Broadcast system having transmission apparatus and receiving apparatus, the receiving apparatus, and program

• US 20040105505A1
• Filed: 08/14/2003
• Published: 06/03/2004
• Est. Priority Date: 08/27/2002
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kitamura, Tomohiko
• Granted Patent: US 7,286,601 B2
• Time in Patent Office: Days
• US Class Current: 375/259
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
• CPC Class Codes: H04H 20/28 Arrangements for simultaneous broadcast of plural pieces of information
• CPC Class Codes: H04H 40/18 Arrangements characterised by circuits or components specially adapted for receiving
• CPC Class Codes: H04N 21/23439 for generating different versions
• CPC Class Codes: H04N 21/2625 for delaying content or additional data distribution, e.g. because of an extended sport event
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/64792 Controlling the complexity of the content stream, e.g. by dropping packets intermediate media network packet handling H04L65/765; proxy provisioning conversion or adaptation for reducing the amount or size of exchanged application data H04L67/5651; negotiation of resources in wireless networks H04W28/16

Abstract

A broadcast system has digital receiving apparatuses that imitate deteriorated reproduction that is observed in analog receiving apparatuses when a transmission path failure occurs, thus preventing the audiences, who are accustomed to the analog broadcasting, from sensing discomfort at the digital broadcasting. A transmission apparatus causes encoding units 11 and 12 to generate low- and high-quality streams based on the same contents, and transmits these streams onto a transmission path while delaying the high-quality stream. In the receiving apparatuses, a reproduction unit 25 reproduces the high-quality stream in a normal state, while packets of the low-quality stream received during a time period T until the current time are accumulated in an accumulation unit 22. If a transmission path failure occurs, a reproduction control unit 26 causes the reproduction unit 25 to reproduce, instead of the high-quality stream, the accumulated packets of the low-quality stream.

Claims

1. A broadcast system including a transmission apparatus and a receiving apparatus, the transmission apparatus including:

a generating unit operable to generate a first digital stream and a second digital stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first digital stream is lower than an encoding bit rate for the second digital stream; and

a transmission unit operable to transmit the first and second digital streams onto a transmission path while delaying the second digital stream relative to the first digital stream, the receiving apparatus including;

a reproduction unit operable to reproduce the second digital stream in a normal state; and

a reproduction control unit operable to, if a transmission path failure occurs, cause the reproduction unit to reproduce, instead of the second digital stream, a portion of the first digital stream that has been received before the occurrence of the transmission path failure.

2. The broadcast system of claim 1, wherein

the receiving apparatus further includes:

a receiving unit operable to receive packets constituting the first and second digital streams for each digital stream; and

an accumulating unit operable to accumulate one or more packets of the first digital stream received by the receiving unit during a predetermined time period until a current time, wherein

the reproduction control unit causes the reproduction unit to reproduce the one or more packets of the first digital stream accumulated in the accumulating unit, if a transmission path failure occurs.

3. The broadcast system of claim 2, wherein

the predetermined time period is equal to a time period by which the second digital stream is delayed by the transmission unit.

4. The broadcast system of claim 2, wherein

the receiving apparatus further includes

a write control unit operable to, each time the receiving unit newly receives a packet, write the newly received packet into the accumulating unit after deleting an oldest packet among the one or more packets accumulated in the accumulating unit.

5. The broadcast system of claim 4, wherein

the predetermined time period is determined based on statistics of a time period for which a transmission path failure continues.

6. The broadcast system of claim 1, wherein

the receiving apparatus superposes a signal resembling a noise on the one or more packets accumulated in the accumulating unit when the one or more packets are reproduced due to occurrence of a transmission path failure.

7. The broadcast system of claim 1, wherein

the receiving apparatus is provided with a pilot lamp that emits light in a manner in which a normal state is distinguished from an abnormal state, wherein in the normal state, the second digital stream is reproduced, and in the abnormal state, the first digital stream is reproduced.

