++] = inp[i]; 00129 } 00130 } 00131 00132 if (outcnt - maxcnt) 00133 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); 00134 00135 c->pic.data[0] = (uint8_t *)c->cur; 00136 c->pic.linesize[0] = w * 2; 00137 00138 *data_size = sizeof(AVFrame); 00139 *(AVFrame*)data = c->pic; 00140 00141 FFSWAP(uint16_t *, c->cur, c->prev); 00142 00143 return avpkt->size; 00144 } 00145 00146 static av_cold int decode_init(AVCodecContext *avctx) 00147 { 00148 KgvContext * const c = avctx->priv_data; 00149 00150 c->avctx = avctx; 00151 avctx->pix_fmt = PIX_FMT_RGB555; 00152 00153 return 0; 00154 } 00155 00156 static av_cold int decode_end(AVCodecContext *avctx) 00157 { 00158 KgvContext * const c = avctx->priv_data; 00159 00160 av_freep(&c->cur); 00161 av_freep(&c->prev); 00162 00163 return 0; 00164 } 00165 00166 AVCodec kgv1_decoder = { 00167 "kgv1", 00168 AVMEDIA_TYPE_VIDEO, 00169 CODEC_ID_KGV1, 00170 sizeof(KgvContext), 00171 decode_init, 00172 NULL, 00173 decode_end, 00174 decode_frame, 00175 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"), 00176 };