Digital video decoding, buffering and frame-rate converting method and apparatus

A digital video presentation system is provided with a decoder to decode full frame MPEG-2 video by a single method that applies regardless of buffer memory and frame rate conversion considerations. A display control module handles frame rate and field sequence in response to host configuration, particularly buffer memory size and display type (NTSC or PAL), to host trick play command signals, and to information in the received bitstream. Pictures are decoded as buffer memory for the decoded pictures becomes available, and picture display attributes are assigned and stored in a table, one string for each decoded picture. Field display logic is informed of the to memory address of the next field to be displayed along with the attributes needed for affecting proper field display sequence, and flagging whether the memory is to be freed for use by the decoder as the field is being displayed and whether the decoder is to decode the next picture as the field is being displayed. Where memory is small, opposite field data can be output. Field sequence order is provided for output buffers in the range of from 0.53 to 0.67 frames in size, or a full frame in size. Buffer memory is optimized by maintaining tables of offset variables and accessing a fixed table of memory pointers as fields of data are being displayed. The offset data tables are identified to the display logic, which uses the data in the specified offset table to address rows of memory in which the consecutive rows of particular field to be displayed are stored. The decoder loads offset values into the offset tables as pictures are being decoded and rows of blocks of the picture are stored as memory becomes free.