  Temporal action segmentation (TAS) in videos aims at densely identifying
video frames in minutes-long videos with multiple action classes. As a
long-range video understanding task, researchers have developed an extended
collection of methods and examined their performance using various benchmarks.
Despite the rapid growth of TAS techniques in recent years, no systematic
survey has been conducted in these sectors. This survey analyzes and summarizes
the most significant contributions and trends. In particular, we first examine
the task definition, common benchmarks, types of supervision, and prevalent
evaluation measures. In addition, we systematically investigate two essential
techniques of this topic, i.e., frame representation and temporal modeling,
which have been studied extensively in the literature. We then conduct a
thorough review of existing TAS works categorized by their levels of
supervision and conclude our survey by identifying and emphasizing several
research gaps. In addition, we have curated a list of TAS resources, which is
available at https://github.com/nus-cvml/awesome-temporal-action-segmentation.
