Abstract: A system and method for transparently transmitting aural signals across a wide area network (WAN). The system of present invention is connected to one or more of a private branch exchange, a key telephone system, a telephone, a facsimile machine, and a modem, for example. In the case of voice transmission, a user places a telephone call using the same procedure that is used when placing a telephone call over a conventional public switched network. The aural signals are translated into a format that is compatible with the local area network (LAN) and the translated signals are transmitted to a router or a switch that connects the LAN to the WAN. The data is transmitted across the WAN to a router or switch coupled to a second LAN. The data is then sent to a destination central site unit or PC which translates the signal into a format that is compatible with the telephone system connected thereto.

Abstract: A real-time receiver and method for receiving and playing out real-time packetized data are disclosed. The receiver includes a packet transmission fixed delay estimator and a packet transmission variable delay estimator. The fixed delay estimator determines, using packets received up to the current point in a conference, the non-variable portion of observed delays. This non-variable portion is subtracted from each packet's observed delay to obtain a variable delay estimate for that packet. Since variable delays actually drive the buffering time needed at the receiver to achieve smooth playout, the packet variable delay estimates can be used directly to adjust playout delay. Adaptive playout delay is preferably set aggressively low, based on observed packet variable delay estimates, to reduce data latency. Playout delay can be adjusted rapidly upwards when higher packet delays are observed, allowing rapid adaptation to network statistical variations and reducing the frequency of late packets.

Abstract: A system and method for transmitting aural signals across a wide area network (WAN) from a local phone coupled to a computer, e.g., a PC-phone, to a remote phone coupled to a KTS, PBX, or PSTN, for example. This capability is provided by the gateway unit of the present invention. The system of the present invention is quickly installed in a server or a personal computer coupled to a local area network. The system is connected to one or more of a PSTN, a private branch exchange, a key telephone system, a telephone, a facsimile machine, and a modem. In the case of voice transmission, a gateway unit translates received telephony signal into a format that is compatible with the telephone system or equipment connected thereto. The present invention can provide a voice quality that approaches, equals, or exceeds the voice quality of conventional telephone switched networks.

Abstract: In a filmless digital camera, each image is individually evaluated and the compression applied in such manner as to retain maximum quality while fitting the data into the pre-assigned memory. For example, such a camera may have a stated image storage capacity for designated number of images, for example, thirty-two black and white images. In one embodiment of this invention, the image data is generated as analog data and converted into digital data. These data representing one complete image, are divided into small discrete blocks. Each of these blocks is compressed using one of the standard compression methods such as the discrete cosine transform (DCT). Each block of compressed data is then examined and a determination made as to the quality of an image resulting from such compression. If the quality falls below a pre-set standard, the block of data is compressed by an alternate method, for example, by differential coding.

Abstract: The pitch frequency of voice signals in successive time frames at a voice coder may be determined as by (1) Cepstrum analysis (time between successive peak amplitudes in each time frame), (2) harmonic gap analysis (amplitude differences between peaks and troughs of the peak amplitude signals in the frequency spectrum) (3) harmonic matching, (4) filtering of the frequency signals in successive pairs of time frames and the performance of (1)-(3) on the filtered signals to provide pitch interpolation on the first frame in the pair and (5) pitch matching. The amplitude and phase of the pitch frequency and harmonic signals are determined by refined techniques to provide amplitude and phase signals with enhanced resolution.