troubleshooting ffmpeg

console.txt

ffmpeg -f avfoundation -list_devices true -i ""

# output

[AVFoundation input device @ 0x7fbd86d03600] AVFoundation video devices:
[AVFoundation input device @ 0x7fbd86d03600] [0] FaceTime HD Camera
[AVFoundation input device @ 0x7fbd86d03600] [1] Capture screen 0
[AVFoundation input device @ 0x7fbd86d03600] AVFoundation audio devices:
[AVFoundation input device @ 0x7fbd86d03600] [0] Background Music
[AVFoundation input device @ 0x7fbd86d03600] [1] Background Music (UI Sounds)
[AVFoundation input device @ 0x7fbd86d03600] [2] Built-in Microphone
[AVFoundation input device @ 0x7fbd86d03600] [3] iShowU Audio Capture
: Input/output error

# end ouputput

# ffmpeg cmd to record mic and screen

ffmpeg -f avfoundation -i "1:2" -max_muxing_queue_size 9999 \
exp27-stock-settings.mkv

# tried the above cmd on macOS 10.13.6 to record the desktop ie. screen and microphone audio, but it appears
# the audio is not recording, or is recording, but there is no playback.

# when i record just audio there appears to be no issue with audio recording, just when i try to recrod
# the screen and mic at the same time.

# ===================================
# update
# ===================================

ffprobe exp27-stock-settings.mkv

# ouput

Input #0, matroska,webm, from 'exp27-stock-settings.mkv':
  Metadata:
    ENCODER         : Lavf58.29.100
  Duration: 00:00:07.80, start: 0.000000, bitrate: 992 kb/s
    Stream #0:0: Video: h264 (High 4:2:2), yuv422p(progressive), 3840x2160, 30 tbr, 1k tbn, 2000k tbc (default)
    Metadata:
      ENCODER         : Lavc58.54.100 libx264
      DURATION        : 00:00:07.800000000
    Stream #0:1: Audio: vorbis, 44100 Hz, stereo, fltp (default)
    Metadata:
      ENCODER         : Lavc58.54.100 libvorbis
      DURATION        : 00:00:06.163000000