libavcodec/eamad.c
Go to the documentation of this file.
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 "bytestream.h"
00033 #include "get_bits.h"
00034 #include "dsputil.h"
00035 #include "aandcttab.h"
00036 #include "mpeg12.h"
00037 #include "mpeg12data.h"
00038 #include "libavutil/imgutils.h"
00039 
00040 #define EA_PREAMBLE_SIZE    8
00041 #define MADk_TAG MKTAG('M', 'A', 'D', 'k')    /* MAD i-frame */
00042 #define MADm_TAG MKTAG('M', 'A', 'D', 'm')    /* MAD p-frame */
00043 #define MADe_TAG MKTAG('M', 'A', 'D', 'e')    /* MAD lqp-frame */
00044 
00045 typedef struct MadContext {
00046     MpegEncContext s;
00047     AVFrame frame;
00048     AVFrame last_frame;
00049     void *bitstream_buf;
00050     unsigned int bitstream_buf_size;
00051     DECLARE_ALIGNED(16, DCTELEM, block)[64];
00052 } MadContext;
00053 
00054 static void bswap16_buf(uint16_t *dst, const uint16_t *src, int count)
00055 {
00056     int i;
00057     for (i=0; i<count; i++)
00058         dst[i] = av_bswap16(src[i]);
00059 }
00060 
00061 static av_cold int decode_init(AVCodecContext *avctx)
00062 {
00063     MadContext *t = avctx->priv_data;
00064     MpegEncContext *s = &t->s;
00065     s->avctx = avctx;
00066     avctx->pix_fmt = PIX_FMT_YUV420P;
00067     if (avctx->idct_algo == FF_IDCT_AUTO)
00068         avctx->idct_algo = FF_IDCT_EA;
00069     dsputil_init(&s->dsp, avctx);
00070     ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);
00071     ff_mpeg12_init_vlcs();
00072     return 0;
00073 }
00074 
00075 static inline void comp(unsigned char *dst, int dst_stride,
00076                         unsigned char *src, int src_stride, int add)
00077 {
00078     int j, i;
00079     for (j=0; j<8; j++)
00080         for (i=0; i<8; i++)
00081             dst[j*dst_stride + i] = av_clip_uint8(src[j*src_stride + i] + add);
00082 }
00083 
00084 static inline void comp_block(MadContext *t, int mb_x, int mb_y,
00085                               int j, int mv_x, int mv_y, int add)
00086 {
00087     MpegEncContext *s = &t->s;
00088     if (j < 4) {
00089         comp(t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
00090              t->frame.linesize[0],
00091              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,
00092              t->last_frame.linesize[0], add);
00093     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
00094         int index = j - 3;
00095         comp(t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x * 8,
00096              t->frame.linesize[index],
00097              t->last_frame.data[index] + (mb_y * 8 + (mv_y/2))*t->last_frame.linesize[index] + mb_x * 8 + (mv_x/2),
00098              t->last_frame.linesize[index], add);
00099     }
00100 }
00101 
00102 static inline void idct_put(MadContext *t, DCTELEM *block, int mb_x, int mb_y, int j)
00103 {
00104     MpegEncContext *s = &t->s;
00105     if (j < 4) {
00106         s->dsp.idct_put(
00107             t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
00108             t->frame.linesize[0], block);
00109     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
00110         int index = j - 3;
00111         s->dsp.idct_put(
00112             t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x*8,
00113             t->frame.linesize[index], block);
00114     }
00115 }
00116 
00117 static inline void decode_block_intra(MadContext * t, DCTELEM * block)
00118 {
00119     MpegEncContext *s = &t->s;
00120     int level, i, j, run;
00121     RLTable *rl = &ff_rl_mpeg1;
00122     const uint8_t *scantable = s->intra_scantable.permutated;
00123     int16_t *quant_matrix = s->intra_matrix;
00124 
00125     block[0] = (128 + get_sbits(&s->gb, 8)) * quant_matrix[0];
00126 
00127     /* The RL decoder is derived from mpeg1_decode_block_intra;
