EP0618728A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Synchronization of audio/video information
Assignee: Sony Corp
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Filing: 1994-02-03
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Granted: —
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Expires: 2014-02-03
Abstract
Abstract A compressed video signal and a compressed audio signal decoding apparatus which including a local access unit counter intended for digital AV applications where access unit headers (e.g. frame headers, audio unit headers or other kind of data unit headers) may be lost or generated by storage media or transmission errors. In order to prevent a resulting AV sync error a value called "access unit count" is included in each elementary stream. With this value each decoder can detect lost or false access unit headers, and correct the AV synchronization. In order to support editing, an extra bit can be added to indicate discontinuity in the access unit count. <IMAGE>
Inventors
- 👤 Markus H. C/O Sony Corporation Veltman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 15:58
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/04; H04N19/00; H04N19/10; H04N19/134; H04N19/146; H04N19/152; H04N19/60; H04N19/61; H04N21/00; H04N21/40; H04N21/43; H04N21/4302; H04N21/4305; H04N21/4307; H04N21/43072; H04N21/434; H04N21/4341; H04N21/439; H04N21/4392; H04N21/44; H04N21/44004; H04N21/80; H04N21/83; H04N21/845; H04N21/8455; H04N5/76; H04N5/91; H04N5/92; H04N5/9201; H04N5/9206; H04N5/926; H04N5/9261; H04N5/9264; H04N5/9265; H04N7/00; H04N7/24; H04N7/52; H04N7/54; H04N7/56; H04N19/50
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
217 words
A demulitplexer for a multiplexed audio video signal, comprising in combination: a clock (118) producing a time reference; a demultiplexing switch (50) for separating a composite data stream into audio sample batches, audio time stamps, video frames, and video time stamps, wherein said audio time stamps are fewer or equal in number than said audio sample batches and wherein said video time stamps are fewer or equal in number than said video frames; an audio phase-locked loop (122), receiving said audio time stamps and said time reference, for comparing said time reference with said audio time stamps to produce an audio timing signal which associates one of said audio sample batches with each of said audio time stamps; an audio decoder (130) receiving said audio sample batches and said audio timing signal, and for decoding said audio sample batches in sychronization with said audio timing signal; a video phase-locked loop (120) receiving said video time stamps and said time reference, for comparing said time reference with said video time stamps to produce a video timing signal which associates one of said video frames with each of said video time stamps; and a video decoder (128) receiving said video frames and said video timing signal, and for decoding said video laces in synchronization with said video timing signal.
Claim 2
Dependent Claim
20 words
The apparatus of claim 1, further comprising: a video timestamp buffer (104) receiving said video timestamps from said demultiplexing switch.
Claim 3
Dependent Claim
20 words
The apparatus of claim 1, further comprising: an audio timestamp buffer (108) receiving said audio timestamps from said demultiplexing switch.
Claim 4
Dependent Claim
19 words
The apparatus of claim 1, further comprising: a video buffer (100) receiving said video frames from said demultiplexing switch.
Claim 5
Dependent Claim
20 words
The apparatus of claim 1, further comprising: an audio buffer (102) receiving said audio sample batches from said demultiplexing switch.
Claim 6
Dependent Claim
20 words
The apparatus of claim 1, wherein said time reference is indicative of an absolute time elapsed since a reference time.
Claim 7
Dependent Claim
12 words
The apparatus of claim 6, wherein said clock (118) operates at 90KHz.
Claim 8
Dependent Claim
16 words
The apparatus of claim 1, wherein said multiplexed audio video signal is an MPEG standard signal.
Claim 9
Dependent Claim
40 words
The apparatus of claim 6, wherein said audio phase-locked loop (122) associates an audio time stamp with the audio sample batch which is decoded closest in time, as measured by said clock, to the value of said audio time stamp.
Claim 10
Dependent Claim
39 words
The apparatus of claim 6, wherein said video phase-locked loop (120) associates a video time stamp with the video frame which is decoded closest in time, as measured by said clock, to the value of said video time stamp.
