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');
  11. goog.requireType('shaka.cea.ICaptionDecoder');
  14. /**
  15.  * CEA-608 captions memory/buffer.
  16.  */
  17. shaka.cea.Cea608Memory = class {
  18.   /**
  19.    * @param {number} fieldNum Field number.
  20.    * @param {number} channelNum Channel number.
  21.    */
  22.   constructor(fieldNum, channelNum) {
  23.     /**
  24.      * Buffer for storing decoded characters.
  25.      * @private @const {!Array<!Array<!shaka.cea.CeaUtils.StyledChar>>}
  26.      */
  27.     this.rows_ = [];
  29.     /**
  30.      * Current row.
  31.      * @private {number}
  32.      */
  33.     this.row_ = 1;
  35.     /**
  36.      * Number of rows in the scroll window. Used for rollup mode.
  37.      * @private {number}
  38.      */
  39.     this.scrollRows_ = 0;
  41.     /**
  42.      * Field number.
  43.      * @private {number}
  44.      */
  45.     this.fieldNum_ = fieldNum;
  47.     /**
  48.      * Channel number.
  49.      * @private {number}
  50.      */
  51.     this.channelNum_ = channelNum;
  53.     /**
  54.      * @private {boolean}
  55.      */
  56.     this.underline_ = false;
  58.     /**
  59.      * @private {boolean}
  60.      */
  61.     this.italics_ = false;
  63.     /**
  64.      * @private {string}
  65.      */
  66.     this.textColor_ = shaka.cea.CeaUtils.DEFAULT_TXT_COLOR;
  68.     /**
  69.      * @private {string}
  70.      */
  71.     this.backgroundColor_ = shaka.cea.CeaUtils.DEFAULT_BG_COLOR;
  73.     this.reset();
  74.   }
  76.   /**
  77.    * Emits a closed caption based on the state of the buffer.
  78.    * @param {number} startTime Start time of the cue.
  79.    * @param {number} endTime End time of the cue.
  80.    * @return {?shaka.cea.ICaptionDecoder.ClosedCaption}
  81.    */
  82.   forceEmit(startTime, endTime) {
  83.     const stream = `CC${(this.fieldNum_<< 1) | this.channelNum_ +1}`;
  84.     const topLevelCue = new shaka.text.Cue(
  85.         startTime, endTime, /* payload= */ '');
  86.     return shaka.cea.CeaUtils.getParsedCaption(
  87.         topLevelCue, stream, this.rows_, startTime, endTime);
  88.   }
  90.   /**
  91.    * Resets the memory buffer.
  92.    */
  93.   reset() {
  94.     this.resetAllRows();
  95.     this.row_ = 1;
  96.   }
  98.   /**
  99.    * @return {number}
  100.    */
  101.   getRow() {
  102.     return this.row_;
  103.   }
  105.   /**
  106.    * @param {number} row
  107.    */
  108.   setRow(row) {
  109.     this.row_ = row;
  110.   }
  112.   /**
  113.    * @return {number}
  114.    */
  115.   getScrollSize() {
  116.     return this.scrollRows_;
  117.   }
  119.   /**
  120.    * @param {number} scrollRows
  121.    */
  122.   setScrollSize(scrollRows) {
  123.     this.scrollRows_ = scrollRows;
  124.   }
  126.   /**
  127.    * Adds a character to the buffer.
  128.    * @param {!shaka.cea.Cea608Memory.CharSet} set Character set.
  129.    * @param {number} b CC byte to add.
  130.    */
  131.   addChar(set, b) {
  132.     // Valid chars are in the range [0x20, 0x7f]
  133.     if (b < 0x20 || b > 0x7f) {
  134.       return;
  135.     }
  137.     let char = '';
  138.     switch (set) {
  139.       case shaka.cea.Cea608Memory.CharSet.BASIC_NORTH_AMERICAN:
  140.         if (shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars.has(b)) {
  141.           char =
  142.                 shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars.get(b);
  143.         } else {
  144.           // Regular ASCII
  145.           char = String.fromCharCode(b);
  146.         }
  147.         break;
  148.       case shaka.cea.Cea608Memory.CharSet.SPECIAL_NORTH_AMERICAN:
  149.         char =
  150.               shaka.cea.Cea608Memory.CharSet.SpecialNorthAmericanChars.get(b);
  151.         break;
  152.       case shaka.cea.Cea608Memory.CharSet.SPANISH_FRENCH:
  153.         // Extended charset does a BS over preceding char, 6.4.2 EIA-608-B.
