A computer system comprising a processor, memory, and storage, wherein the computer system is configured to implement a video processing tool comprising: a formatter configured to pack sample values of an input picture organized according to an input picture format into first and second coded pictures organized according to first and second coded picture formats, respectively, the first coded picture containing sample values for a low chroma resolution version of the input picture, and the second coded picture containing sample values for high chroma resolution details of the input picture; a video encoder system configured to encode the first and second coded pictures to produce encoded data, including, for each of one or more regions: evaluating one or more attributes of the region; and based at least in part on results of the evaluating, determining whether to encode sample values in the region for the high chroma resolution details of the input picture as part of the second coded picture; and a buffer configured to output the encoded data; the video encoder system adapted to encode, in a sequence of coded pictures, the first and second coded pictures as separate coded pictures to produce encoded data; wherein, as part of encoding, the first coded picture is encoded as part of a first sub-sequence of the sequence, and the second coded picture is encoded as part of a second sub-sequence of the sequence; wherein, for purpose of motion compensation, no coded picture in a sub-sequence can reference a coded picture in the other sub-sequence; wherein the video encoder system uses a first set of long-term reference picture indices that identify coded pictures in the first sub-sequence and a second set of long-term reference picture indices that identify coded pictures in the second sub-sequence for managing motion compensation dependencies; a bitstream editing tool for separating the encoded data for the first sub-sequence from the encoded data for the second sub-sequence and for sending either only the first sub-sequence or the first and second sub-sequence to a playback device, depending on at least one of display resolution, computational resources or network connection for playback with high chroma resolution. a formatter configured to pack sample values of an input picture organized according to an input picture format into first and second coded pictures organized according to first and second coded picture formats, respectively, the first coded picture containing sample values for a low chroma resolution version of the input picture, and the second coded picture containing sample values for high chroma resolution details of the input picture; a video encoder system configured to encode the first and second coded pictures to produce encoded data, including, for each of one or more regions: evaluating one or more attributes of the region; and based at least in part on results of the evaluating, determining whether to encode sample values in the region for the high chroma resolution details of the input picture as part of the second coded picture; and evaluating one or more attributes of the region; and based at least in part on results of the evaluating, determining whether to encode sample values in the region for the high chroma resolution details of the input picture as part of the second coded picture; and a buffer configured to output the encoded data; the video encoder system adapted to encode, in a sequence of coded pictures, the first and second coded pictures as separate coded pictures to produce encoded data; wherein, as part of encoding, the first coded picture is encoded as part of a first sub-sequence of the sequence, and the second coded picture is encoded as part of a second sub-sequence of the sequence; wherein, for purpose of motion compensation, no coded picture in a sub-sequence can reference a coded picture in the other sub-sequence; wherein the video encoder system uses a first set of long-term reference picture indices that identify coded pictures in the first sub-sequence and a second set of long-term reference picture indices that identify coded pictures in the second sub-sequence for managing motion compensation dependencies; a bitstream editing tool for separating the encoded data for the first sub-sequence from the encoded data for the second sub-sequence and for sending either only the first sub-sequence or the first and second sub-sequence to a playback device, depending on at least one of display resolution, computational resources or network connection for playback with high chroma resolution.