Content indexing and searching using content identifiers and associated metadata

1. A method for processing media content, the method comprising:

obtaining media content signals from a computer network;

deriving, at a computing device, content identifiers from perceptible visual or audio content of the content signals;

using, at the computing device, the content identifiers to obtain metadata used to classify the media content signals; and

creating, via the computing device, a searchable index of the media content signals based on the metadata, wherein users access the searchable index on the computer network to submit a search query for the searchable index to retrieve links to the media content signals.

2. The method of claim 1 , wherein the content identifiers are extracted from digital watermarks imperceptibly embedded in the content signals by making imperceptible changes to audio or image signals that comprise the content signals.

3. The method of claim 1 , wherein the content identifiers reference metadata corresponding to the media content signals that is stored in remote locations from the media content signals.

4. The method of claim 2 , wherein the digital watermarks comprises content flags that are used to classify the media content signals in the searchable index.

5. The method of claim 1 , further comprising executing search agents on media content signals from different local computer networks that are each connected to the computer network, the search agents extracting the content identifiers from content signals stored within corresponding local computer networks and providing the metadata for indexing in the searchable index.

6. The method of claim 1 , wherein the identifiers are used to obtain usage rules specifying how the content signals from which the identifiers are extracted are to be indexed or used by the users of the searchable index.

7. The method of claim 1 , wherein the metadata is stored in a database accessible to the users, and users update the metadata in the database by supplying metadata about corresponding content signals that then becomes subsequently accessible to other users that submit search queries for content signals on the computer network.

8. A method for searching for audio or images, the method comprising:

from a location in a distributed computer network, receiving a query for content signals related to a first content signal, wherein the first content signal is part of the query;

receiving a content identifier derived from perceptible audio or image data of the first content signal;

using, at a computer, the content identifier to obtain metadata used to classify the first content signal;

searching, via the computer, a searchable index of media content signals based on the metadata, which forms search criteria for the first content signal; and

returning, via the computer, a set of search results including references to content signals stored in the distributed computer network that correspond to the search criteria.

9. The method of claim 8 , wherein the content identifier is extracted from a digital watermark imperceptibly embedded in the first content signals by making imperceptible changes to audio or image signals that comprise the first content signal.

10. The method of claim 8 , wherein the content identifier references metadata corresponding to the first content signal that is stored in a remote location from the first content signal.

11. The method of claim 9 , wherein the digital watermark comprises a content flag that is used to classify the first content signal as part of the search criteria used to search for related content signals in the searchable index.

12. The method of claim 8 , wherein the searchable index is built by executing search agents within different local computer networks that are each connected to the distributed computer network, the search agents extracting content identifiers from content signals stored within corresponding local computer networks and providing metadata for indexing in the searchable index.

13. The method of claim 8 , wherein the identifier extracted from the first content signal is used to obtain a usage rule specifying how the first content signal is to be used by the users of the searchable index.

14. The method of claim 8 , wherein the metadata is stored in a database accessible to the users, and users update the metadata in the database by supplying metadata about corresponding content signals that then becomes subsequently accessible to other users that submit search queries for content signals on the distributed computer network.

15. A tangible computer-readable medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:

obtaining media content signals from a computer network;

deriving content identifiers from perceptible visual or audio content of the content signals;

using the content identifiers to obtain metadata used to classify the media content signals; and

creating a searchable index of the media content signals based on the metadata, wherein users access the searchable index on the computer network to submit a search query for the searchable index to retrieve links to the media content signals.

16. The tangible computer-readable medium of claim 15 , wherein the content identifiers are extracted from digital watermarks imperceptibly embedded in the content signals by making imperceptible changes to audio or image signals that comprise the content signals.

17. The tangible computer-readable medium of claim 15 , wherein the content identifiers reference metadata corresponding to the media content signals that is stored in remote locations from the media content signals.

18. A tangible computer-readable medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:

receiving, from a location in a distributed computer network, a query for content signals related to a first content signal, wherein the first content signal is part of the query;

receiving a content identifier derived from perceptible audio or image data of the first content signal;

using the content identifier to obtain metadata used to classify the first content signal;

searching a searchable index of media content signals based on the metadata, which forms search criteria for the first content signal; and

returning a set of search results including references to content signals stored in the distributed computer network that correspond to the search criteria.

19. The tangible computer-readable medium of claim 18 , wherein the content identifier is extracted from a digital watermark imperceptibly embedded in the first content signals by making imperceptible changes to audio or image signals that comprise the first content signal.

20. The tangible computer-readable medium of claim 18 , wherein the content identifier references metadata corresponding to the first content signal that is stored in a remote location from the first content signal.