  154.         this.eraseChar();
  155.         char =
  156.               shaka.cea.Cea608Memory.CharSet.ExtendedSpanishFrench.get(b);
  157.         break;
  158.       case shaka.cea.Cea608Memory.CharSet.PORTUGUESE_GERMAN:
  159.         this.eraseChar();
  160.         char =
  161.               shaka.cea.Cea608Memory.CharSet.ExtendedPortugueseGerman.get(b);
  162.         break;
  163.     }
  165.     if (char) {
  166.       const styledChar = new shaka.cea.CeaUtils.StyledChar(
  167.           char, this.underline_, this.italics_,
  168.           this.backgroundColor_, this.textColor_);
  169.       this.rows_[this.row_].push(styledChar);
  170.     }
  171.   }
  173.   /**
  174.    * Erases a character from the buffer.
  175.    */
  176.   eraseChar() {
  177.     this.rows_[this.row_].pop();
  178.   }
  180.   /**
  181.    * Moves rows of characters.
  182.    * @param {number} dst Destination row index.
  183.    * @param {number} src Source row index.
  184.    * @param {number} count Count of rows to move.
  185.    */
  186.   moveRows(dst, src, count) {
  187.     if (src < 0 || dst < 0) {
  188.       return;
  189.     }
  191.     if (dst >= src) {
  192.       for (let i = count-1; i >= 0; i--) {
  193.         this.rows_[dst + i] = this.rows_[src + i].map((e) => e);
  194.       }
  195.     } else {
  196.       for (let i = 0; i < count; i++) {
  197.         this.rows_[dst + i] = this.rows_[src + i].map((e) => e);
  198.       }
  199.     }
  200.   }
  202.   /**
  203.    * Resets rows of characters.
  204.    * @param {number} idx Starting index.
  205.    * @param {number} count Count of rows to reset.
  206.    */
  207.   resetRows(idx, count) {
  208.     for (let i = 0; i <= count; i++) {
  209.       this.rows_[idx + i] = [];
  210.     }
  211.   }
  213.   /**
  214.    * Resets the entire memory buffer.
  215.    */
  216.   resetAllRows() {
  217.     this.resetRows(0, shaka.cea.Cea608Memory.CC_ROWS);
  218.   }
  220.   /**
  221.    * Erases entire memory buffer.
  222.    * Doesn't change scroll state or number of rows.
  223.    */
  224.   eraseBuffer() {
  225.     this.row_ = (this.scrollRows_ > 0) ? this.scrollRows_ : 0;
  226.     this.resetAllRows();
  227.   }
  229.   /**
  230.    * @param {boolean} underline
  231.    */
  232.   setUnderline(underline) {
  233.     this.underline_ = underline;
  234.   }
  236.   /**
  237.    * @param {boolean} italics
  238.    */
  239.   setItalics(italics) {
  240.     this.italics_ = italics;
  241.   }
  243.   /**
  244.    * @param {string} color
  245.    */
  246.   setTextColor(color) {
  247.     this.textColor_ = color;
  248.   }
  250.   /**
  251.    * @param {string} color
  252.    */
  253.   setBackgroundColor(color) {
  254.     this.backgroundColor_ = color;
  255.   }
  256. };
  258. /**
  259.  * Maximum number of rows in the buffer.
  260.  * @const {number}
  261.  */
  262. shaka.cea.Cea608Memory.CC_ROWS = 15;
  264. /**
  265.  * Characters sets.
