This method triggers the OITF to initiate a download of the content pointed to by the URL and the given content type.
The contentType attribute SHALL reflect the expected type of content returned by the content server when connecting to the URL. The contentType can be used to evaluate if the content type is part of the list of accepted content types of the OITF. For example, if the OITF does not support content type “video/MP2T”, then the registerDownloadURL method could return undefined to indicate this to the application in advance of the download.
If contentType has value “application/vnd.oipf.ContentAccessDownload+xml”, the method SHALL return a download identifier, after which the OITF SHALL immediately fetch the Content Access Download Descriptor, after which the same SHALL happen as if registerDownload() as defined in section 126.96.36.199 with the given Content Access Download Descriptor as argument was called. The downloadStart argument only applies to the individual Download objects described by the Content Access Download Descriptor and SHALL NOT apply to the retrieval of the Content Access Download Descriptor itself.
Note that if the Content Access Download Descriptor contains multiple content items to be downloaded, the associated Download objects for each of these content items SHALL have the same value for the “id” value. The associated Download objects can be retrieved through method getDownloads() as defined in section 188.8.131.52.
Returns a String value representing a unique identifier to identify the download, if the given arguments are acceptable by the OITF to trigger a download. If the OITF supports the application/oipfDownloadManager as specified in section 7.4.3, this SHALL be the value of the “id” attribute of the associated Download object(s).
The OITF SHALL guarantee that download identifiers are unique in relation to recording identifiers and CODAsset identifiers.
The method returns undefined if the given arguments are not acceptable by the OITF to trigger a download.