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1. (WO1997015888) METHOD AND DEVICE FOR ERROR CONTROL IN VIDEO COMPRESSION
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

1. A method of error control of a macroblock-based video codec, wherein macroblocks are encoded using entropy coding, comprising:
1 A) utilizing, in a decoder, control information and a plurality of picture headers in fixed positions relative to a beginning of a frame wherein the control information provides decoding information for decoding at least a forward sequence of macroblocks;
1 B) detecting errors in the frame and limiting propagation of errors in the frame utilizing the control information and the plurality of picture headers.

2. The method of claim 1 wherein the control information defines a boundary of individual packets and includes:
2A) an absolute count of a next/previous macroblock within the frame;
2B) a relative address of a start of a next macroblock in a next packet; and
2C) absolute values for predetermined differentially encoded information.

3. The method of claim 2 wherein at least one of 3A-3D:
3A) the predetermined differentially encoded information includes at least one of: 3A1 ) a quantization parameter of an immediately previous macroblock; and
3A2) a motion vector value of the immediately previous macroblock;
3B) wherein detecting an error in the frame includes detecting an error in the packet wherein at least one of:
3B1 ) detecting loss of entropy coding synchronization;
3B2) determining whether the absolute count is decreasing ;
3B3) detecting an incorrect error detection code; and
3B4) determining whether invalid coding parameters are present;
3C) wherein, where the relative address is quantized to bytes, and where a quantization remainder determines a number of bits available for an error detection code;
and
3D) further including that encoding of the macroblocks includes outputting the macroblocks in a forward bit order for a predetermined number of macroblocks and in a bit-reversed bit order for a second predetermined number of macroblocks and wherein a control information is used to decode both forward and reverse bit encoded macroblocks, and where selected, wherein an error detection code is inserted between the forward and bit-reversed macroblocks, and where further selected, wherein the relative address is quantized to bytes, and where a quantization remainder determines a number of bits available for an error detection code.

4. The method of claim 1 wherein at least one of 4A-4B:
4A) at least one of the picture headers is utilized to determine a start of the frame; and
4B) wherein the method is a process whose steps are embodied in least one of:
4B1 ) an application specific integrated circuit;
4B2) a field programmable gate array; and
4B3) a microprocessor; and
4B4) a computer-readable memory;
arranged and configured to determine the first modified received signal having minimized distortion and interference in accordance with the scheme of claim 1.

5. A device for error control and concealment of a macroblock-based video codec, wherein macroblocks are encoded using entropy coding, wherein the device is directed by a computer program that is embodied in at least one of:
5A) a memory;
5B) an application specific integrated circuit;
5C) digital signal processor; and
5D) a field programmable gate array,
and the computer program includes steps of: 5E) utilizing control information and a plurality of picture headers in fixed positions relative to a beginning of a frame wherein the control information provides decoding information for decoding at least a forward sequence of macroblocks;
5F) detecting errors in the frame and limiting propagation of errors in the frame utilizing the control information and the plurality of picture headers.

6. The device of claim 5 wherein the control information computed by a bit packet controller defines a boundary of individual packets and includes:

6A) an absolute count of a next/previous macroblock within the frame;
6B) a relative address of a start of a next macroblock in a next packet; and
6C) absolute values for predetermined differentially encoded information.

7. The device of claim 6 wherein at least one of 7A-7D:
7A) the predetermined differentially encoded information includes at least one of 7A1 -7A2:
7A1 ) a quantization parameter of an immediately previous macroblock; and
7A2) a motion vector value of the immediately previous macroblock;

7B) wherein the an error detection unit performs detecting of an error in a packet wherein at least one of:
7B1 ) detecting loss of entropy coding synchronization;
7B2) determining whether the absolute count is decreasing;
7B3) detecting an incorrect error detection code; and
7B4) determining whether invalid coding parameters are present;
7C) wherein, where the relative address is quantized to bytes, and where a quantization remainder determines a number of bits available for an error detection code;
and
7D) wherein at least one of the picture headers is utilized to determine a start of the frame.

8. The method of claim 6 further including two block-based bit reversers utilized such that encoding of the macroblocks includes outputting the macroblocks in a forward bit order for a predetermined number of macroblocks and in a bit-reversed bit order for a second predetermined number of macroblocks and wherein a control information is used to decode both forward and reverse bit encoded macroblocks, and where selected, wherein an error detection code is inserted between the forward and bit-reversed macroblocks, and where further selected, wherein the relative address is quantized to bytes, and where a quantization remainder determines a number of bits available for an error detection code.

9. A device for error control and concealment for packets in a compressed bitstream in a macroblock-based video codec, wherein macroblocks are encoded using entropy coding, and a fixed length packet synchronization system is applied to variable length coded compressed video data, to limit error propagation within a decoded video bitstream, wherein the device comprises at least one of an encoder and a decoder, wherein the encoder comprises:
9A) a bit packet controller, coupled to receive a compressed bitstream, for computing error control information by generating a plurality of predetermined control words, wherein packet control information is placed at a beginning of each packet;
9B) a block-based bit reverser, coupled to receive the compressed bitstream and to the bit packet controller, for reversing a macroblock bit order for macroblocks that are designated as backwards encoded macroblocks; and
9C) a multiplexer, coupled to the bit packet controller, the compressed bitstream and to the block-reversed bit reverser, for multiplexing the error control information and the compressed bitstream with the output of the block-based bit reverser according to a predeteremined scheme;
and in the decoder comprises: 9D) a demultiplexer, coupled to receive a multiplexed bitstream and to a control unit, for removing bits indicated by the control unit in accordance with a predetermined scheme and sending the bits to a second block-based bit reversal unit, a forward block decoder, and an error detector; E) the second block-based bit reversal unit, coupled to the demultiplexer, for reversing a macroblock bit order for macroblocks in accordance with the predetermined scheme to provide an output; and
F) a backward block decoder, coupled to the second block-based bit reversal unit, for decoding the output of the second block-based bit reversal unit;
G) a forward block decoder, coupled to the demultiplexer, for decoding the bits from the demultiplexer;
H) an error detector, coupled to the demultiplexer, the backward block decoder, and to the forward block decoder, for utilizing control information and the decoded bitstreams to signal a presence of specific errors.

10. The device of claim 9 further including at least one of 10A-1 OB:
10A) an error report unit, coupled to the error detector, for outputting an error report, for utilization in error concealment, wherein the error report including at least one of: loss of entropy coding synchronization, errors in an absolute count due to a decreasing count, cyclic redundancy count errors, other coding parameters detected that have been preselected to indicate invalidity, and variable length decoder errors;

and
10B) wherein the bit packet controller generates at least the following control words: picture headers ; absolute count, AC, of next macroblock in the bistream ; relative address, AD, of the next macroblock in the bitstream in bytes ; absolute quantization parameter value, QP, of the last macroblock in a present packet of bits , absolute motion vector, MV, associated with the last macroblock in the present packet of bits ; and a check word, CRC, providing error detection capabilities for the present packet of bits.