text: /**
   * Loader for Basis Universal GPU Texture Codec.
   *
   * Basis Universal is a "supercompressed" GPU texture and texture video
   * compression system that outputs a highly compressed intermediate file format
   * (.basis) that can be quickly transcoded to a wide variety of GPU texture
   * compression formats.
   *
   * This loader parallelizes the transcoding process across a configurable number
   * of web workers, before transferring the transcoded compressed texture back
   * to the main thread.
   */
  THREE.BasisTextureLoader = function ( manager ) {
  
  	THREE.Loader.call( this, manager );
  
  	this.transcoderPath = '';
  	this.transcoderBinary = null;
  	this.transcoderPending = null;
  
  	this.workerLimit = 4;
  	this.workerPool = [];
  	this.workerNextTaskID = 1;
  	this.workerSourceURL = '';
  	this.workerConfig = null;
  };
  
  THREE.BasisTextureLoader.taskCache = new WeakMap();
  
  THREE.BasisTextureLoader.prototype = Object.assign( Object.create( THREE.Loader.prototype ), {
  
  	constructor: THREE.BasisTextureLoader,
  
  	setTranscoderPath: function ( path ) {
  
  		this.transcoderPath = path;
  
  		return this;
  
  	},
  
  	setWorkerLimit: function ( workerLimit ) {
  
  		this.workerLimit = workerLimit;
  
  		return this;
  
  	},
  
  	detectSupport: function ( renderer ) {
  
  		this.workerConfig = {
  			astcSupported: renderer.extensions.has( 'WEBGL_compressed_texture_astc' ),
  			etc1Supported: renderer.extensions.has( 'WEBGL_compressed_texture_etc1' ),
  			etc2Supported: renderer.extensions.has( 'WEBGL_compressed_texture_etc' ),
  			dxtSupported: renderer.extensions.has( 'WEBGL_compressed_texture_s3tc' ),
  			bptcSupported: renderer.extensions.has( 'EXT_texture_compression_bptc' ),
  			pvrtcSupported: renderer.extensions.has( 'WEBGL_compressed_texture_pvrtc' )
  				|| renderer.extensions.has( 'WEBKIT_WEBGL_compressed_texture_pvrtc' )
  		};
  
  		return this;
  
  	},
  
  	load: function ( url, onLoad, onProgress, onError ) {
  
  		var loader = new THREE.FileLoader( this.manager );
  
  		loader.setResponseType( 'arraybuffer' );
  		loader.setWithCredentials( this.withCredentials );
  
  		var texture = new THREE.CompressedTexture();
  
  		loader.load( url, ( buffer ) => {
  
  			// Check for an existing task using this buffer. A transferred buffer cannot be transferred
  			// again from this thread.
  			if ( THREE.BasisTextureLoader.taskCache.has( buffer ) ) {
  
  				var cachedTask = THREE.BasisTextureLoader.taskCache.get( buffer );
  
  				return cachedTask.promise.then( onLoad ).catch( onError );
  
  			}
  
  			this._createTexture( [ buffer ] )
  				.then( function ( _texture ) {
  
  					texture.copy( _texture );
  					texture.needsUpdate = true;
  
  					if ( onLoad ) onLoad( texture );
  
  				} )
  				.catch( onError );
  
  		}, onProgress, onError );
  
  		return texture;
  
  	},
  
  	/** Low-level transcoding API, exposed for use by THREE.KTX2Loader. */
  	parseInternalAsync: function ( options ) {
  
  		var { levels, hasAlpha, basisFormat } = options;
  
  		var buffers = new Set();
  
  		for ( var i = 0; i < levels.length; i ++ ) {
  
  			buffers.add( levels[ i ].data.buffer );
  
  		}
  
  		return this._createTexture( Array.from( buffers ), { ...options, lowLevel: true } );
  
  	},
  
  	/**
  	 * @param {ArrayBuffer[]} buffers
  	 * @param {object?} config
  	 * @return {Promise<THREE.CompressedTexture>}
  	 */
  	_createTexture: function ( buffers, config ) {
  
  		var worker;
  		var taskID;
  
  		var taskConfig = config || {};
  		var taskCost = 0;
  
  		for ( var i = 0; i < buffers.length; i ++ ) {
  
  			taskCost += buffers[ i ].byteLength;
  
