Video signal reproducing apparatus capable of reproducing...

Details Video signal reproducing apparatus capable of reproducing... Video signal reproducing apparatus capable of reproducing...

1999-07-29

2003-11-11

Tran, Thai (Department: 2615)

Motion video signal processing for recording or reproducing

Local trick play processing

With randomly accessible medium

C386S349000, C386S349000

Reexamination Certificate

active

06647202

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video signal reproduction apparatus which is capable of reproducing bitstreams containing audio data, video data, sub-picture data, and additional information which are digitally encoded by an encoding technique (e.g., MPEG) and multiplexed on a pack-by-pack or packet-by-packet basis.
2. Description of the Related Art
Recent years have seen a rapid and wide spread of media capable of accommodating video signals, audio signals, and additional information (e.g., subtitle information) in a digitally encoded and multiplexed format. One example of such media is the DVD (digital video disk).
Reproduction apparatuses for such multiplexed digital signals are associated with the following problems, which may hinder the smooth and normal operation of the reproduction apparatus: input of non-continuous and inconstant bitstreams during a special reproduction mode (such as a forward skip or a backward skip, which may occur without continuous data input); generation of errors at the time of encoding; generation of errors due to damaged disks or noises present on a transmission path; and the like.
On the other hand, the reproducing of audio, video, and sub-picture data generally requires synchronization. If the bitstream has been encoded with a tendency toward underflowing, it is possible that, when skipping sub-picture data by reproduction units, reproduced data may not be complete, thereby hindering proper reproduction.
In the field of digital media, video signals are generally subjected to an encoding scheme that complies with the MPEG standards, while encoding schemes other than MPEG-compatible schemes may be adopted for audio signals. A special bit map data compression technique is adopted for the encoding of subtitles carried on DVDs. The multiplexing of encoded audio or video data is performed by a multiplexing method which complies with the MPEG system standards.
FIGS. 2A and 2B
illustrate code sequences which are multiplexed on the basis of packets
102
.
FIG. 2A
illustrates the structure of a pack
101
as a basic unit of multiplexing. At the beginning of a packet
102
, a packet header
107
B is added which includes a synchronization signal (hereinafter referred to as a “packet start code prefix”)
103
indicating the top or beginning of the packet, a packet identifier (stream_id)
104
for distinguishing video packets from audio packets, packet length information
105
, and video/audio synchronization reproduction information
106
. Although
FIG. 2A
illustrates an example where the pack
101
includes one packet
102
, the pack
101
may alternatively include a plurality of packets
102
.
FIG. 2B
illustrates an exemplary structure of a multiplexed code sequence
108
and sub-picture encoded data
109
. The multiplexed code sequence
108
contains audio packs AP, video packs VP, sub-picture packs SP, and navigation information encoded data packs NP. The audio signal, the video signal, the sub-picture signal, and the navigation information are respectively digitally encoded by an encoder, and multiplexed by a multiplexer on a pack-by-pack basis.
The sub-picture encoded data
109
in
FIG. 2B
is shown as only including the sub-picture encoded data of the sub-picture packs SP extracted from the multiplexed code sequence
108
and combined together. An shown in
FIG. 2B
, each reproduction unit
110
P and
110
Q of the sub-picture encoded data
109
includes a unit header
110
A, an encoded bit map data
110
B, and display control information
110
C corresponding to the bit map data
110
B.
Conventionally, the sub-picture encoded data
109
is reproduced by analyzing the unit header
110
A at the beginning of the reproduction unit
110
P or
110
Q, decoding the encoded bit map data
110
B by using the information described in the unit header
110
P or
110
Q, performing display control functions (such as setting the output timing or adjusting color changes by using the display control information
110
C for the decoded bit map data
110
B), and blending the decoded bit map data
110
B with the video reproduction signal for output. The transition from the reproduction unit
110
P to the reproduction unit
110
Q is achieved by moving the reproduction position to the beginning of the reproduction unit
110
Q in accordance with a reproduction unit length described in the unit header
110
A, and consecutively performing reproduction.
Conventionally, the beginning of the reproduction unit
110
P of any viable sub-picture encoded data
109
(that is free of errors and the like) may be detected by relying on the reproduction unit length described in the unit header
110
A; and the reproduction unit length is used for reproducing the sub-picture encoded data
109
. The illustrated sub-picture encoded data
109
does not itself include a synchronization pattern. Rather, the beginning of the reproduction unit
110
P of the sub-picture encoded data
109
starts with the unit header
110
A. The unit header
110
A cannot be detected by encoded data matching based on a synchronization pattern, as would be performed for video or audio data.
Even if the reproduction unit length described in the unit header
110
A includes an error for some reason, it may still be possible to continue reproducing some or all of the reproduction unit
110
P that is associated with the wrong reproduction unit length. However, the erroneous reproduction unit length makes it difficult to properly move the reproduction position to the beginning of the next reproduction unit
110
Q. Therefore, the unit header
110
A in the reproduction unit
110
Q cannot be detected. Since it is difficult to decode the reproduction unit
110
Q, a sub-picture decoder used for decoding the sub-picture encoded data
109
may hang up. Thus, if an error is present in the unit header
110
A, it becomes difficult to smoothly reproduce the sub-picture encoded data
109
.
FIGS. 3A and 3B
illustrate a data transfer scheme in a special reproduction mode. In
FIG. 3A
, sub-picture packs SPU
1
_
1
, SPU
1
_
2
, and SPU
1
_
3
correspond to the reproduction unit
110
Q of the sub-picture encoded data
109
: and sub-picture packs SPU
2
_
1
, SPU
2
_
2
, and SPU
2
_
3
correspond to the reproduction unit
110
P of the sub-picture encoded data
109
. In the continuous multiplexed code sequence
108
A shown in
FIGS. 3A and 3B
, if a pack within a period DT
1
and a pack within a period DT
2
are reproduced in an intermittent manner in a special reproduction mode, the reproduction unit
110
P for the sub-picture data will not be completed, and the sub-picture packs SPU
1
_
1
and SPU
1
_
2
and the sub-picture pack SPU
2
_
1
in the next reproduction unit
110
Q will be combined into, and processed as, decoded date
111
as shown in FIG.
3
B.
The sub-picture encoded data
109
is reproduced in such a manner that any data present in the uncompleted sub-picture reproduction unit
110
P is reproduced based on the reproduction unit length described in the unit header
110
A (which is included at the beginning of the reproduction unit
110
P).
FIG. 4
illustrates the reproduction of the sub-picture encoded data
109
during intermittent reproduction. A decoding operation is performed so as to first reproduce the reproduction unit
110
P by extracting the reproduction unit length described in the unit header
110
A, reproducing the reproduction unit
110
P, and then reproducing the next reproduction unit
110
Q by commencing a reproduction operation from a position which is distant from the reproduction unit
110
P by the specified reproduction unit length
113
.
However, as shown In
FIG. 4
, the reproduction unit length
113
may not be equal to the actual data length of a reproduction unit
113
A which is stored in a sub-picture bit buffer
13
. Since the actual data length of a reproduction unit
113
A which is stored in a sub-picture bit buffer
13
is smaller than the reproduction unit length
113
, the decoding operation could be continued past the data portion

Affiliated with

Also associated with

Rating

Video signal reproducing apparatus capable of reproducing... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Video signal reproducing apparatus capable of reproducing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Video signal reproducing apparatus capable of reproducing... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3177010