Determination of set of candidate transforms for video encoding

A decoder for decoding a picture from a data stream using block-based prediction and block-based residual decoding, the decoder supporting a set of transforms for the block-based residual decoding and configured to

• determine a selectable list of transforms for a current residual block out of the set of transforms;
• decode transform coefficient data from the data stream which represents a prediction residual within the residual block using one selected transform out of the selectable list of transforms;
• derive the selected transform from the data stream, and/or perform the determination of the selectable list, in a manner depending on the transform coefficient data or on a portion of the data transform coefficient data.

A method for encoding a picture into a data stream using block-based prediction and block-based residual coding, supporting a set of transforms for the block-based residual coding, wherein the method comprises:

• determining a selectable list of transforms for a current residual block out of the set of transforms;
• encoding transform coefficient data into the data stream which represents a prediction residual within the residual block using one selected transform out of the selectable list of transforms;
• signaling the selected transform in the data stream, and/or perform the determination of the selectable list, in a manner depending on the transform coefficient data or on a portion of the transform coefficient data.

A method for decoding a picture from a data stream using block-based prediction and block-based residual decoding, supporting a set of transforms for the block-based residual decoding, wherein the method comprises:

• determining a selectable list of transforms for a current residual block out of the set of transforms;
• decoding transform coefficient data from the data stream which represents a prediction residual within the residual block using one selected transform out of the selectable list of transforms;
• deriving the selected transform from the data stream, and/or perform the determination of the selectable list, in a manner depending on the transform coefficient data or a portion of the data transform coefficient data.