Packet handler of audio data by isochronous mode

• US 6,751,228 B1
• Filed: 03/21/2000
• Issued: 06/15/2004
• Est. Priority Date: 03/23/1999
• Status: Expired due to Term

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Okamura, Kazuhisa
• Primary Examiner(s): Jung, Min
• Application Number:
  US09/532,835
• Time in Patent Office: 1,547 Days
• Field of Search: 370/395.62, 370/412, 370/413, 370/415, 370/503, 370/509, 370/510, 370/512, 370/516, 370/517, 370/519, 370/520, 370/417
• US Class Current: 370/412
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04J 3/0664 unidirectional timestamps
• CPC Class Codes: H04J 3/247 ATM or packet multiplexing
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling

Abstract

A packet receiving apparatus has a plurality of receiving buffers to receive packets from a plurality of transmitting nodes located on a network for reproduction of event sequence data through output channels. The packet contains at least one data block composed of at least one event sequence data and a timestamp added per a predetermined number of data blocks. In the apparatus, an unpacketizing section extracts the event sequence data and the timestamp from the packet. A writing section distributes the extracted event sequence data to the plurality of the receiving buffers for writing the event sequence data into the receiving buffers. A reading section reads out the event sequence data from the receiving buffers in accordance with the extracted timestamp. The receiving buffers are separately allotted to the plurality of the transmitting nodes and are further assigned to channels of the event sequence data contained in each packet of each transmitting node. The writing section distributes the event sequence data of one packet from one transmitting node to a corresponding one of the receiving buffers according to information which is contained in the packet and which identifies the transmitting node and the channel. A patch section allocates the event sequence data read out from the receiving buffers to the output channels according to either of header information contained in the packet and setting information inputted from outside.

Claims

1. A packet receiving apparatus connected to a network for receiving packets transmitted by one or more of transmitting nodes located on the network, said each packet transmitted via an isochronous data transfer per each isochronous cycle, each packet including at least one data block comprised of at least one event sequence data and a timestamp added per a predetermined number of data blocks, the apparatus comprising:

a timestamp output section that retrieves a timestamp from a received packet;

a comparing section that outputs a coincidence pulses signal when a time indicated by the retrieved timestamp coincides with a current time indicated by an internal cycle timer that is synchronized to the network;

a reproduction sampling clock generating section that generates a reproduction sampling clock signal in synchronization with the coincidence pulse signal; and

a data output section having a plurality of buffers for storing one or more of the event sequence data from each data block contained in the packet received, and, in response to the reproduction sampling clock signal, outputting each of the event sequence data stored in each of the buffers per one data block.

2. A packet receiving apparatus connected to a network performing an isochronous data transfer each isochronous cycle for receiving packets transmitted via the isochronous data transfer per each isochronous cycle, said packets received from one or more of transmitting nodes located on the network, the packet including at least one data block comprised of a plurality of event sequence data and a timestamp added per a predetermined number of data blocks, the apparatus comprising:

a timestamp output section that retrieves a timestamp from a packet which is received from one of the transmitting nodes;

a comparing section that outputs a coincidence pulse signal when a time indicated by the timestamp retrieved by the timestamp output section coincides with a current time indicated by an internal cycle timer synchronized to the network performing the isochronous data transfer;

a reproduction sampling clock generating section that generates a reproduction sampling clock in synchronization to the coincidence pulse signal; and

a data output section that has a plurality of receiving buffers for respectively storing the plurality of the event sequence data of each data block contained in the packet received from the transmitting node and that outputs each data block of the plurality of the event sequence data stored in the respective receiving buffers in response to the coincidence pulse signal and the reproduction sampling clock.

