[BUG] - ffmpeg exited with code 1
FFmpeg errors out when trying to view the stream. I am able to view the stream with the same camera using homebridge-camera-ffmpeg. I compared the how both are starting the stream and the only difference seems to be "-vf scale=1280:720" while using dafang plugin.

**homebridge-dafang**
ffmpeg -i rtsp://192.168.1.110:8554/unicast -map 0:0 -vcodec copy -pix_fmt yuv420p -r 15 -f rawvideo -fflags +genpts+discardcorrupt -vf scale=1280:720 -b:v 299k -bufsize 299k -maxrate 299k -payload_type 99 -ssrc 8856484 -f rtp -srtp_out_suite AES_CM_128_HMAC_SHA1_80 -srtp_out_params w9Dkt+stdHMs8zvNkhl8izPxN93YgJzefq+Ot+bS srtp://192.168.1.120:55571?rtcpport=55571&localrtcpport=55571&pkt_size=1316

**homebridge-camera-ffmpeg**
ffmpeg -i rtsp://192.168.1.110:8554/unicast -map 0:0 -vcodec copy -pix_fmt yuv420p -r 15 -f rawvideo -fflags +genpts+discardcorrupt -b:v 299k -bufsize 299k -maxrate 299k -payload_type 99 -ssrc 1222423 -f rtp -srtp_out_suite AES_CM_128_HMAC_SHA1_80 -srtp_out_params MXrm3B4GnA+FA4nY6j2YixqPu96AZaQvRVfDX6Jx srtp://192.168.1.120:54565?rtcpport=54565&localrtcpport=54565&pkt_size=1316 -loglevel debug

I've attached my config.json
[config.txt](https://github.com/sahilchaddha/homebridge-dafang/files/4069254/config.txt)