  		}
  
  		var texturePending = this._allocateWorker( taskCost )
  			.then( ( _worker ) => {
  
  				worker = _worker;
  				taskID = this.workerNextTaskID ++;
  
  				return new Promise( ( resolve, reject ) => {
  
  					worker._callbacks[ taskID ] = { resolve, reject };
  
  					worker.postMessage( { type: 'transcode', id: taskID, buffers: buffers, taskConfig: taskConfig }, buffers );
  
  				} );
  
  			} )
  			.then( ( message ) => {
  
  				var config = this.workerConfig;
  
  				var { mipmaps, width, height, format } = message;
  
  				var texture = new THREE.CompressedTexture( mipmaps, width, height, format, THREE.UnsignedByteType );
  				texture.minFilter = mipmaps.length === 1 ? THREE.LinearFilter : THREE.LinearMipmapLinearFilter;
  				texture.magFilter = THREE.LinearFilter;
  				texture.generateMipmaps = false;
  				texture.needsUpdate = true;
  
  				return texture;
  
  			} );
  
  		// Note: replaced '.finally()' with '.catch().then()' block - iOS 11 support (#19416)
  		texturePending
  			.catch( () => true )
  			.then( () => {
  
  				if ( worker && taskID ) {
  
  					worker._taskLoad -= taskCost;
  					delete worker._callbacks[ taskID ];
  
  				}
  
  			} );
  
  		// Cache the task result.
  		THREE.BasisTextureLoader.taskCache.set( buffers[ 0 ], { promise: texturePending } );
  
  		return texturePending;
  
  	},
  
  	_initTranscoder: function () {
  
  		if ( ! this.transcoderPending ) {
  
  			// Load transcoder wrapper.
  			var jsLoader = new THREE.FileLoader( this.manager );
  			jsLoader.setPath( this.transcoderPath );
  			jsLoader.setWithCredentials( this.withCredentials );
  			var jsContent = new Promise( ( resolve, reject ) => {
  
  				jsLoader.load( 'basis_transcoder.js', resolve, undefined, reject );
  
  			} );
  
  			// Load transcoder WASM binary.
  			var binaryLoader = new THREE.FileLoader( this.manager );
  			binaryLoader.setPath( this.transcoderPath );
  			binaryLoader.setResponseType( 'arraybuffer' );
  			binaryLoader.setWithCredentials( this.withCredentials );
  			var binaryContent = new Promise( ( resolve, reject ) => {
  
  				binaryLoader.load( 'basis_transcoder.wasm', resolve, undefined, reject );
  
  			} );
  
  			this.transcoderPending = Promise.all( [ jsContent, binaryContent ] )
  				.then( ( [ jsContent, binaryContent ] ) => {
  
  					var fn = THREE.BasisTextureLoader.BasisWorker.toString();
  
  					var body = [
  						'/* constants */',
  						'var _EngineFormat = ' + JSON.stringify( BasisTextureLoader.EngineFormat ),
  						'var _TranscoderFormat = ' + JSON.stringify( BasisTextureLoader.TranscoderFormat ),
  						'var _BasisFormat = ' + JSON.stringify( BasisTextureLoader.BasisFormat ),
  						'/* basis_transcoder.js */',
  						jsContent,
  						'/* worker */',
  						fn.substring( fn.indexOf( '{' ) + 1, fn.lastIndexOf( '}' ) )
  					].join( '\n' );
  
  					this.workerSourceURL = URL.createObjectURL( new Blob( [ body ] ) );
  					this.transcoderBinary = binaryContent;
  
  				} );
  
  		}
  
  		return this.transcoderPending;
  
  	},
  
  	_allocateWorker: function ( taskCost ) {
  
  		return this._initTranscoder().then( () => {
  
  			if ( this.workerPool.length < this.workerLimit ) {
  
  				var worker = new Worker( this.workerSourceURL );
  
  				worker._callbacks = {};
  				worker._taskLoad = 0;
  
  				worker.postMessage( {
  					type: 'init',
  					config: this.workerConfig,
  					transcoderBinary: this.transcoderBinary,
  				} );
  
  				worker.onmessage = function ( e ) {
  
  					var message = e.data;
  
  					switch ( message.type ) {
  
  						case 'transcode':
  							worker._callbacks[ message.id ].resolve( message );
  							break;
  
  						case 'error':
  							worker._callbacks[ message.id ].reject( message );
  							break;
  
  						default:
  							console.error( 'THREE.BasisTextureLoader: Unexpected message, "' + message.type + '"' );
  
