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FFmpeg/libavcodec/escape130.c

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  1. /*

  2.  * Escape 130 Video Decoder

  3.  * Copyright (C) 2008 Eli Friedman (eli.friedman <at> gmail.com)

  4.  *

  5.  * This file is part of FFmpeg.

  6.  *

  7.  * FFmpeg is free software; you can redistribute it and/or

  8.  * modify it under the terms of the GNU Lesser General Public

  9.  * License as published by the Free Software Foundation; either

  10.  * version 2.1 of the License, or (at your option) any later version.

  11.  *

  12.  * FFmpeg is distributed in the hope that it will be useful,

  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  15.  * Lesser General Public License for more details.

  16.  *

  17.  * You should have received a copy of the GNU Lesser General Public

  18.  * License along with FFmpeg; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. #include "avcodec.h"

  23. 

  24. #define BITSTREAM_READER_LE

  25. #include "get_bits.h"

  26. #include "internal.h"

  27. 

  28. 

  29. typedef struct Escape130Context {

  30.     AVFrame frame;

  31.     uint8_t *bases;

  32. } Escape130Context;

  33. 

  34. /**

  35.  * Initialize the decoder

  36.  * @param avctx decoder context

  37.  * @return 0 success, negative on error

  38.  */

  39. static av_cold int escape130_decode_init(AVCodecContext *avctx)

  40. {

  41.     Escape130Context *s = avctx->priv_data;

  42.     avctx->pix_fmt = AV_PIX_FMT_YUV420P;

  43. 

  44.     if((avctx->width&1) || (avctx->height&1)){

  45.         av_log(avctx, AV_LOG_ERROR, "Dimensions are not a multiple of the block size\n");

  46.         return AVERROR(EINVAL);

  47.     }

  48. 

  49.     s->bases= av_malloc(avctx->width * avctx->height /4);

  50. 

  51.     return 0;

  52. }

  53. 

  54. static av_cold int escape130_decode_close(AVCodecContext *avctx)

  55. {

  56.     Escape130Context *s = avctx->priv_data;

  57. 

  58.     if (s->frame.data[0])

  59.         avctx->release_buffer(avctx, &s->frame);

  60. 

  61.     av_freep(&s->bases);

  62. 

  63.     return 0;

  64. }

  65. 

  66. static unsigned decode_skip_count(GetBitContext* gb) {

  67.     unsigned value;

  68.     // This function reads a maximum of 27 bits,

  69.     // which is within the padding space

  70.     if (get_bits_left(gb) < 1+3)

  71.         return -1;

  72. 

  73.     value = get_bits1(gb);

  74.     if (value)

  75.         return 0;

  76. 

  77.     value = get_bits(gb, 3);

  78.     if (value)

  79.         return value;

  80. 

  81.     value = get_bits(gb, 8);

  82.     if (value)

  83.         return value + 7;

  84. 

  85.     value = get_bits(gb, 15);

  86.     if (value)

  87.         return value + 262;

  88. 

  89.     return -1;

  90. }

  91. 

  92. /**

  93.  * Decode a single frame

  94.  * @param avctx decoder context

  95.  * @param data decoded frame

  96.  * @param got_frame have decoded frame

  97.  * @param buf input buffer

  98.  * @param buf_size input buffer size

  99.  * @return 0 success, -1 on error

  100.  */

  101. static int escape130_decode_frame(AVCodecContext *avctx,

  102.                                   void *data, int *got_frame,

  103.                                   AVPacket *avpkt)

  104. {

  105.     const uint8_t *buf = avpkt->data;

  106.     int buf_size = avpkt->size;

  107.     Escape130Context *s = avctx->priv_data;

  108. 

  109.     GetBitContext gb;

  110.     unsigned i;

  111. 

  112.     uint8_t *old_y, *old_cb, *old_cr,

  113.             *new_y, *new_cb, *new_cr;

  114.     unsigned old_y_stride, old_cb_stride, old_cr_stride,

  115.              new_y_stride, new_cb_stride, new_cr_stride;

  116.     unsigned total_blocks = avctx->width * avctx->height / 4,

  117.              block_index, row_index = 0;

  118.     unsigned y[4] = {0}, cb = 16, cr = 16;

  119.     unsigned skip = -1;

  120.     unsigned y_base = 0;

  121.     uint8_t *yb= s->bases;

  122. 

  123.     AVFrame new_frame = { { 0 } };

  124. 

