Network media streaming

Details Network media streaming Network media streaming

1999-03-24

2002-05-14

Harrell, Robert B. (Department: 2152)

Electrical computers and digital processing systems: multicomput

Computer-to-computer protocol implementing

Computer-to-computer data streaming

Reexamination Certificate

active

06389473

ABSTRACT:

A computer printout is attached hereto as an appendix in microfiche form and is incorporated herein by reference. The printout comprises executable program files in hexadecimal format. This appendix includes 2 microfiches, containing a total of 138 frames.
FIELD OF THE INVENTION
The present invention relates generally to network data communications, and specifically to real-time multimedia broadcasting over a network.
BACKGROUND OF THE INVENTION
In network broadcasting, data are transmitted over a network in real time from a single transmitting computer to a plurality of clients simultaneously. The network may be a LAN, a WAN, an intranet or a public network such as the Internet. Network broadcasting is most commonly used to stream multimedia data, typically comprising images and sound.
FIG. 1
is a schematic illustration showing a real-time broadcasting system
20
, as is known in the art. One or more input devices
22
(for example, a video camera and/or microphone) are used to generate a multimedia data stream representing an entertainment or informational program to be transmitted to a plurality of clients
30
via a network
28
. Because of bandwidth limitations of the network, the data stream from host
22
must first be compressed by a real-time encoder
24
and then routed to appropriate clients
30
by a broadcast server
26
(since not all clients on the network are necessarily intended to receive the broadcast).
Encoder
24
and server
26
typically comprise high-cost, dedicated computer systems, such as a Sun Station (produced by Sun Microsystems) or a Windows NT server, running suitable RealSystem 5.0 software (produced by RealNetworks Inc., Seattle, Wash.). These dedicated systems are required in order to ensure that the data stream is distributed and received by clients
30
in real time. Similarly, host
22
must typically be connected directly to encoder
24
by a high-speed data link or LAN, and not via the Internet or other narrowband network. Therefore, real-time broadcasting is normally possible only for hosts having a suitable, dedicated encoder and broadcast server and cannot be offered by Internet service providers (ISPs) to their general clientele.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide substantially continuous, high-bandwidth data streaming over a network using common, existing server and network infrastructure.
It is a further object of some aspects of the present invention to provide data broadcasting capability, particularly for multimedia data, without the need for a dedicated broadcast computer system.
It is a further object of some aspects of the present invention to provide apparatus and methods for data broadcasting at reduced cost by comparison with systems known in the art.
It is still another object of some aspects of the present invention to enable a personal computer to remotely broadcast a multimedia program through an Internet service provider (ISP) using common, universally-supported Internet communication protocols.
In preferred embodiments of the present invention, a transmitting computer generates a data stream and broadcasts the data stream via a network server to a plurality of clients. The data stream is divided into a sequence of segments or slices of the data, preferably time slices, wherein the data are preferably compressed. Each slice is preferably assigned a respective slice index. The transmitting computer uploads the sequence of slices to the server substantially in real time, preferably using an Internet protocol, most preferably the File Transfer Protocol (FTP), as is known in the art. The clients download the data stream from the server, preferably using an Internet protocol, as well, most preferably the Hypertext Transfer Protocol (HTTP), or alternatively, using other protocols, such as UDP or RTP, which are similarly known in the art. The clients use the slice indices of the frames to maintain proper synchronization of the playback. The division of the data stream into slices and the inclusion of the slice indices in the data stream to be used by the clients in maintaining synchronization allows the broadcast to go on substantially in real time without the use of special-purpose hardware.
Preferably, each segment or slice is contained in a separate, respective file. Alternatively, the segments or slices may all be contained in a single indexed file, which is streamed to the client in a series of packets, each covering a range of one or more indices. HTTP version
1
.
1
supports this sort of file streaming. Other protocols may also be used for this purpose.
In some preferred embodiments of the present invention, the data stream comprises multimedia data captured or generated by the transmitting computer. The term “multimedia” as used in the context of the present patent application and in the claims refers to images or sound or to data representative of images or of sound or a combination thereof. Multimedia image data may include still images, video, graphics, animation or any combination thereof, including text displayed in conjunction therewith. It will be appreciated, however, that the principles of the present invention may similarly be applied to streaming of other data types.
Preferably, the transmitting computer compresses the frames in the data stream, most preferably using methods of image and audio compression such as those described in U.S. patent application Ser. No. 08/919,027, which is assigned to the assignee of the present patent application and incorporated herein by reference. Alternatively, any suitable methods of compression known in the art may be used. The compressed data are conveyed to the server and thence to the clients, which decompress the data.
In some preferred embodiments of the present invention, the transmitting computer and the clients monitor the uploading and downloading of data to and from the server, respectively, in order to determine the amount of time required to convey each slice and to verify that the slices are conveyed at a sufficient rate. When the data stream comprises multimedia data, the data rate should be generally equal to or faster than the rate at which the data are generated at the transmitting computer.
In some of these preferred embodiments, the transmitting computer and/or the clients each open a plurality of FTP or HTTP links, respectively, with the network server. The slices are transferred over different ones of the links in alternation. Although typically none of the plurality of links has sufficient bandwidth on its own to convey the entire data stream in real time, the combined bandwidths of the plurality of links are generally sufficient for this purpose. Preferably, each of the links is monitored to determine its specific data transfer rate. If the transfer rate of any of the links is below a predetermined minimum, that link is preferably closed, and a new link is opened in its place.
In other preferred embodiments, the slices are provided by the server at multiple resolution or quality levels. Each such level has a different degree of data compression, and thus corresponds to a different data bandwidth requirement. The client or the server monitors the data transfer rate of a data link opened therebetween and selects the level that is appropriate to the link bandwidth. If the monitored data transfer rate changes during transmission, the quality level is preferably reselected accordingly.
Preferably, the transmitting computer monitors the bandwidth of the data stream that it is uploading to the server, and compares the data stream bandwidth to a known or estimated bandwidth of the link or links between the transmitting computer and the server. The transmitting computer preferably compresses the data stream at a compression ratio that is adjusted so as to match the data stream bandwidth to the available link bandwidth, using methods described, for example, in the above-mentioned U.S. patent application Ser. No. 08/919,027.
There is therefore provided, in accordance with a preferred embodiment of t

Affiliated with

Also associated with

Rating

Network media streaming does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Network media streaming, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Network media streaming will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2911181