Extract RTP payload from capture file using tshark

I have a valid capture in pcap-ng format(version 1.0) using tshark command like this:

tshark -i wlp2s0 -n -f "host 192.168.10.48 and udp port 9078" -w capture_tshark_1.pcapng

I want to extract RTP payload in binary format and store it in a file and be reproducible.

I tried this to extract binary data in ASCII format:

tshark -nr capture_tshark_1.pcapng -T fields -e rtp.payload > captura_tshark_1_ascii_data

But it produces empty output. I guess it fails because RTP packets are not detected as RTP streams, because if I open the original capture (capture_tshark_1.pcapng) with Wireshark this is what I see:

It seems that the packets are detected as UDP, not as RTP. So I guess there is no such "rtp.payload" fields to be parsed.

If this works I have a method to transform ASCII data to binary format.

So, again, how can I extract RTP payload in binary format from a capture file?