ffmpeg -protocols

Protocols are the ways in which ffmpeg can read and/or write data. Some common used are file, http and pipe.

protocol in out description
asyncIasynchronous data filling wrapper for input stream
blurayIread BluRay playlist
cacheIcaching wrapper for input stream
concatIphysical concatenation protocol
cryptoIOAES-encrypted stream reading protocol
data
Idata in-line in the URI (typically base64 encoded)
fileIOread from or write to a file
ftpIOread from or write to remote resources using FTP protocol
gopherIOgopher protocol
hlsIread Apple HTTP Live Streaming compliant segmented stream as a uniform one (discouraged)
httpIOread/write over HTTP (Hyper Text Transfer Protocol)
httpproxy IOHTTP over a proxy server
httpsIOread/write over HTTPS (secure HTTP)
icecastOstream to Icecast servers
mmstIMMS (Microsoft Media Server) protocol over TCP
mmshIMMS (Microsoft Media Server) protocol over HTTP
md5OMD5 output protocol (used to test muxers without writing an actual file)
pipeIOread and write from UNIX pipes
rtpIOReal-time Transport Protocol
rtspIOReal-Time Streaming Protocol
srtpIOSecure Real-time Transport Protocol
subfileIextract a segment of a file or another stream