Communication method, communication device, and recording medium for streaming

1. A communication method implemented by a communication device, the communication method comprising:

conducting streaming reproduction of obtained data which is to be obtained by a first obtaining task using at least one of a first line and a second line; and

dividing the first obtaining task into a plurality of second obtaining tasks when data at a reproduction position for the streaming reproduction is unobtained, a size of data to be obtained by each of the plurality of second obtaining tasks being smaller than a size of data to be obtained by the first obtained task;

issuing the plurality of second obtaining tasks using at least one of the first line and the second line;

issuing a task of executing obtainment of head data of the data to be obtained to the first line and the second line, when obtainment of the data to be obtained is started;

judging whether or not a line that completed the obtainment is the first line when the obtainment of the head data has been completed;

determining the first line to be the main line when the line that completed the obtainment is the first line; and

determining the second line to be the main line when the line that completed the obtainment is not the first line.

2. The communication method according to claim 1 , further comprising

issuing a part of an unexecuted part of a task that is currently being executed by the main line to the sub line as a new task, on a basis of a communication state of the main line.

3. The communication method according to claim 2 , wherein the communication state of the main line is detected on a basis of a degree of progress of a process performed on each of tasks currently being executed by the main line.

4. The communication method according to claim 2 , wherein the communication state of the main line is detected on a basis of line quality of the first line and line quality of the second line.

5. The communication method according to claim 2 , further comprising:

judging whether or not data is obtained in an amount equal to or larger than a predetermined volume, while being continuous from a current reproduction position; and

increasing a maximum number of tasks to be issued to the main line when the data is obtained in the amount equal to or larger than the predetermined volume while being continuous from the current reproduction position and decreasing the maximum number of tasks to be issued to the main line when the data is not obtained in the amount equal to or larger than the predetermined volume while being continuous from the current reproduction position.

6. The communication method according to claim 1 , further comprising:

with regard to each task issued to each of the first and the second lines, setting a priority level for executing the task, and

executing the task in descending order of the priority level.

7. A communication device comprising:

a first obtaining unit that obtains data by using a first line;

a second obtaining unit that obtains data by using a second line;

a reproducing unit that conducts streaming reproduction of the data to be obtained by a first obtaining task executed by at least one of the first obtaining unit and the second obtaining unit;

an issuing unit that

divides the data to be obtained into a plurality of second obtaining tasks when data at a reproduction position for the streaming reproduction is unobtained, a size of data to be obtained by each of the plurality of second obtaining tasks being smaller than a size of the data to be obtained by the first obtaining task,

issues the plurality of second obtaining tasks using at least one of the first obtaining unit and the second obtaining unit, and

issues a task of executing obtainment of head data of the data to be obtained to the first obtaining unit and the second obtaining unit, when obtainment of the data to be obtained is started;

a judging unit that judges whether or not a line that completed the obtainment is the first line when the obtainment of the head data has been completed; and

a determining unit that determines the first line to be the main line when the first obtaining unit completed the obtainment, and determines the second line to be the main line when the first obtaining unit did not complete the obtainment.

8. A non-transitory computer-readable recording medium having stored therein a communication program that causes a communication device to execute a process comprising: obtaining data by using one selected from a first line and a second line;

conducting streaming reproduction of the obtained data; and

dividing the first obtaining task into a plurality of second obtaining tasks when data at a reproduction position for the streaming reproduction is unobtained, a size of data to be obtained by each of the plurality of second obtaining tasks being smaller than a size of data to be obtained by the first obtaining task;

issuing the plurality of second obtaining tasks using at least one of the first line and the second line;

issuing a task of executing obtainment of head data of the data to be obtained to the first line and the second line, when obtainment of the data to be obtained is started;

judging whether or not a line that completed the obtainment is the first line when the obtainment of the head data has been completed;

determining the first line to be the main line when the line that completed the obtainment is the first line; and

determining the second line to be the main line when the line that completed the obtainment is not the first line.