MPEG transcoding system and method using motion information
First Claim
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1. A system for converting a stream of compressed video data to a required lower bit rate, comprising:
- a system for determining an importance of each of a set of macroblocks in the stream; and
a system for selectively bit rate transcoding discrete cosine transform (DCT) blocks in the set of macroblocks based on the determined importance of each macroblock.
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Abstract
An open loop system and method of transcoding a stream of compressed video data to a required lower bit rate. The invention includes the steps of: examining motion vectors for each of a set of macroblocks in the stream; determining an importance of each of the set of macroblocks based the motion vectors; and selectively modifying DCT blocks in the set of macroblocks to reduce the bit rate, wherein the modification to each DCT block is based on the determined importance of the macroblock. High coefficient dropping or re-quantization may be utilized.
33 Citations
37 Claims
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1. A system for converting a stream of compressed video data to a required lower bit rate, comprising:
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a system for determining an importance of each of a set of macroblocks in the stream; and
a system for selectively bit rate transcoding discrete cosine transform (DCT) blocks in the set of macroblocks based on the determined importance of each macroblock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A program product stored on a recordable medium for bit rate transcoding a stream of compressed video data to a required lower bit rate, the program product comprising:
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means for determining an importance of each of a set of macroblocks in the stream; and
means for selectively modifying discrete cosine transform (DCT) blocks contained in the set of macroblocks to reduce the bit rate, wherein the modification to each DCT block is based on the determined importance of the macroblock. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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- 25. The program product of claim 25, wherein an amount of re-quantization applied to each DCT block is based on the importance of the macroblock.
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27. A method of transcoding a stream of compressed video data to a required lower bit rate, the comprising:
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examining motion vectors for each of a set of macroblocks in the stream;
determining an importance of each of the set of macroblocks based the motion vectors; and
selectively modifying discrete cosine transform (DCT) blocks in the set of macroblocks to reduce the bit rate, wherein the modification to each DCT block is based on the determined importance of the macroblock. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification