# US 2008/0187075 A1 · Data transfer apparatus and transfer control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0187075 A1 - Document ID: US20080187075A1 - Status: Published application - Kind: A1 - Application number: 11/969,763 - Filed: 2008-01-04 - Published: 2008-08-07 - Earliest claimed: 2007-02-06 - Assignees: Canon Kabushiki Kaisha - Inventors: Toshiyuki Nakagawa - Web page: https://patentgrep.com/patent/US20080187075A1 ## CPC - H04L 65/765: {intermediate} - H04L 65/611: for multicast or broadcast (systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06) - H04N 19/107: between spatial and temporal predictive coding, e.g. picture refresh - H04N 19/40: using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A transfer apparatus includes a control unit to execute control such that one or more of received multicast packets are transferred to at least one receiver, a storage unit to store the received multicast packets or the one or more multicast packets to be transferred to the at least one receiver, and a determining unit to determine whether transfer of the stored multicast packet can be started when a multicast subscribe request is received from the receiver. The control unit transfers the multicast packet based on a determination result of the determining unit such that the multicast packet which is to be first transferred to the at least one is a head packet of a frame coded by a first coding technique which does not require information of any other frames when the multicast packet is decoded. ## Claims ### Claim 1 A transfer apparatus configured to receive multicast packets of moving image data transmitted via a network and to transfer the multicast packets to receivers connected to the transfer apparatus via a network, the transfer apparatus including: a control unit configured to execute control such that one or more of the multicast packets are transferred to at least one receiver in response to a multicast subscribe request received by the transfer apparatus from the at least one receiver; a storage unit configured to store the multicast packets or the one or more of the multicast packets to be transferred to the at least one receiver; and a determining unit configured to determine whether transfer of the multicast packet stored in the storage unit can be started when the multicast subscribe request is received from the at least one receiver, wherein the control unit transfers the multicast packet based on a determination result of the determining unit such that the multicast packet which is to be first transferred to the at least one receiver is a head packet of a frame coded by a first coding technique which does not require information of any other frames when the multicast packet is decoded after the multicast packet has been transferred to the at least one receiver. ### Claim 2 (depends on 1) The transfer apparatus according to claim 1, wherein the determining unit determines the multicast packet, which is to be first transferred, based on transfer start information recorded in the multicast packet. ### Claim 3 (depends on 1) The transfer apparatus according to claim 1, wherein the determining unit analyzes payload data of the multicast packet and determines the multicast packet, which is to be first transferred, based on whether the multicast packet is the head packet of the frame coded by the first coding technique. ### Claim 4 A control method for a transfer apparatus configured to receive multicast packets of moving image data transmitted via a network and to transfer the multicast packets to receivers connected to the transfer apparatus via a network, the control method including: executing control such that one or more of the multicast packets are transferred to at least one receiver in response to a multicast subscribe request received by the transfer apparatus from the at least one receiver; storing, in a transmitted and received data buffer, the multicast packets or the one or more of the multicast packets to be transferred to the at least one receiver; and determining whether transfer of the multicast packet stored in the transmitted and received data buffer can be started when the multicast subscribe request is received from the at least one receiver, wherein the multicast packet is transferred in the controlling step based on a determination result of the determining step such that the multicast packet which is to be first transferred to the at least one receiver is a head packet of a frame coded by a first coding technique which does not require information of any other frames when the multicast packet is decoded after the multicast packet has been transferred to the at least one receiver. ### Claim 5 (depends on 4) The control method according to claim 4, wherein the determining step determines the multicast packet, which is to be first transferred, based on transfer start information recorded in the multicast packet. ### Claim 6 (depends on 4) The control method according to claim 4, wherein the determining step analyzes payload data of the multicast packet and determines the multicast packet, which is to be first transferred, based on whether the multicast packet is the head packet of the frame coded by the first coding technique. ### Claim 7 A computer-readable storage medium storing a program causing a computer to execute a control method for a transfer apparatus configured to receive multicast packets of moving image data transmitted via a network and to transfer the multicast packets to receivers connected to the transfer apparatus via a network, the program including: executing control such that one or more of the multicast packets are transferred to at least one receiver in response in response to a multicast subscribe request received by the transfer apparatus from the at least one receiver; storing, in a transmitted and received data buffer, the multicast packets or the one or more of the multicast packets to be transferred to the at least one receiver; and determining whether transfer of the multicast packet stored in the transmitted and received data buffer can be started when the multicast subscribe request is received from the at least one receiver, wherein the multicast packet is transferred in the controlling step based on a determination result of the determining step such that the multicast packet which is to be first transferred to the at least one receiver is a head packet of a frame coded by a first coding technique which does not require information of any other frames when the multicast packet is decoded after the multicast packet has been transferred to the at least one receiver.