able to load snapshot, but not stream
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**Describe The Problem:**
<!-- A clear and concise description of what the bug is. -->
Snapshot shows up in home app, but stream does not load. Log says "ffmpeg exited with code 1 and signal null (error)" instantly when the video feed is clicked.

**To Reproduce:**
<!-- Steps to reproduce the behavior. -->
Fresh install of centos 7, installed homebridge-camera-ffmpeg with homebridge UI. Trying to connect to a camera in zoneminder.

**Logs:**
<!-- Bug reports that do not contain logs may be closed without warning. -->
Shown in Screenshots below
```
Show the Homebridge logs here.
Remove any sensitive information.
```

**Homebridge Config:**
{
    "bridge": {
        "name": "Homebridge 6F2B",
        "username": "0E:52:69:41:6F:2B",
        "port": 51086,
        "pin": "114-08-864"
    },
    "accessories": [],
    "platforms": [
        {
            "name": "Config",
            "port": 8581,
            "auth": "form",
            "theme": "auto",
            "tempUnits": "f",
            "lang": "en",
            "platform": "config"
        },
        {
            "name": "Nest",
            "googleAuth": {
                "issueToken": "redacted",
                "cookies": redacted"
            },
            "platform": "Nest"
        },
        {
            "name": "Camera FFmpeg",
            "cameras": [
                {
                    "name": "LivingRoomCam",
                    "unbridge": false,
                    "videoConfig": {
                        "source": "-re -i https://zoneminder.redacted.com/cgi-bin-zm/nph-zms?mode=jpeg&monitor=2&scale=100&maxfps=15&buffer=1000&user=redacted&pass=redacted",
                        "audio": false,
                        "debug": true
                    }
                }
            ],
            "platform": "Camera-ffmpeg"
        }
    ]
}
```json
Show your homebridge config.json here.
Remove any sensitive information, such as your homebridge-gsh / google-smarthome token.
```

**Screenshots:**
<!-- If applicable, add screenshots to help explain your problem. -->
![image](https://user-images.githubusercontent.com/50371267/113660160-831b3000-9671-11eb-8069-b30ff2dd1a40.png)


**Environment:**

* **Node.js Version**: v14.16.0
* **NPM Version**: v6.14.11
* **Homebridge Version**: 1.3.4
* **Homebridge Camera FFmpeg Version**: v3.1.2
* **Homebridge Config UI X Plugin Version**: v4.41.0
* **Operating System**: Centos7


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