Video compression
First Claim
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1. An information bus generator, comprising timestamp driven timing means;
- a macroblock rate information buffer;
a variable length decoder operating on the buffer output to derive coefficient and non-coefficient streams;
means for formatting the non-coefficient stream to provide a first information bus component;
means for monitoring the state of the variable length decoder to provide a second information bus component and means for combining the first and second information bus components to provide an information bus.
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Abstract
An MPEG-2 or other compressed video stream (CP) can be manipulated as separate information bus (IB) and coefficient (CP*) streams. The information bus stream (IB) contains motion vector information but also information derived from a previous decoding operation (14, 18) for use in a subsequent coding operation (22). Processing in the coefficient domain enables bit rate conversion without decoding to the pixel level and also simplifies the combination of MPEG layers.
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Citations
20 Claims
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1. An information bus generator, comprising timestamp driven timing means;
- a macroblock rate information buffer;
a variable length decoder operating on the buffer output to derive coefficient and non-coefficient streams;
means for formatting the non-coefficient stream to provide a first information bus component;
means for monitoring the state of the variable length decoder to provide a second information bus component and means for combining the first and second information bus components to provide an information bus. - View Dependent Claims (2)
- a macroblock rate information buffer;
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3. An information bus encoder comprising a variable length coder for receiving a coefficient stream;
- a plurality of parallel paths each serving to interpret and code a piece of information from an information bus and multiplexer means serving to combine all said coded information in a compressed bitstream.
- View Dependent Claims (4)
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5. A method of combining a plurality of compressed signals, comprising the steps of variable length decoding each compressed signal;
- inverse quantising each such decoded signal to produce a coefficient stream;
combining the coefficient streams to form a combined coefficient stream;
re quantising the combined coefficient stream and variable length coding the re-quantised, combined coefficient stream. - View Dependent Claims (6, 13, 14)
- inverse quantising each such decoded signal to produce a coefficient stream;
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7. The method of video signal processing, comprising the steps of variable length decoder a compressed video signal to derive coefficient and noncoefficient streams;
- formatting the non-coefficient stream to provide a first information bus component;
monitoring the state of the variable length decoder to provide a second information bus component and combining the first and second information bus components to provide an information bus.
- formatting the non-coefficient stream to provide a first information bus component;
- 8. A signal transmission process comprising the steps of transmitting a video signal and transmitting synchronously with the video signal an information bus signal, including information derived from a previous decoding operation for use in a subsequent coding operation.
- 9. A signal transmission process comprising the steps of transmitting a video signal and transmitting synchronously with the video signal an information bus signal, including information derived from a pre-processing operation for use in a subsequent coding operation.
- 10. A signal transmission process comprising the steps of transmitting a video signal and transmitting synchronously with the video signal an information bus signal, including information derived from a previous decoding operation for use in a post-processing operation.
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15. A method of synchronizing a compressed video signal with a reference signal comprising the steps of:
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variable length decoding the compressed signal;
inverse quantizing the such decoded signal to produce a coefficient stream;
delaying the coefficient stream to ensure synchronism with the reference signal;
re-quantizing the synchronized coefficient stream; and
variable length coding the re-quantized, synchronized coefficient stream. - View Dependent Claims (16)
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Specification