3. In a system having a packet receiving apparatus connected to a network, wherein said packet receiving apparatus receives packets transmitted by one or more of transmitting nodes located on the network via an isochronous data transfer per each isochronous cycle, wherein each packet including at least one data block comprised of at least one event sequence data and a timestamp added per a predetermined number of data blocks, and wherein said packet receiving apparatus includes a plurality of buffers, a method for processing the received packets, said method comprising the steps of:

retrieving a timestamp from a received packet;

generating a coincidence pulse signal when a time indicated by the retrieved timestamp coincides with a current time indicated by an internal cycle timer that is synchronized to the network;

generating a reproduction sampling clock signal in synchronization with the coincidence pulse signal; and

using said plurality of buffers, storing one or more of the event sequence data from each data block contained in the packet received; and

in response to the reproduction sampling clock signal, outputting each of the event sequence data stored in each of the buffers per one data block.

4. In a system having a packet receiving apparatus connected to a network performing an isochronous data transfer each isochronous cycle, said packet receiving apparatus receiving packets transmitted via the isochronous data transfer per each isochronous cycle, said packets received from one or more of transmitting nodes located on the network, wherein the packet including at least one data block comprised of a plurality of event sequence data and a timestamp added per a predetermined number of data blocks, and wherein the apparatus includes a plurality of receiving buffers, a method for processing the received packets comprising the steps of:

retrieving a timestamp from a packet which is received from one of the transmitting nodes;

outputting a coincidence pulse signal when a time indicated by the timestamp retrieved coincides with a current time indicated by an internal cycle timer synchronized to the network performing the isochronous data transfer;

generating a reproduction sampling clock in synchronization to the coincidence pulse signal; and

respectively storing into the plurality of receiving buffers the plurality of the event sequence data of each data block contained in the packet received from the transmitting node; and

outputting each data block of the plurality of the event sequence data stored in the respective receiving buffers in response to the coincidence pulse signal and the reproduction sampling clock.

5. A machine-readable medium for use in a packet receiving apparatus connected to a network, wherein said packet receiving apparatus receives packets transmitted by one or more of transmitting nodes located on the network via an isochronous data transfer per each isochronous cycle, wherein each packet including at least one data block comprised of at least one event sequence data and a timestamp added per a predetermined number of data blocks, and wherein said packet receiving apparatus includes a plurality of buffers, said machine-readable medium containing a set of instructions for causing the apparatus to execute the steps of:

retrieving a timestamp from a received packet;

generating a coincidence pulse signal when a time indicated by the retrieved timestamp coincides with a current time indicated by an internal cycle timer that is synchronized to the network;

generating a reproduction sampling clock signal in synchronization with the coincidence pulse signal; and

using said plurality of buffers, storing one or more of the event sequence data from each data block contained in the packet received; and

in response to the reproduction sampling clock signal, outputting each of the event sequence data stored in each of the buffers per one data block.

6. A machine-readable medium for use in a packet receiving apparatus connected to a network performing an isochronous data transfer each isochronous cycle, said packet receiving apparatus receiving packets transmitted via the isochronous data transfer per each isochronous cycle, said packets received from one or more of transmitting nodes located on the network, wherein the packet including at least one data block comprised of a plurality of event sequence data and a timestamp added per a predetermined number of data blocks, and wherein the apparatus includes a plurality of receiving buffers, said machine-readable medium containing instructions for causing the apparatus to execute the steps of:

retrieving a timestamp from a packet which is received from one of the transmitting nodes;

outputting a coincidence pulse signal when a time indicated by the timestamp retrieved coincides with a current time indicated by an internal cycle timer synchronized to the network performing the isochronous data transfer;

generating reproduction sampling clock in synchronization to the coincidence pulse signal; and

respectively storing into the plurality of receiving buffers the plurality of the event sequence data of each data block contained in the packet received from the transmitting node; and

outputting each data block of the plurality of the event sequence data stored in the respective receiving buffers in response to the coincidence pulse signal and the reproduction sampling clock.

