Broadcast system with a watermark payload

1. A method of processing a data stream comprising:

(a) receiving said data stream including a watermark message encoded within said data stream;

(b) extracting a watermark message identification indicating a type of message included in said watermark message;

(c) decoding the watermark message identification to determine whether the type of message is an emergency alert message or a content identification message;

(d) based on the decoded watermark message identification extracting, from said watermark message, an expiry time value; and

accessing supplementary content based upon said expiry time value; and

(e) based on the decoded watermark message identification, extracting, from said watermark message and as information for identifying content, a first flag, and a second flag, the first flag indicating whether fields associated with a content ID are present in the watermark message, the second flag indicating whether fields associated with a channel ID are present in the watermark message,

further extracting, as the information for identifying content and in a case where the first flag indicates that the fields associated with content ID are present, a third flag which indicates whether a field associated with validity end time of the content ID is present, and

accessing supplementary content based upon said information for identifying content.

2. The method of claim 1 wherein said supplemental content is accessed based upon a broadband network connection.

3. The method of claim 1 wherein said watermark message is an audio watermark.

4. The method of claim 1 wherein said watermark message is a video watermark.

5. A receiver for processing a data stream comprising:

(a) said receiver receiving said data stream including a watermark message encoded within said data stream;

(b) said receiver extracting a watermark message identification indicating a type of message included in said watermark message;

(c) in a case where said watermark message identification indicates that the type of message is an emergency alert message,

said receiver extracting, from said emergency alert message, an expiry time value; and

said receiver accessing supplementary content based upon said expiry time value; and

(d) in a case where said watermark message identification indicates that the type of message is a content identification message,

said receiver extracting, from said content identification message and as information for identifying content, a first flag, and a second flag, the first flag indicating whether fields associated with a content ID are present in the content identification message, the second flag indicating whether fields associated with a channel ID are present in the content identification message,

said receiver further extracting, as the information for identifying content and in a case where the first flag indicates the fields associated with content ID are present, a third flag which indicates whether a field associated with validity end time of the content ID is present, and

said receiver accessing supplementary content based upon said information for identifying content.

6. The receiver of claim 5 wherein said supplemental content is accessed based upon a broadband network connection.

7. The receiver of claim 5 wherein said watermark message is an audio watermark.

8. The receiver of claim 5 wherein said watermark message is a video watermark.