Transcription conventions used in conversation analysis first published in Sacks, Schegloff, and Jefferson (1974), and developed by Gail
Jefferson (2004).

Professor Manny Schegloff created a transcription tutorial for his students at UCLA, generously made public. The workshop shows each of the conventions with accompanying audio.

Professor Lorenza Mondada expanded basic CA conventions to record multimodal apsects of interaction in transcripts.

Dr Emily Hofstetter outlines the fundamental principles of CA transcription in this excellent seven-minute video.

Recommended reading: Ochs, E. (1979). Transcription as theory. In E. Ochs and B. Schieffelin (eds.), Developmental Pragmatics. New York, NY: Academic Press.

The wonderful EMCA Wiki - home of all things CA - has a comprehsive guide to transcription resources, including a summary of software and further reading.