libavcodec/escape130.c
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00001 /*
00002  * Escape 130 Video Decoder
00003  * Copyright (C) 2008 Eli Friedman (eli.friedman <at> gmail.com)
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 Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avcodec.h"
00023 
00024 #define BITSTREAM_READER_LE
00025 #include "get_bits.h"
00026 
00027 typedef struct Escape130Context {
00028     AVFrame frame;
00029     uint8_t *bases;
00030 } Escape130Context;
00031 
00037 static av_cold int escape130_decode_init(AVCodecContext *avctx)
00038 {
00039     Escape130Context *s = avctx->priv_data;
00040     avctx->pix_fmt = PIX_FMT_YUV420P;
00041 
00042     if((avctx->width&1) || (avctx->height&1)){
00043         av_log(avctx, AV_LOG_ERROR, "Dimensions are not a multiple of the block size\n");
00044         return AVERROR(EINVAL);
00045     }
00046 
00047     s->bases= av_malloc(avctx->width * avctx->height /4);
00048 
00049     return 0;
00050 }
00051 
00052 static av_cold int escape130_decode_close(AVCodecContext *avctx)
00053 {
00054     Escape130Context *s = avctx->priv_data;
00055 
00056     if (s->frame.data[0])
00057         avctx->release_buffer(avctx, &s->frame);
00058 
00059     av_freep(&s->bases);
00060 
00061     return 0;
00062 }
00063 
00064 static unsigned decode_skip_count(GetBitContext* gb) {
00065     unsigned value;
00066     // This function reads a maximum of 27 bits,
00067     // which is within the padding space
00068     if (get_bits_left(gb) < 1+3)
00069         return -1;
00070 
00071     value = get_bits1(gb);
00072     if (value)
00073         return 0;
00074 
00075     value = get_bits(gb, 3);
00076     if (value)
00077         return value;
00078 
00079     value = get_bits(gb, 8);
00080     if (value)
00081         return value + 7;
00082 
00083     value = get_bits(gb, 15);
00084     if (value)
00085         return value + 262;
00086 
00087     return -1;
00088 }
00089 
00099 static int escape130_decode_frame(AVCodecContext *avctx,
00100                                   void *data, int *data_size,
00101                                   AVPacket *avpkt)
00102 {
00103     const uint8_t *buf = avpkt->data;
00104     int buf_size = avpkt->size;
00105     Escape130Context *s = avctx->priv_data;
00106 
00107     GetBitContext gb;
00108     unsigned i;
00109 
00110     uint8_t *old_y, *old_cb, *old_cr,
00111             *new_y, *new_cb, *new_cr;
00112     unsigned old_y_stride, old_cb_stride, old_cr_stride,
00113              new_y_stride, new_cb_stride, new_cr_stride;
00114     unsigned total_blocks = avctx->width * avctx->height / 4,
00115              block_index, row_index = 0;
00116     unsigned y[4] = {0}, cb = 16, cr = 16;
00117     unsigned skip = -1;
00118     unsigned y_base = 0;
00119     uint8_t *yb= s->bases;
00120 
00121     AVFrame new_frame = { { 0 } };
00122 
00123     init_get_bits(&gb, buf, buf_size * 8);
00124 
00125     if (get_bits_left(&gb) < 128)
00126         return -1;
00127 
00128     // Header; no useful information in here
00129     skip_bits_long(&gb, 128);
00130 
00131     new_frame.reference = 3;
00132     if (avctx->get_buffer(avctx, &new_frame)) {
00133         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00134         return -1;
00135     }
00136 
00137     new_y = new_frame.data[0];
00138     new_cb = new_frame.data[1];
00139     new_cr = new_frame.data[2];
00140     new_y_stride = new_frame.linesize[0];
00141     new_cb_stride = new_frame.linesize[1];
00142     new_cr_stride = new_frame.linesize[2];
00143     old_y = s->frame.data[0];
00144     old_cb = s->frame.data[1];
00145     old_cr = s->frame.data[2];
00146     old_y_stride = s->frame.linesize[0];
00147     old_cb_stride = s->frame.linesize[1];
00148     old_cr_stride = s->frame.linesize[2];
00149 
00150     av_log(avctx, AV_LOG_DEBUG,
00151            "Strides: %i, %i\n",
00152            new_y_stride, new_cb_stride);
00153 
00154     for (block_index = 0; block_index < total_blocks; block_index++) {
00155         // Note that this call will make us skip the rest of the blocks
00156         // if the frame prematurely ends
00157         if (skip == -1)
00158             skip = decode_skip_count(&gb);
00159 
00160         if (skip) {
00161             if (old_y) {
00162                 y[0] = old_y[0] / 4;
00163                 y[1] = old_y[1] / 4;
00164                 y[2] = old_y[old_y_stride] / 4;
00165                 y[3] = old_y[old_y_stride+1] / 4;
00166                 y_base= yb[0];
00167                 cb = old_cb[0] / 8;
00168                 cr = old_cr[0] / 8;
00169             } else {
00170                 y_base=y[0] = y[1] = y[2] = y[3] = 0;
00171                 cb = cr = 16;
00172             }
00173         } else {
00174             if (get_bits1(&gb)) {
00175                 static const uint8_t offset_table[] = {2, 4, 10, 20};
00176                 static const int8_t sign_table[64][4] =
00177                     { {0, 0, 0, 0},
00178                       {-1, 1, 0, 0},
00179                       {1, -1, 0, 0},
00180                       {-1, 0, 1, 0},
00181                       {-1, 1, 1, 0},
00182                       {0, -1, 1, 0},
00183                       {1, -1, 1, 0},
00184                       {-1, -1, 1, 0},
00185                       {1, 0, -1, 0},
00186                       {0, 1, -1, 0},
00187                       {1, 1, -1, 0},
