generateDataDescriptors = function (streamInfo) {
    var descriptor = "";
    descriptor = signature.DATA_DESCRIPTOR +
        // crc-32                          4 bytes
        decToHex(streamInfo['crc32'], 4) +
        // compressed size                 4 bytes
        decToHex(streamInfo['compressedSize'], 4) +
        // uncompressed size               4 bytes
        decToHex(streamInfo['uncompressedSize'], 4);

    return descriptor;
}
Generate data descriptors for a file entry.
@param {Object} streamInfo the hash generated by a worker, containing informations
on the file entry.
@return {String} the data descriptors.