Adjustments to encoding and decoding when switching color spaces

A computing system comprising one or more processing units and memory, the computing system implementing a video encoder configured to perform encoding operations comprising:

• encoding video to produce encoded data, wherein the encoding the video includes:
• evaluating a condition for a sequence of the video;
• conditionally signaling a syntax element that indicates whether adaptive color space transformation (“ACT”) is enabled for the sequence of the video, including signaling the syntax element that indicates whether ACT is enabled if the condition is satisfied but otherwise skipping the signaling the syntax element that indicates whether ACT is enabled;
• for each of multiple coding units (“CUs”) of a picture of the sequence of the video, encoding the CU to produce part of the encoded data, wherein the encoding the CU includes:
• evaluating a condition for the CU, wherein the evaluating the condition for the CU includes checking whether ACT is enabled for the sequence of the video;
• and
• conditionally signaling a syntax element that indicates color space for the CU, including signaling the syntax element that indicates the color space for the CU if the condition for the CU is satisfied but otherwise skipping the signaling the syntax element that indicates the color space for the CU;
• and
• outputting the encoded data as part of a bitstream.

In a computing system with a video decoder, a method comprising:

• receiving encoded data as part of a bitstream;
• and
• decoding the encoded data to reconstruct video, wherein the decoding the encoded data to reconstruct the video includes:
• evaluating a condition for a sequence of the video;
• conditionally parsing a syntax element that indicates whether adaptive color space transformation (“ACT”) is enabled for the sequence of the video, including parsing the syntax element that indicates whether ACT is enabled if the condition is satisfied but otherwise skipping the parsing the syntax element that indicates whether ACT is enabled;
• for each of multiple coding units (“CUs”) of a picture of the sequence of the video, decoding part of the encoded data to reconstruct the CU, wherein the decoding the part of the encoded data to reconstruct the CU includes:
• evaluating a condition for the CU, wherein the evaluating the condition for the CU includes checking whether ACT is enabled for the sequence of the video;
• and
• conditionally parsing a syntax element that indicates color space for the CU, including parsing the syntax element that indicates the color space for the CU if the condition for the CU is satisfied but otherwise skipping the parsing the syntax element that indicates the color space for the CU.

One or more computer-readable media having stored thereon encoded data as part of a bitstream, wherein the encoded data includes a syntax element that indicates whether adaptive color space transformation (“ACT”) is enabled for a sequence of video, the encoded data being configured to facilitate decoding of the encoded data to reconstruct video, wherein the decoding the encoded data to reconstruct the video includes:

• evaluating a condition for the sequence of the video;
• conditionally parsing the syntax element that indicates whether ACT is enabled for the sequence of the video, including parsing the syntax element that indicates whether ACT is enabled if the condition is satisfied but otherwise skipping the parsing the syntax element that indicates whether ACT is enabled;
• for each of multiple coding units (“CUs”) of a picture of the sequence of the video, decoding part of the encoded data to reconstruct the CU, wherein the decoding the part of the encoded data to reconstruct the CU includes:
• evaluating a condition for the CU, wherein the evaluating the condition for the CU includes checking whether ACT is enabled for the sequence of the video;
• and
• conditionally parsing a syntax element that indicates color space for the CU, including parsing the syntax element that indicates the color space for the CU if the condition for the CU is satisfied but otherwise skipping the parsing the syntax element that indicates the color space for the CU.