00188                       {-1, 1, -1, 0},
00189                       {1, -1, -1, 0},
00190                       {-1, 0, 0, 1},
00191                       {-1, 1, 0, 1},
00192                       {0, -1, 0, 1},
00193 
00194                       {0, 0, 0, 0},
00195                       {1, -1, 0, 1},
00196                       {-1, -1, 0, 1},
00197                       {-1, 0, 1, 1},
00198                       {-1, 1, 1, 1},
00199                       {0, -1, 1, 1},
00200                       {1, -1, 1, 1},
00201                       {-1, -1, 1, 1},
00202                       {0, 0, -1, 1},
00203                       {1, 0, -1, 1},
00204                       {-1, 0, -1, 1},
00205                       {0, 1, -1, 1},
00206                       {1, 1, -1, 1},
00207                       {-1, 1, -1, 1},
00208                       {0, -1, -1, 1},
00209                       {1, -1, -1, 1},
00210 
00211                       {0, 0, 0, 0},
00212                       {-1, -1, -1, 1},
00213                       {1, 0, 0, -1},
00214                       {0, 1, 0, -1},
00215                       {1, 1, 0, -1},
00216                       {-1, 1, 0, -1},
00217                       {1, -1, 0, -1},
00218                       {0, 0, 1, -1},
00219                       {1, 0, 1, -1},
00220                       {-1, 0, 1, -1},
00221                       {0, 1, 1, -1},
00222                       {1, 1, 1, -1},
00223                       {-1, 1, 1, -1},
00224                       {0, -1, 1, -1},
00225                       {1, -1, 1, -1},
00226                       {-1, -1, 1, -1},
00227 
00228                       {0, 0, 0, 0},
00229                       {1, 0, -1, -1},
00230                       {0, 1, -1, -1},
00231                       {1, 1, -1, -1},
00232                       {-1, 1, -1, -1},
00233                       {1, -1, -1, -1} };
00234                 unsigned sign_selector = get_bits(&gb, 6);
00235                 unsigned difference_selector = get_bits(&gb, 2);
00236                 y_base = 2 * get_bits(&gb, 5);
00237                 for (i = 0; i < 4; i++) {
00238                     y[i] = av_clip((int)y_base + offset_table[difference_selector] *
00239                                             sign_table[sign_selector][i], 0, 63);
00240                 }
00241             } else if (get_bits1(&gb)) {
00242                 if (get_bits1(&gb)) {
00243                     y_base = get_bits(&gb, 6);
00244                 } else {
00245                     unsigned adjust_index = get_bits(&gb, 3);
00246                     static const int8_t adjust[] = {-4, -3, -2, -1, 1, 2, 3, 4};
00247                     y_base = (y_base + adjust[adjust_index]) & 63;
00248                 }
00249                 for (i = 0; i < 4; i++)
00250                     y[i] = y_base;
00251             }
00252 
00253             if (get_bits1(&gb)) {
00254                 if (get_bits1(&gb)) {
00255                     cb = get_bits(&gb, 5);
00256                     cr = get_bits(&gb, 5);
00257                 } else {
00258                     unsigned adjust_index = get_bits(&gb, 3);
00259                     static const int8_t adjust[2][8] =
00260                         {  { 1, 1, 0, -1, -1, -1,  0,  1 },
00261                            { 0, 1, 1,  1,  0, -1, -1, -1 } };
00262                     cb = (cb + adjust[0][adjust_index]) & 31;
00263                     cr = (cr + adjust[1][adjust_index]) & 31;
00264                 }
00265             }
00266         }
00267         *yb++= y_base;
00268 
00269         new_y[0] = y[0] * 4;
00270         new_y[1] = y[1] * 4;
00271         new_y[new_y_stride] = y[2] * 4;
00272         new_y[new_y_stride + 1] = y[3] * 4;
00273         *new_cb = cb * 8;
00274         *new_cr = cr * 8;
00275 
00276         if (old_y)
00277             old_y += 2, old_cb++, old_cr++;
00278         new_y += 2, new_cb++, new_cr++;
00279         row_index++;
00280         if (avctx->width / 2 == row_index) {
00281             row_index = 0;
00282             if (old_y) {
00283                 old_y  += old_y_stride * 2  - avctx->width;
00284                 old_cb += old_cb_stride - avctx->width / 2;
00285                 old_cr += old_cr_stride - avctx->width / 2;
00286             }
00287             new_y  += new_y_stride * 2  - avctx->width;
00288             new_cb += new_cb_stride - avctx->width / 2;
00289             new_cr += new_cr_stride - avctx->width / 2;
00290         }
00291 
00292         skip--;
00293     }
00294 
00295     av_log(avctx, AV_LOG_DEBUG,
00296            "Escape sizes: %i, %i\n",
00297            buf_size, get_bits_count(&gb) / 8);
00298 
00299     if (s->frame.data[0])
00300         avctx->release_buffer(avctx, &s->frame);
00301 
00302     *(AVFrame*)data = s->frame = new_frame;
00303     *data_size = sizeof(AVFrame);
00304 
00305     return buf_size;
00306 }
00307 
00308 
00309 AVCodec ff_escape130_decoder = {
00310     .name           = "escape130",
00311     .type           = AVMEDIA_TYPE_VIDEO,
00312     .id             = CODEC_ID_ESCAPE130,
00313     .priv_data_size = sizeof(Escape130Context),
00314     .init           = escape130_decode_init,
00315     .close          = escape130_decode_close,
00316     .decode         = escape130_decode_frame,
00317     .capabilities   = CODEC_CAP_DR1,
00318     .long_name = NULL_IF_CONFIG_SMALL("Escape 130"),
00319 };