Restriction of escape pixel signaled values in palette mode video coding

A method of encoding video data comprising:

• determining, by an encoding apparatus and based on at least a component bitdepth, a maximum value for escape values used in a palette mode for encoding the video data, wherein the maximum value is determined according to (1<<(n+b))−1, wherein n is the component bitdepth and b is an integer, and wherein the escape values represent samples in a block of the video data to be encoded;
• restricting, by the encoding apparatus, one or more escape values to be no greater than the maximum value;
• and
• encoding, by the encoding apparatus, the one or more escape values in an encoded video data bitstream.

A method of decoding video data comprising:

• receiving, by a decoding apparatus, a bitstream that includes information for determining at least one escape value used in a palette mode for decoding the video data, wherein the bitstream is constrained such that it is compliant with a restriction ensuring that the at least one escape value is quantized according to a quantization parameter that is not less than a quantization parameter lower bound, and wherein the bitstream is further constrained such that escape values used in the palette mode for decoding the video data are no greater than a maximum value, wherein the maximum value is based on at least a component bitdepth, wherein the maximum value is calculated according to (1<<(n+b))−1, and wherein n is the component bitdepth and b is an integer;
• determining, by the decoding apparatus, the at least one escape value from the bitstream based on the restriction;
• and
• reconstructing, by the decoding apparatus, a sample of the video data using the at least one escape value.

A method of encoding video data comprising:

• determining, by an encoding apparatus, a quantization parameter value for the video data;
• determining, by the encoding apparatus, a quantization parameter lower bound;
• quantizing, by the encoding apparatus, escape values used in a palette mode for encoding the video data according to the quantization parameter lower bound if the quantization parameter value is less than the quantization parameter lower bound, wherein the escape values represent samples in a block of the video data to be encoded;
• determining, by the encoding apparatus and based on at least a component bitdepth, a maximum value for the escape values, wherein the maximum value is determined according to (1<<(n+b))−1, and wherein n is the component bitdepth and b is an integer;
• restricting, by the encoding apparatus, one or more escape values to be no greater than the maximum value;
• and
• encoding, by the encoding apparatus, the escape values in an encoded video data bitstream.

An apparatus configured to decode video data, the apparatus comprising:

• a memory configured to store the video data;
• and
• one or more processors configured to:
• receive a bitstream that is constrained such that escape values used in a palette mode for decoding the video data are no greater than a maximum value, wherein the maximum value is based on at least a component bitdepth, wherein the maximum value is calculated according to (1<<(n+b))−1, wherein n is the component bitdepth and b is an integer, and wherein the bitstream includes information for determining at least one escape value representing a sample in a block of the video data to be decoded, and
• reconstruct the sample in the block of the video data using the information for determining the at least one escape value.

An apparatus configured to encode video data, the apparatus comprising:

• a memory configured to store the video data;
• and
• one or more processors configured to:
• determine, based on at least a component bitdepth, a maximum value for escape values used in a palette mode for encoding the video data, wherein the maximum value is determined according to (1<<(n+b))−1, wherein n is the component bitdepth and b is an integer, and wherein the escape values represent samples in a block of the video data to be encoded,
• restrict one or more escape values to be no greater than the maximum value, and
• encode the one or more escape values in an encoded video data bitstream.

An apparatus configured to decode video data, the apparatus comprising:

• a memory configured to store the video data;
• and
• one or more processors configured to:
• receive a bitstream that includes information for determining at least one escape value used in a palette mode for decoding the video data, wherein the bitstream is constrained such that it is compliant with a restriction ensuring that the at least one escape value is quantized according to a quantization parameter that is not less than a quantization parameter lower bound, and wherein the bitstream is further constrained such that escape values used in the palette mode for decoding the video data are no greater than a maximum value, wherein the maximum value is based on at least a component bitdepth, wherein the maximum value is calculated according to (1<<(n+b))−1, and wherein n is the component bitdepth and b is an integer,
• determine the at least one escape value from the bitstream based on the restriction, and
• reconstruct a sample of the video data using the at least one escape value.

An apparatus configured to encode video data, the apparatus comprising:

• a memory configured to store the video data;
• and
• one or more processors configured to:
• determine a quantization parameter value for the video data;
• determine a quantization parameter lower bound,
• quantize escape values used in a palette mode for encoding the video data according to the quantization parameter lower bound if the quantization parameter value is less than the quantization parameter lower bound, wherein the escape values represent samples in a block of the video data to be encoded,
• determine, based on at least a component bitdepth, a maximum value for the escape values, wherein the maximum value is determined according to (1<<(n+b))−1, and wherein n is the component bitdepth and b is an integer,
• restrict one or more escape values to be no greater than the maximum value, and
• encode the escape values in an encoded video data bitstream.

An apparatus configured to decode video data, the apparatus comprising:

• means for receiving a bitstream that includes information for determining at least one escape value used in a palette mode for decoding the video data, wherein the bitstream is constrained such that it is compliant with a restriction ensuring that the at least one escape value is quantized according to a quantization parameter that is not less than a quantization parameter lower bound, and wherein the bitstream is further constrained such that escape values used in the palette mode for decoding the video data are no greater than a maximum value, wherein the maximum value is based on at least a component bitdepth, wherein the maximum value is calculated according to (1<<(n+b))−1, and wherein n is the component bitdepth and b is an integer;
• means for determining the at least one escape value from the bitstream based on the restriction;
• and
• means for reconstructing a sample of the video data using the at least one escape value.

A non-transitory computer-readable medium having stored thereon instructions that, when executed, cause one or more processors to:

• receive a bitstream that includes information for determining at least one escape value used in a palette mode for decoding the video data, wherein the bitstream is constrained such that it is compliant with a restriction ensuring that the at least one escape value is quantized according to a quantization parameter that is not less than a quantization parameter lower bound, and wherein the bitstream is further constrained such that escape values used in the palette mode for decoding the video data are no greater than a maximum value, wherein the maximum value is based on at least a component bitdepth, wherein the maximum value is calculated according to (1<<(n+b))−1, and wherein n is the component bitdepth and b is an integer;
• determine the at least one escape value from the bitstream based on the restriction;
• and
• reconstruct a sample of the video data using the at least one escape value.