2.2.1.4 Defined Properties

This section defines the possible properties. Some of the properties are optional, as indicated by the ABNF grammar. Properties that are included in the .nsc file MUST appear in the file in the order that is specified by the ABNF grammar.

Name: Optional. A comma-separated listing of "Machine Name", "Publishing Point Name" for the server that is transmitting the MSB packets.

NSC Format Version: Optional. MUST be set to 3.0.

Multicast Adapter: Optional. If this field is present, it MUST specify the IP address that is used as the source IP address of the MSB Protocol IP multicast packets.

IP Address: The IP address of the multicast group to which the MSB packets are transmitted.

IP Port: The UDP port number to which the MSB packets are addressed.

Time To Live: Optional. If specified, the server MUST set the IPv4 TTL field or IPv6 Hop Count field to this value when transmitting the MSB packets.<1>

Default Ecc: Optional. The maximum number of ASF data packets, not including the ASF parity packet, in an error-correction cycle. This property SHOULD be specified when error correction is used.

Log URL: Optional. The HTTP URL to which the client is supposed to submit logging information during or after the multicast session. If this field is present, it MUST specify an http:// URL and the resource that is identified by the URL MUST be capable of receiving the Windows Media Player logging messages (as specified in [MS-WMLOG]) that are submitted by using an HTTP POST request.

Unicast URL: Optional. Data type: string. The failover URL for a unicast feed when the client fails to receive the multicast. If this field is present, the URL SHOULD be an mms:// or http:// URL, because other URLs cannot be supported by all clients.

Allow Splitting: Optional. The value MUST be 1 if the stream can be split, and it MUST be 0 if it cannot be split. A stream is being split if it is forwarded to multiple recipients or forwarded to multiple IP multicast groups.

Allow Caching: Optional. The value MUST be 1 if the stream can be cached, and it MUST be 0 if it cannot be cached.

Cache Expiration Time: Optional. The time, in seconds, after which cached data is considered expired.

Network Buffer Time: Optional. The network buffer time, in milliseconds.<2> A client SHOULD use the value that is specified by the Network Buffer Time parameter as the amount of multimedia data to keep in the buffer as protection against the effects of network jitter. For example, if the amount of multimedia data that is buffered by a client is determined by some encoding-specific buffering time, plus an additional amount that is intended to protect against the effects of network jitter, then the value that is specified by the Network Buffer Time parameter SHOULD be used as a replacement for only the latter amount.

Format<x>: The Advanced Systems Format (ASF) header that contains the format information about a particular encoded format. The ASF header consists of the entire ASF Header object (as specified in [ASF] section 3.1) plus the 50-byte fixed initial portion of the ASF Data object (as specified in [ASF] section 5.1). When the ASF header is encoded into a sequence of ASCII characters, as specified in "Encoded-Block" Syntax Element (section 2.2.1.3), the Key field of the EncodedDataHeader structure MUST be set to an 11-bit Format ID value. Each ASF header in the .nsc file MUST be identified by a different Format ID value. Any 11-bit sequence number can be used as the Format ID; however, a cryptographically secure hash that is computed over the ASF header is likely to ensure that identical ASF headers are listed only one time in the .nsc file.

Description<x>: Optional. A human-readable string that describes the content that is associated with the ASF header.