@chapter Protocols @c man begin PROTOCOLS Protocols are configured elements in FFmpeg that enable access to resources that require specific protocols. When you configure your FFmpeg build, all the supported protocols are enabled by default. You can list all available ones using the configure option "--list-protocols". You can disable all the protocols using the configure option "--disable-protocols", and selectively enable a protocol using the option "--enable-protocol=@var{PROTOCOL}", or you can disable a particular protocol using the option "--disable-protocol=@var{PROTOCOL}". The option "-protocols" of the ff* tools will display the list of supported protocols. A description of the currently available protocols follows. @section bluray Read BluRay playlist. The accepted options are: @table @option @item angle BluRay angle @item chapter Start chapter (1...N) @item playlist Playlist to read (BDMV/PLAYLIST/?????.mpls) @end table Examples: Read longest playlist from BluRay mounted to /mnt/bluray: @example bluray:/mnt/bluray @end example Read angle 2 of playlist 4 from BluRay mounted to /mnt/bluray, start from chapter 2: @example -playlist 4 -angle 2 -chapter 2 bluray:/mnt/bluray @end example @section cache Caching wrapper for input stream. Cache the input stream to temporary file. It brings seeking capability to live streams. @example cache:@var{URL} @end example @section concat Physical concatenation protocol. Allow to read and seek from many resource in sequence as if they were a unique resource. A URL accepted by this protocol has the syntax: @example concat:@var{URL1}|@var{URL2}|...|@var{URLN} @end example where @var{URL1}, @var{URL2}, ..., @var{URLN} are the urls of the resource to be concatenated, each one possibly specifying a distinct protocol. For example to read a sequence of files @file{split1.mpeg}, @file{split2.mpeg}, @file{split3.mpeg} with @command{ffplay} use the command: @example ffplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg @end example Note that you may need to escape the character "|" which is special for many shells. @section crypto AES-encrypted stream reading protocol. The accepted options are: @table @option @item key Set the AES decryption key binary block from given hexadecimal representation. @item iv Set the AES decryption initialization vector binary block from given hexadecimal representation. @end table Accepted URL formats: @example crypto:@var{URL} crypto+@var{URL} @end example @section data Data in-line in the URI. See @url{http://en.wikipedia.org/wiki/Data_URI_scheme}. For example, to convert a GIF file given inline with @command{ffmpeg}: @example ffmpeg -i "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywAAAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png @end example @section file File access protocol. Allow to read from or read to a file. For example to read from a file @file{input.mpeg} with @command{ffmpeg} use the command: @example ffmpeg -i file:input.mpeg output.mpeg @end example The ff* tools default to the file protocol, that is a resource specified with the name "FILE.mpeg" is interpreted as the URL "file:FILE.mpeg". This protocol accepts the following options: @table @option @item truncate Truncate existing files on write, if set to 1. A value of 0 prevents truncating. Default value is 1. @item blocksize Set I/O operation maximum block size, in bytes. Default value is @code{INT_MAX}, which results in not limiting the requested block size. Setting this value reasonably low improves user termination request reaction time, which is valuable for files on slow medium. @end table @section ftp FTP (File Transfer Protocol). Allow to read from or write to remote resources using FTP protocol. Following syntax is required. @example ftp://[user[:password]@@]server[:port]/path/to/remote/resource.mpeg @end example This protocol accepts the following options. @table @option @item timeout Set timeout of socket I/O operations used by the underlying low level operation. By default it is set to -1, which means that the timeout is not specified. @item ftp-anonymous-password Password used when login as anonymous user. Typically an e-mail address should be used. @item ftp-write-seekable Control seekability of connection during encoding. If set to 1 the resource is supposed to be seekable, if set to 0 it is assumed not to be seekable. Default value is 0. @end table NOTE: Protocol can be used as output, but it is recommended to not do it, unless special care is taken (tests, customized server configuration etc.). Different FTP servers behave in different way during seek operation. ff* tools may produce incomplete content