1. Multimedia Retrieval Architecture Electrical Communication Engineering, Indian Institute of Science, Bangalore – 560012, India Multimedia Retrieval Architecture

2. Introduction Multimedia retrieval refers to fetching continuous multimedia data from the disk. Multimedia involves very large amounts of data. Retrieving multimedia needs to be perfectly executed under real-time constraints. Multimedia retrieval scheme:  Step 1: Host CPU send the retrieval request to I/O subsystem.  Step 2: I/O subsystem moves compressed data from disk to memory.  Step 3: Host CPU decompresses the compressed data.  Step 4: Host CPU waits for the ready signal from the display subsystem, and moves the decompressed data from memory to display device and speakers via the display subsystem.

3. Multimedia Retrieval Architecture Multimedia retrieval architecture

4. Multimedia Retrieval Architecture Principles of Multimedia Data Retrieval Client/Server Model:  Servers have resources and information that other components called clients wish to access. Multimedia Server:  Digitally store multimedia content on a large array of high- capacity storage devices referred as multimedia storage.  video, audio, text differ in characteristics, and require different management techniques Multimedia Client  Process which sets-up a multimedia query to extract multimedia information.

5. Multimedia Retrieval Architecture Standard client server model for developing network applications. A server is a process that is offering some service A client is a process that is requesting the service. Server or client may in same machine or running on different machines, Server waits for the request from the client(s)

6. Multimedia Retrieval Architecture Server Client 1 Client 2 Client 3

7. Multimedia Retrieval Architecture Working scenario: The server process starts first Initializes then goes to sleep waiting for a client request. A client process starts Sends request to server. When server process has finished providing its service, server goes back to sleep waiting for the next Client request to arrive. Process repeats.

8. Multimedia Retrieval Architecture Two types of Servers Iterative server Concurrent server

9. Multimedia Retrieval Architecture Iterative servers This is used when the server process knows in advance how long it takes to handle each request and it handles each request itself. Main single copy of server process runs through out Client may have to wait if the serve is busy Service time is small.

10. Multimedia Retrieval Architecture Concurrent server This server is used when amount of work required to handle a request is unknown. Server starts another process to handle each request. A copy of server caters to a client's request in a dedicated fashion, As many copies of server as there are client requests.

11. Multimedia Retrieval Architecture Using TCP or UDP Before start of communication a connection has to be established between 2 hosts. There are 5 components in a connection, Protocol used Source IP address Source port number Destination IP address Destination port number

12. Multimedia Retrieval Architecture Network Application Best way to use some standard and well accepted protocol Data link layer uses—ethernet Network layer—IP Transport layer-TCP Application layer—Berkeley socket interface

13. Multimedia Retrieval Architecture Socket Socket is Berkeley socket distribution achieving inter- process communication over network Allows to communicate one process to another process Association={Protocol, local IP-address, port number, Destination address and port number} Source opens socket destination opens socket, with help of some process communication takes place.

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16. Multimedia Data Retrieval Architecture Sequential retrieval architecture Sequential retrieval architecture serialize read and display (similarly, capture, and store) operations. Each block is transferred from storage to a buffer in client device and then the client processes the date either for display on the monitor or playout After the consumption the sequence retrieval architecture initiates the transfer of the next block. Buffer required is at least two- a read buffer and display buffer.

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18. Pipeline retrieval architecture Pipeline performs read and display operations in parallel. It reads data and transfers data for display. While display is in progress, the second reading is done. This is simultaneous read and display.

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20. Concurrent retrieval architecture Concurrent architecture perform multiple disk read operations in parallel.

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22. Storing Multiple Media Strands Heterogeneous Blocks: Multiple media being recorded are stored within the same block, which may entail additional processing for combining these media during storage, and for separating The advantage of this them during retrieval. scheme is that it provides implicit inter-media synchronization. Homogenous: Blocks: Each block contains exactly one medium. This scheme permits the file system to exploit the properties of each medium to independently optimize its storage. However, the file system must maintain explicit temporal relationships among the media so as to ensure synchronization between them during retrieval.

23. Multimedia Retrieval Architecture For homogeneous blocks, the number of blocks to be retrieved increases with the number of media. Hence, if the duration of playback of audio block is n times that of a video block, an audio block is retrieved from disk for every n video blocks. Hence, the continuity requirement On the other hand, if the duration of audio blocks is identical to that of video blocks (i.e., n = 1), then the continuity requirement reduces to

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