Source: lib/cea/cea608_memory.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.cea.Cea608Memory');
  9. goog.require('shaka.cea.CeaUtils');
  10. goog.require('shaka.text.Cue');
  13. /**
  14.  * CEA-608 captions memory/buffer.
  15.  */
  16. shaka.cea.Cea608Memory = class {
  17.   /**
  18.    * @param {number} fieldNum Field number.
  19.    * @param {number} channelNum Channel number.
  20.    */
  21.   constructor(fieldNum, channelNum) {
  22.     /**
  23.      * Buffer for storing decoded characters.
  24.      * @private @const {!Array<!Array<!shaka.cea.CeaUtils.StyledChar>>}
  25.      */
  26.     this.rows_ = [];
  28.     /**
  29.      * Current row.
  30.      * @private {number}
  31.      */
  32.     this.row_ = 1;
  34.     /**
  35.      * Number of rows in the scroll window. Used for rollup mode.
  36.      * @private {number}
  37.      */
  38.     this.scrollRows_ = 0;
  40.     /**
  41.      * Field number.
  42.      * @private {number}
  43.      */
  44.     this.fieldNum_ = fieldNum;
  46.     /**
  47.      * Channel number.
  48.      * @private {number}
  49.      */
  50.     this.channelNum_ = channelNum;
  52.     /**
  53.      * @private {boolean}
  54.      */
  55.     this.underline_ = false;
  57.     /**
  58.      * @private {boolean}
  59.      */
  60.     this.italics_ = false;
  62.     /**
  63.      * @private {string}
  64.      */
  65.     this.textColor_ = shaka.cea.CeaUtils.DEFAULT_TXT_COLOR;
  67.     /**
  68.      * @private {string}
  69.      */
  70.     this.backgroundColor_ = shaka.cea.CeaUtils.DEFAULT_BG_COLOR;
  72.     this.reset();
  73.   }
  75.   /**
  76.    * Emits a closed caption based on the state of the buffer.
  77.    * @param {number} startTime Start time of the cue.
  78.    * @param {number} endTime End time of the cue.
  79.    * @return {?shaka.extern.ICaptionDecoder.ClosedCaption}
  80.    */
  81.   forceEmit(startTime, endTime) {
  82.     const stream = `CC${((this.fieldNum_<< 1) | this.channelNum_) + 1}`;
  83.     const topLevelCue = new shaka.text.Cue(
  84.         startTime, endTime, /* payload= */ '');
  85.     topLevelCue.lineInterpretation =
  86.         shaka.text.Cue.lineInterpretation.PERCENTAGE;
  87.     const line = shaka.cea.Cea608Memory.ROW_TO_LINE_CONVERSION_.get(this.row_);
  88.     if (line) {
  89.       topLevelCue.line = line;
  90.     }
  91.     return shaka.cea.CeaUtils.getParsedCaption(
  92.         topLevelCue, stream, this.rows_, startTime, endTime);
  93.   }
  95.   /**
  96.    * Resets the memory buffer.
  97.    */
  98.   reset() {
  99.     this.resetAllRows();
  100.     this.row_ = 1;
  101.   }
  103.   /**
  104.    * @return {number}
  105.    */
  106.   getRow() {
  107.     return this.row_;
  108.   }
  110.   /**
  111.    * @param {number} row
  112.    */
  113.   setRow(row) {
  114.     this.row_ = row;
  115.   }
  117.   /**
  118.    * @return {number}
  119.    */
  120.   getScrollSize() {
  121.     return this.scrollRows_;
  122.   }
  124.   /**
  125.    * @param {number} scrollRows
  126.    */
  127.   setScrollSize(scrollRows) {
  128.     this.scrollRows_ = scrollRows;
  129.   }
  131.   /**
  132.    * Adds a character to the buffer.
  133.    * @param {!shaka.cea.Cea608Memory.CharSet} set Character set.
  134.    * @param {number} b CC byte to add.
