Methods and apparatus for re-timing and scaling input video tracks

An apparatus comprising a processor in communication with memory, the processor being configured to execute instructions stored in the memory that cause the processor to perform:

• accessing multimedia data comprising a hierarchical track structure comprising at least:
• a first track at a first level of the hierarchical track structure comprising first media data, wherein the first media data comprises a first sequence of video media units;
• and
• a second track at a second level in the hierarchical track structure that is different than the first level of the first track, the second track comprising metadata specifying a re-timing derivation operation and not any of the video media units from the first sequence of video media units;
• and
• generating output video media units according to the second track, comprising performing the re-timing derivation operation on the first sequence of video media units to modify a timing of the first sequence of video media units by one or more of:
• (a) removing one or more video media units associated with the re-timing derivation operation, (b) shifting timing information of the first sequence of video media units, (c) skipping one or more video media units associated with the re-timing derivation operation and (d) inserting one or more video media units associated with the re-timing derivation operation.

An apparatus comprising a processor in communication with memory, the processor being configured to execute instructions stored in the memory that cause the processor to perform:

• encoding multimedia data comprising a hierarchical track structure comprising at least:
• a first track at a first level of the hierarchical track structure comprising first media data, wherein the first media data comprises a first sequence of video media units;
• and
• a second track at a second level in the hierarchical track structure that is different than the first level of the first track, the second track comprising metadata specifying a re-timing derivation operation and not any of the video media units from the first sequence of video media units,
• such that output video media units can be generated according to the second track by performing the re-timing derivation operation on the first sequence of video media units to modify a timing of the first sequence of video media units by one or more of:
• (a) removing one or more video media units associated with the re-timing derivation operation, (b) shifting timing information of the first sequence of video media units, (c) skipping one or more video media units associated with the re-timing derivation operation and (d) inserting one or more video media units associated with the re-timing derivation operation.