  125.     init_get_bits(&gb, buf, buf_size * 8);

  126. 

  127.     if (get_bits_left(&gb) < 128)

  128.         return -1;

  129. 

  130.     // Header; no useful information in here

  131.     skip_bits_long(&gb, 128);

  132. 

  133.     new_frame.reference = 3;

  134.     if (ff_get_buffer(avctx, &new_frame)) {

  135.         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

  136.         return -1;

  137.     }

  138. 

  139.     new_y = new_frame.data[0];

  140.     new_cb = new_frame.data[1];

  141.     new_cr = new_frame.data[2];

  142.     new_y_stride = new_frame.linesize[0];

  143.     new_cb_stride = new_frame.linesize[1];

  144.     new_cr_stride = new_frame.linesize[2];

  145.     old_y = s->frame.data[0];

  146.     old_cb = s->frame.data[1];

  147.     old_cr = s->frame.data[2];

  148.     old_y_stride = s->frame.linesize[0];

  149.     old_cb_stride = s->frame.linesize[1];

  150.     old_cr_stride = s->frame.linesize[2];

  151. 

  152.     av_log(avctx, AV_LOG_DEBUG,

  153.            "Strides: %i, %i\n",

  154.            new_y_stride, new_cb_stride);

  155. 

  156.     for (block_index = 0; block_index < total_blocks; block_index++) {

  157.         // Note that this call will make us skip the rest of the blocks

  158.         // if the frame prematurely ends

  159.         if (skip == -1)

  160.             skip = decode_skip_count(&gb);

  161. 

  162.         if (skip) {

  163.             if (old_y) {

  164.                 y[0] = old_y[0] / 4;

  165.                 y[1] = old_y[1] / 4;

  166.                 y[2] = old_y[old_y_stride] / 4;

  167.                 y[3] = old_y[old_y_stride+1] / 4;

  168.                 y_base= yb[0];

  169.                 cb = old_cb[0] / 8;

  170.                 cr = old_cr[0] / 8;

  171.             } else {

  172.                 y_base=y[0] = y[1] = y[2] = y[3] = 0;

  173.                 cb = cr = 16;

  174.             }

  175.         } else {

  176.             if (get_bits1(&gb)) {

  177.                 static const uint8_t offset_table[] = {2, 4, 10, 20};

  178.                 static const int8_t sign_table[64][4] =

  179.                     { {0, 0, 0, 0},

  180.                       {-1, 1, 0, 0},

  181.                       {1, -1, 0, 0},

  182.                       {-1, 0, 1, 0},

  183.                       {-1, 1, 1, 0},

  184.                       {0, -1, 1, 0},

  185.                       {1, -1, 1, 0},

  186.                       {-1, -1, 1, 0},

  187.                       {1, 0, -1, 0},

  188.                       {0, 1, -1, 0},

  189.                       {1, 1, -1, 0},

  190.                       {-1, 1, -1, 0},

  191.                       {1, -1, -1, 0},

  192.                       {-1, 0, 0, 1},

  193.                       {-1, 1, 0, 1},

  194.                       {0, -1, 0, 1},

  195. 

  196.                       {0, 0, 0, 0},

  197.                       {1, -1, 0, 1},

  198.                       {-1, -1, 0, 1},

  199.                       {-1, 0, 1, 1},

  200.                       {-1, 1, 1, 1},

  201.                       {0, -1, 1, 1},

  202.                       {1, -1, 1, 1},

  203.                       {-1, -1, 1, 1},

  204.                       {0, 0, -1, 1},

  205.                       {1, 0, -1, 1},

  206.                       {-1, 0, -1, 1},

  207.                       {0, 1, -1, 1},

  208.                       {1, 1, -1, 1},

  209.                       {-1, 1, -1, 1},

  210.                       {0, -1, -1, 1},

  211.                       {1, -1, -1, 1},

  212. 

  213.                       {0, 0, 0, 0},

  214.                       {-1, -1, -1, 1},

  215.                       {1, 0, 0, -1},

  216.                       {0, 1, 0, -1},

  217.                       {1, 1, 0, -1},

  218.                       {-1, 1, 0, -1},

  219.                       {1, -1, 0, -1},

  220.                       {0, 0, 1, -1},

  221.                       {1, 0, 1, -1},

  222.                       {-1, 0, 1, -1},

  223.                       {0, 1, 1, -1},

  224.                       {1, 1, 1, -1},

  225.                       {-1, 1, 1, -1},

  226.                       {0, -1, 1, -1},

  227.                       {1, -1, 1, -1},

  228.                       {-1, -1, 1, -1},

  229. 

