dashjs
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A reference client implementation for the playback of MPEG DASH via Javascript and compliant browsers.
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JavaScript
;Object.defineProperty(exports,"__esModule",{value:true});var _FactoryMaker=require('../../core/FactoryMaker');var _FactoryMaker2=_interopRequireDefault(_FactoryMaker);function _interopRequireDefault(obj){return obj&&obj.__esModule?obj:{default:obj};}/**
* Creates an instance of an EBMLParser class which implements a large subset
* of the functionality required to parse Matroska EBML
*
* @param {Object} config object with data member which is the buffer to parse
* @ignore
*/function EBMLParser(config){config=config||{};var instance=void 0;var data=new DataView(config.data);var pos=0;function getPos(){return pos;}function setPos(value){pos=value;}/**
* Consumes an EBML tag from the data stream.
*
* @param {Object} tag to parse, A tag is an object with at least a {number} tag and
* {boolean} required flag.
* @param {boolean} test whether or not the function should throw if a required
* tag is not found
* @return {boolean} whether or not the tag was found
* @throws will throw an exception if a required tag is not found and test
* param is false or undefined, or if the stream is malformed.
* @memberof EBMLParser
*/function consumeTag(tag,test){var found=true;var bytesConsumed=0;var p1=void 0,p2=void 0;if(test===undefined){test=false;}if(tag.tag>0xFFFFFF){if(data.getUint32(pos)!==tag.tag){found=false;}bytesConsumed=4;}else if(tag.tag>0xFFFF){// 3 bytes
p1=data.getUint16(pos);p2=data.getUint8(pos+2);// shift p1 over a byte and add p2
if(p1*256+p2!==tag.tag){found=false;}bytesConsumed=3;}else if(tag.tag>0xFF){if(data.getUint16(pos)!==tag.tag){found=false;}bytesConsumed=2;}else{if(data.getUint8(pos)!==tag.tag){found=false;}bytesConsumed=1;}if(!found&&tag.required&&!test){throw new Error('required tag not found');}if(found){pos+=bytesConsumed;}return found;}/**
* Consumes an EBML tag from the data stream. If the tag is found then this
* function will also remove the size field which follows the tag from the
* data stream.
*
* @param {Object} tag to parse, A tag is an object with at least a {number} tag and
* {boolean} required flag.
* @param {boolean} test whether or not the function should throw if a required
* tag is not found
* @return {boolean} whether or not the tag was found
* @throws will throw an exception if a required tag is not found and test
* param is false or undefined, or if the stream is malformedata.
* @memberof EBMLParser
*/function consumeTagAndSize(tag,test){var found=consumeTag(tag,test);if(found){getMatroskaCodedNum();}return found;}/**
* Consumes an EBML tag from the data stream. If the tag is found then this
* function will also remove the size field which follows the tag from the
* data stream. It will use the value of the size field to parse a binary
* field, using a parser defined in the tag itself
*
* @param {Object} tag to parse, A tag is an object with at least a {number} tag,
* {boolean} required flag, and a parse function which takes a size parameter
* @return {boolean} whether or not the tag was found
* @throws will throw an exception if a required tag is not found,
* or if the stream is malformed
* @memberof EBMLParser
*/function parseTag(tag){var size=void 0;consumeTag(tag);size=getMatroskaCodedNum();return instance[tag.parse](size);}/**
* Consumes an EBML tag from the data stream. If the tag is found then this
* function will also remove the size field which follows the tag from the
* data stream. It will use the value of the size field to skip over the
* entire section of EBML encapsulated by the tag.
*
* @param {Object} tag to parse, A tag is an object with at least a {number} tag, and
* {boolean} required flag
* @param {boolean} test a flag to indicate if an exception should be thrown
* if a required tag is not found
* @return {boolean} whether or not the tag was found
* @throws will throw an exception if a required tag is not found and test is
* false or undefined or if the stream is malformed
* @memberof EBMLParser
*/function skipOverElement(tag,test){var found=consumeTag(tag,test);var headerSize=void 0;if(found){headerSize=getMatroskaCodedNum();pos+=headerSize;}return found;}/**
* Returns and consumes a number encoded according to the Matroska EBML
* specification from the bitstream.
*
* @param {boolean} retainMSB whether or not to retain the Most Significant Bit (the
* first 1). this is usually true when reading Tag IDs.
* @return {number} the decoded number
* @throws will throw an exception if the bit stream is malformed or there is
* not enough data
* @memberof EBMLParser
*/function getMatroskaCodedNum(retainMSB){var bytesUsed=1;var mask=0x80;var maxBytes=8;var extraBytes=-1;var num=0;var ch=data.getUint8(pos);var i=0;for(i=0;i<maxBytes;i+=1){if((ch&mask)===mask){num=retainMSB===undefined?ch&~mask:ch;extraBytes=i;break;}mask>>=1;}for(i=0;i<extraBytes;i+=1,bytesUsed+=1){num=num<<8|0xff&data.getUint8(pos+bytesUsed);}pos+=bytesUsed;return num;}/**
* Returns and consumes a float from the bitstream.
*
* @param {number} size 4 or 8 byte floats are supported
* @return {number} the decoded number
* @throws will throw an exception if the bit stream is malformed or there is
* not enough data
* @memberof EBMLParser
*/function getMatroskaFloat(size){var outFloat=void 0;switch(size){case 4:outFloat=data.getFloat32(pos);pos+=4;break;case 8:outFloat=data.getFloat64(pos);pos+=8;break;}return outFloat;}/**
* Consumes and returns an unsigned int from the bitstream.
*
* @param {number} size 1 to 8 bytes
* @return {number} the decoded number
* @throws will throw an exception if the bit stream is malformed or there is
* not enough data
* @memberof EBMLParser
*/function getMatroskaUint(size){var val=0;for(var i=0;i<size;i+=1){val<<=8;val|=data.getUint8(pos+i)&0xff;}pos+=size;return val;}/**
* Tests whether there is more data in the bitstream for parsing
*
* @return {boolean} whether there is more data to parse
* @memberof EBMLParser
*/function moreData(){return pos<data.byteLength;}instance={getPos:getPos,setPos:setPos,consumeTag:consumeTag,consumeTagAndSize:consumeTagAndSize,parseTag:parseTag,skipOverElement:skipOverElement,getMatroskaCodedNum:getMatroskaCodedNum,getMatroskaFloat:getMatroskaFloat,getMatroskaUint:getMatroskaUint,moreData:moreData};return instance;}EBMLParser.__dashjs_factory_name='EBMLParser';exports.default=_FactoryMaker2.default.getClassFactory(EBMLParser);
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