Electrical computers and digital processing systems: support – Synchronization of clock or timing signals – data – or pulses
Reexamination Certificate
1998-12-21
2001-05-15
Heckler, Thomas M. (Department: 2182)
Electrical computers and digital processing systems: support
Synchronization of clock or timing signals, data, or pulses
Reexamination Certificate
active
06233695
ABSTRACT:
BACKGROUND
1. Technical Field
The present invention relates to a data transmission control system and, particularly, to a data transmission control system in a set top box(hereinafter, referred to STB) for matching timings between transmission data and synchronous signal of the data exactly, in case that transmission paths of the transmission data and the synchronous signal in the STB are different.
2. Background
Generally, a data transmission control system in a conventional STB has a demultiplexer DEMUX
10
for receiving compressed video/audio bitstreams from a video server and demultiplexing the bitstreams, a microprocessor
20
for synchronizing a presentation signal with a system clock, and a video decoder
30
and an audio decoder
40
for encoding the video/audio bitstreams and providing the bitstreams to a video output device and an audio output device, shown in FIG.
1
.
The DEMUX
10
demultiplexes the compressed video/audio bitstreams transmitted from the video server using MPEG-2(Moving Picture Experts Group-2) to a Presentation Time Stamps PTS and a video bitstream ES(Elementary Stream) and an audio bitstream ES. The audio ES is transmitted through a transmission path connected to the audio decoder
40
. The video ES is transmitted through a transmission path connected to the video decoder
30
. Here, the PTS is transmitted to the video decoder
30
via the microprocessor
20
in order to be synchronized with the video ES. Accordingly, transmission time of the PTS affects the synchronization of the video signal.
The video decoder
30
allocates the PTS on the basis of a sequence header inside of the video ES. Referring to
FIG. 2
the video ES and the PTS are synchronized with PTS
1
and ES
1
, PTS
2
and ES
2
, and PTS
3
and ES
3
, respectively when the video signal is normally synchronized. Thereby, the video decoder
30
may decode video data exactly.
Further information can be found in copending U.S. Pat. No. 5,559,999, entitled “MPEG decoding system including tag list for associating presentation time stamps with encoded data units”, which is incorporated by reference herein.
However, the PTS may be not synchronized with the video ES in case that the PTS is applied to the video decoder
30
upon being delayed from the microprocessor
20
, referring to FIG.
3
. Here, the video decoder
30
recognizes that the first PTS
1
is a synchronization signal of the ES
1
correctly. But, the ES
2
signal has already applied to the video decoder
30
when the PTS
2
signal is applied to the video decoder
30
. Accordingly, the video decoder
30
misses the ES
2
sequence header and recognizes that the PTS
2
signal is the synchronization signal of the ES
3
, and the synchronization between the PTS signal and the ES signal is therefore asynchronized.
Consequently, there are problems that the presentation screen is distorted or trembled and also lip sink is not matched with audio when the PTS and the video ES are asynchronized.
SUMMARY
Accordingly, in order to solve the problems in the prior art it is an object of the present invention to provide a data transmission control system in Set Top Box STB capable of matching output timings of a video or an audio signal and a synchronous signal of the video or audio signal by controlling the transmission of the data bitstreams when transmission paths of video data or audio data and the synchronous signal of the video or audio data, are different from each other.
In order to achieve the above object, in accordance with an aspect of the present invention, there is provided a data transmission control system in STB, comprising a control unit in a data transmission path where PTS and data bitstream ES are selected from compressed data ES respectively, which are transmitted for dynamic image presentation, decoding the ESs according to the PTS, and applying the decoded ES to an output device on the data transmission path, the control unit for supervising the PTS transmission timing and the ES, and matching timings of the ES and the PTS with a supervising result.
Additionally, the data transmission control system in the STB further comprises a bitstream delay means of which output is automatically controlled by the control means on the data transmission path.
REFERENCES:
patent: 5396497 (1995-03-01), Veltman
patent: 5430485 (1995-07-01), Lankford et al.
patent: 5559999 (1996-09-01), Maturi et al.
patent: 5959684 (1999-09-01), Tan et al.
patent: 5960006 (1999-09-01), Maturi et al.
patent: 5973758 (1999-10-01), Soroushian et al.
patent: 6002687 (1999-12-01), Magee et al.
patent: 6041161 (2000-03-01), Okamoto et al.
patent: 6115422 (2000-09-01), Anderson et al.
patent: 6148135 (2000-11-01), Suzuki
Heckler Thomas M.
LG Information & Communications Ltd.
Long Aldridge & Norman LLP
LandOfFree
Data transmission control system in set top box does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Data transmission control system in set top box, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data transmission control system in set top box will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2497706