  					}
  
  				};
  
  				this.workerPool.push( worker );
  
  			} else {
  
  				this.workerPool.sort( function ( a, b ) {
  
  					return a._taskLoad > b._taskLoad ? - 1 : 1;
  
  				} );
  
  			}
  
  			var worker = this.workerPool[ this.workerPool.length - 1 ];
  
  			worker._taskLoad += taskCost;
  
  			return worker;
  
  		} );
  
  	},
  
  	dispose: function () {
  
  		for ( var i = 0; i < this.workerPool.length; i ++ ) {
  
  			this.workerPool[ i ].terminate();
  
  		}
  
  		this.workerPool.length = 0;
  
  		return this;
  
  	}
  
  } );
  
  /* CONSTANTS */
  
  THREE.BasisTextureLoader.BasisFormat = {
  	ETC1S: 0,
  	UASTC_4x4: 1,
  };
  
  THREE.BasisTextureLoader.TranscoderFormat = {
  	ETC1: 0,
  	ETC2: 1,
  	BC1: 2,
  	BC3: 3,
  	BC4: 4,
  	BC5: 5,
  	BC7_M6_OPAQUE_ONLY: 6,
  	BC7_M5: 7,
  	PVRTC1_4_RGB: 8,
  	PVRTC1_4_RGBA: 9,
  	ASTC_4x4: 10,
  	ATC_RGB: 11,
  	ATC_RGBA_INTERPOLATED_ALPHA: 12,
  	RGBA32: 13,
  	RGB565: 14,
  	BGR565: 15,
  	RGBA4444: 16,
  };
  
  THREE.BasisTextureLoader.EngineFormat = {
  	RGBAFormat: THREE.RGBAFormat,
  	RGBA_ASTC_4x4_Format: THREE.RGBA_ASTC_4x4_Format,
  	RGBA_BPTC_Format: THREE.RGBA_BPTC_Format,
  	RGBA_ETC2_EAC_Format: THREE.RGBA_ETC2_EAC_Format,
  	RGBA_PVRTC_4BPPV1_Format: THREE.RGBA_PVRTC_4BPPV1_Format,
  	RGBA_S3TC_DXT5_Format: THREE.RGBA_S3TC_DXT5_Format,
  	RGB_ETC1_Format: THREE.RGB_ETC1_Format,
  	RGB_ETC2_Format: THREE.RGB_ETC2_Format,
  	RGB_PVRTC_4BPPV1_Format: THREE.RGB_PVRTC_4BPPV1_Format,
  	RGB_S3TC_DXT1_Format: THREE.RGB_S3TC_DXT1_Format,
  };
  
  
  /* WEB WORKER */
  
  THREE.BasisTextureLoader.BasisWorker = function () {
  
  	var config;
  	var transcoderPending;
  	var BasisModule;
  
  	var EngineFormat = _EngineFormat; // eslint-disable-line no-undef
  	var TranscoderFormat = _TranscoderFormat; // eslint-disable-line no-undef
  	var BasisFormat = _BasisFormat; // eslint-disable-line no-undef
  
  	onmessage = function ( e ) {
  
  		var message = e.data;
  
  		switch ( message.type ) {
  
  			case 'init':
  				config = message.config;
  				init( message.transcoderBinary );
  				break;
  
  			case 'transcode':
  				transcoderPending.then( () => {
  
  					try {
  
  						var { width, height, hasAlpha, mipmaps, format } = message.taskConfig.lowLevel
  							? transcodeLowLevel( message.taskConfig )
  							: transcode( message.buffers[ 0 ] );
  
  						var buffers = [];
  
  						for ( var i = 0; i < mipmaps.length; ++ i ) {
  
  							buffers.push( mipmaps[ i ].data.buffer );
  
  						}
  
  						self.postMessage( { type: 'transcode', id: message.id, width, height, hasAlpha, mipmaps, format }, buffers );
  
  					} catch ( error ) {
  
  						console.error( error );
  
  						self.postMessage( { type: 'error', id: message.id, error: error.message } );
  
  					}
  
  				} );
  				break;
  
  		}
  
  	};
  
  	function init( wasmBinary ) {
  
  		transcoderPending = new Promise( ( resolve ) => {
  
  			BasisModule = { wasmBinary, onRuntimeInitialized: resolve };
  			BASIS( BasisModule ); // eslint-disable-line no-undef
  
