Block vector prediction in video and image coding/decoding

One or more non-volatile memory or storage devices having stored thereon encoded data in a bitstream, the encoded data including a merge mode index value for a current block of a picture, the current block having been compressed with intra-picture coding in merge mode, the encoded data having been encoded, with a computing device that implements a video encoder, by operations comprising:

• determining a set of multiple block vector (“BV”) predictor candidates for the current block, the set of multiple BV predictor candidates including actual BV values of previous blocks in a neighborhood around the current block, wherein the determining the set of multiple BV predictor candidates for the current block includes:
• determining that a given BV predictor candidate is redundant with one of the set of multiple BV predictor candidates for the current block;
• and
• replacing the given BV predictor candidate with another BV predictor candidate of the set of multiple BV predictor candidates for the current block;
• selecting one of the multiple BV predictor candidates to use for the current block, the merge mode index value indicating the selected BV predictor candidate;
• and
• encoding the current block using intra block copy prediction with the selected BV predictor candidate, wherein the selected BV predictor candidate indicates a displacement to a region within the picture.

In a computing device that implements a video decoder, a method comprising:

• receiving encoded data in a bitstream, the encoded data including a merge mode index value;
• and
• decoding the encoded data to reconstruct a picture, including:
• parsing, from the bitstream, the merge mode index value;
• determining a set of multiple block vector (“BV”) predictor candidates for a current block of a picture, the current block having been compressed with intra-picture coding in merge mode, the set of multiple BV predictor candidates including actual BV values of previous blocks in a neighborhood around the current block, wherein the determining the set of multiple BV predictor candidates for the current block includes:
• determining that a given BV predictor candidate is redundant with one of the set of multiple BV predictor candidates for the current block;
• and
• replacing the given BV predictor candidate with another BV predictor candidate of the set of multiple BV predictor candidates for the current block;
• based on the merge mode index value, selecting one of the multiple BV predictor candidates to use for the current block;
• and
• decoding the current block using intra block copy prediction with the selected BV predictor candidate, wherein the selected BV predictor candidate indicates a displacement to a region within the picture.