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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.     avcodec_get_frame_defaults(&s->frame);

  44. 

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

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

  47.         return AVERROR(EINVAL);

  48.     }

  49. 

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

  51. 

  52.     return 0;

  53. }

  54. 

  55. static av_cold int escape130_decode_close(AVCodecContext *avctx)

  56. {

  57.     Escape130Context *s = avctx->priv_data;

  58. 

  59.     av_frame_unref(&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.     int ret;

  112. 

  113.     uint8_t *old_y, *old_cb, *old_cr,

  114.             *new_y, *new_cb, *new_cr;

  115.     unsigned old_y_stride, old_cb_stride, old_cr_stride,

  116.              new_y_stride, new_cb_stride, new_cr_stride;

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

  118.              block_index, row_index = 0;

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

  120.     unsigned skip = -1;

  121.     unsigned y_base = 0;

  122.     uint8_t *yb= s->bases;

  123. 

  124.     AVFrame *frame = data;

  125. 

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

  127. 

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

  129.         return -1;

  130. 

  131.     // Header; no useful information in here

  132.     skip_bits_long(&gb, 128);

  133. 

  134.     if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)

  135.         return ret;

  136. 

  137.     new_y = frame->data[0];

  138.     new_cb = frame->data[1];

  139.     new_cr = frame->data[2];

  140.     new_y_stride = frame->linesize[0];

  141.     new_cb_stride = frame->linesize[1];

  142.     new_cr_stride = frame->linesize[2];

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

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

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

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

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

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

  149. 

  150.     av_log(avctx, AV_LOG_DEBUG,

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

  152.            new_y_stride, new_cb_stride);

  153. 

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

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

  156.         // if the frame prematurely ends

  157.         if (skip == -1)

  158.             skip = decode_skip_count(&gb);

  159. 

  160.         if (skip) {

  161.             if (old_y) {

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

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

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

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

  166.                 y_base= yb[0];

  167.                 cb = old_cb[0] / 8;

  168.                 cr = old_cr[0] / 8;

  169.             } else {

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

  171.                 cb = cr = 16;

  172.             }

  173.         } else {

  174.             if (get_bits1(&gb)) {

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

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

  177.                     { {0, 0, 0, 0},

  178.                       {-1, 1, 0, 0},

  179.                       {1, -1, 0, 0},

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

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

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

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

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

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

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

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

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

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

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

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

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

  193. 

  194.                       {0, 0, 0, 0},

  195.                       {1, -1, 0, 1},

  196.                       {-1, -1, 0, 1},

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

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

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

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

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

  202.                       {0, 0, -1, 1},

  203.                       {1, 0, -1, 1},

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

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

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

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

  208.                       {0, -1, -1, 1},

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

  210. 

  211.                       {0, 0, 0, 0},

  212.                       {-1, -1, -1, 1},

  213.                       {1, 0, 0, -1},

  214.                       {0, 1, 0, -1},

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

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

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

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

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

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

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

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

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

  224.                       {0, -1, 1, -1},

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

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

  227. 

  228.                       {0, 0, 0, 0},

  229.                       {1, 0, -1, -1},

  230.                       {0, 1, -1, -1},

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

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

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

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

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

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

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

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

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

  240.                 }

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

  242.                 if (get_bits1(&gb)) {

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

  244.                 } else {

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

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

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

  248.                 }

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

  250.                     y[i] = y_base;

  251.             }

  252. 

  253.             if (get_bits1(&gb)) {

  254.                 if (get_bits1(&gb)) {

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

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

  257.                 } else {

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

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

  260.                         {  { 1, 1, 0, -1, -1, -1,  0,  1 },

  261.                            { 0, 1, 1,  1,  0, -1, -1, -1 } };

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

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

  264.                 }

  265.             }

  266.         }

  267.         *yb++= y_base;

  268. 

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

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

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

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

  273.         *new_cb = cb * 8;

  274.         *new_cr = cr * 8;

  275. 

  276.         if (old_y)

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

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

  279.         row_index++;

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

  281.             row_index = 0;

  282.             if (old_y) {

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

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

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

  286.             }

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

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

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

  290.         }

  291. 

  292.         skip--;

  293.     }

  294. 

  295.     av_log(avctx, AV_LOG_DEBUG,

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

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

  298. 

  299.     av_frame_unref(&s->frame);

  300.     if ((ret = av_frame_ref(&s->frame, frame)) < 0)

  301.         return ret;

  302. 

  303.     *got_frame = 1;

  304. 

  305.     return buf_size;

  306. }

  307. 

  308. 

  309. AVCodec ff_escape130_decoder = {

  310.     .name           = "escape130",

  311.     .type           = AVMEDIA_TYPE_VIDEO,

  312.     .id             = AV_CODEC_ID_ESCAPE130,

  313.     .priv_data_size = sizeof(Escape130Context),

  314.     .init           = escape130_decode_init,

  315.     .close          = escape130_decode_close,

  316.     .decode         = escape130_decode_frame,

  317.     .capabilities   = CODEC_CAP_DR1,

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

  319. };