Values.FlacSettingsSourceRequired when you set Codec, under AudioDescriptions>CodecSettings, to the value FLAC.
type nonrec t = {bitDepth : int option;Specify Bit depth (BitDepth), in bits per sample, to choose the encoding quality for this audio track.
*)channels : int option;Specify the number of channels in this output audio track. Valid values are 0, 1, and even numbers up to 8. Choose 0 to follow the number of channels from your input audio. Otherwise, manually choose from 1, 2, 4, 6, and 8.
*)sampleRate : int option;Sample rate in Hz.
*)}