7. A packet receiving apparatus connected to a network for receiving packets transmitted from a plurality of transmitting nodes being located on the network, said plurality of transmitting nodes include a synchronous reproduction reference node, wherein the packet includes at least one data block comprised of at least one event sequence data per each sampling period and a timestamp added per a predetermined number of data blocks, the apparatus comprising:

a cycle timer that outputs a cycle time synchronized to the network;

a unpacketizing section that receives packets transmitted from a plurality of transmitting nodes and retrieves the timestamp together with the data blocks from the received packets;

a reproduction sampling clock generating section that generates a reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved by the unpacketizing section from a packet received from the synchronous reproduction reference node;

a buffer that sequentially stores the data blocks retrieved by the unpacketizing section;

a data output section that reads out the data blocks from the buffer in response to the reproduction sampling clock signal received from the reproduction sampling clock generating section, thereby outputting the event sequence data; and

a reproduction time adjust section that adjusts a reading point of the data block from the buffer when a time indicated by the timestamp outputted by the unpacketizing section from the packet of the synchronous reproduction reference node coincides with the cycle time outputted from the cycle timer, thereby controlling the data output section to output the data block corresponding to a time indicated by the timestamp.

8. The packet receiving apparatus according to claim 7, comprising a master apparatus having the receiving buffer, the data output section and control input and output terminal, and one or more of slave apparatus being connected in series to the master apparatus and each having the receiving buffer, the data output section and control input and output terminals, wherein

the master apparatus outputs a control signal from the control output terminal to the slave apparatus when the receiving buffer has no space to store next event sequence data, and wherein

the slave apparatus responds to the control signal inputted from the master apparatus to the control input terminal for storing the next event sequence data into the receiving buffer, the slave apparatus outputting another control signal from the control output terminal to another slave apparatus when the receiving buffer has no space to store event sequence data.

9. The packet receiving apparatus according to claim 8, wherein the master apparatus has the reproduction sampling clock generating section and a clock output terminal such that the master apparatus outputs the event sequence data in response to the reproduction sampling clock and outputs the reproduction sampling clock from the clock output terminal to the slave apparatus, and wherein

the slave apparatus receives the reproduction sampling clock from the clock input terminal, and outputs the event sequence data in response to the reproduction sampling clock received from the master apparatus, the slave apparatus outputting the reproduction sampling clock from the clock output terminal to another slave apparatus.

10. The packet receiving apparatus according to claim 7, comprising a plurality of receiving buffers allotted to a plurality of transmitting nodes for storing the respective event sequence data transmitted from the respective transmitting nodes, and a patch section that allocates the respective event sequence data retrieved from the respective receiving buffers by the data output section to output channels according to either of header information contained in the packet transmitted from each transmitting node or setting information inputted from outside.

11. A packet receiving apparatus connected to a network for receiving packets transmitted from a first and a second transmitting node located on the network, each packet containing at least one data block comprised of one or more of event sequence data per sampling period and a timestamp per a predetermined number of data blocks, the apparatus comprising:

a cycle timer that outputs a cycles time synchronized to the network;

an unpacketizing section that receives packets transmitted from a first and a second transmitting node and retrieves the timestamp together with the data blocks from the received packets;

a reproduction sampling clock generating section that generates a reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved from a packet transmitted from the first transmitting node;

a first buffer that sequentially stores the data blocks of the received packet from the first transmitting node;

a first data output section that reads out the data blocks from the first buffer in accordance with the reproduction sampling clock fed from the reproduction sampling clock generating section, thereby outputting the event sequence data;

a first reproduction time adjust section that adjusts a reading point of the data block from the first buffer when a time indicated by the timestamp from the packet received from the first transmitting node coincides with the cycle time outputted from the cycle timer, thereby controlling the first data output section to output the data block corresponding to a time indicated by the timestamp;

a second buffer that sequentially stores the data blocks of the packet received from the second transmitting node;

a second data output section that reads out the data blocks from the second buffer in accordance with the reproduction signal received from the reproduction sampling clock generation section, therby outputting the event sequence data;

a second reproduction time adjust section that adjusts a reading point of the data block from the second buffer when a time indicated by the timestamp from the packet of the second transmitting node coincides with the cycle time outputted from the cycle timer, thereby controlling the second data output section to output the data block corresponding to a time indicated by the timestamp.

