Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Matsushita Electrical Industrial Co., Ltd.

Koji Imura

Akihiro Miyazaki

Daiji Ido

Koichi Hata

Carsten Burmeister

Yutaka Machida

Tadamasa Toma

Tsuyoshi Nakamura

Yoshinori Matsui

Youji Notoya

Kohkichi Hashimoto

Naoto Otake

A packet compressoroperates under a reliable mode or an optimistic mode. A mode determination unitcounts the number of ACK packets or NACK packets received by a unit time X by an ACK/NACK packet receiver. When the counted number of NACK packets is larger than a predetermined value Y, the mode determination unitswitches the operation mode of the packet compressorto the reliable mode. When the counted number of ACK packets is larger than a predetermined value Z, the mode determination unitswitches the operation mode of the packet compressorto the optimistic mode.

Method and apparatus for header compression

In a header decompression apparatus, a header decompressorrefers to reference information stored in a reference information managerto decompress a compressed header of a packet received by a packet receiver. An error detectordetects a CRC error in the packet with its header decompressed by the packet receiver, and outputs only a correct packet. A successive error countercounts the number of successive errors detected by the error detector. A successive decompression success countercounts the number of decompression successes that successively appear. By referring to these counted numbers, an update request unittransmits an update request to a transmitting side as required. The reference information managermanages the reference information for header decompression. With this structure, the header decompression apparatus can request update of the reference information based on the state of the error.

Apparatus and method for header decompression

A demultiplexing apparatus includes a data obtainment unit to obtain the MP4 file data, and a decoding unit to demultiplex the MP4 file data obtained by the data obtainment unit into pairs of a moov and a mdat and pairs of a moof and a mdat, and decode those pairs pair-by-pair. A content duration specification unit specifies the content total duration based on the content total duration information contained in the moov of the MP4 file data obtained by the data obtainment unit and a playback unit displays the content total duration specified by the content duration specification unit.

Demultiplexing device

A packet transmission apparatus and method may divide data into a plurality of packets and transmit the packets. At a transmitting end, a context identifying number, identifying a data stream, is selected based on a relationship between a sequence number of a packet that is to be transmitted and a sequence number in an immediately preceding packet. A sequence number denoting an order of a packet divided on a per context basis is compressed, and transmission data assigned to the context identifying number with the compressed sequence number is transmitted on a per packet basis. At the receiving end, the compressed sequence number is decompressed on a per context basis. The context is separated based on the context identifying number, and data is combined by reassembling a packet into the order of a decompressed sequence number.

Packet transmitting/receiving apparatus and packet transmission method

A packet receiving method may include receiving a packet having either a compressed header or a noncompressed header. A packet received with a compressed header is decompressed to regenerate a non-compressed header for the packet. Error detection is performed to detect the presence of an error in a packet: (1) received with a noncompressed header, (2) having a regenerated non-compressed header, or (3) having a replacement non-compressed header. Part of the non-compressed header, in a packet having a regenerated non-compressed header, is replaced with previously stored non-compressed header information, which is known to be correct, when an error is detected in the packet so as to produce a replacement non-compressed header. A packet is output as a correctly received packet when no error is detected in the packet.

Packet receiving apparatus and packet transmission method

Received packets are preserved in a receiving buffer; a playback decision sectiondecides whether the preserved packets are in time for the playback time or not; the playback orders and the preservation addresses of the preserved packets which have been decided to be in time are memorized in a pointerfor playback; the preserved packets are read and played back according to the pointerfor playback. And, the playback orders and the preservation addresses of the preserved packets are memorized in a pointerfor preservation; and a media conversion sectionreads the preserved packets according to the pointerfor preservation, and memorizes them after conversion into packets with a form by which the packets may be memorized in a preservation memory

Data transmitter, data receiver, and data transmitting/receiving method

When an error is detected in a received header, in estimating reference information while assuming an error in a packet receiving interval, a header is decompressed using at least one value of another candidate sequence numbers used in correcting an erroneous sequence number, corresponding to a time that elapses between previously receiving a packet correctly and receiving a current packet and to the packet receiving internal. It is thereby possible to increase a possibility of estimating the reference information correctly and suppress the number of discarded packets at a receiving side, while suppressing increases in introduced processing amount in data transmission with header compression.

Header compressed packet receiving apparatus and method

A data transmitting apparatus and a data receiving apparatus, which are capable of retransmitting a packet even when a retransmission request is made by a client after transmitting a session close notice packet to the client. A session is closed by a session closing meanswhen a predetermined period of time has passed after transmitting the session close notice packet, which is generated by a control command generating meansas the session close notice packet, from a packet transmitting meansto the client.

Data transmitting apparatus and data receiving apparatus

In a bit counter, an amount of codes included in one transmission unit is counted; in a significance decision section, the amount of codes counted in the bit counteris divided by the number of coded macroblocks included in the one transmission unit to calculate an average amount of codes per one coded macroblocks; and in a threshold comparing section, the significance of the pertinent transmission unit is decided by comparing the average amount of codes to the calculated threshold based on a frame rate and a bit rate.

Image coding apparatus and image coding method

A transmission end (header compression end) and a reception end (header decompression end) share the same timestamp calculation information which is previously prepared. At the transmission end, in the case that the timestamp of the current packet to be subjected to header compression cannot be compressed with the current timestamp calculation information, the history record which covers timestamp calculation information previously transmitted is referred to for determining whether to transmit a packet header carrying the timestamp without updating the current timestamp calculation information, or a packet header carrying the timestamp by updating the current timestamp calculation information.

Scheme, apparatus, and program for header compression

In a header decompression apparatusa header decompressorrefers to reference information stored in a reference information managerto decompress a compressed header of a packet received by a packet receiverAn error detectordetects a CRC error in the packet with its header decompressed by the packet receiverand outputs only a correct packet. A successive error countercounts the number of successive errors detected by the error detectorA successive decompression success countercounts the number of decompression successes that successively appear. By referring to these counted numbers, an update request unittransmits an update request to a transmitting side as required. A reference information managermanages the reference information for header decompression. With this structure, the header decompression apparatus can request update of the reference information based on the state of the error.

A data transmittertransmits packets each with a sequence number and a priority added. A data receiverdetects any packet loss by referring to the sequence numbers added to the packets, and if detecting any packet of high priority as having been lost, requests for packet retransmission. Based on information about thus detected packet loss, the data receivergenerates and transmits an RR packetindicating the packet reception state. The data transmitterextracts from the RR packeta packet loss ratio, and therewith, changes manners of priority assignment. The manners are so changed that the packet of high priority is found with a lower ratio when the packet loss ratiois high, and when the packet loss ratiois low, found with a higher ratio.

Transmission apparatus and method for changing data packets priority assignment depending on the reception feedback

In a header decompression apparatus, a header decompressorrefers to reference information stored in a reference information managerto decompress a compressed header of a packet received by a packet receiver. An error detectordetects a CRC error in the packet with its header decompressed by the packet receiver, and outputs only a correct packet. A successive error countercounts the number of successive errors detected by the error detector. A successive decompression success countercounts the number of decompression successes that successively appear. By referring to these counted numbers, an update request unittransmits an update request to a transmitting side as required. A reference information managermanages the reference information for header decompression. With this structure, the header decompression apparatus can request update of the reference information based on the state of the error.

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Koji Imura