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 24 * Kega Game Video decoder 25 */ 26 27#include "libavutil/common.h" 28#include "libavutil/intreadwrite.h" 29#include "libavutil/imgutils.h" 30#include "avcodec.h" 31#include "internal.h" 32 33typedef struct { 34 uint16_t *frame_buffer; 35 uint16_t *last_frame_buffer; 36} KgvContext; 37 38static void decode_flush(AVCodecContext *avctx) 39{ 40 KgvContext * const c = avctx->priv_data; 41 42 av_freep(&c->frame_buffer); 43 av_freep(&c->last_frame_buffer); 44} 45 46static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, 47 AVPacket *avpkt) 48{ 49 AVFrame *frame = data; 50 const uint8_t *buf = avpkt->data; 51 const uint8_t *buf_end = buf + avpkt->size; 52 KgvContext * const c = avctx->priv_data; 53 int offsets[8]; 54 uint8_t *out, *prev; 55 int outcnt = 0, maxcnt; 56 int w, h, i, res; 57 58 if (avpkt->size < 2) 59 return AVERROR_INVALIDDATA; 60 61 w = (buf[0] + 1) * 8; 62 h = (buf[1] + 1) * 8; 63 buf += 2; 64 65 if (w != avctx->width || h != avctx->height) { 66 av_freep(&c->frame_buffer); 67 av_freep(&c->last_frame_buffer); 68 if ((res = ff_set_dimensions(avctx, w, h)) < 0) 69 return res; 70 } 71 72 if (!c->frame_buffer) { 73 c->frame_buffer = av_mallocz(avctx->width * avctx->height * 2); 74 c->last_frame_buffer = av_mallocz(avctx->width * avctx->height * 2); 75 if (!c->frame_buffer || !c->last_frame_buffer) { 76 decode_flush(avctx); 77 return AVERROR(ENOMEM); 78 } 79 } 80 81 maxcnt = w * h; 82 83 if ((res = ff_get_buffer(avctx, frame, 0)) < 0) 84 return res; 85 out = (uint8_t*)c->frame_buffer; 86 prev = (uint8_t*)c->last_frame_buffer; 87 88 for (i = 0; i < 8; i++) 89 offsets[i] = -1; 90 91 while (outcnt < maxcnt && buf_end - 2 >= buf) { 92 int code = AV_RL16(buf); 93 buf += 2; 94 95 if (!(code & 0x8000)) { 96 AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly 97 outcnt++; 98 } else { 99 int count; 100 101 if ((code & 0x6000) == 0x6000) { 102 // copy from previous frame 103 int oidx = (code >> 10) & 7; 104 int start; 105 106 count = (code & 0x3FF) + 3; 107 108 if (offsets[oidx] < 0) { 109 if (buf_end - 3 < buf) 110 break; 111 offsets[oidx] = AV_RL24(buf); 112 buf += 3; 113 } 114 115 start = (outcnt + offsets[oidx]) % maxcnt; 116 117 if (maxcnt - start < count || maxcnt - outcnt < count) 118 break; 119 120 if (!prev) { 121 av_log(avctx, AV_LOG_ERROR, 122 "Frame reference does not exist\n"); 123 break; 124 } 125 126 memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count); 127 } else { 128 // copy from earlier in this frame 129 int offset = (code & 0x1FFF) + 1; 130 131 if (!(code & 0x6000)) { 132 count = 2; 133 } else if ((code & 0x6000) == 0x2000) { 134 count = 3; 135 } else { 136 if (buf_end - 1 < buf) 137 break; 138 count = 4 + *buf++; 139 } 140 141 if (outcnt < offset || maxcnt - outcnt < count) 142 break; 143 144 av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count); 145 } 146 outcnt += count; 147 } 148 } 149 150 if (outcnt - maxcnt) 151 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); 152 153 av_image_copy_plane(frame->data[0], frame->linesize[0], 154 (const uint8_t*)c->frame_buffer, avctx->width * 2, 155 avctx->width * 2, avctx->height); 156 FFSWAP(uint16_t *, c->frame_buffer, c->last_frame_buffer); 157 158 *got_frame = 1; 159 160 return avpkt->size; 161} 162 163static av_cold int decode_init(AVCodecContext *avctx) 164{ 165 avctx->pix_fmt = AV_PIX_FMT_RGB555; 166 167 return 0; 168} 169 170static av_cold int decode_end(AVCodecContext *avctx) 171{ 172 decode_flush(avctx); 173 return 0; 174} 175 176AVCodec ff_kgv1_decoder = { 177 .name = "kgv1", 178 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"), 179 .type = AVMEDIA_TYPE_VIDEO, 180 .id = AV_CODEC_ID_KGV1, 181 .priv_data_size = sizeof(KgvContext), 182 .init = decode_init, 183 .close = decode_end, 184 .decode = decode_frame, 185 .flush = decode_flush, 186 .capabilities = CODEC_CAP_DR1, 187}; 188