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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 ALT_BITSTREAM_READER_LE

  25. #include "get_bits.h"

  26. 

  27. typedef struct Escape130Context {

  28.     AVFrame frame;

  29.     uint8_t *bases;

  30. } Escape130Context;

  31. 

  32. static int can_safely_read(GetBitContext* gb, int bits) {

  33.     return get_bits_count(gb) + bits <= gb->size_in_bits;

  34. }

  35. 

  36. /**

  37.  * Initialize the decoder

  38.  * @param avctx decoder context

  39.  * @return 0 success, negative on error

  40.  */

  41. static av_cold int escape130_decode_init(AVCodecContext *avctx)

  42. {

  43.     Escape130Context *s = avctx->priv_data;

  44.     avctx->pix_fmt = PIX_FMT_YUV420P;

  45. 

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

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

  48.         return AVERROR(EINVAL);

  49.     }

  50. 

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

  52. 

  53.     return 0;

  54. }

  55. 

  56. static av_cold int escape130_decode_close(AVCodecContext *avctx)

  57. {

  58.     Escape130Context *s = avctx->priv_data;

  59. 

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

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

  62. 

  63.     av_freep(&s->bases);

  64. 

  65.     return 0;

  66. }

  67. 

  68. static unsigned decode_skip_count(GetBitContext* gb) {

  69.     unsigned value;

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

  71.     // which is within the padding space

  72.     if (!can_safely_read(gb, 1+3))

  73.         return -1;

  74. 

  75.     value = get_bits1(gb);

  76.     if (value)

  77.         return 0;

  78. 

  79.     value = get_bits(gb, 3);

  80.     if (value)

  81.         return value;

  82. 

  83.     value = get_bits(gb, 8);

  84.     if (value)

  85.         return value + 7;

  86. 

  87.     value = get_bits(gb, 15);

  88.     if (value)

  89.         return value + 262;

  90. 

  91.     return -1;

  92. }

  93. 

  94. /**

  95.  * Decode a single frame

  96.  * @param avctx decoder context

  97.  * @param data decoded frame

  98.  * @param data_size size of the decoded frame

  99.  * @param buf input buffer

  100.  * @param buf_size input buffer size

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

  102.  */

  103. static int escape130_decode_frame(AVCodecContext *avctx,

  104.                                   void *data, int *data_size,

  105.                                   AVPacket *avpkt)

  106. {

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

  108.     int buf_size = avpkt->size;

  109.     Escape130Context *s = avctx->priv_data;

  110. 

  111.     GetBitContext gb;

  112.     unsigned i;

  113. 

  114.     uint8_t *old_y, *old_cb, *old_cr,

  115.             *new_y, *new_cb, *new_cr;

  116.     unsigned old_y_stride, old_cb_stride, old_cr_stride,

  117.              new_y_stride, new_cb_stride, new_cr_stride;

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

  119.              block_index, row_index = 0;

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

  121.     unsigned skip = -1;

  122.     unsigned y_base = 0;

  123.     uint8_t *yb= s->bases;

  124. 

  125.     AVFrame new_frame = { { 0 } };

  126. 

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

  128. 

  129.     if (!can_safely_read(&gb, 128))

  130.         return -1;

  131. 

  132.     // Header; no useful information in here

  133.     skip_bits_long(&gb, 128);

  134. 

  135.     new_frame.reference = 3;

  136.     if (avctx->get_buffer(avctx, &new_frame)) {

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

  138.         return -1;

  139.     }

  140. 

  141.     new_y = new_frame.data[0];

  142.     new_cb = new_frame.data[1];

  143.     new_cr = new_frame.data[2];

  144.     new_y_stride = new_frame.linesize[0];

  145.     new_cb_stride = new_frame.linesize[1];

  146.     new_cr_stride = new_frame.linesize[2];

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

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

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

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

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

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

  153. 

  154.     av_log(NULL, AV_LOG_DEBUG,

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

  156.            new_y_stride, new_cb_stride);

  157. 

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

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

  160.         // if the frame prematurely ends

  161.         if (skip == -1)

  162.             skip = decode_skip_count(&gb);

  163. 

  164.         if (skip) {

  165.             if (old_y) {

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

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

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

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

  170.                 y_base= yb[0];

  171.                 cb = old_cb[0] / 8;

  172.                 cr = old_cr[0] / 8;

  173.             } else {

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

  175.                 cb = cr = 16;

  176.             }

  177.         } else {

  178.             if (get_bits1(&gb)) {

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

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

  181.                     { {0, 0, 0, 0},

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  197. 

  198.                       {0, 0, 0, 0},

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

  200.                       {-1, -1, 0, 1},

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

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

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

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

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

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

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

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

  209.                       {0, 1, -1, 1},

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

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

  212.                       {0, -1, -1, 1},

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

  214. 

  215.                       {0, 0, 0, 0},

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

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

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

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

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

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

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

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

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

  225.                       {0, 1, 1, -1},

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

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

  228.                       {0, -1, 1, -1},

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

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

  231. 

  232.                       {0, 0, 0, 0},

  233.                       {1, 0, -1, -1},

  234.                       {0, 1, -1, -1},

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

  236.                       {-1, 1, -1, -1},

  237.                       {1, -1, -1, -1} };

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

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

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

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

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

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

  244.                 }

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

  246.                 if (get_bits1(&gb)) {

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

  248.                 } else {

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

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

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

  252.                 }

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

  254.                     y[i] = y_base;

  255.             }

  256. 

  257.             if (get_bits1(&gb)) {

  258.                 if (get_bits1(&gb)) {

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

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

  261.                 } else {

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

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

  264.                         {  { 1, 1, 0, -1, -1, -1,  0,  1 },

  265.                            { 0, 1, 1,  1,  0, -1, -1, -1 } };

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

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

  268.                 }

  269.             }

  270.         }

  271.         *yb++= y_base;

  272. 

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

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

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

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

  277.         *new_cb = cb * 8;

  278.         *new_cr = cr * 8;

  279. 

  280.         if (old_y)

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

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

  283.         row_index++;

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

  285.             row_index = 0;

  286.             if (old_y) {

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

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

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

  290.             }

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

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

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

  294.         }

  295. 

  296.         skip--;

  297.     }

  298. 

  299.     av_log(NULL, AV_LOG_DEBUG,

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

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

  302. 

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

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

  305. 

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

  307.     *data_size = sizeof(AVFrame);

  308. 

  309.     return buf_size;

  310. }

  311. 

  312. 

  313. AVCodec ff_escape130_decoder = {

  314.     .name           = "escape130",

  315.     .type           = AVMEDIA_TYPE_VIDEO,

  316.     .id             = CODEC_ID_ESCAPE130,

  317.     .priv_data_size = sizeof(Escape130Context),

  318.     .init           = escape130_decode_init,

  319.     .close          = escape130_decode_close,

  320.     .decode         = escape130_decode_frame,

  321.     .capabilities   = CODEC_CAP_DR1,

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

  323. };