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libavcodec/mdec.c

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00001 /*
00002  * Sony PlayStation MDEC (Motion DECoder)
00003  * Copyright (c) 2003 Michael Niedermayer
00004  *
00005  * based upon code from Sebastian Jedruszkiewicz <elf@frogger.rules.pl>
00006  *
00007  * This file is part of FFmpeg.
00008  *
00009  * FFmpeg is free software; you can redistribute it and/or
00010  * modify it under the terms of the GNU Lesser General Public
00011  * License as published by the Free Software Foundation; either
00012  * version 2.1 of the License, or (at your option) any later version.
00013  *
00014  * FFmpeg is distributed in the hope that it will be useful,
00015  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00016  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017  * Lesser General Public License for more details.
00018  *
00019  * You should have received a copy of the GNU Lesser General Public
00020  * License along with FFmpeg; if not, write to the Free Software
00021  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00022  */
00023 
00030 #include "avcodec.h"
00031 #include "dsputil.h"
00032 #include "mpegvideo.h"
00033 #include "mpeg12.h"
00034 
00035 typedef struct MDECContext{
00036     AVCodecContext *avctx;
00037     DSPContext dsp;
00038     AVFrame picture;
00039     GetBitContext gb;
00040     ScanTable scantable;
00041     int version;
00042     int qscale;
00043     int last_dc[3];
00044     int mb_width;
00045     int mb_height;
00046     int mb_x, mb_y;
00047     DECLARE_ALIGNED(16, DCTELEM, block)[6][64];
00048     uint8_t *bitstream_buffer;
00049     unsigned int bitstream_buffer_size;
00050     int block_last_index[6];
00051 } MDECContext;
00052 
00053 //very similar to MPEG-1
00054 static inline int mdec_decode_block_intra(MDECContext *a, DCTELEM *block, int n)
00055 {
00056     int level, diff, i, j, run;
00057     int component;
00058     RLTable *rl = &ff_rl_mpeg1;
00059     uint8_t * const scantable= a->scantable.permutated;
00060     const uint16_t *quant_matrix= ff_mpeg1_default_intra_matrix;
00061     const int qscale= a->qscale;
00062 
00063     /* DC coefficient */
00064     if(a->version==2){
00065         block[0]= 2*get_sbits(&a->gb, 10) + 1024;
00066     }else{
00067         component = (n <= 3 ? 0 : n - 4 + 1);
00068         diff = decode_dc(&a->gb, component);
00069         if (diff >= 0xffff)
00070             return -1;
00071         a->last_dc[component]+= diff;
00072         block[0] = a->last_dc[component]<<3;
00073     }
00074 
00075     i = 0;
00076     {
00077         OPEN_READER(re, &a->gb);
00078         /* now quantify & encode AC coefficients */
00079         for(;;) {
00080             UPDATE_CACHE(re, &a->gb);
00081             GET_RL_VLC(level, run, re, &a->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
00082 
00083             if(level == 127){
00084                 break;
00085             } else if(level != 0) {
00086                 i += run;
00087                 j = scantable[i];
00088                 level= (level*qscale*quant_matrix[j])>>3;
00089                 level = (level ^ SHOW_SBITS(re, &a->gb, 1)) - SHOW_SBITS(re, &a->gb, 1);
00090                 LAST_SKIP_BITS(re, &a->gb, 1);
00091             } else {
00092                 /* escape */
00093                 run = SHOW_UBITS(re, &a->gb, 6)+1; LAST_SKIP_BITS(re, &a->gb, 6);
00094                 UPDATE_CACHE(re, &a->gb);
00095                 level = SHOW_SBITS(re, &a->gb, 10); SKIP_BITS(re, &a->gb, 10);
00096                 i += run;
00097                 j = scantable[i];
00098                 if(level<0){
00099                     level= -level;
00100                     level= (level*qscale*quant_matrix[j])>>3;
00101                     level= (level-1)|1;
00102                     level= -level;
00103                 }else{
00104                     level= (level*qscale*quant_matrix[j])>>3;
00105                     level= (level-1)|1;
00106                 }
00107             }
00108             if (i > 63){
00109                 av_log(a->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", a->mb_x, a->mb_y);
00110                 return -1;
00111             }
00112 
00113             block[j] = level;
00114         }
00115         CLOSE_READER(re, &a->gb);
00116     }
00117     a->block_last_index[n] = i;
00118     return 0;
00119 }
00120 
00121 static inline int decode_mb(MDECContext *a, DCTELEM block[6][64]){
00122     int i;
00123     const int block_index[6]= {5,4,0,1,2,3};
00124 
00125     a->dsp.clear_blocks(block[0]);
00126 
00127     for(i=0; i<6; i++){
00128         if( mdec_decode_block_intra(a, block[ block_index[i] ], block_index[i]) < 0)