  		} ).then( () => {
  
  			BasisModule.initializeBasis();
  
  		} );
  
  	}
  
  	function transcodeLowLevel ( taskConfig ) {
  
  		var { basisFormat, width, height, hasAlpha } = taskConfig;
  
  		var { transcoderFormat, engineFormat } = getTranscoderFormat( basisFormat, width, height, hasAlpha );
  
  		var blockByteLength = BasisModule.getBytesPerBlockOrPixel( transcoderFormat );
  
  		assert( BasisModule.isFormatSupported( transcoderFormat ), 'THREE.BasisTextureLoader: Unsupported format.' );
  
  		var mipmaps = [];
  
  		if ( basisFormat === BasisFormat.ETC1S ) {
  
  			var transcoder = new BasisModule.LowLevelETC1SImageTranscoder();
  
  			var { endpointCount, endpointsData, selectorCount, selectorsData, tablesData } = taskConfig.globalData;
  
  			try {
  
  				var ok;
  
  				ok = transcoder.decodePalettes( endpointCount, endpointsData, selectorCount, selectorsData );
  
  				assert( ok, 'THREE.BasisTextureLoader: decodePalettes() failed.' );
  
  				ok = transcoder.decodeTables( tablesData );
  
  				assert( ok, 'THREE.BasisTextureLoader: decodeTables() failed.' );
  
  				for ( var i = 0; i < taskConfig.levels.length; i ++ ) {
  
  					var level = taskConfig.levels[ i ];
  					var imageDesc = taskConfig.globalData.imageDescs[ i ];
  
  					var dstByteLength = getTranscodedImageByteLength( transcoderFormat, level.width, level.height );
  					var dst = new Uint8Array( dstByteLength );
  
  					ok = transcoder.transcodeImage(
  						transcoderFormat,
  						dst, dstByteLength / blockByteLength,
  						level.data,
  						getWidthInBlocks( transcoderFormat, level.width ),
  						getHeightInBlocks( transcoderFormat, level.height ),
  						level.width, level.height, level.index,
  						imageDesc.rgbSliceByteOffset, imageDesc.rgbSliceByteLength,
  						imageDesc.alphaSliceByteOffset, imageDesc.alphaSliceByteLength,
  						imageDesc.imageFlags,
  						hasAlpha,
  						false,
  						0, 0
  					);
  
  					assert( ok, 'THREE.BasisTextureLoader: transcodeImage() failed for level ' + level.index + '.' );
  
  					mipmaps.push( { data: dst, width: level.width, height: level.height } );
  
  				}
  
  			} finally {
  
  				transcoder.delete();
  
  			}
  
  		} else {
  
  			for ( var i = 0; i < taskConfig.levels.length; i ++ ) {
  
  				var level = taskConfig.levels[ i ];
  
  				var dstByteLength = getTranscodedImageByteLength( transcoderFormat, level.width, level.height );
  				var dst = new Uint8Array( dstByteLength );
  
  				var ok = BasisModule.transcodeUASTCImage(
  					transcoderFormat,
  					dst, dstByteLength / blockByteLength,
  					level.data,
  					getWidthInBlocks( transcoderFormat, level.width ),
  					getHeightInBlocks( transcoderFormat, level.height ),
  					level.width, level.height, level.index,
  					0,
  					level.data.byteLength,
  					0,
  					hasAlpha,
  					false,
  					0, 0,
  					-1, -1
  				);
  
  				assert( ok, 'THREE.BasisTextureLoader: transcodeUASTCImage() failed for level ' + level.index + '.' );
  
  				mipmaps.push( { data: dst, width: level.width, height: level.height } );
  
  			}
  
  		}
  
  		return { width, height, hasAlpha, mipmaps, format: engineFormat };
  
  	}
  
  	function transcode( buffer ) {
  
  		var basisFile = new BasisModule.BasisFile( new Uint8Array( buffer ) );
  
  		var basisFormat = basisFile.isUASTC() ? BasisFormat.UASTC_4x4 : BasisFormat.ETC1S;
  		var width = basisFile.getImageWidth( 0, 0 );
  		var height = basisFile.getImageHeight( 0, 0 );
  		var levels = basisFile.getNumLevels( 0 );
  		var hasAlpha = basisFile.getHasAlpha();
  
  		function cleanup() {
  
  			basisFile.close();
  			basisFile.delete();
  
