Streaming raspberry pi camera via nginx-rtmp - nginx

Question

I have compiled nginx with rtmp, and I'm trying to use to it stream a raspberry pi camera over the network. I've done a lot of googling, and there are a lot of approaches, but none seem to work for me. So far, I have this:
rtmp {
server {
listen 1935;
chunk_size 4096;
application rtmp {
live on;
record off;
exec_static /usr/bin/ffmpeg -f video4linux2 -input_format h264 -video_size 1280x720 -framerate 30 -i /dev/video0 -vcodec copy rtmp://localhost/rtmp 2>>/home/pi/test.log
}
}
}
I would have expected the stream from the camera to be available on rtmp://pi_ip/rtmp, but instead, the log file reports:
libavutil 56. 22.100 / 56. 22.100
libavcodec 58. 35.100 / 58. 35.100
libavformat 58. 20.100 / 58. 20.100
libavdevice 58. 5.100 / 58. 5.100
libavfilter 7. 40.101 / 7. 40.101
libavresample 4. 0. 0 / 4. 0. 0
libswscale 5. 3.100 / 5. 3.100
libswresample 3. 3.100 / 3. 3.100
libpostproc 55. 3.100 / 55. 3.100
Input #0, video4linux2,v4l2, from '/dev/video0':
Duration: N/A, start: 12021.310578, bitrate: N/A
Stream #0:0: Video: h264 (High), yuv420p(progressive), 1280x720, 30 fps, 30 tbr, 1000k tbn, 2000k tbc
[NULL # 0x1ca35d0] Unable to find a suitable output format for 'rtmp://localhost/rtmp'
rtmp://localhost/rtmp: Invalid argument
Presumably there is something wrong with ffmpeg command, but I have no idea what it is.