TRANSMITTING DATA WITH VARIABLE UNIT FOR PLAYBACK

• US 20090119566A1
• Filed: 11/05/2008
• Published: 05/07/2009
• Est. Priority Date: 11/07/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hiromitsu, Toshiro, Idei, Seiichi, Numano, Kazuaki, Tsukamoto, Yasushi
• Granted Patent: US 8,214,724 B2
• Time in Patent Office: Days
• US Class Current: 714/752
• CPC Class Codes: H03M 13/13 Linear codes
• CPC Class Codes: H03M 13/373 with erasure correction and erasure determination, e.g. for packet loss recovery or setting of erasures for the decoding of Reed-Solomon codes
• CPC Class Codes: H03M 13/6547 TCP, UDP, IP and associated protocols, e.g. RTP
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence

Abstract

Provided is a transmitter for continuously and sequentially transmitting data with a variable unit for playback. The transmitter includes an obtaining section, a buffer, a computing section and a transmitting section. The obtaining section sequentially obtains segment data of the data to be transmitted. The buffer stores an error correction code to correct an error caused in the data by transmission. The computing section computes, every time newly obtained segment data reaches a predetermined size, XOR of the error correction code already stored in the buffer and the newly obtained segment data, and then updates the error correction code with the computed XOR. The transmitting section sequentially transmits the obtained segment data, as well as reads from the buffer and transmits the updated error correction code every time the computing section computes XOR for data in a size corresponding to the unit for playback.

Claims

1. A transmitter for continuously and sequentially transmitting data with a variable unit for playback, comprising:

an obtaining section for sequentially obtaining segment data of the data to be transmitted;

a buffer for storing an error correction code to correct an error caused in the data by transmission;

a computing section for computing, every time newly obtained segment data from the data to be transmitted reaches a predetermined size, an XORed value of the error correction code already stored in the buffer and the newly obtained segment data, and then for updating the error correction code with the computed XORed value; and

a transmitting section for sequentially transmitting the sequentially obtained segment data, concurrently with reading from the buffer and transmitting the updated error correction code, every time the computing section updates the error correction code with the computed XORed value, for the latest-obtained segment data of the data corresponding to the unit for playback.

2. The transmitter according to claim 1, wherein

the data to be transmitted represents a moving image;

the unit for playback is one frame of the moving image; and

the predetermined size is the size of data transmitted in one communication packet by the transmitting section.

3. The transmitter according to claim 2, wherein

the obtaining section obtains, as the data to be transmitted, pieces of data whose sizes vary among the frames;

and

every time the computing section updates the error correction code after computing an XORed value, for the latest-obtained segment data of the data piece corresponding to one frame of the data to be transmitted, the transmitting section reads from the buffer and transmits the updated error correction code.

4. The transmitter according to claim 2, wherein

the transmitting section sequentially transmits the sequentially obtained segment data;

and

the transmitting section retransmits at least a part of the sequentially obtained segment data to an extent that a total size of the transmitted data does not exceed an upper limit size predetermined as transmittable for one frame, on condition that the total size of the data to be transmitted does not reach the upper limit size even while including the error correction code read from the buffer.

5. The transmitter according to claim 4, wherein

the transmitting section sequentially transmits the sequentially obtained segment data;

and

the transmitting section retransmits the sequentially obtained segment data in order of obtaining, on condition that the total size of the data to be transmitted does not reach an upper limit size predetermined as transmittable for one frame even while including the error correction code read from the buffer.

6. The transmitter according to claim 1, wherein, on condition that the size of newly obtained segment data after a last computation of an XORed value, does not reach the predetermined size while a total size of the sequentially obtained segment data reaches the unit for playback, the computing section computes an XORed value of the newly obtained segment data and the error correction code already stored in the buffer, and then updates the error correction code with the XORed value.

7. A receiver for continuously and sequentially receiving data with a variable unit for playback, comprising:

a receiving section for receiving data to be played back, concurrently with receiving, as an error correction code to correct an error in the data to be played back, an XORed value of data pieces obtained by dividing the data to be played back into predetermined sizes;

an error correction section for performing error correction on the received data to be played back by use of the received error correction code, on condition that a size of the received data to be played back does not reach a unit for playback; and

an outputting section for outputting the data to be played back either on the condition that the size of the received data to be played back reaches the unit for playback, or on the condition that the size of the received data to be played back reaches the unit for playback after error correction is performed on the received data to be played back by use of the error correction code.

8. The receiver according to claim 7, wherein

the data to be played back represents a moving image;

the unit for playback is one frame of the moving image; and

the predetermined size is the size of data received in one communication packet by the receiving section.

9. The receiver according to claim 8, further comprising

a buffer for storing the received data to be played back for each of frames and also for each of communication packets in which the data is transmitted, wherein

the receiving section sequentially stores the received pieces of data to be played back in the buffer for each of the received communication packets;

and

upon finding, through scanning the buffer, that data to be played back for a certain frame except for one communication packet is stored in the buffer, the error correction section performs error correction on the stored data to be played back by use of the received error correction code.

10. A method for continuously and sequentially transmitting data with a variable unit for playback by use of a transmitter, the transmitter including a buffer for storing an error correction code to correct an error caused in the data by transmission, comprising:

sequentially obtaining segment data of the data to be transmitted;

computing, every time newly obtained segment data from the data to be transmitted reaches a predetermined size, an XORed value of the error correction code already stored in the buffer and the newly obtained segment data, and then updating the error correction code with the computed XORed value; and

sequentially transmitting the sequentially obtained segment data, concurrently with reading from the buffer and transmitting the updated error correction code, every time the error correction code is updated with the computed XORed value, for the latest-obtained segment data of the data corresponding to the unit for playback.

11. A method for continuously and sequentially receiving data with a variable unit for playback by use of a receiver, comprising:

receiving data to be played back, concurrently with receiving, as an error correction code to correct an error in the data to be played back, an XORed value of data pieces obtained by dividing the data to be played back into predetermined sizes;

performing error correction on the received data to be played back by use of the received error correction code, on condition that a size of the received data to be played back does not reach the unit for playback; and

outputting the data to be played back on the condition that the size of the received data to be played back reaches the unit for playback, or on the condition that the size of the received data to be played back reaches the unit for playback after error correction is performed on the received data to be played back by use of the error correction code.

12. A program causing a computer to function as a transmitter for continuously and sequentially transmitting data with a variable unit for playback, the computer including a buffer for storing an error correction code to correct an error caused in the data by transmission, and the program, when executed, causing the computer to function as:

an obtaining section for sequentially obtaining segment data of the data to be transmitted;

a computing section for computing, every time newly obtained segment data from the data to be transmitted reaches a predetermined size, an XORed value of the error correction code already stored in the buffer and the newly obtained segment data, and then for updating the error correction code with the computed XORed value; and

a transmitting section for sequentially transmitting the sequentially obtained segment data, concurrently with reading from the buffer and transmitting the updated error correction code, every time the computing section updates the error correction code with the computed XORed value, for the latest-obtained segment data of the data corresponding to the unit for playback.