Claim 11
Dependent Claim
365 words
A demultiplexer for an MPEG standard multiplexed audio video signal, comprising in combination: a 90 KHz clock (118) producing a time reference indicative of an absolute time elapsed since a reference time; a demultiplexing switch (50) for separating a composite data stream into audio sample batches, audio time stamps, video frames, and video time stamps, wherein said audio time stamps are fewer or equal in number than said audio sample batches and said video time stamps are fewer or equal in number than said video frames; a video timestamp buffer (104) receiving said video timestamps from said demultiplexing switch; an audio timestamp buffer (108) receiving said audio timestamps from said demultiplexing switch; a video buffer (100) receiving said video frames from said demultiplexing switch; an audio buffer (102) receiving said audio sample batches from said demultiplexing switch; an audio phase-locked loop (130), receiving said audio time stamps from said audio timestamp buffer (108) and receiving said time reference, for comparing said time reference with said audio time stamps to produce an audio timing signal which associates one of said audio sample batches with each of said audio time stamps, wherein said audio phase-locked loop (130) associates an audio time stamp with the audio sample batch which is decoded closest in time, as measured by said clock, to the value of said audio time stamp; an audio decoder (130) receiving said audio sample batches and said audio timing signal, and for decoding said audio sample batches in synchronization with said audio timing signal; a video phase-locked loop (120), receiving said video time stamps from said video time stamp buffer (104) and receiving said time reference, for comparing said time reference with said video time stamps to produce a video timing signal which associates one of said video frames with each of said video time stamps, wherein said video phase-locked loop (120) associates a video time stamp with the video frame which is decoded closest in time, as measured by said clock, to the value of said video time stamp; and a video decoder (128) receiving said video frames and said video timing signal, and for decoding said video frames in synchronization with said video timing signal.
Claim 12
Dependent Claim
132 words
A decoder, comprising in combination: a clock producing a time reference; means for separating a composite data stream into data units and data time stamps, wherein said data time stamps are fewer or equal in number than said data units; a phase-locked loop, receiving said time stamps and said time reference, for comparing said time reference with said time stamps to produce a timing signal which associates one of said data units with each of said time stamps, wherein said phase-locked loop associates a time stamp with the data unit which is decoded closest in time, as measured by said clock, to the value of said data time stamp; and a decoder receiving said data units and said audio timing signal, and for decoding said units in synchronization with said timing signal.
Claim 13
Dependent Claim
218 words
A demultiplexer for a multiplexed audio video signal, comprising in combination: a demultiplexing switch (50) for separating a composite data stream into audio sample batches, audio time stamps, video frames, and video time stamps; an audio phase-locked loop (122), receiving said audio time stamps, for producing an audio timing signal in synchronization with said audio time stamps; an audio decoder (230) receiving said audio sample batches and said audio timing signal, and for decoding said audio sample batches in synchronization with said audio timing signal; said audio decoder (230) including means (240) for extracting an access unit count from said audio sample batches and comparing said access unit count with a stored access unit count (244) to verify that said audio decoder is operating in proper synchronization; a video phase-locked loop (120) receiving said video time stamps, for producing a video timing signal in synchronization with said video time stamps; a video decoder (228) receiving said video frames and said video timing signal, and for decoding said video frames in synchronization with said video timing signal; and said video decoder (228) including means (234) for extracting an access unit count from said video frames and comparing said access unit count (238) with a stored access unit count to verify that said video decoder is operating in proper synchronization.
Claim 14
Dependent Claim
20 words
The apparatus of claim 13, further comprising: a video timestamp buffer (104) receiving said video timestamps from said demultiplexing switch.
Claim 15
Dependent Claim
20 words
The apparatus of claim 13, further comprising: an audio timestamp buffer (108) receiving said audio timestamps from said demultiplexing switch.
Claim 16
Dependent Claim
19 words
The apparatus of claim 13, further comprising: a video buffer (100) receiving said video frames from said demultiplexing switch.
Claim 17
Dependent Claim
20 words
The apparatus of claim 13, further comprising: an audio buffer (102) receiving said audio sample batches from said demultiplexing switch.
