Libav 0.7.1
libavcodec/eamad.c
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00001 /*
00002  * Electronic Arts Madcow Video Decoder
00003  * Copyright (c) 2007-2009 Peter Ross
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 St, Fifth Floor, Boston, MA  02110-1301  USA
00020  */
00021 
00031 #include "avcodec.h"
00032 #include "get_bits.h"
00033 #include "dsputil.h"
00034 #include "aandcttab.h"
00035 #include "mpeg12.h"
00036 #include "mpeg12data.h"
00037 #include "libavutil/imgutils.h"
00038 
00039 #define EA_PREAMBLE_SIZE    8
00040 #define MADk_TAG MKTAG('M', 'A', 'D', 'k')    /* MAD i-frame */
00041 #define MADm_TAG MKTAG('M', 'A', 'D', 'm')    /* MAD p-frame */
00042 #define MADe_TAG MKTAG('M', 'A', 'D', 'e')    /* MAD lqp-frame */
00043 
00044 typedef struct MadContext {
00045     MpegEncContext s;
00046     AVFrame frame;
00047     AVFrame last_frame;
00048     void *bitstream_buf;
00049     unsigned int bitstream_buf_size;
00050     DECLARE_ALIGNED(16, DCTELEM, block)[64];
00051 } MadContext;
00052 
00053 static void bswap16_buf(uint16_t *dst, const uint16_t *src, int count)
00054 {
00055     int i;
00056     for (i=0; i<count; i++)
00057         dst[i] = av_bswap16(src[i]);
00058 }
00059 
00060 static av_cold int decode_init(AVCodecContext *avctx)
00061 {
00062     MadContext *t = avctx->priv_data;
00063     MpegEncContext *s = &t->s;
00064     s->avctx = avctx;
00065     avctx->pix_fmt = PIX_FMT_YUV420P;
00066     if (avctx->idct_algo == FF_IDCT_AUTO)
00067         avctx->idct_algo = FF_IDCT_EA;
00068     dsputil_init(&s->dsp, avctx);
00069     ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);
00070     ff_mpeg12_init_vlcs();
00071     return 0;
00072 }
00073 
00074 static inline void comp(unsigned char *dst, int dst_stride,
00075                         unsigned char *src, int src_stride, int add)
00076 {
00077     int j, i;
00078     for (j=0; j<8; j++)
00079         for (i=0; i<8; i++)
00080             dst[j*dst_stride + i] = av_clip_uint8(src[j*src_stride + i] + add);
00081 }
00082 
00083 static inline void comp_block(MadContext *t, int mb_x, int mb_y,
00084                               int j, int mv_x, int mv_y, int add)
00085 {
00086     MpegEncContext *s = &t->s;
00087     if (j < 4) {
00088         comp(t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
00089              t->frame.linesize[0],
00090              t->last_frame.data[0] + (mb_y*16 + ((j&2)<<2) + mv_y)*t->last_frame.linesize[0] + mb_x*16 + ((j&1)<<3) + mv_x,
00091              t->last_frame.linesize[0], add);
00092     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
00093         int index = j - 3;
00094         comp(t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x * 8,
00095              t->frame.linesize[index],
00096              t->last_frame.data[index] + (mb_y * 8 + (mv_y/2))*t->last_frame.linesize[index] + mb_x * 8 + (mv_x/2),
00097              t->last_frame.linesize[index], add);
00098     }
00099 }
00100 
00101 static inline void idct_put(MadContext *t, DCTELEM *block, int mb_x, int mb_y, int j)
00102 {
00103     MpegEncContext *s = &t->s;
00104     if (j < 4) {
00105         s->dsp.idct_put(
00106             t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
00107             t->frame.linesize[0], block);
00108     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
00109         int index = j - 3;
00110         s->dsp.idct_put(
00111             t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x*8,
00112             t->frame.linesize[index], block);
00113     }
00114 }
00115 
00116 static inline void decode_block_intra(MadContext * t, DCTELEM * block)
