Libav 0.7.1
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00001 /* 00002 * Kega Game Video (KGV1) decoder 00003 * Copyright (c) 2010 Daniel Verkamp 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav 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 * Libav 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 Libav; 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 "libavutil/imgutils.h" 00029 #include "avcodec.h" 00030 00031 typedef struct { 00032 AVCodecContext *avctx; 00033 AVFrame prev, cur; 00034 } KgvContext; 00035 00036 static void decode_flush(AVCodecContext *avctx) 00037 { 00038 KgvContext * const c = avctx->priv_data; 00039 00040 if (c->prev.data[0]) 00041 avctx->release_buffer(avctx, &c->prev); 00042 } 00043 00044 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) 00045 { 00046 const uint8_t *buf = avpkt->data; 00047 const uint8_t *buf_end = buf + avpkt->size; 00048 KgvContext * const c = avctx->priv_data; 00049 int offsets[8]; 00050 uint16_t *out, *prev; 00051 int outcnt = 0, maxcnt; 00052 int w, h, i, res; 00053 00054 if (avpkt->size < 2) 00055 return -1; 00056 00057 w = (buf[0] + 1) * 8; 00058 h = (buf[1] + 1) * 8; 00059 buf += 2; 00060 00061 if (av_image_check_size(w, h, 0, avctx)) 00062 return -1; 00063 00064 if (w != avctx->width || h != avctx->height) { 00065 if (c->prev.data[0]) 00066 avctx->release_buffer(avctx, &c->prev); 00067 avcodec_set_dimensions(avctx, w, h); 00068 } 00069 00070 maxcnt = w * h; 00071 00072 c->cur.reference = 3; 00073 if ((res = avctx->get_buffer(avctx, &c->cur)) < 0) 00074 return res; 00075 out = (uint16_t *) c->cur.data[0]; 00076 if (c->prev.data[0]) { 00077 prev = (uint16_t *) c->prev.data[0]; 00078 } else { 00079 prev = NULL; 00080 } 00081 00082 for (i = 0; i < 8; i++) 00083 offsets[i] = -1; 00084 00085 while (outcnt < maxcnt && buf_end - 2 > buf) { 00086 int code = AV_RL16(buf); 00087 buf += 2; 00088 00089 if (!(code & 0x8000)) { 00090 out[outcnt++] = code; // rgb555 pixel coded directly 00091 } else { 00092 int count; 00093 int inp_off; 00094 uint16_t *inp; 00095 00096 if ((code & 0x6000) == 0x6000) { 00097 // copy from previous frame 00098 int oidx = (code >> 10) & 7; 00099 int start; 00100 00101 count = (code & 0x3FF) + 3; 00102 00103 if (offsets[oidx] < 0) { 00104 if (buf_end - 3 < buf) 00105 break; 00106 offsets[oidx] = AV_RL24(buf); 00107 buf += 3; 00108 } 00109 00110 start = (outcnt + offsets[oidx]) % maxcnt; 00111 00112 if (maxcnt - start < count) 00113 break; 00114 00115 if (!prev) { 00116 av_log(avctx, AV_LOG_ERROR, 00117 "Frame reference does not exist\n"); 00118 break; 00119 } 00120 00121 inp = prev; 00122 inp_off = start; 00123 } else { 00124 // copy from earlier in this frame 00125 int offset = (code & 0x1FFF) + 1; 00126 00127 if (!(code & 0x6000)) { 00128 count = 2; 00129 } else if ((code & 0x6000) == 0x2000) { 00130 count = 3; 00131 } else { 00132 if (buf_end - 1 < buf) 00133 break; 00134 count = 4 + *buf++; 00135 } 00136 00137 if (outcnt < offset) 00138 break; 00139 00140 inp = out; 00141 inp_off = outcnt - offset; 00142 } 00143 00144 if (maxcnt - outcnt < count) 00145 break; 00146 00147 for (i = inp_off; i < count + inp_off; i++) { 00148 out[outcnt++] = inp[i]; 00149 } 00150 } 00151 } 00152 00153 if (outcnt - maxcnt) 00154 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); 00155 00156 *data_size = sizeof(AVFrame); 00157 *(AVFrame*)data = c->cur; 00158 00159 if (c->prev.data[0]) 00160 avctx->release_buffer(avctx, &c->prev); 00161 FFSWAP(AVFrame, c->cur, c->prev); 00162 00163 return avpkt->size; 00164 } 00165 00166 static av_cold int decode_init(AVCodecContext *avctx) 00167 { 00168 KgvContext * const c = avctx->priv_data; 00169 00170 c->avctx = avctx; 00171 avctx->pix_fmt = PIX_FMT_RGB555; 00172 avctx->flags |= CODEC_FLAG_EMU_EDGE; 00173 00174 return 0; 00175 } 00176 00177 static av_cold int decode_end(AVCodecContext *avctx) 00178 { 00179 decode_flush(avctx); 00180 return 0; 00181 } 00182 00183 AVCodec ff_kgv1_decoder = { 00184 .name = "kgv1", 00185 .type = AVMEDIA_TYPE_VIDEO, 00186 .id = CODEC_ID_KGV1, 00187 .priv_data_size = sizeof(KgvContext), 00188 .init = decode_init, 00189 .close = decode_end, 00190 .decode = decode_frame, 00191 .flush = decode_flush, 00192 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"), 00193 };