  135.    */
  136.   addChar(set, b) {
  137.     // Valid chars are in the range [0x20, 0x7f]
  138.     if (b < 0x20 || b > 0x7f) {
  139.       return;
  140.     }
  142.     let char = '';
  143.     switch (set) {
  144.       case shaka.cea.Cea608Memory.CharSet.BASIC_NORTH_AMERICAN:
  145.         if (shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars.has(b)) {
  146.           char =
  147.                 shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars.get(b);
  148.         } else {
  149.           // Regular ASCII
  150.           char = String.fromCharCode(b);
  151.         }
  152.         break;
  153.       case shaka.cea.Cea608Memory.CharSet.SPECIAL_NORTH_AMERICAN:
  154.         char =
  155.               shaka.cea.Cea608Memory.CharSet.SpecialNorthAmericanChars.get(b);
  156.         break;
  157.       case shaka.cea.Cea608Memory.CharSet.SPANISH_FRENCH:
  158.         // Extended charset does a BS over preceding char, 6.4.2 EIA-608-B.
  159.         this.eraseChar();
  160.         char =
  161.               shaka.cea.Cea608Memory.CharSet.ExtendedSpanishFrench.get(b);
  162.         break;
  163.       case shaka.cea.Cea608Memory.CharSet.PORTUGUESE_GERMAN:
  164.         this.eraseChar();
  165.         char =
  166.               shaka.cea.Cea608Memory.CharSet.ExtendedPortugueseGerman.get(b);
  167.         break;
  168.     }
  170.     if (char) {
  171.       const styledChar = new shaka.cea.CeaUtils.StyledChar(
  172.           char, this.underline_, this.italics_,
  173.           this.backgroundColor_, this.textColor_);
  174.       this.rows_[this.row_].push(styledChar);
  175.     }
  176.   }
  178.   /**
  179.    * Erases a character from the buffer.
  180.    */
  181.   eraseChar() {
  182.     this.rows_[this.row_].pop();
  183.   }
  185.   /**
  186.    * Moves rows of characters.
  187.    * @param {number} dst Destination row index.
  188.    * @param {number} src Source row index.
  189.    * @param {number} count Count of rows to move.
  190.    */
  191.   moveRows(dst, src, count) {
  192.     if (src < 0 || dst < 0) {
  193.       return;
  194.     }
  196.     if (dst >= src) {
  197.       for (let i = count-1; i >= 0; i--) {
  198.         this.rows_[dst + i] = this.rows_[src + i].map((e) => e);
  199.       }
  200.     } else {
  201.       for (let i = 0; i < count; i++) {
  202.         this.rows_[dst + i] = this.rows_[src + i].map((e) => e);
  203.       }
  204.     }
  205.   }
  207.   /**
  208.    * Resets rows of characters.
  209.    * @param {number} idx Starting index.
  210.    * @param {number} count Count of rows to reset.
  211.    */
  212.   resetRows(idx, count) {
  213.     for (let i = 0; i <= count; i++) {
  214.       this.rows_[idx + i] = [];
  215.     }
  216.   }
  218.   /**
  219.    * Resets the entire memory buffer.
  220.    */
  221.   resetAllRows() {
  222.     this.resetRows(0, shaka.cea.Cea608Memory.CC_ROWS);
  223.   }
  225.   /**
  226.    * Erases entire memory buffer.
  227.    * Doesn't change scroll state or number of rows.
  228.    */
  229.   eraseBuffer() {
  230.     this.row_ = (this.scrollRows_ > 0) ? this.scrollRows_ : 0;
  231.     this.resetAllRows();
  232.   }
  234.   /**
  235.    * @param {boolean} underline
  236.    */
  237.   setUnderline(underline) {
  238.     this.underline_ = underline;
  239.   }
  241.   /**
  242.    * @param {boolean} italics
  243.    */
  244.   setItalics(italics) {
  245.     this.italics_ = italics;
  246.   }
  248.   /**
  249.    * @param {string} color
  250.    */
  251.   setTextColor(color) {
  252.     this.textColor_ = color;
  253.   }
  255.   /**
  256.    * @param {string} color
  257.    */
  258.   setBackgroundColor(color) {
  259.     this.backgroundColor_ = color;
  260.   }
  261. };
  263. /**
  264.  * Maximum number of rows in the buffer.
  265.  * @const {number}
  266.  */
  267. shaka.cea.Cea608Memory.CC_ROWS = 15;
  269. /**
  270.  * Characters sets.
  271.  * @const @enum {number}
  272.  */
  273. shaka.cea.Cea608Memory.CharSet = {
  274.   BASIC_NORTH_AMERICAN: 0,
  275.   SPECIAL_NORTH_AMERICAN: 1,
  276.   SPANISH_FRENCH: 2,
  277.   PORTUGUESE_GERMAN: 3,
  278. };
  280. /**
  281.  * Basic North American char set deviates from ASCII with these exceptions.