  230.                       {0, 0, 0, 0},

  231.                       {1, 0, -1, -1},

  232.                       {0, 1, -1, -1},

  233.                       {1, 1, -1, -1},

  234.                       {-1, 1, -1, -1},

  235.                       {1, -1, -1, -1} };

  236.                 unsigned sign_selector = get_bits(&gb, 6);

  237.                 unsigned difference_selector = get_bits(&gb, 2);

  238.                 y_base = 2 * get_bits(&gb, 5);

  239.                 for (i = 0; i < 4; i++) {

  240.                     y[i] = av_clip((int)y_base + offset_table[difference_selector] *

  241.                                             sign_table[sign_selector][i], 0, 63);

  242.                 }

  243.             } else if (get_bits1(&gb)) {

  244.                 if (get_bits1(&gb)) {

  245.                     y_base = get_bits(&gb, 6);

  246.                 } else {

  247.                     unsigned adjust_index = get_bits(&gb, 3);

  248.                     static const int8_t adjust[] = {-4, -3, -2, -1, 1, 2, 3, 4};

  249.                     y_base = (y_base + adjust[adjust_index]) & 63;

  250.                 }

  251.                 for (i = 0; i < 4; i++)

  252.                     y[i] = y_base;

  253.             }

  254. 

  255.             if (get_bits1(&gb)) {

  256.                 if (get_bits1(&gb)) {

  257.                     cb = get_bits(&gb, 5);

  258.                     cr = get_bits(&gb, 5);

  259.                 } else {

  260.                     unsigned adjust_index = get_bits(&gb, 3);

  261.                     static const int8_t adjust[2][8] =

  262.                         {  { 1, 1, 0, -1, -1, -1,  0,  1 },

  263.                            { 0, 1, 1,  1,  0, -1, -1, -1 } };

  264.                     cb = (cb + adjust[0][adjust_index]) & 31;

  265.                     cr = (cr + adjust[1][adjust_index]) & 31;

  266.                 }

  267.             }

  268.         }

  269.         *yb++= y_base;

  270. 

  271.         new_y[0] = y[0] * 4;

  272.         new_y[1] = y[1] * 4;

  273.         new_y[new_y_stride] = y[2] * 4;

  274.         new_y[new_y_stride + 1] = y[3] * 4;

  275.         *new_cb = cb * 8;

  276.         *new_cr = cr * 8;

  277. 

  278.         if (old_y)

  279.             old_y += 2, old_cb++, old_cr++;

  280.         new_y += 2, new_cb++, new_cr++;

  281.         row_index++;

  282.         if (avctx->width / 2 == row_index) {

  283.             row_index = 0;

  284.             if (old_y) {

  285.                 old_y  += old_y_stride * 2  - avctx->width;

  286.                 old_cb += old_cb_stride - avctx->width / 2;

  287.                 old_cr += old_cr_stride - avctx->width / 2;

  288.             }

  289.             new_y  += new_y_stride * 2  - avctx->width;

  290.             new_cb += new_cb_stride - avctx->width / 2;

  291.             new_cr += new_cr_stride - avctx->width / 2;

  292.         }

  293. 

  294.         skip--;

  295.     }

  296. 

  297.     av_log(avctx, AV_LOG_DEBUG,

  298.            "Escape sizes: %i, %i\n",

  299.            buf_size, get_bits_count(&gb) / 8);

  300. 

  301.     if (s->frame.data[0])

  302.         avctx->release_buffer(avctx, &s->frame);

  303. 

  304.     *(AVFrame*)data = s->frame = new_frame;

  305.     *got_frame = 1;

  306. 

  307.     return buf_size;

  308. }

  309. 

  310. 

  311. AVCodec ff_escape130_decoder = {

  312.     .name           = "escape130",

  313.     .type           = AVMEDIA_TYPE_VIDEO,

  314.     .id             = AV_CODEC_ID_ESCAPE130,

  315.     .priv_data_size = sizeof(Escape130Context),

  316.     .init           = escape130_decode_init,

  317.     .close          = escape130_decode_close,

  318.     .decode         = escape130_decode_frame,

  319.     .capabilities   = CODEC_CAP_DR1,

  320.     .long_name      = NULL_IF_CONFIG_SMALL("Escape 130"),

  321. };