00128        Escaped level and run values a decoded differently */
00129     i = 0;
00130     {
00131         OPEN_READER(re, &s->gb);
00132         /* now quantify & encode AC coefficients */
00133         for (;;) {
00134             UPDATE_CACHE(re, &s->gb);
00135             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
00136 
00137             if (level == 127) {
00138                 break;
00139             } else if (level != 0) {
00140                 i += run;
00141                 if (i > 63) {
00142                     av_log(s->avctx, AV_LOG_ERROR,
00143                            "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
00144                     return;
00145                 }
00146                 j = scantable[i];
00147                 level = (level*quant_matrix[j]) >> 4;
00148                 level = (level-1)|1;
00149                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
00150                 LAST_SKIP_BITS(re, &s->gb, 1);
00151             } else {
00152                 /* escape */
00153                 UPDATE_CACHE(re, &s->gb);
00154                 level = SHOW_SBITS(re, &s->gb, 10); SKIP_BITS(re, &s->gb, 10);
00155 
00156                 UPDATE_CACHE(re, &s->gb);
00157                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
00158 
00159                 i += run;
00160                 if (i > 63) {
00161                     av_log(s->avctx, AV_LOG_ERROR,
00162                            "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
00163                     return;
00164                 }
00165                 j = scantable[i];
00166                 if (level < 0) {
00167                     level = -level;
00168                     level = (level*quant_matrix[j]) >> 4;
00169                     level = (level-1)|1;
00170                     level = -level;
00171                 } else {
00172                     level = (level*quant_matrix[j]) >> 4;
00173                     level = (level-1)|1;
00174                 }
00175             }
00176 
00177             block[j] = level;
00178         }
00179         CLOSE_READER(re, &s->gb);
00180     }
00181 }
00182 
00183 static int decode_motion(GetBitContext *gb)
00184 {
00185     int value = 0;
00186     if (get_bits1(gb)) {
00187         if (get_bits1(gb))
00188             value = -17;
00189         value += get_bits(gb, 4) + 1;
00190     }
00191     return value;
00192 }
00193 
00194 static void decode_mb(MadContext *t, int inter)
00195 {
00196     MpegEncContext *s = &t->s;
00197     int mv_map = 0;
00198     int mv_x, mv_y;
00199     int j;
00200 
00201     if (inter) {
00202         int v = decode210(&s->gb);
00203         if (v < 2) {
00204             mv_map = v ? get_bits(&s->gb, 6) : 63;
00205             mv_x = decode_motion(&s->gb);
00206             mv_y = decode_motion(&s->gb);
00207         } else {
00208             mv_map = 0;
00209         }
00210     }
00211 
00212     for (j=0; j<6; j++) {
00213         if (mv_map & (1<<j)) {  // mv_x and mv_y are guarded by mv_map
00214             int add = 2*decode_motion(&s->gb);
00215             comp_block(t, s->mb_x, s->mb_y, j, mv_x, mv_y, add);
00216         } else {
00217             s->dsp.clear_block(t->block);
00218             decode_block_intra(t, t->block);
00219             idct_put(t, t->block, s->mb_x, s->mb_y, j);
00220         }
00221     }
00222 }
00223 
00224 static void calc_intra_matrix(MadContext *t, int qscale)
00225 {
00226     MpegEncContext *s = &t->s;
00227     int i;
00228 
00229     if (s->avctx->idct_algo == FF_IDCT_EA) {
00230         s->intra_matrix[0] = (ff_inv_aanscales[0]*ff_mpeg1_default_intra_matrix[0]) >> 11;
00231         for (i=1; i<64; i++)
00232             s->intra_matrix[i] = (ff_inv_aanscales[i]*ff_mpeg1_default_intra_matrix[i]*qscale + 32) >> 10;
