摘要:
A packet compressor 12 operates under a reliable mode or an optimistic mode. A mode determination unit 31 counts the number of ACK packets or NACK packets received by a unit time X by an ACK/NACK packet receiver 14. When the counted number of NACK packets is larger than a predetermined value Y, the mode determination unit 31 switches the operation mode of the packet compressor 12 to the reliable mode. When the counted number of ACK packets is larger than a predetermined value Z, the mode determination unit 31 switches the operation mode of the packet compressor 12 to the optimistic mode.
摘要:
Received packets are preserved in a receiving buffer 102; a playback decision section 103 decides 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 pointer 104 for playback; the preserved packets are read and played back according to the pointer 104 for playback. And, the playback orders and the preservation addresses of the preserved packets are memorized in a pointer 106 for preservation; and a media conversion section 107 reads the preserved packets according to the pointer 106 for preservation, and memorizes them after conversion into packets with a form by which the packets may be memorized in a preservation memory 108.
摘要:
In a header decompression apparatus 709, a header decompressor 703 refers to reference information stored in a reference information manager 707 to decompress a compressed header of a packet received by a packet receiver 704. An error detector 702 detects a CRC error in the packet with its header decompressed by the packet receiver 704, and outputs only a correct packet. A successive error counter 705 counts the number of successive errors detected by the error detector 702. A successive decompression success counter 706 counts the number of decompression successes that successively appear. By referring to these counted numbers, an update request unit 708 transmits an update request to a transmitting side as required. The reference information manager 707 manages 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.
摘要:
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.
摘要:
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.
摘要:
In a bit counter 214, an amount of codes included in one transmission unit is counted; in a significance decision section 217, the amount of codes counted in the bit counter 214 is 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 220, 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.
摘要:
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.
摘要:
In a header decompression apparatus 709, a header decompressor 703 refers to reference information stored in a reference information manager 707 to decompress a compressed header of a packet received by a packet receiver 704. An error detector 702 detects a CRC error in the packet with its header decompressed by the packet receiver 704, and outputs only a correct packet. A successive error counter 705 counts the number of successive errors detected by the error detector 702. A successive decompression success counter 706 counts the number of decompression successes that successively appear. By referring to these counted numbers, an update request unit 708 transmits an update request to a transmitting side as required. A reference information manager 707 manages 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.
摘要:
A packet compressor 12 operates under a reliable mode or an optimistic mode. A mode determination unit 31 counts the number of ACK packets or NACK packets received by a unit time X by an ACK/NACK packet receiver 14. When the counted number of NACK packets is larger than a predetermined value Y, the mode determination unit 31 switches the operation mode of the packet compressor 12 to the reliable mode. When the counted number of ACK packets is larger than a predetermined value Z, the mode determination unit 31 switches the operation mode of the packet compressor 12 to the optimistic mode.
摘要:
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.