Claim 18
Dependent Claim
95 words
A decoder, comprising in combination: means for separating a composite data stream into data units and data time stamps; timing means receiving said data time stamps, for producing a timing signal in synchronization with said data time stamps; a decoder receiving said data units and said timing signal, for decoding said data units in syhchronization with said timing signal; said decoder including means for extracting an access unit count from each said packet and comparing said access unit count with a stored access unit count to verify that said decoder is operating in proper synchronization.
Claim 19
Dependent Claim
13 words
The apparatus of claim 8, wherein said timing means includes a phase-locked loop.
Claim 20
Independent Claim
144 words
A method for demultiplexing a mulitplexed audio video signal, comprising the steps of: separating a composite data stream into audio sample batches, audio time stamps, video frames, and video time stamps; producing an audio timing signal in synchronization with said audio time stamps; decoding said audio sample batches in syncronization with said audio timing signal; extracting an access unit count from said audio sample batches and comparing said access unit count with a stored access unit count to verify audio synchronization; producing a video timing signal in synchronization with said video time stamps; decoding said video frames in synchronization with said video timing signal; extracting an access unit count from said video frames and comparing said access unit count with a stored access unit count to verify video synchronization; and incrementing the stored access unit count each time a new access unit is received.
Claim 21
Dependent Claim
31 words
The method of claim 20, further comprising the step of duplicating a video frame if said access unit count for said video frame is larger than said stored access unit count.
Claim 22
Dependent Claim
31 words
The method of claim 20, further comprising the step of omitting a video frame if said access unit count for said video frame is smaller than said stored access unit count.
Claim 23
Dependent Claim
33 words
The method of claim 20, further comprising the step of omitting an audio sample batch if said access unit count for said audio sample batch is smaller than said stored access unit count.
Claim 24
Dependent Claim
33 words
The method of claim 20, further comprising the step of duplicating an audio sample batch if said access unit count for said audio sample batch is larger than said stored access unit count.
Claim 25
Independent Claim
100 words
A method for processing a video and an associated audio signal, comprising the steps of: providing a signal having audio sample batches and video frames; decoding said audio sample batches; extracting an access unit count from said audio sample batches and comparing said access unit count with a stored access unit count to verify audio synchronization; decoding said video frames; extracting an access unit count from said video frames and comparing said access unit count with a stored access unit count to verify video synchronization; and incrementing said stored access unit count each time a new access unit is received.
Claim 26
Dependent Claim
31 words
The method of claim 25, further comprising the step of duplicating a video frame if said access unit count for said video frame is larger than said stored access unit count.
Claim 27
Dependent Claim
31 words
The method of claim 25, further comprising the step of omitting a video frame if said access unit count for said video frame is smaller than said stored access unit count.
Claim 28
Dependent Claim
33 words
The method of claim 25, further comprising the step of omitting an audio sample batch if said access unit count for said audio sample batch is smaller than said stored access unit count.
Claim 29
Dependent Claim
33 words
The method of claim 25, further comprising the step of duplicating an audio sample batch if said access unit count for said audio sample batch is larger than said stored access unit count.
Claim 30
Dependent Claim
29 words
The method of claim 25, wherein said audio video signal includes audio and video time stamps associated with presentation of certain of said audio sample batches and video frames.
Claim 31
Independent Claim
141 words
A method for processing a stream of data bits, comprising the steps of: initializing a register with an access unit count corresponding to a frist frame header; receiving and decoding one or more subsequent frames; incrementing said register for each said subsequent frame and comparing the content of said register with an access unit count with each said subsequent frame; determining if said access unit count from each said subsequent frame is the same as that stored in said register to verify synchronisation; omitting a video frame if said access unit count for said video frame is smaller than said stored access unit count; omitting an audio sample batch if said access unit count for said audio sample batch is smaller than said stored access unit count; detecting a discontinuity bit; and reinitializing said register upon detection of said discontinuity bit.
Claim 32
Dependent Claim
19 words
The method of claim 31, wherein said register is reinitialized with an access unit count following said discontinuity bit.
References Cited (Backward Citations)
No citation records indexed.
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