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.     /**
  73.      * @private {?number}
  74.      */
  75.     this.offset_ = null;
  77.     /**
  78.      * @private {?number}
  79.      */
  80.     this.indent_ = null;
  82.     this.reset();
  83.   }
  85.   /**
  86.    * Emits a closed caption based on the state of the buffer.
  87.    * @param {number} startTime Start time of the cue.
  88.    * @param {number} endTime End time of the cue.
  89.    * @return {?shaka.extern.ICaptionDecoder.ClosedCaption}
  90.    */
  91.   forceEmit(startTime, endTime) {
  92.     const Cea608Memory = shaka.cea.Cea608Memory;
  93.     const stream = `CC${((this.fieldNum_<< 1) | this.channelNum_) + 1}`;
  94.     const topLevelCue = new shaka.text.Cue(
  95.         startTime, endTime, /* payload= */ '');
  96.     topLevelCue.lineInterpretation =
  97.         shaka.text.Cue.lineInterpretation.PERCENTAGE;
  98.     let line = Cea608Memory.ROW_TO_LINE_CONVERSION_.get(this.row_);
  99.     if (line) {
  100.       topLevelCue.line = line;
  101.     }
  102.     if (this.indent_ != null && this.offset_ != null) {
  103.       topLevelCue.position = 10 + Math.min(70, this.indent_ * 10) +
  104.           this.offset_ * 2.5;
  105.     }
  106.     const ret = shaka.cea.CeaUtils.getParsedCaption(
  107.         topLevelCue, stream, this.rows_, startTime, endTime);
  108.     // If the text and its lines are larger than what we can show on the
  109.     // screen, we move the lines up so that the text does not come out of the
  110.     // video.
  111.     if (ret && (this.row_ + ret.cue.nestedCues.length - 3) > 15) {
  112.       const newLinePosition = this.row_ + 3 - ret.cue.nestedCues.length;
  113.       line = Cea608Memory.ROW_TO_LINE_CONVERSION_.get(newLinePosition);
  114.       if (line) {
  115.         topLevelCue.line = line;
  116.       }
  117.     }
  118.     return ret;
  119.   }
  121.   /**
  122.    * Resets the memory buffer.
  123.    */
  124.   reset() {
  125.     this.resetAllRows();
  126.     this.row_ = 1;
  127.   }
  129.   /**
  130.    * @return {number}
  131.    */
  132.   getRow() {
  133.     return this.row_;
  134.   }
  136.   /**
  137.    * @param {number} row
  138.    */
  139.   setRow(row) {
  140.     this.row_ = row;
  141.   }
  143.   /**
  144.    * @return {number}
  145.    */
  146.   getScrollSize() {
  147.     return this.scrollRows_;
  148.   }
  150.   /**
  151.    * @param {number} scrollRows
  152.    */
  153.   setScrollSize(scrollRows) {
  154.     this.scrollRows_ = scrollRows;
  155.   }
  157.   /**
  158.    * Adds a character to the buffer.
  159.    * @param {!shaka.cea.Cea608Memory.CharSet} set Character set.
  160.    * @param {number} b CC byte to add.
  161.    */
  162.   addChar(set, b) {
  163.     // Valid chars are in the range [0x20, 0x7f]
  164.     if (b < 0x20 || b > 0x7f) {
  165.       return;
  166.     }
  168.     let char = '';
  169.     switch (set) {
  170.       case shaka.cea.Cea608Memory.CharSet.BASIC_NORTH_AMERICAN:
  171.         if (shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars.has(b)) {
  172.           char =
  173.                 shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars.get(b);
  174.         } else {
  175.           // Regular ASCII
  176.           char = String.fromCharCode(b);
  177.         }
  178.         break;
  179.       case shaka.cea.Cea608Memory.CharSet.SPECIAL_NORTH_AMERICAN:
  180.         char =
  181.               shaka.cea.Cea608Memory.CharSet.SpecialNorthAmericanChars.get(b);
  182.         break;
  183.       case shaka.cea.Cea608Memory.CharSet.SPANISH_FRENCH:
  184.         // Extended charset does a BS over preceding char, 6.4.2 EIA-608-B.