  282.  * @private @const {!Map<number, string>}
  283.  */
  284. shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars = new Map([
  285.   [0x27, '’'], [0x2a, 'á'], [0x5c, 'é'], [0x5c, 'é'], [0x5e, 'í'], [0x5f, 'ó'],
  286.   [0x60, 'ú'], [0x7b, 'ç'], [0x7c, '÷'], [0x7d, 'Ñ'], [0x7e, 'ñ'], [0x7f, '█'],
  287. ]);
  289. /**
  290.  * Special North American char set.
  291.  * Note: Transparent Space is currently implemented as a regular space.
  292.  * @private @const {!Map<number, string>}
  293.  */
  294. shaka.cea.Cea608Memory.CharSet.SpecialNorthAmericanChars = new Map([
  295.   [0x30, '®'], [0x31, '°'], [0x32, '½'], [0x33, '¿'], [0x34, '™'], [0x35, '¢'],
  296.   [0x36, '£'], [0x37, '♪'], [0x38, 'à'], [0x39, ' '], [0x3a, 'è'], [0x3b, 'â'],
  297.   [0x3c, 'ê'], [0x3d, 'î'], [0x3e, 'ô'], [0x3f, 'û'],
  298. ]);
  300. /**
  301.  * Extended Spanish/Misc/French char set.
  302.  * @private @const {!Map<number, string>}
  303.  */
  304. shaka.cea.Cea608Memory.CharSet.ExtendedSpanishFrench = new Map([
  305.   [0x20, 'Á'], [0x21, 'É'], [0x22, 'Ó'], [0x23, 'Ú'], [0x24, 'Ü'], [0x25, 'ü'],
  306.   [0x26, '‘'], [0x27, '¡'], [0x28, '*'], [0x29, '\''], [0x2a, '─'], [0x2b, '©'],
  307.   [0x2c, '℠'], [0x2d, '·'], [0x2e, '“'], [0x2f, '”'], [0x30, 'À'], [0x31, 'Â'],
  308.   [0x32, 'Ç'], [0x33, 'È'], [0x34, 'Ê'], [0x35, 'Ë'], [0x36, 'ë'], [0x37, 'Î'],
  309.   [0x38, 'Ï'], [0x39, 'ï'], [0x3a, 'Ô'], [0x3b, 'Ù'], [0x3c, 'ù'], [0x3d, 'Û'],
  310.   [0x3e, '«'], [0x3f, '»'],
  311. ]);
  313. /**
  314.  * Extended Portuguese/German/Danish char set.
  315.  * @private @const {!Map<number, string>}
  316.  */
  317. shaka.cea.Cea608Memory.CharSet.ExtendedPortugueseGerman = new Map([
  318.   [0x20, 'Ã'], [0x21, 'ã'], [0x22, 'Í'], [0x23, 'Ì'], [0x24, 'ì'], [0x25, 'Ò'],
  319.   [0x26, 'ò'], [0x27, 'Õ'], [0x28, 'õ'], [0x29, '{'], [0x2a, '}'], [0x2b, '\\'],
  320.   [0x2c, '^'], [0x2d, '_'], [0x2e, '|'], [0x2f, '~'], [0x30, 'Ä'], [0x31, 'ä'],
  321.   [0x32, 'Ö'], [0x33, 'ö'], [0x34, 'ß'], [0x35, '¥'], [0x36, '¤'], [0x37, '│'],
  322.   [0x38, 'Å'], [0x39, 'å'], [0x3a, 'Ø'], [0x3b, 'ø'], [0x3c, '┌'], [0x3d, '┐'],
  323.   [0x3e, '└'], [0x3f, '┘'],
  324. ]);
  326. /**
  327.  * @private @const {!Map<number, number>}
  328.  */
  329. shaka.cea.Cea608Memory.ROW_TO_LINE_CONVERSION_ = new Map([
  330.   [1, 10], [2, 15.33], [3, 20.66], [4, 26], [5, 31.33], [6, 36.66], [7, 42],
  331.   [8, 47.33], [9, 52.66], [10, 58], [11, 63.33], [12, 68.66], [13, 74],
  332.   [14, 79.33], [15, 84.66],
  333. ]);