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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
  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.  
  33. typedef struct KgvContext {
  34.     uint16_t *frame_buffer;
  35.     uint16_t *last_frame_buffer;
  36. } KgvContext;
  37.  
  38. static 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.  
  46. static 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.  
  163. static av_cold int decode_init(AVCodecContext *avctx)
  164. {
  165.     avctx->pix_fmt = AV_PIX_FMT_RGB555;
  166.  
  167.     return 0;
  168. }
  169.  
  170. static av_cold int decode_end(AVCodecContext *avctx)
  171. {
  172.     decode_flush(avctx);
  173.     return 0;
  174. }
  175.  
  176. AVCodec 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   = AV_CODEC_CAP_DR1,
  187. };
  188.