  		}
  
  		var { transcoderFormat, engineFormat } = getTranscoderFormat( basisFormat, width, height, hasAlpha );
  
  		if ( ! width || ! height || ! levels ) {
  
  			cleanup();
  			throw new Error( 'THREE.BasisTextureLoader:	Invalid texture' );
  
  		}
  
  		if ( ! basisFile.startTranscoding() ) {
  
  			cleanup();
  			throw new Error( 'THREE.BasisTextureLoader: .startTranscoding failed' );
  
  		}
  
  		var mipmaps = [];
  
  		for ( var mip = 0; mip < levels; mip ++ ) {
  
  			var mipWidth = basisFile.getImageWidth( 0, mip );
  			var mipHeight = basisFile.getImageHeight( 0, mip );
  			var dst = new Uint8Array( basisFile.getImageTranscodedSizeInBytes( 0, mip, transcoderFormat ) );
  
  			var status = basisFile.transcodeImage(
  				dst,
  				0,
  				mip,
  				transcoderFormat,
  				0,
  				hasAlpha
  			);
  
  			if ( ! status ) {
  
  				cleanup();
  				throw new Error( 'THREE.BasisTextureLoader: .transcodeImage failed.' );
  
  			}
  
  			mipmaps.push( { data: dst, width: mipWidth, height: mipHeight } );
  
  		}
  
  		cleanup();
  
  		return { width, height, hasAlpha, mipmaps, format: engineFormat };
  
  	}
  
  	//
  
  	// Optimal choice of a transcoder target format depends on the Basis format (ETC1S or UASTC),
  	// device capabilities, and texture dimensions. The list below ranks the formats separately
  	// for ETC1S and UASTC.
  	//
  	// In some cases, transcoding UASTC to RGBA32 might be preferred for higher quality (at
  	// significant memory cost) compared to ETC1/2, BC1/3, and PVRTC. The transcoder currently
  	// chooses RGBA32 only as a last resort and does not expose that option to the caller.
  	var FORMAT_OPTIONS = [
  		{
  			if: 'astcSupported',
  			basisFormat: [BasisFormat.UASTC_4x4],
  			transcoderFormat: [TranscoderFormat.ASTC_4x4, TranscoderFormat.ASTC_4x4],
  			engineFormat: [EngineFormat.RGBA_ASTC_4x4_Format, EngineFormat.RGBA_ASTC_4x4_Format],
  			priorityETC1S: Infinity,
  			priorityUASTC: 1,
  			needsPowerOfTwo: false,
  		},
  		{
  			if: 'bptcSupported',
  			basisFormat: [BasisFormat.ETC1S, BasisFormat.UASTC_4x4],
  			transcoderFormat: [TranscoderFormat.BC7_M5, TranscoderFormat.BC7_M5],
  			engineFormat: [EngineFormat.RGBA_BPTC_Format, EngineFormat.RGBA_BPTC_Format],
  			priorityETC1S: 3,
  			priorityUASTC: 2,
  			needsPowerOfTwo: false,
  		},
  		{
  			if: 'dxtSupported',
  			basisFormat: [BasisFormat.ETC1S, BasisFormat.UASTC_4x4],
  			transcoderFormat: [TranscoderFormat.BC1, TranscoderFormat.BC3],
  			engineFormat: [EngineFormat.RGB_S3TC_DXT1_Format, EngineFormat.RGBA_S3TC_DXT5_Format],
  			priorityETC1S: 4,
  			priorityUASTC: 5,
  			needsPowerOfTwo: false,
  		},
  		{
  			if: 'etc2Supported',
  			basisFormat: [BasisFormat.ETC1S, BasisFormat.UASTC_4x4],
  			transcoderFormat: [TranscoderFormat.ETC1, TranscoderFormat.ETC2],
  			engineFormat: [EngineFormat.RGB_ETC2_Format, EngineFormat.RGBA_ETC2_EAC_Format],
  			priorityETC1S: 1,
  			priorityUASTC: 3,
  			needsPowerOfTwo: false,
  		},
  		{
  			if: 'etc1Supported',
  			basisFormat: [BasisFormat.ETC1S, BasisFormat.UASTC_4x4],
  			transcoderFormat: [TranscoderFormat.ETC1, TranscoderFormat.ETC1],
  			engineFormat: [EngineFormat.RGB_ETC1_Format, EngineFormat.RGB_ETC1_Format],
  			priorityETC1S: 2,
  			priorityUASTC: 4,
  			needsPowerOfTwo: false,
  		},
  		{
  			if: 'pvrtcSupported',
  			basisFormat: [BasisFormat.ETC1S, BasisFormat.UASTC_4x4],
  			transcoderFormat: [TranscoderFormat.PVRTC1_4_RGB, TranscoderFormat.PVRTC1_4_RGBA],
  			engineFormat: [EngineFormat.RGB_PVRTC_4BPPV1_Format, EngineFormat.RGBA_PVRTC_4BPPV1_Format],
  			priorityETC1S: 5,
  			priorityUASTC: 6,
  			needsPowerOfTwo: true,
  		},
  	];
  
