content/browser/resources/media/ssrc_info_manager.js

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5
   6
   7 /**
   8  * Get the ssrc if |report| is an ssrc report.
   9  *
  10  * @param {!Object} report The object contains id, type, and stats, where stats
  11  *     is the object containing timestamp and values, which is an array of
  12  *     strings, whose even index entry is the name of the stat, and the odd
  13  *     index entry is the value.
  14  * @return {?string} The ssrc.
  15  */
  16 function GetSsrcFromReport(report) {
  17   if (report.type != 'ssrc') {
  18     console.warn("Trying to get ssrc from non-ssrc report.");
  19     return null;
  20   }
  21
  22   // If the 'ssrc' name-value pair exists, return the value; otherwise, return
  23   // the report id.
  24   // The 'ssrc' name-value pair only exists in an upcoming Libjingle change. Old
  25   // versions use id to refer to the ssrc.
  26   //
  27   // TODO(jiayl): remove the fallback to id once the Libjingle change is rolled
  28   // to Chrome.
  29   if (report.stats && report.stats.values) {
  30     for (var i = 0; i < report.stats.values.length - 1; i += 2) {
  31       if (report.stats.values[i] == 'ssrc') {
  32         return report.stats.values[i + 1];
  33       }
  34     }
  35   }
  36   return report.id;
  37 };
  38
  39 /**
  40  * SsrcInfoManager stores the ssrc stream info extracted from SDP.
  41  */
  42 var SsrcInfoManager = (function() {
  43   'use strict';
  44
  45   /**
  46    * @constructor
  47    */
  48   function SsrcInfoManager() {
  49     /**
  50      * Map from ssrc id to an object containing all the stream properties.
  51      * @type {!Object<!Object<string>>}
  52      * @private
  53      */
  54     this.streamInfoContainer_ = {};
  55
  56     /**
  57      * The string separating attibutes in an SDP.
  58      * @type {string}
  59      * @const
  60      * @private
  61      */
  62     this.ATTRIBUTE_SEPARATOR_ = /[\r,\n]/;
  63
  64     /**
  65      * The regex separating fields within an ssrc description.
  66      * @type {RegExp}
  67      * @const
  68      * @private
  69      */
  70     this.FIELD_SEPARATOR_REGEX_ = / .*:/;
  71
  72     /**
  73      * The prefix string of an ssrc description.
  74      * @type {string}
  75      * @const
  76      * @private
  77      */
  78     this.SSRC_ATTRIBUTE_PREFIX_ = 'a=ssrc:';
  79
  80     /**
  81      * The className of the ssrc info parent element.
  82      * @type {string}
  83      * @const
  84      */
  85     this.SSRC_INFO_BLOCK_CLASS = 'ssrc-info-block';
  86   }
  87
  88   SsrcInfoManager.prototype = {
  89     /**
  90      * Extracts the stream information from |sdp| and saves it.
  91      * For example:
  92      *     a=ssrc:1234 msid:abcd
  93      *     a=ssrc:1234 label:hello
  94      *
  95      * @param {string} sdp The SDP string.
  96      */
  97     addSsrcStreamInfo: function(sdp) {
  98       var attributes = sdp.split(this.ATTRIBUTE_SEPARATOR_);
  99       for (var i = 0; i < attributes.length; ++i) {
 100         // Check if this is a ssrc attribute.
 101         if (attributes[i].indexOf(this.SSRC_ATTRIBUTE_PREFIX_) != 0)
 102           continue;
 103
 104         var nextFieldIndex = attributes[i].search(this.FIELD_SEPARATOR_REGEX_);
 105
 106         if (nextFieldIndex == -1)
 107           continue;
 108
 109         var ssrc = attributes[i].substring(this.SSRC_ATTRIBUTE_PREFIX_.length,
 110                                            nextFieldIndex);
 111         if (!this.streamInfoContainer_[ssrc])
 112           this.streamInfoContainer_[ssrc] = {};
 113
 114         // Make |rest| starting at the next field.
 115         var rest = attributes[i].substring(nextFieldIndex + 1);
 116         var name, value;
 117         while (rest.length > 0) {
 118           nextFieldIndex = rest.search(this.FIELD_SEPARATOR_REGEX_);
 119           if (nextFieldIndex == -1)
 120             nextFieldIndex = rest.length;
 121
 122           // The field name is the string before the colon.
 123           name = rest.substring(0, rest.indexOf(':'));
 124           // The field value is from after the colon to the next field.
 125           value = rest.substring(rest.indexOf(':') + 1, nextFieldIndex);
 126           this.streamInfoContainer_[ssrc][name] = value;
 127
 128           // Move |rest| to the start of the next field.
 129           rest = rest.substring(nextFieldIndex + 1);
 130         }
 131       }
 132     },
 133
 134     /**
 135      * @param {string} sdp The ssrc id.
 136      * @return {!Object<string>} The object containing the ssrc infomation.
 137      */
 138     getStreamInfo: function(ssrc) {
 139       return this.streamInfoContainer_[ssrc];
 140     },
 141
 142     /**
 143      * Populate the ssrc information into |parentElement|, each field as a
 144      * DIV element.
 145      *
 146      * @param {!Element} parentElement The parent element for the ssrc info.
 147      * @param {string} ssrc The ssrc id.
 148      */
 149     populateSsrcInfo: function(parentElement, ssrc) {
 150       if (!this.streamInfoContainer_[ssrc])
 151         return;
 152
 153       parentElement.className = this.SSRC_INFO_BLOCK_CLASS;
 154
 155       var fieldElement;
 156       for (var property in this.streamInfoContainer_[ssrc]) {
 157         fieldElement = document.createElement('div');
 158         parentElement.appendChild(fieldElement);
 159         fieldElement.textContent =
 160             property + ':' + this.streamInfoContainer_[ssrc][property];
 161       }
 162     }
 163   };
 164
 165   return SsrcInfoManager;
 166 })();