8. The broadcast system of claim 2, wherein

if a transmission path failure continues exceeding the predetermined time period during which the one or more packets are accumulated in the accumulating unit, the receiving apparatus reproduces supplementary data so as to complement the reproduction of the accumulated packets.

9. The broadcast system of claim 1, wherein

the receiving apparatus further includes:

an operation receiving unit operable to receive input of an operation by a user to request real time reproduction; and

a switch unit operable to switch from reproduction of the second digital stream to reproduction of the first digital stream if the operation receiving unit receives the input of the operation by the user.

10. The broadcast system of claim 1, wherein

the generating unit of the transmission apparatus includes two encoders that respectively generate the first digital stream and the second digital stream by performing a variable-length encoding onto an analog signal.

11. A broadcast system including a transmission apparatus and a receiving apparatus, the transmission apparatus including:

a generating unit operable to generate a first digital stream, a second digital stream, and a third digital stream by encoding a same signal respectively at different encoding bit rates, where an encoding bit rate for the first digital stream is the lowest among the encoding bits rates, an encoding bit rate for the second digital stream is the middle between encoding bit rates for the first and third digital streams, and an encoding bit rate for the third digital stream is the highest among the encoding bits rates; and

a transmission unit operable to transmit the first, second, and third digital streams onto a transmission path while delaying the second digital stream by time period T1 and delaying the third digital stream by time period T2, wherein T2>

T1,

the receiving apparatus including;

an accumulating unit operable to accumulate part of the first and second digital streams received from the transmission apparatus;

are production unit operable to reproduce the third digital stream in a normal state; and

a reproduction control unit operable to cause the reproduction unit to reproduce, instead of the third digital stream, the part of the second digital stream accumulated in the accumulating unit if a transmission path failure continues for the time period T2 or more, and to reproduce the part of the first digital stream accumulated in the accumulating unit following the reproduction of the part of the second digital stream accumulated in the accumulating unit.

12. A broadcast system including a transmission apparatus and a receiving apparatus, the transmission apparatus including:

a first generating unit operable to generate a first audio stream and a second audio stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first audio stream is lower than an encoding bit rate for the second audio stream;

a second generating unit operable to generate a first video stream and a second video stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first video stream is lower than an encoding bit rate for the second video stream; and

a transmission unit operable to transmit the first and second audio streams and the first and second video streams onto a transmission path while delaying the second video stream by a time period T1 and delaying the second audio stream by a time period T2, wherein T2>

T1,

the receiving apparatus including;

a first accumulating unit operable to accumulate part of the first video stream received during the time period T1 until a current time;

a second accumulating unit operable to accumulate part of the first audio stream received during the time period T2 until the current time;

a reproduction unit operable to reproduce the second video stream and the second audio stream in a normal state; and

a reproduction control unit operable to cause the reproduction unit to reproduce (i) the part of the first video stream accumulated in the first accumulating unit and (ii) the part of the first audio stream accumulated in the second accumulating unit for the time period T1 if a transmission path failure continues for the time period T2 or more, and to reproduce, after the time period T1, the part of the first audio stream accumulated in the second accumulating unit.

13. A receiving apparatus for use in a broadcast system including a transmission apparatus that generates a first digital stream and a second digital stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first digital stream is lower than an encoding bit rate for the second digital stream, and transmits the first and second digital streams onto a transmission path while delaying the second digital stream relative to the first digital stream, the receiving apparatus comprising:

a reproduction unit operable to reproduce the second digital stream in a normal state; and

a reproduction control unit operable to, if a transmission path failure occurs, cause the reproduction unit to reproduce, instead of the second digital stream, a portion of the first digital stream that has been received before the occurrence of the transmission path failure.

14. The receiving apparatus of claim 13 further comprising:

a receiving unit operable to receive packets constituting the first and second digital streams for each digital stream; and

an accumulating unit operable to accumulate one or more packets of the first digital stream received by the receiving unit during a predetermined time period until a current time, wherein

the reproduction control unit causes the reproduction unit to reproduce the one or more packets of the first digital stream accumulated in the accumulating unit, if a transmission path failure occurs.

