Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via frequency channels
Reexamination Certificate
2000-02-16
2004-11-02
Patel, Ajit (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via frequency channels
C348S462000
Reexamination Certificate
active
06813281
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of assigning an audio channel identification (ID) by which it is possible to follow up and select the audio channel selected by a user even when a program or an audio data stream is changed in an audio/video (A/V) device for reproducing a program including a plurality of audio data streams, a method of selecting an audio channel using the same, and an optical recording and reproducing apparatus suitable therefor.
2. Description of the Related Art
Currently, a moving picture expert group (MPEG) and AC3 are often used as methods for compressively encoding an audio signal. In a linear pulse code modulation (PCM), the audio signal is not compressively encoded but recorded as it is. In digital TV broadcasting or video CDS and digital video disks (DVDs) which are digital A/V devices, the MPEG format is mainly used.
When the encoded data streams of MPEG A/V data and other data streams are integrated and applied to a real application, it is necessary to make a data stream by integrating these data streams. Auxiliary data can be additionally used according to a certain application. The role of the MPEG system is synchronizing and multiplexing video and audio data.
In the MPEG system, multiplexing by packets is adopted. In the multiplexing by the packets, each of the video and audio data is divided into data streams called packets having an appropriate length, information such as headers are attached to the packets, and the packets of the video and audio data are multiplexed.
The packets include information for identifying whether the data items are video or audio data in a region called a packet header as shown in FIG.
1
. The length of the packet depends on a transmission medium or application.
Table 1 is for showing the contents of the packet headers shown in FIG.
1
.
TABLE 1
Main items
Packet_start_code_prefix
″00 00 01″h
stream_id
1 byte, for distinguishing
kinds of data items
PTS value
(DTS value)
Data
Video data, MPEG audio data
or private data
In Table 1, Packet_start_code_prefix represents the start of a packet and stream_id represents kinds of data items in a packet. For example, in the case of video data, stream_id is a binary code “1110 0000”b. In the case of audio data, stream_id is a binary code “1100 0***”b. Here, *** shows that eight kinds of audio data streams can exist from 000b to 111b. In the MPEG system, other data items besides the two data items are classified as private streams. A code “1011 1101”b can be used for the private stream.
A presentation time stamp (PTS) and a decoding time stamp (DTS), defined in the MPEG system standard, respectively represent time taken to output and decode a presentation unit in the video or audio data. The presentation unit is a frame of a picture in the video data and a frame of audio in the audio data. The DTS is not necessary in the case of the audio data.
Except for MPEG audio data, audio data such as AC3 or LPCM is realized by private streams. The contents of the packet header adopted to the private streams is shown in Table 2.
TABLE 2
Main items
Packet_start_code_prefix
″00 00 01″h
stream_id
″1011 1101″b
PTS value
substream_id
AC3 or LPCM
number_of_audio_channels
Number of audio channels
Data
In the Table 2, the substream_id is used in order to distinguish the kinds of audio data encoding such as AC3 or LPCM. For example, in the case of the AC3, the substream_id is “1010 0***”b. Here, *** means that up to eight data streams can exist like in the MPEG audio. In the MPEG system, one program can have various video data streams and audio data streams.
The term “number_of_audio_channels” denotes the number of channels. There can be 1ch, 2ch, 3ch, 4ch, and a dual mono channel. Here, channels are different from channels selected by a user. Namely, the above channels appear as one channel to the user excluding the dual mono. The dual mono is recognized as two channels.
In an MPEG-1 or MPEG-2 program stream (PS), an upper layer of the video or audio packet, called a pack, exists. In general, a pack formed by integrating a plurality of packets is considered to be a basic unit.
FIG. 2
shows the structure of the pack. Additional information for a time based reference for synchronous reproduction exists in a pack header.
Table 3 shows the contents of a pack header shown in FIG.
2
.
TABLE 3
Main items
Pack_start_code
″00 00 01 BA″h
″01″
shows that data is MPEG-2
SCR value
program_mux_rate
pack_stuffing_length
In the Table 3, the Pack_start_code is a code from which pack data starts. The SCR value represents the time at which the pack data reaches the buffer of a decoder and is used for synchronizing the system clock of an encoding port with the system clock of a decoding port. The program_mux_rate represents a transmission rate at which video, audio, and private data items are multiplexed and transmitted. In order to decode data correctly, the data must be transmitted at higher than the transmission rate. The pack_stuffing_length represents the number of dummy data.
FIG. 3
schematically shows channels and audio signals corresponding thereto. As shown in
FIG. 3
, audio signals are output through decoders. The data of the dual mono channel having outputs, the audio data of CH
0
and the audio data of CH
1
is similar to the 2ch data. However, the dual mono data is different from the 2ch data in that left and right audio signals are related to each other in the 2ch data, whereas CH
0
and CH
1
are separate audio signals in the dual mono data.
For example, Korean language audio data can be loaded into CH
0
and English language audio data can be loaded into CH
1
in the dual mono channel. Therefore, in general, only one of the two channels is output or the CH
0
audio data and the CH
1
audio data are output through a left speaker and a right speaker, respectively.
FIG. 4
shows an example of an apparatus for decoding and outputting the data of the dual mono channel. When a select signal is 0, the apparatus shown in
FIG. 4
outputs CH
0
audio as left audio and right audio. When the select signal is 1, the apparatus outputs CH
1
audio as left audio and right audio. When the select signal is 2, the apparatus outputs CH
1
audio and CH
2
audio as left audio and right audio, respectively.
FIG. 5
schematically shows a method of recording or reproducing a multi voice audio signal as dual mono audio data. The multi voice audio signal is formed of main audio data and sub-audio data. When data is recorded, the main audio data and the sub-audio data are encoded into an audio data stream through a multi-voice encoder. At this time, the main audio data is encoded into the CH
0
audio data and the sub-audio data is encoded into the CH
1
audio data.
When data is reproduced, an audio data stream is decoded into the CH
0
audio data and the CH
1
audio data through a multi-voice decoder. The CH
0
audio data is main audio data and the CH
1
audio data is sub-audio data.
Here, it is assumed that a plurality of audio data streams exist. As an example, when two audio data streams exist in an A/V data stream, the user can select one among the two channels. When the selected audio data stream is dual mono data, that is, sub-audio data streams are included, the user can select two channels.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of assigning a channel identification (ID) to a sub-audio data stream included in an audio data stream when each audio data stream is in a dual mode in an audio/video (A/V) stream including a plurality of audio data streams.
It is another object of the present invention to provide a method of selecting the same kind of audio channel by following up the audio channel selection input of a user although a program or an audio data stream is changed in an A/V device for reproducing a plurality of audio data streams which allow a dual mono mode.
It is still another object of the present invention to provide an apparatus suitable fo
Chung Tae-yun
Kang Jung-suk
Moon Seong-jin
Oh Young-nam
Park Bong-kil
Ha Yvonne Quy
Patel Ajit
Staas & Halsey , LLP
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