Logitech C922 Pro on macOS: "Video device not found" even though ffmpeg can use it.
**Describe The Problem:**
I'm trying to make my "Logitech C922 Pro Stream Webcam" work with this plugin. I'm able to use the camera via ffmpeg and also kinda with the command printed by the debug logs of the plugin but there's an error that I don't know where it comes from:

```
[AVFoundation indev @ 0x7f8523404c00] [error] Video device not found
```

**To Reproduce:**

1) Check that webcam is using with the following command:

```
ffmpeg -f avfoundation -r 30 -s 1280x720 -i "C922 Pro Stream Webcam" out.mpg
```

This works and saves the streamed video.

2) Install the plugin in homebridge (`homebridge-camera-ffmpeg v3.0.3`)

3) Set up config like this:

```
        {
            "name": "Camera FFmpeg",
            "cameras": [
                {
                    "name": "Logitech 922",
                    "videoConfig": {
                        "source": "-f avfoundation -r 30 -s 1280x720 -i \"C922 Pro Stream Webcam\"",
                        "stillImageSource": "-f avfoundation -s 1280x720 -i \"C922 Pro Stream Webcam\"",
                        "maxStreams": 2,
                        "maxWidth": 1280,
                        "maxHeight": 720,
                        "maxFPS": 30,
                        "vcodec": "h264_omx",
                        "audio": false,
                        "debug": true
                    }
                }
            ],
            "platform": "Camera-ffmpeg"
        }
```

4) See error in logs,

5) Test printed stream command (without the filter / codec commands) manually: works!

```
Desktop|⇒ /usr/local/lib/node_modules/homebridge-camera-ffmpeg/node_modules/ffmpeg-for-homebridge/ffmpeg -f avfoundation -r 30 -s 1280x720 -i "C922 Pro Stream Webcam" out.mpg
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.62)
  configuration: --enable-videotoolbox --pkgconfigdir=/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace/lib/pkgconfig --prefix=/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace --pkg-config-flags=--static --extra-cflags=-I/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace/include --extra-ldflags=-L/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace/lib --extra-libs='-lpthread -lm' --enable-static --disable-debug --disable-shared --disable-ffplay --disable-doc --enable-openssl --enable-gpl --enable-version3 --enable-nonfree --enable-pthreads --enable-libvpx --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libx264 --enable-runtime-cpudetect --enable-libfdk-aac --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-decoder=h264 --enable-network --enable-protocol=tcp --enable-libspeex --enable-demuxer=rtsp
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[avfoundation @ 0x7fc39c809c00] Selected pixel format (yuv420p) is not supported by the input device.
[avfoundation @ 0x7fc39c809c00] Supported pixel formats:
[avfoundation @ 0x7fc39c809c00]   uyvy422
[avfoundation @ 0x7fc39c809c00]   yuyv422
[avfoundation @ 0x7fc39c809c00]   nv12
[avfoundation @ 0x7fc39c809c00]   0rgb
[avfoundation @ 0x7fc39c809c00]   bgr0
[avfoundation @ 0x7fc39c809c00] Overriding selected pixel format to use uyvy422 instead.
Input #0, avfoundation, from 'C922 Pro Stream Webcam':
  Duration: N/A, start: 34259.829033, bitrate: N/A
    Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 1280x720, 9.08 tbr, 1000k tbn, 1000k tbc
File 'out.mpg' already exists. Overwrite? [y/N] y
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> mpeg1video (native))
Press [q] to stop, [?] for help
[mpeg @ 0x7fc39c819a00] VBV buffer size not set, using default size of 230KB
If you want the mpeg file to be compliant to some specification
Like DVD, VCD or others, make sure you set the correct buffer size
Output #0, mpeg, to 'out.mpg':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0: Video: mpeg1video, yuv420p, 1280x720, q=2-31, 200 kb/s, 30 fps, 90k tbn, 30 tbc
    Metadata:
      encoder         : Lavc58.91.100 mpeg1video
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
frame=   17 fps=6.3 q=31.0 Lsize=     362kB time=00:00:00.50 bitrate=5930.9kbits/s dup=2 drop=0 speed=0.187x
video:360kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.565104%
Exiting normally, received signal 2.
```

