create stream from USB video graber with seperate audio and video devices

[T-Lancer]

Question

I am trying to create a stream using a USB video grabber (generic USB 3 HDMI video grabber)

I have video0 as the video source. and HW:1,0 is the audio stream. The audio stream is unfortunately not linked automatically to the video stream. I need to mix these together into the RTSP stream, but I am having trouble figuring out the right command. video works fine, but audio give me an error.

ffmpeg -re -stream_loop -1 -i /dev/video0 -f alsa -i hw:1,0 -c:v libx264 -c:a aac copy -f rtsp -rtsp_transport tcp rtsp://192.168.0.2:8557/mystream

[AVFormatContext @ 0x556de76b1780] Unable to choose an output format for 'copy'; use a standard extension for the filename or specify the format manually.
[out#0 @ 0x556de76b1e00] Error initializing the muxer for copy: Invalid argument
Error opening output file copy.
Error opening output files: Invalid argument

maybe i ned to use the map command? but I really am a bit lost here. Maybe someone could provide me with the appropriate command?

thanks!