Encoding strategies for adaptive switching of color spaces, color sampling rates and/or bit depths

A computer system comprising one or more processors and memory, wherein the computer system implements a video encoder configured to perform operations comprising:

• encoding video in a sequence, thereby producing encoded data, including:
• determining that color space conversion operations between an RGB-type color space and a YCoCg color space are permitted for the sequence;
• setting a value of a syntax element, for a sequence parameter set for the sequence, that indicates the color space conversion operations between the RGB-type color space and the YCoCg color space are permitted for the sequence;
• switching color spaces, color sampling rates and/or bit depths spatially and/or temporally between at least some units of the video within the sequence during the encoding, the color spaces including the RGB-type color space and the YCoCg color space, wherein the switching includes performing the color space conversion operations between the RGB-type color space and the YCoCg color space for a given unit of the units of the video, the color space conversion operations implementing a matrix multiplication operation with addition, subtraction, and bit shifting operations to convert values for an R component, values for a G component, and values for a B component into values for a Y component, values for a Co component, and values for a Cg component;
• setting a flag value for the given unit, the flag value indicating a selection between the RGB-type color space and the YCoCg color space for the given unit;
• and
• entropy coding the flag value using context-adaptive binary arithmetic coding;
• and
• outputting the encoded data in a bitstream, the encoded data including the sequence parameter set, and the encoded data further including one or more signals indicating how the color spaces, the color sampling rates and/or the bit depths switch between the at least some units of the video within the sequence, wherein the one or more signals include the flag value for the given unit.

One or more non-transitory computer-readable media having stored thereon computer-executable instructions for causing one or more processors, when programmed thereby, to perform operations comprising:

• receiving encoded data in a bitstream, the encoded data including a sequence parameter set for a sequence, the sequence parameter set including a value of a syntax element that indicates color space conversion operations between a YCoCg color space and an RGB-type color space are permitted for the sequence, and the encoded data further including one or more signals indicating how color spaces, color sampling rates and/or bit depths switch between at least some units of video within the sequence, the color spaces including the RGB-type color space and the YCoCg color space, wherein the one or more signals include a flag value for a given unit of the units of the video, the flag value having been entropy coded using context-adaptive binary arithmetic coding, and wherein the flag value indicates a selection between the RGB-type color space and the YCoCg color space for the given unit;
• and
• decoding the encoded data, including:
• based on the value of the syntax element of the sequence parameter set, determining that the color space conversion operations between the YCoCg color space and the RGB-type color space are permitted for the sequence;
• entropy decoding the flag value;
• switching the color spaces, the color sampling rates and/or the bit depths spatially and/or temporally between the at least some units of the video within the sequence during the decoding, wherein the switching includes performing the color space conversion operations between the YCoCg color space and the RGB-type color space for the given unit, the color space conversion operations implementing a matrix multiplication operation with addition, subtraction, and bit shifting operations to convert values for a Y component, values for a Co component, and values for a Cg component into values for an R component, values for a G component, and values for a B component.

One or more non-transitory computer-readable media having stored thereon encoded data in a bitstream, the encoded data including a sequence parameter set for a sequence, the sequence parameter set including a value of a syntax element that indicates color space conversion operations between a RGB-type color space and an YCoCg color space are permitted for the sequence, and the encoded data further including one or more signals indicating how color spaces, color sampling rates and/or bit depths switch between at least some units of video within the sequence, the color spaces including the RGB-type color space and the YCoCg color space, wherein the one or more signals include a flag value for a given unit of the units of the video, the flag value having been entropy coded using context-adaptive binary arithmetic coding, and wherein the flag value indicates a selection between the RGB-type color space and the YCoCg color space for the given unit, the encoded data resulting from encoding by operations that include:

• determining that the color space conversion operations between the RGB-type color space and the YCoCg color space are permitted for the sequence;
• setting the value of the syntax element, for the sequence parameter set for the sequence, that indicates the color space conversion operations between the RGB-type color space and the YCoCg color space are permitted for the sequence;
• switching color spaces, color sampling rates and/or bit depths spatially and/or temporally between at least some units of the video within the sequence during the encoding, wherein the switching includes performing the color space conversion operations between the RGB-type color space and the YCoCg color space for the given unit of the units of the video, the color space conversion operations implementing a matrix multiplication operation with addition, subtraction, and bit shifting operations to convert values for an R component, values for a G component, and values for a B component into values for a Y component, values for a Co component, and values for a Cg component;
• setting the flag value for the given unit;
• and
• entropy coding the flag value using context-adaptive binary arithmetic coding.