**Logs:**

Note: The `Logitech C270` in the logs can be ignored, I just renamed it in the config but that's just the display name.
```
[9/26/2020, 2:54:13 PM] Homebridge v1.2.3 is running on port 51104.
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] Video stream requested: 1280 x 720, 30 fps, 299 kbps
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] Starting video stream: 1280 x 720, 30 fps, 299 kbps
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] Stream command: /usr/local/lib/node_modules/homebridge-camera-ffmpeg/node_modules/ffmpeg-for-homebridge/ffmpeg -f avfoundation -r 30 -s 1280x720 -i "C922 Pro Stream Webcam" -an -sn -dn -codec:v h264_omx -pix_fmt yuv420p -color_range mpeg -r 30 -f rawvideo -filter:v scale='min(1280,iw)':'min(720,ih)':force_original_aspect_ratio=decrease,scale=trunc(iw/2)*2:trunc(ih/2)*2 -b:v 299k -payload_type 99 -ssrc 11613244 -f rtp -srtp_out_suite AES_CM_128_HMAC_SHA1_80 -srtp_out_params 7I8kQHqk937a6LELHObKNsI2038U9i1s3ttLtjeu srtp://192.168.178.48:52693?rtcpport=52693&pkt_size=1316 -loglevel level+verbose
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info] ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   built with Apple clang version 11.0.3 (clang-1103.0.32.62)
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] 
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   configuration: --enable-videotoolbox --pkgconfigdir=/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace/lib/pkgconfig --prefix=/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace --pkg-config-flags=--static --extra-cflags=-I/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace/include --extra-ldflags=-L/Users/runner/work/ffmpeg-for-homebridge/ffmpeg-for-homebridge/build/workspace/lib --extra-libs='-lpthread -lm' --enable-static --disable-debug --disable-shared --disable-ffplay --disable-doc --enable-openssl --enable-gpl --enable-version3 --enable-nonfree --enable-pthreads --enable-libvpx --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libx264 --enable-runtime-cpudetect --enable-libfdk-aac --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-decoder=h264 --enable-network --enable-protocol=tcp --enable-libspeex --enable-demuxer=rtsp
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] 
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libavutil      56. 51.100 / 56. 51.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libavcodec     58. 91.100 / 58. 91.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libavformat    58. 45.100 / 58. 45.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] 
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libavdevice    58. 10.100 / 58. 10.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libavfilter     7. 85.100 /  7. 85.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libswscale      5.  7.100 /  5.  7.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libswresample   3.  7.100 /  3.  7.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [info]   libpostproc    55.  7.100 / 55.  7.100
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] 
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [AVFoundation indev @ 0x7f8523404c00] [error] Video device not found
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] 
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] [error] "C922: Input/output error
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] 
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] FFmpeg exited with code: 1 and signal: null (Error)
[9/26/2020, 2:54:28 PM] [Camera FFmpeg] [Logitech C270] Stopped video stream.
```

**Homebridge Config:**

```json
{
    "bridge": {
        "name": "Homebridge AE17",
        "username": "snip",
        "port": 51104,
        "pin": "snip"
    },
    "accessories": [],
    "platforms": [
        {
            "name": "Config",
            "port": 8581,
            "platform": "config"
        },
        {
            "name": "Camera FFmpeg",
            "cameras": [
                {
                    "name": "Logitech C270",
                    "videoConfig": {
                        "source": "-f avfoundation -r 30 -s 1280x720 -i \"C922 Pro Stream Webcam\"",
                        "stillImageSource": "-f avfoundation -s 1280x720 -i \"C922 Pro Stream Webcam\"",
                        "maxStreams": 2,
                        "maxWidth": 1280,
                        "maxHeight": 720,
                        "maxFPS": 30,
                        "vcodec": "h264_omx",
                        "audio": false,
                        "debug": true
                    }
                }
            ],
            "platform": "Camera-ffmpeg"
        }
    ]
}
```

**Environment:**

* **Node.js Version**: v14.11.0
* **NPM Version**: 6.14.8
* **Homebridge Version**: 1.2.3
* **Homebridge Camera FFmpeg Version**: 3.0.3
* **Homebridge Config UI X Plugin Version**:
* **Operating System**: macOS
