Block processing pipeline methods and apparatus in which reference data are stored to a memory according to tile formats to reduce memory accesses when fetching the data from the memory. When the pipeline stores reference data from a current frame being processed to memory as a reference frame, the reference samples are stored in macroblock sequential order. Each macroblock sample set is stored as a tile. Reference data may be stored in tile formats for luma and chroma. Chroma reference data may be stored in tile formats for chroma 4:2:0, 4:2:2, and/or 4:4:4 formats. A stage of the pipeline may write luma and chroma reference data for macroblocks to memory according to one or more of the macroblock tile formats in a modified knight's order. The stage may delay writing the reference data from the macroblocks until the macroblocks have been fully processed by the pipeline.