12. A packet receiving apparatus connected to a network for receiving packets transmitted from a plurality of transmitting nodes located on the network, the packet including at least one data block comprised of at least one event sequence data per sampling period and a timestamp per a predetermined number of data blocks, the apparatus comprising:

a cycle timer that outputs a cycle time synchronized to the network;

an unpacketizing section that receives packets from the transmitting nodes and retrieves the timestamp together with the data blocks from the received packets;

a reproduction sampling clock generating section that generates a reproduction sampling clock signal that is synchronized among nodes on the network;

a buffer that sequentially stores the data blocks outputted from the unpacketizing section;

a data output section that reads out the data blocks from the buffer in accordance with the reproduction sampling clock signal received from the reproduction sampling clock generating section, thereby outputting the event sequence data; and

a reproduction time adjust section that adjusts a reading point of the data block of a particular transmitting node from the buffer when a time indicated by the timestamp outputted by the unpacketizing section from the packet of the particular transmitting node and added with an offset time given to the particular transmitting node coincides with the cycle time outputted from the cycle timer, thereby controlling the data output section to output the data block corresponding to a time indicated by the timestamp of the particular transmitting node.

13. The packet receiving apparatus according to claim 12, wherein the reproduction sampling clock generating section generates the reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved a packet received from the transmitting node that is predetermined as a synchronous reproduction reference node.

14. The packet receiving apparatus according to claim 12, further comprising an offset setting section that sets the offset time for each of the transmitting nodes.

15. In a system having a packet receiving apparatus connected to a network for receiving packets transmitted from a plurality of transmitting nodes being located on the network, said plurality of transmitting nodes include a synchronous reproduction reference node, wherein the packet includes at least one data block comprised of at least one event sequence data per each sampling period and a timestamp added per a predetermined number of data blocks, wherein the packet receiving apparatus includes a plurality of buffers for storing data, a method for processing the received packet, said method comprising the steps of:

outputting a cycle time synchronized to the network;

retrieving the timestamp together with the data blocks from the received packet;

generating a reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved from a packet received from the synchronous reproduction reference node;

storing in the buffers the data blocks retrieved from the received packets;

reading out the data blocks from the buffer in accordance with the generated reproduction sampling clock signal; and

adjusting a reading point of the data block from the buffer when a time indicated by the timestamp retrieved from the packet of the synchronous reproduction reference node coincides with the cycle time, thereby controlling the output of the data block corresponding to a time indicated by the timestamp.

16. A machine-readable medium for use in a packet receiving apparatus connected to a network for receiving packets transmitted from a plurality of transmitting nodes being located on the network, said plurality of transmitting nodes include a synchronous reproduction reference node, wherein the packet includes at least one data block comprised of at least one event sequence data per each sampling period and a timestamp added per a predetermined number of data blocks, wherein the packet receiving apparatus includes a plurality of buffers for storing data, a method for processing the received packet, said machine-readable medium containing a set of instructions for causing the apparatus to execute the steps of:

outputting a cycle time synchronized to the network;

retrieving the timestamp together with the data blocks from the received packet;

generation a reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved from a packet received from the synchronous reproduction reference node;

storing in the buffers the data blocks retrieved from the received packets;

reading out the data blocks from the buffer in accordance with the generated reproduction sampling clock signal; and

adjusting a reading point of the data block from the buffer when a time indicated by the timestamp retrieved from the packet of the synchronous reproduction reference node coincides with the cycle time, thereby controlling the output of the data block corresponding to a time indicated by the timestamp.

17. In a system having a packet receiving apparatus connected to a network for receiving packets transmitted from a first and a second transmitting node located on the network, wherein each packet containing at least one data block comprised of one or more of event sequence data per sampling period and a timestamp per a predetermined number of data blocks, and wherein the apparatus includes a first and second buffer, a method for processing the received packets, said method comprising the steps of:

outputting a cycle time synchronized to the network;

retrieving the timestamp together with the data blocks from the received packets;

generating a reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved from a packet transmitted from the first transmitting node;

sequentially storing into the first buffer data blocks retrieved from the received packet from the first transmitting node;

reading out the data blocks from the first buffer in accordance with the reproduction sampling clock signal, thereby outputting the event sequence data;

adjusting a reading point of the data block from the first buffer when a time indicated by the timestamp from the packet received from the first transmitting node coincides with the cycle time outputted from the cycle timer, thereby controlling the output of the data block corresponding to a time indicated by the timestamp;

sequentially storing in the second buffer data blocks of the packet received from the second transmitting node;

reading out the data blocks from the second buffer in accordance with the reproduction sampling clock signal, thereby outputting the event sequence data;

adjust a reading point of the data block from the second buffer when a time indicated by the timestamp from the received from second transmitting node coincides with the cycle time, thereby controlling the output of the data block corresponding to a time indicated by the timestamp.