15. The receiving apparatus of claim 14, wherein

the predetermined time period is equal to a time period by which the second digital stream is delayed by the transmission apparatus.

16. The receiving apparatus of claim 14 further comprising

a write control unit operable to, each time the receiving unit newly receives a packet, write the newly received packet into the accumulating unit after deleting an oldest packet among the one or more packets accumulated in the accumulating unit.

17. The receiving apparatus of claim 16, wherein

the predetermined time period is determined based on statistics of a time period for which a transmission path failure continues.

18. The receiving apparatus of claim 13, wherein

the receiving apparatus superposes a signal resembling a noise on the one or more packets accumulated in the accumulating unit when the one or more packets are reproduced due to occurrence of a transmission path failure.

19. The receiving apparatus of claim 13, wherein

the receiving apparatus is provided with a pilot lamp that emits light in a manner in which a normal state is distinguished from an abnormal state, wherein in the normal state, the second digital stream is reproduced with delay, and in the abnormal state, the first digital stream is reproduced without delay.

20. The receiving apparatus of claim 13, wherein

if a transmission path failure continues exceeding the predetermined time period during which the one or more packets are accumulated in the accumulating unit, the receiving apparatus reproduces supplementary data so as to complement the reproduction of the accumulated packets.

21. The receiving apparatus of claim 13 further comprising:

an operation receiving unit operable to receive input of an operation by a user to request real time reproduction; and

a switch unit operable to switch from reproduction of the second digital stream to reproduction of the first digital stream if the operation receiving unit receives the input of the operation by the user.

22. A receiving apparatus for use in a broadcast system including a transmission apparatus that generates a first digital stream, a second digital stream, and a third digital stream by encoding a same signal respectively at different encoding bit rates, where an encoding bit rate for the first digital stream is the lowest among the encoding bits rates, an encoding bit rate for the second digital stream is the middle between encoding bit rates for the first and third digital streams, and an encoding bit rate for the third digital stream is the highest among the encoding bits rates, and transmits the first, second, and third digital streams onto a transmission path while delaying the second digital stream by time period T1 and delaying the third digital stream by time period T2, wherein T2>

T1, the receiving apparatus comprising;

an accumulating unit operable to accumulate part of the first and second digital streams received from the transmission apparatus;

a reproduction unit operable to reproduce the third digital stream in a normal state; and

a reproduction control unit operable to cause the reproduction unit to reproduce, instead of the third digital stream, the part of the second digital stream accumulated in the accumulating unit if a transmission path failure continues for the time period T2 or more, and to reproduce the part of the first digital stream accumulated in the accumulating unit following the reproduction of the part of the second digital stream accumulated in the accumulating unit.

23. A receiving apparatus for use in a broadcast system including a transmission apparatus that generates a first audio stream and a second audio stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first audio stream is lower than an encoding bit rate for the second audio stream, generates a first video stream and a second video stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first video stream is lower than an encoding bit rate for the second video stream, and transmits the first and second audio streams and the first and second video streams onto a transmission path while delaying the second video stream by a time period T1 and delaying the second audio stream by a time period T2, wherein T2>

T1, the receiving apparatus comprising;

a first accumulating unit operable to accumulate part of the first video stream received during the time period T1 until a current time;

a second accumulating unit operable to accumulate part of the first audio stream received during the time period T2 until the current time;

a reproduction unit operable to reproduce the second video stream and the second audio stream in a normal state; and

a reproduction control unit operable to cause the reproduction unit to reproduce (i) the part of the first video stream accumulated in the first accumulating unit and (ii) the part of the first audio stream accumulated in the second accumulating unit for the time period T1 if a transmission path failure continues for the time period T2 or more, and to reproduce, after the time period T1, the part of the first audio stream accumulated in the second accumulating unit.

