libavcodec/wnv1.c

   1 /*
   2  * Winnov WNV1 codec
   3  * Copyright (c) 2005 Konstantin Shishkov
   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 wnv1.c
  24  * Winnov WNV1 codec.
  25  */
  26
  27 #include "avcodec.h"
  28 #include "bitstream.h"
  29
  30
  31 typedef struct WNV1Context{
  32     AVCodecContext *avctx;
  33     AVFrame pic;
  34
  35     int shift;
  36     GetBitContext gb;
  37 } WNV1Context;
  38
  39 static const uint16_t code_tab[16][2]={
  40 {0x1FD,9}, {0xFD,8}, {0x7D,7}, {0x3D,6}, {0x1D,5}, {0x0D,4}, {0x005,3},
  41 {0x000,1},
  42 {0x004,3}, {0x0C,4}, {0x1C,5}, {0x3C,6}, {0x7C,7}, {0xFC,8}, {0x1FC,9}, {0xFF,8}
  43 };
  44
  45 #define CODE_VLC_BITS 9
  46 static VLC code_vlc;
  47
  48 /* returns modified base_value */
  49 static inline int wnv1_get_code(WNV1Context *w, int base_value)
  50 {
  51     int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);
  52
  53     if(v==15)
  54         return ff_reverse[ get_bits(&w->gb, 8 - w->shift) ];
  55     else
  56         return base_value + ((v - 7)<<w->shift);
  57 }
  58
  59 static int decode_frame(AVCodecContext *avctx,
  60                         void *data, int *data_size,
  61                         uint8_t *buf, int buf_size)
  62 {
  63     WNV1Context * const l = avctx->priv_data;
  64     AVFrame * const p= (AVFrame*)&l->pic;
  65     unsigned char *Y,*U,*V;
  66     int i, j;
  67     int prev_y = 0, prev_u = 0, prev_v = 0;
  68
  69     if(p->data[0])
  70         avctx->release_buffer(avctx, p);
  71
  72     p->reference = 0;
  73     if(avctx->get_buffer(avctx, p) < 0){
  74         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  75         return -1;
  76     }
  77     p->key_frame = 1;
  78
  79     for(i=8; i<buf_size; i++)
  80         buf[i]= ff_reverse[ buf[i] ]; //FIXME ensure that the buffer is modifyable or use a temp one
  81     init_get_bits(&l->gb, buf+8, (buf_size-8)*8);
  82
  83     if (buf[2] >> 4 == 6)
  84         l->shift = 2;
  85     else {
  86         l->shift = 8 - (buf[2] >> 4);
  87         if (l->shift > 4) {
  88             av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
  89             l->shift = 4;
  90         }
  91         if (l->shift < 1) {
  92             av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
  93             l->shift = 1;
  94         }
  95     }
  96
  97     Y = p->data[0];
  98     U = p->data[1];
  99     V = p->data[2];
 100     for (j = 0; j < avctx->height; j++) {
 101         for (i = 0; i < avctx->width / 2; i++) {
 102             Y[i * 2] = wnv1_get_code(l, prev_y);
 103             prev_u = U[i] = wnv1_get_code(l, prev_u);
 104             prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
 105             prev_v = V[i] = wnv1_get_code(l, prev_v);
 106         }
 107         Y += p->linesize[0];
 108         U += p->linesize[1];
 109         V += p->linesize[2];
 110     }
 111
 112
 113     *data_size = sizeof(AVFrame);
 114     *(AVFrame*)data = l->pic;
 115
 116     return buf_size;
 117 }
 118
 119 static av_cold int decode_init(AVCodecContext *avctx){
 120     WNV1Context * const l = avctx->priv_data;
 121
 122     l->avctx = avctx;
 123     avctx->pix_fmt = PIX_FMT_YUV422P;
 124
 125     if(!code_vlc.table){
 126         init_vlc(&code_vlc, CODE_VLC_BITS, 16,
 127                     &code_tab[0][1], 4, 2,
 128                     &code_tab[0][0], 4, 2, 1);
 129     }
 130
 131     return 0;
 132 }
 133
 134 AVCodec wnv1_decoder = {
 135     "wnv1",
 136     CODEC_TYPE_VIDEO,
 137     CODEC_ID_WNV1,
 138     sizeof(WNV1Context),
 139     decode_init,
 140     NULL,
 141     NULL,
 142     decode_frame,
 143     CODEC_CAP_DR1,
 144     .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
 145 };