Method and apparatus for encoding a digital signal, recording medium used for storing the digital signal, and method and apparatus for transmitting the digital signal

• US 5,949,792 A
• Filed: 04/30/1997
• Issued: 09/07/1999
• Est. Priority Date: 05/02/1996
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Tahara, Katsumi, Yasuda, Mikita, Oishi, Noriaki, Negishi, Shinji
• Primary Examiner(s): Hofsass, Jeffery A.
• Assistant Examiner(s): Slavitt, Mitchell
• Application Number:
  US08/841,681
• Time in Patent Office: 860 Days
• Field of Search: 370/474, 370/471, 370/473, 370/477, 370/505, 370/506, 370/468, 370/466
• US Class Current: 370/474
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/2525 Magneto-optical [MO] discs
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 27/3027 used signal is digitally coded
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/50 using predictive coding H04N19/61 takes precedence
• CPC Class Codes: H04N 21/21805 enabling multiple viewpoints, e.g. using a plurality of cameras
• CPC Class Codes: H04N 21/42646 for reading from or writing on a non-volatile solid state storage medium, e.g. DVD, CD-ROM
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 5/85 on discs or drums
• CPC Class Codes: H04N 7/52 Systems for transmission of a pulse code modulated video signal with one or more other pulse code modulated signals, e.g. an audio signal or a synchronizing signal assembling of a multiplex stream by combining a video stream with other content or additional data, remultiplexing of multiplex streams, insertion of stuffing bits into the multiplex stream, assembling of a packetised elementary stream at server side H04N21/236; disassembling of a multiplex stream, remultiplexing of multiplex streams, extraction or processing of Service Information, disassembling of packetised elementary stream at client side H04N21/434
• CPC Class Codes: H04N 9/8042 involving data reduction
• CPC Class Codes: H04N 9/8227 the additional signal being at least another television signal

Abstract

A method for encoding a digital signal which is free from overflow and/or underflow of decoder buffer when video and audio data are reproduced while switching a plurality of bit streams from one to another, is disclosed. The method includes the steps of receiving a plurality of digital signal bit streams, detecting sizes of access units, as an encoding unit, of the plural digital signal bit streams, and decode times thereof, comparing the detected sizes of the access units at each decode time, with each other to select a maximum value thereof, providing a virtual stream composed of access units each having a size identical to the selected maximum value at each decode time, and packetizing each of the plural digital signal bit streams, wherein the plural digital signal bit streams are packetized by using padding packets each having a size corresponding to a difference in size between each access unit of the plural digital signal bit streams and that of the virtual stream, when the size of the access unit of the plural digital signal bit streams is less than the size of the access unit of the virtual stream. In accordance with the present invention, there are also provided an apparatus for encoding the digital signal, a method for recording the digital signal on a recording medium, and a method for transmitting the digital signal.

Claims

1. A method for encoding a digital signal, comprising the steps of:

receiving a plurality of digital signal bit streams;

detecting sizes of access units, as an encoding unit, of said plurality of digital signal bit streams, and decode times thereof;

comparing the detected sizes of the access units at each decode time, with each other to select a maximum value thereof;

providing a virtual stream composed of access units each having a size identical to the selected maximum value at each decode time; and

packetizing each of said plurality of digital signal bit streams,

said plurality of digital signal bit streams being packetized by using padding packets each having a size corresponding to a difference in size between each access unit of said plurality of digital signal bit streams and that of said virtual stream, when the size of the access unit of said plurality of digital signal bit streams is less than the size of the access unit of said virtual stream.

2. A method according to claim 1 wherein said plurality of digital signal video streams are video streams, further comprising the steps of:

receiving at least an audio stream; and

determining a supply time at which said virtual stream as a virtual video stream and said at least an audio stream are supplied to a decoder, and a size of each packet produced,

said video streams and said at least an audio stream being packetized by using information concerning said supply time and said size of each packet produced.

3. An apparatus for encoding a digital signal, comprising:

a receiving terminal for receiving a plurality of digital signal bit streams;

an access unit detecting device for detecting sizes of access units, as an encoding unit, of said plurality of digital signal bit streams, and decode times thereof;

a maximum value detecting device for comparing the detected sizes of the access units at each decode time, with each other to select a maximum value thereof;

a scheduler for providing a virtual stream composed of access units each having a size identical to the selected maximum value at each decode time; and

a packetizing device for packetizing each of said plurality of digital signal bit streams,

said plurality of digital signal bit streams being packetized by using padding packets each having a size corresponding to a difference in size between each access unit of said plurality of digital signal bit streams and that of said virtual stream, when the size of the access unit of said plurality of digital signal bit streams is less than the size of the access unit of said virtual stream.

4. An apparatus according to claim 3 wherein said plurality of digital signal video streams are video streams, further comprising a receiving terminal for receiving at least an audio stream,

said scheduler determining a supply time at which said virtual stream as a virtual video stream and said at least an audio stream are supplied to a decoder, and a size of each packet produced, and said video streams and said at least an audio stream being packetized by using information concerning said supply time and said size of each packet produced.

5. A method for transmitting a digital signal, comprising the steps of:

receiving a plurality of digital signal bit streams;

detecting sizes of access units, as an encoding unit, of said plurality of digital signal bit streams, and decode times thereof;

comparing the detected sizes of the access units at each decode time, with each other to select a maximum value thereof;

providing a virtual stream composed of access units each having a size identical to the selected maximum value at each decode time; and

packetizing each of said plurality of digital signal bit streams,

said plurality of digital signal bit streams being packetized by using padding packets each having a size corresponding to a difference in size between each access unit of said plurality of digital signal bit streams and that of said virtual stream, when the size of the access unit of said plurality of digital signal bit streams is less than the size of the access unit of said virtual stream, thereby transmitting one stream produced by packetizing said plurality of digital signal bit streams.

6. A method according to claim 5 wherein said plurality of digital signal video streams are video streams, further comprising the steps of:

receiving at least an audio stream; and

determining a supply time at which said virtual stream as a virtual video stream and said at least an audio stream are supplied to a decoder, and a size of each packet produced,

said video streams and said at least an audio stream being packetized by using information concerning said supply time and said size of each packet produced.

7. A recording medium on which a recording signal is stored, said recording medium being produced by a method comprising the steps of:

receiving a plurality of digital signal bit streams;

detecting sizes of access units, as an encoding unit, of said plurality of digital signal bit streams, and decode times thereof;

comparing the detected sizes of the access units at each decode time, with each other to select a maximum value thereof;

providing a virtual stream composed of access units each having a size identical to the selected maximum value at each decode time; and

packetizing each of said plurality of digital signal bit streams,

said plurality of digital signal bit streams being packetized by using padding packets each having a size corresponding to a difference in size between each access unit of said plurality of digital signal bit streams and that of said virtual stream, when the size of the access unit of said plurality of digital signal bit streams is less than the size of the access unit of said virtual stream.

8. A recording medium according to claim 7 wherein said plurality of digital signal video streams are video streams, said method for producing the recording medium further comprising the steps of:

receiving at least an audio stream; and

determining a supply time at which said virtual stream as a virtual video stream and said at least an audio stream are supplied to a decoder, and a size of each packet produced,

said video streams and said at least an audio stream being packetized by using information concerning said supply time and said size of each packet produced.