00129             return -1;
00130     }
00131     return 0;
00132 }
00133 
00134 static inline void idct_put(MDECContext *a, int mb_x, int mb_y){
00135     DCTELEM (*block)[64]= a->block;
00136     int linesize= a->picture.linesize[0];
00137 
00138     uint8_t *dest_y  = a->picture.data[0] + (mb_y * 16* linesize              ) + mb_x * 16;
00139     uint8_t *dest_cb = a->picture.data[1] + (mb_y * 8 * a->picture.linesize[1]) + mb_x * 8;
00140     uint8_t *dest_cr = a->picture.data[2] + (mb_y * 8 * a->picture.linesize[2]) + mb_x * 8;
00141 
00142     a->dsp.idct_put(dest_y                 , linesize, block[0]);
00143     a->dsp.idct_put(dest_y              + 8, linesize, block[1]);
00144     a->dsp.idct_put(dest_y + 8*linesize    , linesize, block[2]);
00145     a->dsp.idct_put(dest_y + 8*linesize + 8, linesize, block[3]);
00146 
00147     if(!(a->avctx->flags&CODEC_FLAG_GRAY)){
00148         a->dsp.idct_put(dest_cb, a->picture.linesize[1], block[4]);
00149         a->dsp.idct_put(dest_cr, a->picture.linesize[2], block[5]);
00150     }
00151 }
00152 
00153 static int decode_frame(AVCodecContext *avctx,
00154                         void *data, int *data_size,
00155                         AVPacket *avpkt)
00156 {
00157     const uint8_t *buf = avpkt->data;
00158     int buf_size = avpkt->size;
00159     MDECContext * const a = avctx->priv_data;
00160     AVFrame *picture = data;
00161     AVFrame * const p= &a->picture;
00162     int i;
00163 
00164     if(p->data[0])
00165         avctx->release_buffer(avctx, p);
00166 
00167     p->reference= 0;
00168     if(avctx->get_buffer(avctx, p) < 0){
00169         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00170         return -1;
00171     }
00172     p->pict_type= FF_I_TYPE;
00173     p->key_frame= 1;
00174 
00175     av_fast_malloc(&a->bitstream_buffer, &a->bitstream_buffer_size, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
00176     if (!a->bitstream_buffer)
00177         return AVERROR(ENOMEM);
00178     for(i=0; i<buf_size; i+=2){
00179         a->bitstream_buffer[i]  = buf[i+1];
00180         a->bitstream_buffer[i+1]= buf[i  ];
00181     }
00182     init_get_bits(&a->gb, a->bitstream_buffer, buf_size*8);
00183 
00184     /* skip over 4 preamble bytes in stream (typically 0xXX 0xXX 0x00 0x38) */
00185     skip_bits(&a->gb, 32);
00186 
00187     a->qscale=  get_bits(&a->gb, 16);
00188     a->version= get_bits(&a->gb, 16);
00189 
00190     a->last_dc[0]=
00191     a->last_dc[1]=
00192     a->last_dc[2]= 128;
00193 
00194     for(a->mb_x=0; a->mb_x<a->mb_width; a->mb_x++){
00195         for(a->mb_y=0; a->mb_y<a->mb_height; a->mb_y++){
00196             if( decode_mb(a, a->block) <0)
00197                 return -1;
00198 
00199             idct_put(a, a->mb_x, a->mb_y);
00200         }
00201     }
00202 
00203     p->quality= a->qscale * FF_QP2LAMBDA;
00204     memset(p->qscale_table, a->qscale, a->mb_width);
00205 
00206     *picture   = a->picture;
00207     *data_size = sizeof(AVPicture);
00208 
00209     return (get_bits_count(&a->gb)+31)/32*4;
00210 }
00211 
00212 static av_cold void mdec_common_init(AVCodecContext *avctx){
00213     MDECContext * const a = avctx->priv_data;
00214 
00215     dsputil_init(&a->dsp, avctx);
00216 
00217     a->mb_width   = (avctx->coded_width  + 15) / 16;
00218     a->mb_height  = (avctx->coded_height + 15) / 16;
00219 
00220     avctx->coded_frame= &a->picture;
00221     a->avctx= avctx;
00222 }
00223 
00224 static av_cold int decode_init(AVCodecContext *avctx){
00225     MDECContext * const a = avctx->priv_data;
00226     AVFrame *p= &a->picture;
00227 
00228     mdec_common_init(avctx);
00229     ff_mpeg12_init_vlcs();
00230     ff_init_scantable(a->dsp.idct_permutation, &a->scantable, ff_zigzag_direct);
00231 
00232     p->qstride= 0;
00233     p->qscale_table= av_mallocz(a->mb_width);
00234     avctx->pix_fmt= PIX_FMT_YUV420P;
00235 
00236     return 0;
00237 }
00238 
00239 static av_cold int decode_end(AVCodecContext *avctx){
00240     MDECContext * const a = avctx->priv_data;
00241 
00242     if(a->picture.data[0])
00243         avctx->release_buffer(avctx, &a->picture);
00244     av_freep(&a->bitstream_buffer);
00245     av_freep(&a->picture.qscale_table);
00246     a->bitstream_buffer_size=0;
00247 
00248     return 0;
00249 }
00250 
00251 AVCodec mdec_decoder = {
00252     "mdec",
00253     AVMEDIA_TYPE_VIDEO,
00254     CODEC_ID_MDEC,
00255     sizeof(MDECContext),
00256     decode_init,
00257     NULL,
00258     decode_end,
00259     decode_frame,
00260     CODEC_CAP_DR1,
00261     .long_name= NULL_IF_CONFIG_SMALL("Sony PlayStation MDEC (Motion DECoder)"),
00262 };
00263 

Generated on Fri Sep 16 2011 17:17:39 for FFmpeg by  doxygen 1.7.1