ffmpeg to extract left channel from double audio MP4

strip all audio sounds out of a video file


https://www.youtube.com/watch?v=SaJK8bZs0bw&list=PLWftZzBMTv2LOzPW1ZwaVVFT3P7OrlvtI&index=2&t=0s

C:\python\GitHub\basic>ffmpeg -i "Desktop 2020.03.12 - 22.34.34.01.mp4"


which give us
Microsoft Windows [Version 10.0.18362.778]
(c) 2019 Microsoft Corporation. All rights reserved.

C:\python\GitHub\basic>ffmpeg -i "Desktop 2020.03.12 - 22.34.34.01.mp4"
ffmpeg version 4.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9.1.1 (GCC) 20190807
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Desktop 2020.03.12 - 22.34.34.01.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2020-03-12T22:35:53.000000Z
    date            : 2020
  Duration: 00:01:18.23, start: 0.000000, bitrate: 19240 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, smpte170m/smpte170m/bt470m), 3840x2160 [SAR 1:1 DAR 16:9], 18917 kb/s, 60 fps, 60 tbr, 90k tbn, 120 tbc (default)
    Metadata:
      creation_time   : 2020-03-12T22:35:53.000000Z
      handler_name    : VideoHandle
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 117 kb/s (default)
    Metadata:
      creation_time   : 2020-03-12T22:35:53.000000Z
      handler_name    : SoundHandle
    Stream #0:2(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      creation_time   : 2020-03-12T22:35:53.000000Z
      handler_name    : SoundHandle
At least one output file must be specified


showing TWO audio tracks & one video file
ffmpeg -i "Desktop 2020.03.12 - 22.34.34.01.mp4" -c:a libmp3lame -b:a 320k -map 0:2 cars2.mp3


NEXT
https://trac.ffmpeg.org/wiki/AudioChannelManipulation

forces the microphone track that i want out my file audio file
ffmpeg -i cars2.mp3 -filter_complex "[0:a]channelsplit=channel_layout=stereo[left][right]" -map "[left]" left.wav -map "[right]" right.wav

HOWEVER

just syncing the two together is the next step
ffmpeg -i "Desktop 2020.03.12 - 22.34.34.01.mp4" -filter_complex "[0:a]channelsplit=channel_layout=stereo[left][right]" -map "[left]" left2.wav -map "[right]" right2.wav