  	var ETC1S_OPTIONS = FORMAT_OPTIONS.sort( function ( a, b ) { return a.priorityETC1S - b.priorityETC1S; } );
  	var UASTC_OPTIONS = FORMAT_OPTIONS.sort( function ( a, b ) { return a.priorityUASTC - b.priorityUASTC; } );
  
  	function getTranscoderFormat ( basisFormat, width, height, hasAlpha ) {
  
  		var transcoderFormat;
  		var engineFormat;
  
  		var options = basisFormat === BasisFormat.ETC1S ? ETC1S_OPTIONS : UASTC_OPTIONS;
  
  		for ( var i = 0; i < options.length; i ++ ) {
  
  			var opt = options[ i ];
  
  			if ( ! config[ opt.if ] ) continue;
  			if ( ! opt.basisFormat.includes( basisFormat ) ) continue;
  			if ( opt.needsPowerOfTwo && ! ( isPowerOfTwo( width ) && isPowerOfTwo( height ) ) ) continue;
  
  			transcoderFormat = opt.transcoderFormat[ hasAlpha ? 1 : 0 ];
  			engineFormat = opt.engineFormat[ hasAlpha ? 1 : 0 ];
  
  			return { transcoderFormat, engineFormat };
  
  		}
  
  		console.warn( 'THREE.BasisTextureLoader: No suitable compressed texture format found. Decoding to RGBA32.' );
  
  		transcoderFormat = TranscoderFormat.RGBA32;
  		engineFormat = EngineFormat.RGBAFormat;
  
  		return { transcoderFormat, engineFormat };
  
  	}
  
  	function assert ( ok, message ) {
  
  		if ( ! ok ) throw new Error( message );
  
  	}
  
  	function getWidthInBlocks ( transcoderFormat, width ) {
  
  		return Math.ceil( width / BasisModule.getFormatBlockWidth( transcoderFormat ) );
  
  	}
  
  	function getHeightInBlocks ( transcoderFormat, height ) {
  
  		return Math.ceil( height / BasisModule.getFormatBlockHeight( transcoderFormat ) );
  
  	}
  
  	function getTranscodedImageByteLength ( transcoderFormat, width, height ) {
  
  		var blockByteLength = BasisModule.getBytesPerBlockOrPixel( transcoderFormat );
  
  		if ( BasisModule.formatIsUncompressed( transcoderFormat ) ) {
  
  			return width * height * blockByteLength;
  
  		}
  
  		if ( transcoderFormat === TranscoderFormat.PVRTC1_4_RGB
  				|| transcoderFormat === TranscoderFormat.PVRTC1_4_RGBA ) {
  
  			// GL requires extra padding for very small textures:
  			// https://www.khronos.org/registry/OpenGL/extensions/IMG/IMG_texture_compression_pvrtc.txt
  			var paddedWidth = ( width + 3 ) & ~ 3;
  			var paddedHeight = ( height + 3 ) & ~ 3;
  
  			return ( Math.max( 8, paddedWidth ) * Math.max( 8, paddedHeight ) * 4 + 7 ) / 8;
  
  		}
  
  		return ( getWidthInBlocks( transcoderFormat, width )
  			* getHeightInBlocks( transcoderFormat, height )
  			* blockByteLength );
  
  	}
  
  	function isPowerOfTwo ( value ) {
  
  		if ( value <= 2 ) return true;
  
  		return ( value & ( value - 1 ) ) === 0 && value !== 0;
  
  	}
  
  };
  