00117 {
00118     MpegEncContext *s = &t->s;
00119     int level, i, j, run;
00120     RLTable *rl = &ff_rl_mpeg1;
00121     const uint8_t *scantable = s->intra_scantable.permutated;
00122     int16_t *quant_matrix = s->intra_matrix;
00123 
00124     block[0] = (128 + get_sbits(&s->gb, 8)) * quant_matrix[0];
00125 
00126     /* The RL decoder is derived from mpeg1_decode_block_intra;
00127        Escaped level and run values a decoded differently */
00128     i = 0;
00129     {
00130         OPEN_READER(re, &s->gb);
00131         /* now quantify & encode AC coefficients */
00132         for (;;) {
00133             UPDATE_CACHE(re, &s->gb);
00134             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
00135 
00136             if (level == 127) {
00137                 break;
00138             } else if (level != 0) {
00139                 i += run;
00140                 j = scantable[i];
00141                 level = (level*quant_matrix[j]) >> 4;
00142                 level = (level-1)|1;
00143                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
00144                 LAST_SKIP_BITS(re, &s->gb, 1);
00145             } else {
00146                 /* escape */
00147                 UPDATE_CACHE(re, &s->gb);
00148                 level = SHOW_SBITS(re, &s->gb, 10); SKIP_BITS(re, &s->gb, 10);
00149 
00150                 UPDATE_CACHE(re, &s->gb);
00151                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
00152 
00153                 i += run;
00154                 j = scantable[i];
00155                 if (level < 0) {
00156                     level = -level;
00157                     level = (level*quant_matrix[j]) >> 4;
00158                     level = (level-1)|1;
00159                     level = -level;
00160                 } else {
00161                     level = (level*quant_matrix[j]) >> 4;
00162                     level = (level-1)|1;
00163                 }
00164             }
00165             if (i > 63) {
00166                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
00167                 return;
00168             }
00169 
00170             block[j] = level;
00171         }
00172         CLOSE_READER(re, &s->gb);
00173     }
00174 }
00175 
00176 static int decode_motion(GetBitContext *gb)
00177 {
00178     int value = 0;
00179     if (get_bits1(gb)) {
00180         if (get_bits1(gb))
00181             value = -17;
00182         value += get_bits(gb, 4) + 1;
00183     }
00184     return value;
00185 }
00186 
00187 static void decode_mb(MadContext *t, int inter)
00188 {
00189     MpegEncContext *s = &t->s;
00190     int mv_map = 0;
00191     int mv_x, mv_y;
00192     int j;
00193 
00194     if (inter) {
00195         int v = decode210(&s->gb);
00196         if (v < 2) {
00197             mv_map = v ? get_bits(&s->gb, 6) : 63;
00198             mv_x = decode_motion(&s->gb);
00199             mv_y = decode_motion(&s->gb);
00200         } else {
00201             mv_map = 0;
00202         }
00203     }
00204 
00205     for (j=0; j<6; j++) {
00206         if (mv_map & (1<<j)) {  // mv_x and mv_y are guarded by mv_map
00207             int add = 2*decode_motion(&s->gb);
00208             comp_block(t, s->mb_x, s->mb_y, j, mv_x, mv_y, add);
00209         } else {
00210             s->dsp.clear_block(t->block);
00211             decode_block_intra(t, t->block);
00212             idct_put(t, t->block, s->mb_x, s->mb_y, j);
00213         }
00214     }
00215 }
00216 
00217 static void calc_intra_matrix(MadContext *t, int qscale)
00218 {
00219     MpegEncContext *s = &t->s;
00220     int i;
00221 
