Insertion of noise for reduction in the number of bits for variable-length coding of (run, level) pairs

A method of variable-length encoding a block of pixels, the method comprising:

• a) computing a two-dimensional discrete cosine transform (DCT) of the block of pixels to produce a series of DCT coefficient values;
• b) quantizing the DCT coefficient values to produce quantized coefficient values;
• c) producing an original series of (run, level) pairs each having a level value indicating a respective non-zero quantized coefficient value;
• d) inspecting the (run, level) pairs in the original series of (run, level) pairs to determine whether or not modification of at least one (run, level) pair in the original series of (run, level) pairs would produce a desirable decrease in a number of bits required for variable-length encoding of said block of pixels despite introduction of noise into the variable-length encoding of said block of pixels;
• and
• e) upon determining that modification of said at least one (run, level) pair in the original series of (run, level) pairs would produce a desirable decrease in the number of bits required for variable-length encoding of said block of pixels despite introduction of noise into the variable-length encoding of said block of pixels, modifying said at least one (run, level) pair to produce a modified series of (run, level) pairs from the original series of (run, level) pairs;
• and
• f) variable-length encoding the modified series of (run, level) pairs.

A method of producing MPEG encoded video from an original series of MPEG-compliant (run, level) pairs, said method comprising:

• a) inspecting the (run, level) pairs in the original series of (run, level) pairs to determine whether or not modification of at least one (run, level) pair in the original series of (run, level) pairs would produce a desirable decrease in a number of bits in the MPEG encoded video despite introduction of noise into the MPEG encoded video;
• and
• b) upon determining that modification of said at least one (run, level) pair in the original series of (run, level) pairs would produce a desirable decrease in the number of bits in the MPEG encoded video despite introduction of noise into the MPEG encoded video, replacing said at least one (run, level) pair with a sequence of a first (run, level) pair and a second (run, level) pair to produce a modified series of (run, level) pairs from the original series of (run, level) pairs, said at least one (run, level) pair having a non-zero run length of M and a non-zero level value of N, the first (run, level) pair having a run length of M−1 and a level magnitude of one, and the second (run, level) pair having a run length of zero and a level value of N;
• and
• c) variable-length encoding the modified series of (run, level) pairs to produce the MPEG encoded video.

A method of decoding MPEG encoded video that includes noise introduced during the encoding process by insertion of at least one (run, level) pair having a level magnitude of one, said method comprising;

• a) decoding a series of (run, level) pairs from the MPEG encoded video;
• and
• b) inspecting the series of (run, level) pairs to find said at least one (run, level) pair having a level magnitude of one;
• and
• c) determining that said at least one (run, level) pair having a level magnitude of one is likely to represent noise introduced during the encoding process, and therefore rejecting said at least one (run, level) pair having a level magnitude of one in order to reduce noise.

A digital computer for producing MPEG encoded video from an original series of MPEG-compliant (run, level) pairs, said digital computer comprising at least one processor programmed for:

• a) inspecting the (run, level) pairs in the original series of (run, level) pairs to determine whether or not modification of at least one (run, level) pair in the original series of (run, level) pairs would produce a desirable decrease in a number of bits in the MPEG encoded video despite introduction of noise into the MPEG encoded video;
• and
• b) upon determining that modification of said at least one (run, level) pair in the original series of (run, level) pairs would produce a desirable decrease in the number of bits in the MPEG encoded video despite introduction of noise into the MPEG encoded video, replacing said at least one (run, level) pair with a sequence of a first (run, level) pair and a second (run, level) pair to produce a modified series of (run, level) pairs from the original series of (run, level) pairs, said at least one (run, level) pair having a non-zero run length of M and a non-zero level value of N, the first (run, level) pair having a run length of M−1 and a level magnitude of one, and the second (run, level) pair having a run length of zero and a level value of N;
• and
• c) variable-length encoding the modified series of (run, level) pairs to produce the MPEG encoded video.

A decoder for decoding MPEG encoded video that includes noise introduced during the encoding process by insertion of at least one (run, level) pair having a level magnitude of one, the decoder comprising at least one processor programmed for:

• a) decoding a series of (run, level) pairs from the MPEG encoded video;
• and
• b) inspecting the (run, level) pairs to find said at least one (run, level) pair having a level magnitude of one;
• and
• c) determining that said at least one (run, level) pair having a level magnitude of one is likely to represent noise introduced during the encoding process, and therefore rejecting said at least one (run, level) pair having a level magnitude of one in order to reduce noise.