  185.         this.eraseChar();
  186.         char =
  187.               shaka.cea.Cea608Memory.CharSet.ExtendedSpanishFrench.get(b);
  188.         break;
  189.       case shaka.cea.Cea608Memory.CharSet.PORTUGUESE_GERMAN:
  190.         this.eraseChar();
  191.         char =
  192.               shaka.cea.Cea608Memory.CharSet.ExtendedPortugueseGerman.get(b);
  193.         break;
  194.     }
  196.     if (char) {
  197.       const styledChar = new shaka.cea.CeaUtils.StyledChar(
  198.           char, this.underline_, this.italics_,
  199.           this.backgroundColor_, this.textColor_);
  200.       this.rows_[this.row_].push(styledChar);
  201.     }
  202.   }
  204.   /**
  205.    * Erases a character from the buffer.
  206.    */
  207.   eraseChar() {
  208.     this.rows_[this.row_].pop();
  209.   }
  211.   /**
  212.    * Moves rows of characters.
  213.    * @param {number} dst Destination row index.
  214.    * @param {number} src Source row index.
  215.    * @param {number} count Count of rows to move.
  216.    */
  217.   moveRows(dst, src, count) {
  218.     if (src < 0 || dst < 0) {
  219.       return;
  220.     }
  222.     if (dst >= src) {
  223.       for (let i = count-1; i >= 0; i--) {
  224.         this.rows_[dst + i] = this.rows_[src + i].map((e) => e);
  225.       }
  226.     } else {
  227.       for (let i = 0; i < count; i++) {
  228.         this.rows_[dst + i] = this.rows_[src + i].map((e) => e);
  229.       }
  230.     }
  231.   }
  233.   /**
  234.    * Resets rows of characters.
  235.    * @param {number} idx Starting index.
  236.    * @param {number} count Count of rows to reset.
  237.    */
  238.   resetRows(idx, count) {
  239.     for (let i = 0; i <= count; i++) {
  240.       this.rows_[idx + i] = [];
  241.     }
  242.   }
  244.   /**
  245.    * Resets the entire memory buffer.
  246.    */
  247.   resetAllRows() {
  248.     this.resetRows(0, shaka.cea.Cea608Memory.CC_ROWS);
  249.   }
  251.   /**
  252.    * Erases entire memory buffer.
  253.    * Doesn't change scroll state or number of rows.
  254.    */
  255.   eraseBuffer() {
  256.     this.row_ = (this.scrollRows_ > 0) ? this.scrollRows_ : 0;
  257.     this.resetAllRows();
  258.   }
  260.   /**
  261.    * @param {boolean} underline
  262.    */
  263.   setUnderline(underline) {
  264.     this.underline_ = underline;
  265.   }
  267.   /**
  268.    * @param {boolean} italics
  269.    */
  270.   setItalics(italics) {
  271.     this.italics_ = italics;
  272.   }
  274.   /**
  275.    * @param {string} color
  276.    */
  277.   setTextColor(color) {
  278.     this.textColor_ = color;
  279.   }
  281.   /**
  282.    * @param {string} color
  283.    */
  284.   setBackgroundColor(color) {
  285.     this.backgroundColor_ = color;
  286.   }
  288.   /**
  289.    * @param {number} offset
  290.    */
  291.   setOffset(offset) {
  292.     this.offset_ = offset;
  293.   }
  295.   /**
  296.    * @param {?number} indent
  297.    */
  298.   setIndent(indent) {
  299.     this.indent_ = indent;
  300.   }
  301. };
  303. /**
  304.  * Maximum number of rows in the buffer.
  305.  * @const {number}
  306.  */
  307. shaka.cea.Cea608Memory.CC_ROWS = 15;
  309. /**
  310.  * Characters sets.
  311.  * @const @enum {number}
  312.  */
  313. shaka.cea.Cea608Memory.CharSet = {
  314.   BASIC_NORTH_AMERICAN: 0,
  315.   SPECIAL_NORTH_AMERICAN: 1,
  316.   SPANISH_FRENCH: 2,
  317.   PORTUGUESE_GERMAN: 3,
  318. };
  320. /**
  321.  * Basic North American char set deviates from ASCII with these exceptions.