00222     if (s->avctx->idct_algo == FF_IDCT_EA) {
00223         s->intra_matrix[0] = (ff_inv_aanscales[0]*ff_mpeg1_default_intra_matrix[0]) >> 11;
00224         for (i=1; i<64; i++)
00225             s->intra_matrix[i] = (ff_inv_aanscales[i]*ff_mpeg1_default_intra_matrix[i]*qscale + 32) >> 10;
00226     } else {
00227         s->intra_matrix[0] = ff_mpeg1_default_intra_matrix[0];
00228         for (i=1; i<64; i++)
00229             s->intra_matrix[i] = (ff_mpeg1_default_intra_matrix[i]*qscale) << 1;
00230     }
00231 }
00232 
00233 static int decode_frame(AVCodecContext *avctx,
00234                         void *data, int *data_size,
00235                         AVPacket *avpkt)
00236 {
00237     const uint8_t *buf = avpkt->data;
00238     int buf_size       = avpkt->size;
00239     const uint8_t *buf_end = buf+buf_size;
00240     MadContext *t     = avctx->priv_data;
00241     MpegEncContext *s = &t->s;
00242     int chunk_type;
00243     int inter;
00244 
00245     if (buf_size < 17) {
00246         av_log(avctx, AV_LOG_ERROR, "Input buffer too small\n");
00247         *data_size = 0;
00248         return -1;
00249     }
00250 
00251     chunk_type = AV_RL32(&buf[0]);
00252     inter = (chunk_type == MADm_TAG || chunk_type == MADe_TAG);
00253     buf += 8;
00254 
00255     av_reduce(&avctx->time_base.num, &avctx->time_base.den,
00256               AV_RL16(&buf[6]), 1000, 1<<30);
00257 
00258     s->width  = AV_RL16(&buf[8]);
00259     s->height = AV_RL16(&buf[10]);
00260     calc_intra_matrix(t, buf[13]);
00261     buf += 16;
00262 
00263     if (avctx->width != s->width || avctx->height != s->height) {
00264         if (av_image_check_size(s->width, s->height, 0, avctx) < 0)
00265             return -1;
00266         avcodec_set_dimensions(avctx, s->width, s->height);
00267         if (t->frame.data[0])
00268             avctx->release_buffer(avctx, &t->frame);
00269     }
00270 
00271     t->frame.reference = 1;
00272     if (!t->frame.data[0]) {
00273         if (avctx->get_buffer(avctx, &t->frame) < 0) {
00274             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00275             return -1;
00276         }
00277     }
00278 
00279     av_fast_malloc(&t->bitstream_buf, &t->bitstream_buf_size, (buf_end-buf) + FF_INPUT_BUFFER_PADDING_SIZE);
00280     if (!t->bitstream_buf)
00281         return AVERROR(ENOMEM);
00282     bswap16_buf(t->bitstream_buf, (const uint16_t*)buf, (buf_end-buf)/2);
00283     init_get_bits(&s->gb, t->bitstream_buf, 8*(buf_end-buf));
00284 
00285     for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)
00286         for (s->mb_x=0; s->mb_x < (avctx->width +15)/16; s->mb_x++)
00287             decode_mb(t, inter);
00288 
00289     *data_size = sizeof(AVFrame);
00290     *(AVFrame*)data = t->frame;
00291 
00292     if (chunk_type != MADe_TAG)
00293         FFSWAP(AVFrame, t->frame, t->last_frame);
00294 
00295     return buf_size;
00296 }
00297 
00298 static av_cold int decode_end(AVCodecContext *avctx)
00299 {
00300     MadContext *t = avctx->priv_data;
00301     if (t->frame.data[0])
00302         avctx->release_buffer(avctx, &t->frame);
00303     if (t->last_frame.data[0])
00304         avctx->release_buffer(avctx, &t->last_frame);
00305     av_free(t->bitstream_buf);
00306     return 0;
00307 }
00308 
00309 AVCodec ff_eamad_decoder = {
00310     "eamad",
00311     AVMEDIA_TYPE_VIDEO,
00312     CODEC_ID_MAD,
00313     sizeof(MadContext),
00314     decode_init,
00315     NULL,
00316     decode_end,
00317     decode_frame,
00318     CODEC_CAP_DR1,
00319     .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts Madcow Video")
00320 };