FFmpeg

FFmpeg can read a stream from the server in several ways. The recommended one consists in reading with RTSP.

FFmpeg and RTSP

ffmpeg -i rtsp://localhost:8554/mystream -c copy output.mp4

FFmpeg and RTMP

ffmpeg -i rtmp://localhost/mystream -c copy output.mp4

In order to read AV1, VP9, H265, Opus, AC3 tracks and in order to read multiple video or audio tracks, the -rtmp_enhanced_codecs flag must be present:

ffmpeg -rtmp_enhanced_codecs ac-3,av01,avc1,ec-3,fLaC,hvc1,.mp3,mp4a,Opus,vp09 \
-i rtmp://localhost/mystream -c copy output.mp4

FFmpeg and SRT

ffmpeg -i 'srt://localhost:8890?streamid=read:test' -c copy output.mp4