18. A machine-readable medium for use in a apparatus connected to a network for receiving packets transmitted from a first and a second transmitting node located on the network, wherein each packet containing at least one data block comprised of one or more of event sequence data per sampling period and a timestamp per a predetermined number of data blocks, and wherein the apparatus includes a first and second buffer, said machine-readable medium contain instructions for causing the apparatus to execute the steps of:

outputting a cycle time synchronized to the network;

retrieving the timestamp together with the data blocks from the received packets;

generating a reproduction sampling clock signal by synchronous reproduction using the timestamp retrieved from a packet transmitted from the first transmitting node;

sequentially storing into the first buffer data blocks retrieved from the received packet from the first transmitting node;

reading out the data blocks from the first buffer in accordance with the reproduction sampling clock signal, thereby outputting the event sequence data;

adjusting a reading point of the data block from the first buffer when a time indicated by the timestamp from the packet received from the first transmitting node coincides with the cycle time, thereby controlling the output of the data block corresponding to a time indicated by the timestamp;

sequentially storing in the second buffer data blocks of the packet received from the second transmitting node;

reading out the data blocks from the second buffer in accordance with the reproduction sampling clock signal, thereby outputting the event sequence data;

adjust a reading point of the block from the second buffer when a time indicated by the timestamp from the second transmitting node coincides with the cycle time, thereby controlling the output of the data a block corresponding to a time indicated by the timestamp.

19. In a system having a packet receiving apparatus connected to a network for receiving packets transmitted from a plurality of transmitting nodes located on the network, wherein the packet includes at least one data block comprised of at least one event sequence data per sampling period and a timestamp per a predetermined number of data blocks, wherein the apparatus includes buffer for storing data, a method for processing the received packets, said method comprising the steps of:

outputting a cycle time synchronized to the network;

retrieving the timestamp together with the data blocks from the received packets;

generating a reproduction sampling clock signal that is synchronized among nodes on the network;

sequentially storing in the buffer data blocks retrieved from the received packets;

reading out the data blocks from the buffer in accordance with the reproduction sampling clock signal, thereby outputting the event sequence data; and

adjusting a reading point of the data block of a particular transmitting node from the buffer when a time indicated by the timestamp from the packet of the particular transmitting node and added with an offset time given to the particular transmitting node coincides with the outputted cycle time, thereby controlling the outputting of the data block corresponding to a time indicated by the timestamp of the particular transmitting node.

20. A machine-readable medium for use in a packet receiving apparatus connected to a network for receiving packets transmitted from a plurality of transmitting nodes located on the network, wherein the packet includes at least one data block comprised of at least one event sequence data per sampling period and a timestamp per a predetermined number of data blocks, wherein the apparatus includes buffer for storing data, said machine-readable medium containing instructions for causing the apparatus to execute the steps of:

outputting a cycle time synchronized to the network;

retrieving the timestamp together with the data blocks from the received packets;

generating a reproduction sampling clock signal that is synchronized among nodes on the network;

sequentially storing in the buffer data blocks retrieved from the received packets;

reading out the data blocks from the buffer in accordance with the reproduction sampling clock signal, thereby outputting the event sequence data; and

adjusting a reading point of the data block of a particular transmitting node from the buffer when a time indicated by the timestamp from the packet of the particular transmitting node and added with an offset time given to the particular transmitting node coincides with the outputted cycle time, thereby controlling the outputting of the data block corresponding to a time indicated by the timestamp of the particular transmitting node.