Libav 0.7.1
libavcodec/wnv1.c
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00001 /*
00002  * Winnov WNV1 codec
00003  * Copyright (c) 2005 Konstantin Shishkov
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 "avcodec.h"
00028 #include "get_bits.h"
00029 #include "libavutil/common.h"
00030 
00031 
00032 typedef struct WNV1Context{
00033     AVCodecContext *avctx;
00034     AVFrame pic;
00035 
00036     int shift;
00037     GetBitContext gb;
00038 } WNV1Context;
00039 
00040 static const uint16_t code_tab[16][2]={
00041 {0x1FD,9}, {0xFD,8}, {0x7D,7}, {0x3D,6}, {0x1D,5}, {0x0D,4}, {0x005,3},
00042 {0x000,1},
00043 {0x004,3}, {0x0C,4}, {0x1C,5}, {0x3C,6}, {0x7C,7}, {0xFC,8}, {0x1FC,9}, {0xFF,8}
00044 };
00045 
00046 #define CODE_VLC_BITS 9
00047 static VLC code_vlc;
00048 
00049 /* returns modified base_value */
00050 static inline int wnv1_get_code(WNV1Context *w, int base_value)
00051 {
00052     int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);
00053 
00054     if(v==15)
00055         return av_reverse[ get_bits(&w->gb, 8 - w->shift) ];
00056     else
00057         return base_value + ((v - 7)<<w->shift);
00058 }
00059 
00060 static int decode_frame(AVCodecContext *avctx,
00061                         void *data, int *data_size,
00062                         AVPacket *avpkt)
00063 {
00064     const uint8_t *buf = avpkt->data;
00065     int buf_size = avpkt->size;
00066     WNV1Context * const l = avctx->priv_data;
00067     AVFrame * const p= (AVFrame*)&l->pic;
00068     unsigned char *Y,*U,*V;
00069     int i, j;
00070     int prev_y = 0, prev_u = 0, prev_v = 0;
00071     uint8_t *rbuf;
00072 
00073     rbuf = av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
00074     if(!rbuf){
00075         av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");
00076         return -1;
00077     }
00078 
00079     if(p->data[0])
00080         avctx->release_buffer(avctx, p);
00081 
00082     p->reference = 0;
00083     if(avctx->get_buffer(avctx, p) < 0){
00084         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00085         av_free(rbuf);
00086         return -1;
00087     }
00088     p->key_frame = 1;
00089 
00090     for(i=8; i<buf_size; i++)
00091         rbuf[i]= av_reverse[ buf[i] ];
00092     init_get_bits(&l->gb, rbuf+8, (buf_size-8)*8);
00093 
00094     if (buf[2] >> 4 == 6)
00095         l->shift = 2;
00096     else {
00097         l->shift = 8 - (buf[2] >> 4);
00098         if (l->shift > 4) {
00099             av_log_ask_for_sample(avctx, "Unknown WNV1 frame header value %i\n",
00100                                   buf[2] >> 4);
00101             l->shift = 4;
00102         }
00103         if (l->shift < 1) {
00104             av_log_ask_for_sample(avctx, "Unknown WNV1 frame header value %i\n",
00105                                   buf[2] >> 4);
00106             l->shift = 1;
00107         }
00108     }
00109 
00110     Y = p->data[0];
00111     U = p->data[1];
00112     V = p->data[2];
00113     for (j = 0; j < avctx->height; j++) {
00114         for (i = 0; i < avctx->width / 2; i++) {
00115             Y[i * 2] = wnv1_get_code(l, prev_y);
00116             prev_u = U[i] = wnv1_get_code(l, prev_u);
00117             prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
00118             prev_v = V[i] = wnv1_get_code(l, prev_v);
00119         }
00120         Y += p->linesize[0];
00121         U += p->linesize[1];
00122         V += p->linesize[2];
00123     }
00124 
00125 
00126     *data_size = sizeof(AVFrame);
00127     *(AVFrame*)data = l->pic;
00128     av_free(rbuf);
00129 
00130     return buf_size;
00131 }
00132 
00133 static av_cold int decode_init(AVCodecContext *avctx){
00134     WNV1Context * const l = avctx->priv_data;
00135     static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];
00136 
00137     l->avctx = avctx;
00138     avctx->pix_fmt = PIX_FMT_YUV422P;
00139 
00140     code_vlc.table = code_table;
00141     code_vlc.table_allocated = 1 << CODE_VLC_BITS;
00142     init_vlc(&code_vlc, CODE_VLC_BITS, 16,
00143              &code_tab[0][1], 4, 2,
00144              &code_tab[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);
00145 
00146     return 0;
00147 }
00148 
00149 static av_cold int decode_end(AVCodecContext *avctx){
00150     WNV1Context * const l = avctx->priv_data;
00151     AVFrame *pic = &l->pic;
00152 
00153     if (pic->data[0])
00154         avctx->release_buffer(avctx, pic);
00155 
00156     return 0;
00157 }
00158 
00159 AVCodec ff_wnv1_decoder = {
00160     "wnv1",
00161     AVMEDIA_TYPE_VIDEO,
00162     CODEC_ID_WNV1,
00163     sizeof(WNV1Context),
00164     decode_init,
00165     NULL,
00166     decode_end,
00167     decode_frame,
00168     CODEC_CAP_DR1,
00169     .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
00170 };