00233     } else {
00234         s->intra_matrix[0] = ff_mpeg1_default_intra_matrix[0];
00235         for (i=1; i<64; i++)
00236             s->intra_matrix[i] = (ff_mpeg1_default_intra_matrix[i]*qscale) << 1;
00237     }
00238 }
00239 
00240 static int decode_frame(AVCodecContext *avctx,
00241                         void *data, int *data_size,
00242                         AVPacket *avpkt)
00243 {
00244     const uint8_t *buf = avpkt->data;
00245     int buf_size       = avpkt->size;
00246     MadContext *t     = avctx->priv_data;
00247     GetByteContext gb;
00248     MpegEncContext *s = &t->s;
00249     int chunk_type;
00250     int inter;
00251 
00252     bytestream2_init(&gb, buf, buf_size);
00253 
00254     chunk_type = bytestream2_get_le32(&gb);
00255     inter = (chunk_type == MADm_TAG || chunk_type == MADe_TAG);
00256     bytestream2_skip(&gb, 10);
00257 
00258     av_reduce(&avctx->time_base.num, &avctx->time_base.den,
00259               bytestream2_get_le16(&gb), 1000, 1<<30);
00260 
00261     s->width  = bytestream2_get_le16(&gb);
00262     s->height = bytestream2_get_le16(&gb);
00263     bytestream2_skip(&gb, 1);
00264     calc_intra_matrix(t, bytestream2_get_byte(&gb));
00265     bytestream2_skip(&gb, 2);
00266 
00267     if (bytestream2_get_bytes_left(&gb) < 2) {
00268         av_log(avctx, AV_LOG_ERROR, "Input data too small\n");
00269         return AVERROR_INVALIDDATA;
00270     }
00271 
00272     if (avctx->width != s->width || avctx->height != s->height) {
00273         if (av_image_check_size(s->width, s->height, 0, avctx) < 0)
00274             return -1;
00275         avcodec_set_dimensions(avctx, s->width, s->height);
00276         if (t->frame.data[0])
00277             avctx->release_buffer(avctx, &t->frame);
00278     }
00279 
00280     t->frame.reference = 1;
00281     if (!t->frame.data[0]) {
00282         if (avctx->get_buffer(avctx, &t->frame) < 0) {
00283             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00284             return -1;
00285         }
00286     }
00287 
00288     av_fast_malloc(&t->bitstream_buf, &t->bitstream_buf_size,
00289                    bytestream2_get_bytes_left(&gb) + FF_INPUT_BUFFER_PADDING_SIZE);
00290     if (!t->bitstream_buf)
00291         return AVERROR(ENOMEM);
00292     bswap16_buf(t->bitstream_buf, (const uint16_t *)(buf + bytestream2_tell(&gb)),
00293                 bytestream2_get_bytes_left(&gb) / 2);
00294     init_get_bits(&s->gb, t->bitstream_buf, 8*(bytestream2_get_bytes_left(&gb)));
00295     for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)
00296         for (s->mb_x=0; s->mb_x < (avctx->width +15)/16; s->mb_x++)
00297             decode_mb(t, inter);
00298 
00299     *data_size = sizeof(AVFrame);
00300     *(AVFrame*)data = t->frame;
00301 
00302     if (chunk_type != MADe_TAG)
00303         FFSWAP(AVFrame, t->frame, t->last_frame);
00304 
00305     return buf_size;
00306 }
00307 
00308 static av_cold int decode_end(AVCodecContext *avctx)
00309 {
00310     MadContext *t = avctx->priv_data;
00311     if (t->frame.data[0])
00312         avctx->release_buffer(avctx, &t->frame);
00313     if (t->last_frame.data[0])
00314         avctx->release_buffer(avctx, &t->last_frame);
00315     av_free(t->bitstream_buf);
00316     return 0;
00317 }
00318 
00319 AVCodec ff_eamad_decoder = {
00320     .name           = "eamad",
00321     .type           = AVMEDIA_TYPE_VIDEO,
00322     .id             = CODEC_ID_MAD,
00323     .priv_data_size = sizeof(MadContext),
00324     .init           = decode_init,
00325     .close          = decode_end,
00326     .decode         = decode_frame,
00327     .capabilities   = CODEC_CAP_DR1,
00328     .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts Madcow Video")
00329 };