Abstract: To provide a communication apparatus for achieving further improvements in communication quality and power saving effect, without depending on network environments. A portable terminal (211) as a communication apparatus includes: a communication I/F unit (108) performing data transmission/reception with a transmitter apparatus (203) on a communication protocol having flow control such as TCP; a power control unit (106) switching power on and off to the communication I/F unit (108); and a suppression/resumption control unit (104) determining cycle interval Tc and cycle data size Dc according to communication quality required by a communication application program and, per cycle interval Tc, causing data of cycle data size Dc to be transmitted in a burst state, suppressing data transmission from the transmitter apparatus (203), and causing the power control unit (106) to power off the communication I/F unit (108) while the data transmission is suppressed (T2 to T3), using the flow control mechanism.

Abstract: A transmitting side communications device transmits a Delete Payload of an IPsec SA using an ISAKMP SA that satisfies a transmission condition, and more preferably using all ISAKMP SAs that exist between communications devices. The receiving side communications device accepts a Delete Payload by an ISAKMP SA that satisfies a reception condition, and preferably any ISAKMP SA that exists between the communications devices. As long as there exists an IPsec SA that was established using the ISAKMP SA, it remains possible to maintain an ISAKMP SA, without completely deleting it, and to transmit and receive a Delete Payload by that ISAKMP SA.

Abstract: An encryption information determination section in a communication device negotiates an encryption algorithm to be used for encrypted communications with an encryption information determination section in a network camera, which is a communication counterpart. At this time, the encryption algorithm to be selected is varied depending on the CPU load of the communication device. That is, if the CPU utilization rate is high, a low-load encryption algorithm is selected, and if the CPU utilization rate is low, a high-load encryption algorithm is selected. A encryption/decryption processing section performs code processing using the encryption algorithm selected by the encryption information determination section.

Abstract: A transmitting side communications device transmits a Delete Payload of an IPsec SA using an ISAKMP SA that satisfies a transmission condition, and more preferably using all ISAKMP SAs that exist between communications devices. The receiving side communications device accepts a Delete Payload by an ISAKMP SA that satisfies a reception condition, and preferably any ISAKMP SA that exists between the communications devices. As long as there exists an IPsec SA that was established using the ISAKMP SA, it remains possible to maintain an ISAKMP SA, without completely deleting it, and to transmit and receive a Delete Payload by that ISAKMP SA.

Abstract: Upon receipt of a public value X from a device A, a device B estimates a time to be taken for calculation of a public value Y and a time to be taken for calculation of a common key K, and then calculates a required operation time Tb required at the device B for a key exchanging process for transmission to the device A to report a response delay time S306 and S307. Then, the device B actually calculates the public value Y and the common key K S309 and S310. Upon receipt of the required operation time Tb, the device A extends a waiting limit (timeout time) for a response from the device B to a time when the required operation time Tb elapses from the reception S311.

Abstract: An encryption information determination section 32 in a communication device 24 negotiates an encryption algorithm to be used for encrypted communications with an encryption information determination section 18 in a network camera 12, which is a communication counterpart. At this time, the encryption algorithm to be selected is varied depending on the CPU load of the communication device 24. That is, if the CPU utilization rate is high, a low-load encryption algorithm is selected, and if the CPU utilization rate is low, a high-load encryption algorithm is selected. A encryption/decyption processing section 38 performs code processing using the encryption algorithm selected by the encryption information determination section 32.

Abstract: A system for generating a digest of a moving image includes a generating section for generating a moving image having a plurality of frames, and for generating an operation signal in response to an input received by the generating section during the generating of the moving image; a priority assigning section for assigning a priority to each of the plurality of frames as a function of the operation signal; a selecting section for selecting at least one image of a plurality of images corresponding to the plurality of frames, based on the priority; and an output section for outputting at least one image selected by the selecting section.

Abstract: A system for generating a digest of a moving image according to the present invention includes: a generating section for generating a moving image having a plurality of frames, and for generating an operation signal in response to an input received by the generating section during the generating of the moving image; a priority assigning section for assigning a priority to each of the plurality of frames as a function of the operation signal; a selecting section for selecting at least one image of a plurality of images corresponding to the plurality of frames, based on the priority; and an output section for outputting at least one image selected by the selecting section.

Abstract: A video for one frame is captured and two adjacent frames are compared, the result of which is detected as a change degree of the video. Then, based on the magnitude of the change degree, it is determined whether a scene change (SC) exists. If an SC exists, it is examined whether its change degree alters rapidly or gradually, to determine the SC as a momentum or gradual SC. For the momentum SC, its determination point is detected as the momentum SC. For the gradual SC, its determination points is detected as the start of the gradual SC, thereafter, its end is detected. According, for one gradual SC, plural SC's are not detected and a midway illegible video is not indicated as an index picture.