  322.  * @private @const {!Map<number, string>}
  323.  */
  324. shaka.cea.Cea608Memory.CharSet.BasicNorthAmericanChars = new Map([
  325.   [0x27, '’'], [0x2a, 'á'], [0x5c, 'é'], [0x5c, 'é'], [0x5e, 'í'], [0x5f, 'ó'],
  326.   [0x60, 'ú'], [0x7b, 'ç'], [0x7c, '÷'], [0x7d, 'Ñ'], [0x7e, 'ñ'], [0x7f, '█'],
  327. ]);
  329. /**
  330.  * Special North American char set.
  331.  * Note: Transparent Space is currently implemented as a regular space.
  332.  * @private @const {!Map<number, string>}
  333.  */
  334. shaka.cea.Cea608Memory.CharSet.SpecialNorthAmericanChars = new Map([
  335.   [0x30, '®'], [0x31, '°'], [0x32, '½'], [0x33, '¿'], [0x34, '™'], [0x35, '¢'],
  336.   [0x36, '£'], [0x37, '♪'], [0x38, 'à'], [0x39, ' '], [0x3a, 'è'], [0x3b, 'â'],
  337.   [0x3c, 'ê'], [0x3d, 'î'], [0x3e, 'ô'], [0x3f, 'û'],
  338. ]);
  340. /**
  341.  * Extended Spanish/Misc/French char set.
  342.  * @private @const {!Map<number, string>}
  343.  */
  344. shaka.cea.Cea608Memory.CharSet.ExtendedSpanishFrench = new Map([
  345.   [0x20, 'Á'], [0x21, 'É'], [0x22, 'Ó'], [0x23, 'Ú'], [0x24, 'Ü'], [0x25, 'ü'],
  346.   [0x26, '‘'], [0x27, '¡'], [0x28, '*'], [0x29, '\''], [0x2a, '─'], [0x2b, '©'],
  347.   [0x2c, '℠'], [0x2d, '·'], [0x2e, '“'], [0x2f, '”'], [0x30, 'À'], [0x31, 'Â'],
  348.   [0x32, 'Ç'], [0x33, 'È'], [0x34, 'Ê'], [0x35, 'Ë'], [0x36, 'ë'], [0x37, 'Î'],
  349.   [0x38, 'Ï'], [0x39, 'ï'], [0x3a, 'Ô'], [0x3b, 'Ù'], [0x3c, 'ù'], [0x3d, 'Û'],
  350.   [0x3e, '«'], [0x3f, '»'],
  351. ]);
  353. /**
  354.  * Extended Portuguese/German/Danish char set.
  355.  * @private @const {!Map<number, string>}
  356.  */
  357. shaka.cea.Cea608Memory.CharSet.ExtendedPortugueseGerman = new Map([
  358.   [0x20, 'Ã'], [0x21, 'ã'], [0x22, 'Í'], [0x23, 'Ì'], [0x24, 'ì'], [0x25, 'Ò'],
  359.   [0x26, 'ò'], [0x27, 'Õ'], [0x28, 'õ'], [0x29, '{'], [0x2a, '}'], [0x2b, '\\'],
  360.   [0x2c, '^'], [0x2d, '_'], [0x2e, '|'], [0x2f, '~'], [0x30, 'Ä'], [0x31, 'ä'],
  361.   [0x32, 'Ö'], [0x33, 'ö'], [0x34, 'ß'], [0x35, '¥'], [0x36, '¤'], [0x37, '│'],
  362.   [0x38, 'Å'], [0x39, 'å'], [0x3a, 'Ø'], [0x3b, 'ø'], [0x3c, '┌'], [0x3d, '┐'],
  363.   [0x3e, '└'], [0x3f, '┘'],
  364. ]);
  366. /**
  367.  * @private @const {!Map<number, number>}
  368.  */
  369. shaka.cea.Cea608Memory.ROW_TO_LINE_CONVERSION_ = new Map([
  370.   [1, 10], [2, 15.33], [3, 20.66], [4, 26], [5, 31.33], [6, 36.66], [7, 42],
  371.   [8, 47.33], [9, 52.66], [10, 58], [11, 63.33], [12, 68.66], [13, 74],
  372.   [14, 79.33], [15, 84.66],
  373. ]);