24. A program that causes a computer to execute a reception process in a broadcast system including a transmission apparatus that generates a first digital stream and a second digital stream from a same signal source by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first digital stream is lower than an encoding bit rate for the second digital stream, and transmits the first and second digital streams onto a transmission path while delaying the second digital stream relative to the first digital stream, the reception process including:

a reproduction step for reproducing the second digital stream in a normal state; and

a reproduction control step for causing, if a transmission path failure occurs, the reproduction step to reproduce, instead of the second digital stream, a portion of the first digital stream that has been received before the occurrence of the transmission path failure.

25. The program of claim 24, wherein

the computer includes:

a receiving unit operable to receive packets constituting the first and second digital streams for each digital stream; and

an accumulating unit operable to accumulate one or more packets of the first digital stream received by the receiving unit during a predetermined time period until a current time, wherein

the reproduction control step causes the reproduction step to reproduce the one or more packets of the first digital stream accumulated in the accumulating unit, if a transmission path failure occurs.

26. The program of claim 25, wherein

the predetermined time period is equal to a time period by which the second digital stream is delayed by the transmission apparatus.

27. The program of claim 25, wherein

the reception process further includes

a write control step for, each time the receiving unit newly receives a packet, writing the newly received packet into the accumulating unit after deleting an oldest packet among the one or more packets accumulated in the accumulating unit.

28. The program of claim 27, wherein

the predetermined time period is determined based on statistics of a time period for which a transmission path failure continues.

29. The program of claim 24, wherein

the computer further includes

an operation receiving unit operable to receive input of an operation by a user to request real time reproduction, and

the reception process further includes

a switch step for switching from reproduction of the second digital stream to reproduction of the first digital stream if the operation receiving unit receives the input of the operation by the user.

30. A program that causes a computer to execute a reception process in a broadcast system including a transmission apparatus that generates a first digital stream, a second digital stream, and a third digital stream by encoding a same signal respectively at different encoding bit rates, where an encoding bit rate for the first digital stream is the lowest among the encoding bits rates, an encoding bit rate for the second digital stream is the middle between encoding bit rates for the first and third digital streams, and an encoding bit rate for the third digital stream is the highest among the encoding bits rates, and transmits the first, second, and third digital streams onto a transmission path while delaying the second digital stream by time period T1 and delaying the third digital stream by time period T2, wherein T2>

T1, the computer including

an accumulating unit operable to accumulate part of the first and second digital streams received from the transmission apparatus,

the reception process including;

a reproduction step for reproducing the third digital stream in a normal state; and

a reproduction control step for causing the reproduction step to reproduce, instead of the third digital stream, the part of the second digital stream accumulated in the accumulating unit if a transmission path failure continues for the time period T2 or more, and to reproduce the part of the first digital stream accumulated in the accumulating unit following the reproduction of the part of the second digital stream accumulated in the accumulating unit.

31. A program that causes a computer to execute a reception process in a broadcast system including a transmission apparatus that generates a first audio stream and a second audio stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first audio stream is lower than an encoding bit rate for the second audio stream, generates a first video stream and a second video stream by encoding a same signal at different encoding bit rates, where an encoding bit rate for the first video stream is lower than an encoding bit rate for the second video stream, and transmits the first and second audio streams and the first and second video streams onto a transmission path while delaying the second video stream by a time period T1 and delaying the second audio stream by a time period T2, wherein T2>

T1, the computer including;

a first accumulating unit operable to accumulate part of the first video stream received during the time period T1 until a current time; and

a second accumulating unit operable to accumulate part of the first audio stream received during the time period T2 until the current time,

the reception process comprising;

a reproduction step for reproducing the second video stream and the second audio stream in a normal state; and

a reproduction control step for causing the reproduction step to reproduce (i) the part of the first video stream accumulated in the first accumulating unit and (ii) the part of the first audio stream accumulated in the second accumulating unit for the time period T1 if a transmission path failure continues for the time period T2 or more, and to reproduce, after the time period Ti, the part of the first audio stream accumulated in the second accumulating unit.