Quantization parameter signaling for joint chroma residual mode in video coding

A device for decoding video data, the device comprising

• a memory configured to store at least a portion of an encoded video bitstream;
• and
• one or more processors that are implemented in circuitry and configured to:
• decode, from the encoded video bitstream, a sequence parameter set (SPS) referred to by one or more pictures of video data, wherein, to decode the SPS, the one or more processors are configured to:
• parse, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS;
• and
• parse, at a second position in the SPS that is after the first position and based on a value of the syntax element that indicates whether joint coding of chroma residuals is enabled or disabled, one or more syntax elements representing a quantization parameter (QP) mapping table;
• decode, from the encoded video bitstream, a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data, wherein, to decode the PPS, the one or more processors are configured to:
• parse a syntax element that indicates whether a QP offset for jointly coded chroma residuals is included in a chroma QP offset table and whether a syntax element that specifies an offset to a luma quantization parameter Qp′Y used for deriving Qp′CbCr is coded;
• and
• decode the picture based on the SPS and the PPS.

A method of encoding video data, the method comprising:

• encoding, in an encoded video bitstream, a sequence parameter set (SPS) referred to by one or more pictures of video data, wherein encoding the SPS comprises:
• encoding, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS;
• and
• encoding, at a second position in the SPS that is after the first position and based on whether joint coding of chroma residuals is enabled or disabled, one or more syntax elements representing a quantization parameter (QP) mapping table;
• and
• encoding, in the encoded video bitstream, a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data, wherein encoding the PPS comprises:
• encoding a syntax element that indicates whether a QP offset for jointly coded chroma residuals is included in a chroma QP offset table and whether a syntax element that specifies an offset to a luma quantization parameter Qp′Y used for deriving Qp′CbCr is coded.

A device for encoding video data, the device comprising

• a memory configured to store at least a portion of an encoded video bitstream;
• and
• one or more processors that are implemented in circuitry and configured to:
• encode, in the encoded video bitstream, a sequence parameter set (SPS) referred to by one or more pictures of video data, wherein, to encode the SPS, the one or more processors are configured to:
• encode, at a first position in the SPS, a syntax element that indicates whether joint coding of chroma residuals is enabled or disabled for the one or more pictures of video data referring to the SPS;
• and
• encode, at a second position in the SPS that is after the first position and based on whether joint coding of chroma residuals is enabled or disabled, one or more syntax elements representing a quantization parameter (QP) mapping table;
• and
• encode, in the encoded video bitstream, a picture parameter set (PPS) referred to by a picture of the one or more pictures of video data, wherein, to encode the PPS, the one or more processors are configured to:
• encode a syntax element that indicates whether a QP offset for jointly coded chroma residuals is included in a chroma QP offset table and whether a syntax element that specifies an offset to a luma quantization parameter Qp′Y used for deriving Qp′CbCr is coded.