FFmpeg: libavcodec/eamad.c Source File

00001 /*
00002  * Electronic Arts Madcow Video Decoder
00003  * Copyright (c) 2007-2009 Peter Ross
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 
00038 #define EA_PREAMBLE_SIZE    8
00039 #define MADk_TAG MKTAG('M', 'A', 'D', 'k')    /* MAD i-frame */
00040 #define MADm_TAG MKTAG('M', 'A', 'D', 'm')    /* MAD p-frame */
00041 #define MADe_TAG MKTAG('M', 'A', 'D', 'e')    /* MAD lqp-frame */
00042 
00043 typedef struct MadContext {
00044     MpegEncContext s;
00045     AVFrame frame;
00046     AVFrame last_frame;
00047     void *bitstream_buf;
00048     unsigned int bitstream_buf_size;
00049     DECLARE_ALIGNED(16, DCTELEM, block)[64];
00050 } MadContext;
00051 
00052 static void bswap16_buf(uint16_t *dst, const uint16_t *src, int count)
00053 {
00054     int i;
00055     for (i=0; i<count; i++)
00056         dst[i] = bswap_16(src[i]);
00057 }
00058 
00059 static av_cold int decode_init(AVCodecContext *avctx)
00060 {
00061     MadContext *t = avctx->priv_data;
00062     MpegEncContext *s = &t->s;
00063     s->avctx = avctx;
00064     avctx->pix_fmt = PIX_FMT_YUV420P;
00065     if (avctx->idct_algo == FF_IDCT_AUTO)
00066         avctx->idct_algo = FF_IDCT_EA;
00067     dsputil_init(&s->dsp, avctx);
00068     ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);
00069     ff_mpeg12_init_vlcs();
00070     return 0;
00071 }
00072 
00073 static inline void comp(unsigned char *dst, int dst_stride,
00074                         unsigned char *src, int src_stride, int add)
00075 {
00076     int j, i;
00077     for (j=0; j<8; j++)
00078         for (i=0; i<8; i++)
00079             dst[j*dst_stride + i] = av_clip_uint8(src[j*src_stride + i] + add);
00080 }
00081 
00082 static inline void comp_block(MadContext *t, int mb_x, int mb_y,
00083                               int j, int mv_x, int mv_y, int add)
00084 {
00085     MpegEncContext *s = &t->s;
00086     if (j < 4) {
00087         comp(t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
00088              t->frame.linesize[0],
00089              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,
00090              t->last_frame.linesize[0], add);
00091     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
00092         int index = j - 3;
00093         comp(t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x * 8,
00094              t->frame.linesize[index],
00095              t->last_frame.data[index] + (mb_y * 8 + (mv_y/2))*t->last_frame.linesize[index] + mb_x * 8 + (mv_x/2),
00096              t->last_frame.linesize[index], add);
00097     }
00098 }
00099 
00100 static inline void idct_put(MadContext *t, DCTELEM *block, int mb_x, int mb_y, int j)
00101 {
00102     MpegEncContext *s = &t->s;
00103     if (j < 4) {
00104         s->dsp.idct_put(
00105             t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
00106             t->frame.linesize[0], block);
00107     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
00108         int index = j - 3;
00109         s->dsp.idct_put(
00110             t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x*8,
00111             t->frame.linesize[index], block);
00112     }
00113 }
00114 
00115 static inline void decode_block_intra(MadContext * t, DCTELEM * block)
00116 {
00117     MpegEncContext *s = &t->s;
00118     int level, i, j, run;
00119     RLTable *rl = &ff_rl_mpeg1;
00120     const uint8_t *scantable = s->intra_scantable.permutated;
00121     int16_t *quant_matrix = s->intra_matrix;
00122 
00123     block[0] = (128 + get_sbits(&s->gb, 8)) * quant_matrix[0];
00124 
00125     /* The RL decoder is derived from mpeg1_decode_block_intra;
00126        Escaped level and run values a decoded differently */
00127     i = 0;
00128     {
00129         OPEN_READER(re, &s->gb);
00130         /* now quantify & encode AC coefficients */
00131         for (;;) {
00132             UPDATE_CACHE(re, &s->gb);
00133             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
00134 
00135             if (level == 127) {
00136                 break;
00137             } else if (level != 0) {
00138                 i += run;
00139                 j = scantable[i];
00140                 level = (level*quant_matrix[j]) >> 4;
00141                 level = (level-1)|1;
00142                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
00143                 LAST_SKIP_BITS(re, &s->gb, 1);
00144             } else {
00145                 /* escape */
00146                 UPDATE_CACHE(re, &s->gb);
00147                 level = SHOW_SBITS(re, &s->gb, 10); SKIP_BITS(re, &s->gb, 10);
00148 
00149                 UPDATE_CACHE(re, &s->gb);
00150                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
00151 
00152                 i += run;
00153                 j = scantable[i];
00154                 if (level < 0) {
00155                     level = -level;
00156                     level = (level*quant_matrix[j]) >> 4;
00157                     level = (level-1)|1;
00158                     level = -level;
00159                 } else {
00160                     level = (level*quant_matrix[j]) >> 4;
00161                     level = (level-1)|1;
00162                 }
00163             }
00164             if (i > 63) {