  266.  * @const @enum {number}
  267.  */
  268. shaka.cea.Cea608Memory.CharSet = {
  269.   BASIC_NORTH_AMERICAN: 0,
  270.   SPECIAL_NORTH_AMERICAN: 1,
  271.   SPANISH_FRENCH: 2,
  272.   PORTUGUESE_GERMAN: 3,
  273. };
  275. /**
  276.  * Basic North American char set deviates from ASCII with these exceptions.
  277.  * @private @const {!Map<number, string>}
  278.  */
  279. shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars = new Map([
  280.   [0x27, '’'], [0x2a, 'á'], [0x5c, 'é'], [0x5c, 'é'], [0x5e, 'í'], [0x5f, 'ó'],
  281.   [0x60, 'ú'], [0x7b, 'ç'], [0x7c, '÷'], [0x7d, 'Ñ'], [0x7e, 'ñ'], [0x7f, '█'],
  282. ]);
  284. /**
  285.  * Special North American char set.
  286.  * Note: Transparent Space is currently implemented as a regular space.
  287.  * @private @const {!Map<number, string>}
  288.  */
  289. shaka.cea.Cea608Memory.CharSet.SpecialNorthAmericanChars = new Map([
  290.   [0x30, '®'], [0x31, '°'], [0x32, '½'], [0x33, '¿'], [0x34, '™'], [0x35, '¢'],
  291.   [0x36, '£'], [0x37, '♪'], [0x38, 'à'], [0x39, '⠀'], [0x3a, 'è'], [0x3b, 'â'],
  292.   [0x3c, 'ê'], [0x3d, 'î'], [0x3e, 'ô'], [0x3f, 'û'],
  293. ]);
  295. /**
  296.  * Extended Spanish/Misc/French char set.
  297.  * @private @const {!Map<number, string>}
  298.  */
  299. shaka.cea.Cea608Memory.CharSet.ExtendedSpanishFrench = new Map([
  300.   [0x20, 'Á'], [0x21, 'É'], [0x22, 'Ó'], [0x23, 'Ú'], [0x24, 'Ü'], [0x25, 'ü'],
  301.   [0x26, '‘'], [0x27, '¡'], [0x28, '*'], [0x29, '\''], [0x2a, '─'], [0x2b, '©'],
  302.   [0x2c, '℠'], [0x2d, '·'], [0x2e, '“'], [0x2f, '”'], [0x30, 'À'], [0x31, 'Â'],
  303.   [0x32, 'Ç'], [0x33, 'È'], [0x34, 'Ê'], [0x35, 'Ë'], [0x36, 'ë'], [0x37, 'Î'],
  304.   [0x38, 'Ï'], [0x39, 'ï'], [0x3a, 'Ô'], [0x3b, 'Ù'], [0x3c, 'ù'], [0x3d, 'Û'],
  305.   [0x3e, '«'], [0x3f, '»'],
  306. ]);
  308. /**
  309.  * Extended Portuguese/German/Danish char set.
  310.  * @private @const {!Map<number, string>}
  311.  */
  312. shaka.cea.Cea608Memory.CharSet.ExtendedPortugueseGerman = new Map([
  313.   [0x20, 'Ã'], [0x21, 'ã'], [0x22, 'Í'], [0x23, 'Ì'], [0x24, 'ì'], [0x25, 'Ò'],
  314.   [0x26, 'ò'], [0x27, 'Õ'], [0x28, 'õ'], [0x29, '{'], [0x2a, '}'], [0x2b, '\\'],
  315.   [0x2c, '^'], [0x2d, '_'], [0x2e, '|'], [0x2f, '~'], [0x30, 'Ä'], [0x31, 'ä'],
  316.   [0x32, 'Ö'], [0x33, 'ö'], [0x34, 'ß'], [0x35, '¥'], [0x36, '¤'], [0x37, '│'],
  317.   [0x38, 'Å'], [0x39, 'å'], [0x3a, 'Ø'], [0x3b, 'ø'], [0x3c, '┌'], [0x3d, '┐'],
  318.   [0x3e, '└'], [0x3f, '┘'],
  319. ]);