Here is the data sheet for the Sony PCM-F1 Digital Audio Processor, introduced in 1981. This was an update to the original Sony digital processor which allowed battery operation for in-the-field recording.
Encoding of audio information into an NTSC video signal was sufficiently robust that it could survive recording and replay even by consumer-grade Beta or VHS cassette recorders in long-play mode. Professionals, for example those recording masters for Compact Disc production later in the 1980s, preferred broadcast-grade U-matic gear, but it was not required.