00165                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
00166                 return;
00167             }
00168 
00169             block[j] = level;
00170         }
00171         CLOSE_READER(re, &s->gb);
00172     }
00173 }
00174 
00175 static int decode_motion(GetBitContext *gb)
00176 {
00177     int value = 0;
00178     if (get_bits1(gb)) {
00179         if (get_bits1(gb))
00180             value = -17;
00181         value += get_bits(gb, 4) + 1;
00182     }
00183     return value;
00184 }
00185 
00186 static void decode_mb(MadContext *t, int inter)
00187 {
00188     MpegEncContext *s = &t->s;
00189     int mv_map = 0;
00190     int mv_x, mv_y;
00191     int j;
00192 
00193     if (inter) {
00194         int v = decode210(&s->gb);
00195         if (v < 2) {
00196             mv_map = v ? get_bits(&s->gb, 6) : 63;
00197             mv_x = decode_motion(&s->gb);
00198             mv_y = decode_motion(&s->gb);
00199         } else {
00200             mv_map = 0;
00201         }
00202     }
00203 
00204     for (j=0; j<6; j++) {
00205         if (mv_map & (1<<j)) {  // mv_x and mv_y are guarded by mv_map
00206             int add = 2*decode_motion(&s->gb);
00207             comp_block(t, s->mb_x, s->mb_y, j, mv_x, mv_y, add);
00208         } else {
00209             s->dsp.clear_block(t->block);
00210             decode_block_intra(t, t->block);
00211             idct_put(t, t->block, s->mb_x, s->mb_y, j);
00212         }
00213     }
00214 }
00215 
00216 static void calc_intra_matrix(MadContext *t, int qscale)
00217 {
00218     MpegEncContext *s = &t->s;
00219     int i;
00220 
00221     if (s->avctx->idct_algo == FF_IDCT_EA) {
00222         s->intra_matrix[0] = (ff_inv_aanscales[0]*ff_mpeg1_default_intra_matrix[0]) >> 11;
00223         for (i=1; i<64; i++)
00224             s->intra_matrix[i] = (ff_inv_aanscales[i]*ff_mpeg1_default_intra_matrix[i]*qscale + 32) >> 10;
00225     } else {
00226         s->intra_matrix[0] = ff_mpeg1_default_intra_matrix[0];
00227         for (i=1; i<64; i++)
00228             s->intra_matrix[i] = (ff_mpeg1_default_intra_matrix[i]*qscale) << 1;
00229     }
00230 }
00231 
00232 static int decode_frame(AVCodecContext *avctx,
00233                         void *data, int *data_size,
00234                         AVPacket *avpkt)
00235 {
00236     const uint8_t *buf = avpkt->data;
00237     int buf_size       = avpkt->size;
00238     const uint8_t *buf_end = buf+buf_size;
00239     MadContext *t     = avctx->priv_data;
00240     MpegEncContext *s = &t->s;
00241     int chunk_type;
00242     int inter;
00243 
00244     if (buf_size < 17) {
00245         av_log(avctx, AV_LOG_ERROR, "Input buffer too small\n");
00246         *data_size = 0;
00247         return -1;
00248     }
00249 
00250     chunk_type = AV_RL32(&buf[0]);
00251     inter = (chunk_type == MADm_TAG || chunk_type == MADe_TAG);
00252     buf += 8;
00253 
00254     av_reduce(&avctx->time_base.num, &avctx->time_base.den,
00255               AV_RL16(&buf[6]), 1000, 1<<30);
00256 
00257     s->width  = AV_RL16(&buf[8]);
00258     s->height = AV_RL16(&buf[10]);
00259     calc_intra_matrix(t, buf[13]);
00260     buf += 16;
00261 
00262     if (avctx->width != s->width || avctx->height != s->height) {
00263         if (avcodec_check_dimensions(avctx, s->width, s->height) < 0)
00264             return -1;
00265         avcodec_set_dimensions(avctx, s->width, s->height);
00266         if (t->frame.data[0])
00267             avctx->release_buffer(avctx, &t->frame);
00268     }
00269 
00270     t->frame.reference = 1;
00271     if (!t->frame.data[0]) {
00272         if (avctx->get_buffer(avctx, &t->frame) < 0) {
00273             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00274             return -1;
00275         }
00276     }
00277 
00278     av_fast_malloc(&t->bitstream_buf, &t->bitstream_buf_size, (buf_end-buf) + FF_INPUT_BUFFER_PADDING_SIZE);
00279     if (!t->bitstream_buf)
00280         return AVERROR(ENOMEM);
00281     bswap16_buf(t->bitstream_buf, (const uint16_t*)buf, (buf_end-buf)/2);
00282     init_get_bits(&s->gb, t->bitstream_buf, 8*(buf_end-buf));
00283 
00284     for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)
00285         for (s->mb_x=0; s->mb_x < (avctx->width +15)/16; s->mb_x++)
00286             decode_mb(t, inter);
00287 
00288     *data_size = sizeof(AVFrame);
00289     *(AVFrame*)data = t->frame;
00290 
00291     if (chunk_type != MADe_TAG)
00292         FFSWAP(AVFrame, t->frame, t->last_frame);
00293 
00294     return buf_size;
00295 }
00296 
00297 static av_cold int decode_end(AVCodecContext *avctx)
00298 {
00299     MadContext *t = avctx->priv_data;
00300     if (t->frame.data[0])
00301         avctx->release_buffer(avctx, &t->frame);
00302     if (t->last_frame.data[0])
00303         avctx->release_buffer(avctx, &t->last_frame);
00304     av_free(t->bitstream_buf);
00305     return 0;
00306 }
00307 
00308 AVCodec eamad_decoder = {
00309     "eamad",
00310     AVMEDIA_TYPE_VIDEO,
00311     CODEC_ID_MAD,
00312     sizeof(MadContext),
00313     decode_init,
00314     NULL,
00315     decode_end,
00316     decode_frame,
00317     CODEC_CAP_DR1,
00318     .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts Madcow Video")
00319 };