due to server limitations. @section gopher Gopher protocol. @section hls Read Apple HTTP Live Streaming compliant segmented stream as a uniform one. The M3U8 playlists describing the segments can be remote HTTP resources or local files, accessed using the standard file protocol. The nested protocol is declared by specifying "+@var{proto}" after the hls URI scheme name, where @var{proto} is either "file" or "http". @example hls+http://host/path/to/remote/resource.m3u8 hls+file://path/to/local/resource.m3u8 @end example Using this protocol is discouraged - the hls demuxer should work just as well (if not, please report the issues) and is more complete. To use the hls demuxer instead, simply use the direct URLs to the m3u8 files. @section http HTTP (Hyper Text Transfer Protocol). This protocol accepts the following options. @table @option @item seekable Control seekability of connection. If set to 1 the resource is supposed to be seekable, if set to 0 it is assumed not to be seekable, if set to -1 it will try to autodetect if it is seekable. Default value is -1. @item chunked_post If set to 1 use chunked transfer-encoding for posts, default is 1. @item headers Set custom HTTP headers, can override built in default headers. The value must be a string encoding the headers. @item content_type Force a content type. @item user-agent Override User-Agent header. If not specified the protocol will use a string describing the libavformat build. @item multiple_requests Use persistent connections if set to 1. By default it is 0. @item post_data Set custom HTTP post data. @item timeout Set timeout of socket I/O operations used by the underlying low level operation. By default it is set to -1, which means that the timeout is not specified. @item mime_type Set MIME type. @item icy If set to 1 request ICY (SHOUTcast) metadata from the server. If the server supports this, the metadata has to be retrieved by the application by reading the @option{icy_metadata_headers} and @option{icy_metadata_packet} options. The default is 0. @item icy_metadata_headers If the server supports ICY metadata, this contains the ICY specific HTTP reply headers, separated with newline characters. @item icy_metadata_packet If the server supports ICY metadata, and @option{icy} was set to 1, this contains the last non-empty metadata packet sent by the server. @item cookies Set the cookies to be sent in future requests. The format of each cookie is the same as the value of a Set-Cookie HTTP response field. Multiple cookies can be delimited by a newline character. @end table @subsection HTTP Cookies Some HTTP requests will be denied unless cookie values are passed in with the request. The @option{cookies} option allows these cookies to be specified. At the very least, each cookie must specify a value along with a path and domain. HTTP requests that match both the domain and path will automatically include the cookie value in the HTTP Cookie header field. Multiple cookies can be delimited by a newline. The required syntax to play a stream specifying a cookie is: @example ffplay -cookies "nlqptid=nltid=tsn; path=/; domain=somedomain.com;" http://somedomain.com/somestream.m3u8 @end example @section mmst MMS (Microsoft Media Server) protocol over TCP. @section mmsh MMS (Microsoft Media Server) protocol over HTTP. The required syntax is: @example mmsh://@var{server}[:@var{port}][/@var{app}][/@var{playpath}] @end example @section md5 MD5 output protocol. Computes the MD5 hash of the data to be written, and on close writes this to the designated output or stdout if none is specified. It can be used to test muxers without writing an actual file. Some examples follow. @example # Write the MD5 hash of the encoded AVI file to the file output.avi.md5. ffmpeg -i input.flv -f avi -y md5:output.avi.md5 # Write the MD5 hash of the encoded AVI file to stdout. ffmpeg -i input.flv -f avi -y md5: @end example Note that some formats (typically MOV) require the output protocol to be seekable, so they will fail with the MD5 output protocol. @section pipe UNIX pipe access protocol. Allow to read and write from UNIX pipes. The accepted syntax is: @example pipe:[@var{number}] @end example @var{number} is the number corresponding to the file descriptor of the pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If @var{number} is not specified, by default the stdout file descriptor will be used for writing, stdin for reading. For example to read from stdin with @command{ffmpeg}: @example cat test.wav | ffmpeg -i pipe:0 # ...this is the same as... cat test.wav | ffmpeg -i pipe: @end example For writing to stdout with @command{ffmpeg}: @example ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi # ...this is the same as... ffmpeg -i test.wav -f avi pipe: | cat > test.avi @end example This protocol accepts the following options: @table @option @item blocksize Set I/O operation maximum block size, in bytes. Default value is @code{INT_MAX}, which results in not limiting the requested block size. Setting this value reasonably low improves user termination request reaction time, which is valuable if data transmission is slow. @end table Note that some formats (typically MOV), require the output protocol to be seekable, so they will fail with the pipe output protocol. @section rtmp Real-Time Messaging Protocol. The Real-Time Messaging Protocol (RTMP) is used for streaming multimedia content across a TCP/IP network. The required syntax is: @example rtmp://[@var{username}:@var{password}@@]@var{server}[:@var{port}][/@var{app}][/@var{instance}][/@var{playpath}] @end example The accepted parameters are: @table @option @item username An optional username (mostly for publishing). @item password An optional password (mostly for publishing). @item server The address of the RTMP server. @item port The number of the TCP port to use (by default is 1935). @item app It is the name of the application to access. It usually corresponds to the path where the application is installed on the RTMP server (e.g. @file{/ondemand/}, @file{/flash/live/}, etc.). You can override the value parsed from the URI through the @code{rtmp_app} option, too. @item playpath It is the path or name of the resource to play with reference to the application specified in @var{app}, may be prefixed by "mp4:". You can override the value parsed from the URI through the @code{rtmp_playpath} option, too. @item listen Act as a server, listening for an incoming connection. @item timeout Maximum time to wait for the incoming connection. Implies listen. @end table Additionally, the following parameters can be set via command line options (or in code via @code{AVOption}s): @table @option @item rtmp_app Name of application to connect on the RTMP server. This option overrides the parameter specified in the URI. @item rtmp_buffer Set the client buffer time in milliseconds. The default is 3000. @item rtmp_conn Extra arbitrary AMF connection parameters, parsed from a string, e.g. like @code{B:1 S:authMe O:1 NN:code:1.23 NS:flag:ok O:0}. Each value is prefixed by a single character denoting the type, B for Boolean, N for number, S for string, O for object, or Z for null, followed by a colon. For Booleans the data must be either 0 or 1 for FALSE or TRUE, respectively. Likewise for Objects the data must be 0 or 1 to end or begin an object, respectively. Data items in subobjects may be named, by prefixing the type with 'N' and specifying the name before the value (i.e. @code{NB:myFlag:1}). This option may be used multiple times to construct arbitrary AMF sequences. @item rtmp_flashver Version of the Flash plugin used to run the SWF player. The default is LNX 9,0,124,2. (When publishing, the default is FMLE/3.0 (compatible; ).) @item rtmp_flush_interval Number of packets flushed in the same request (RTMPT only). The default is 10. @item rtmp_live Specify that the media is a live stream. No resuming or seeking in live streams is possible. The default value is @code{any}, which means the subscriber first tries to play the live stream specified in the playpath. If a live stream of that name is not found, it plays the recorded stream. The other possible values are @code{live} and @code{recorded}. @item rtmp_pageurl URL of the web page in which the media was embedded. By default no value will be sent. @item rtmp_playpath Stream identifier to play or to publish. This option overrides the parameter specified in the URI. @item rtmp_subscribe Name of live stream to subscribe to. By default no value will be sent. It is only sent if the option is specified or if rtmp_live is set to live. @item rtmp_swfhash SHA256 hash of the decompressed SWF file (32 bytes). @item rtmp_swfsize Size of the decompressed SWF file, required for SWFVerification. @item rtmp_swfurl URL of the SWF player for the media. By default no value will be sent. @item rtmp_swfverify URL to player swf file, compute hash/size automatically. @item rtmp_tcurl URL of the target stream. Defaults to proto://host[:port]/app. @end table For example to read with @command{ffplay} a multimedia resource named "sample" from the application "vod" from an RTMP server "myserver": @example ffplay rtmp://myserver/vod/sample @end example To publish to a password protected server, passing the playpath and app names separately: @example ffmpeg -re -i -f flv -rtmp_playpath some/long/path -rtmp_app long/app/name rtmp://username:password@@myserver/ @end example @section rtmpe Encrypted Real-Time Messaging Protocol. The Encrypted Real-Time Messaging Protocol (RTMPE) is used for streaming multimedia content within standard cryptographic primitives, consisting of Diffie-Hellman key exchange and HMACSHA256, generating a pair of RC4 keys. @section rtmps Real-Time Messaging Protocol over a secure SSL connection. The Real-Time Messaging Protocol (RTMPS) is used for streaming multimedia content across an encrypted connection. @section rtmpt Real-Time Messaging Protocol tunneled through HTTP. The Real-Time Messaging Protocol tunneled through HTTP (RTMPT) is used for streaming multimedia content within HTTP requests to traverse firewalls. @section rtmpte Encrypted Real-Time Messaging Protocol tunneled through HTTP. The Encrypted Real-Time Messaging Protocol tunneled through HTTP (RTMPTE) is used for streaming multimedia content within HTTP requests to traverse firewalls. @section rtmpts Real-Time Messaging Protocol tunneled through HTTPS. The Real-Time Messaging Protocol tunneled through HTTPS (RTMPTS) is used for streaming multimedia content within HTTPS requests to traverse firewalls. @section libssh Secure File Transfer Protocol via libssh Allow to read from or write to remote resources using SFTP protocol. Following syntax is required. @example sftp://[user[:password]@@]server[:port]/path/to/remote/resource.mpeg @end example This protocol accepts the following options. @table @option @item timeout Set timeout of socket I/O operations used by the underlying low level operation. By default it is set to -1, which means that the timeout is not specified. @item truncate Truncate existing files on write, if set to 1. A value of 0 prevents truncating. Default value is 1. @end table Example: Play a file stored on remote server. @example ffplay sftp://user:password@@server_address:22/home/user/resource.mpeg @end example @section librtmp rtmp, rtmpe, rtmps, rtmpt, rtmpte Real-Time Messaging Protocol and its variants supported through librtmp. Requires the presence of the librtmp headers and library during configuration. You need to explicitly configure the build with "--enable-librtmp". If enabled this will replace the native RTMP protocol. This protocol provides most client functions and a few server functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT), encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled variants of these encrypted types (RTMPTE, RTMPTS). The required syntax is: @example @var{rtmp_proto}://@var{server}[:@var{port}][/@var{app}][/@var{playpath}] @var{options} @end example where @var{rtmp_proto} is one of the strings "rtmp", "rtmpt", "rtmpe", "rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and @var{server}, @var{port}, @var{app} and @var{playpath} have the same meaning as specified for the RTMP native protocol. @var{options} contains a list of space-separated options of the form @var{key}=@var{val}. See the librtmp manual page (man 3 librtmp) for more information. For example, to stream a file in real-time to an RTMP server using @command{ffmpeg}: @example ffmpeg -re -i myfile -f flv rtmp://myserver/live/mystream @end example To play the same stream using @command{ffplay}: @example ffplay "rtmp://myserver/live/mystream live=1" @end example @section rtp Real-Time Protocol. The required syntax for an RTP URL is: rtp://@var{hostname}[:@var{port}][?@var{option}=@var{val}...] @var{port} specifies the RTP port to use. The following URL options are supported: @table @option @item ttl=@var{n} Set the TTL (Time-To-Leave) value (for multicast only). @item rtcpport=@var{n} Set the remote RTCP port to @var{n}. @item localrtpport=@var{n} Set the local RTP port to @var{n}. @item localrtcpport=@var{n}' Set the local RTCP port to @var{n}. @item pkt_size=@var{n} Set max packet size (in bytes) to @var{n}. @item connect=0|1 Do a @code{connect()} on the UDP socket (if set to 1) or not (if set to 0). @item sources=@var{ip}[,@var{ip}] List allowed source IP addresses. @item block=@var{ip}[,@var{ip}] List disallowed (blocked) source IP addresses. @item write_to_source=0|1 Send packets to the source address of the latest received packet (if set to 1) or to a default remote address (if set to 0). @item localport=@var{n} (DEPRECATED) Set the local port to @var{n}. @end table Important notes: @enumerate @item if @option{rtcpport} is not set the RTCP port will be set to the RTP port value plus 1. @item If @option{localport} (the local RTP port) is not set any available port will be used for the local RTP and RTCP ports. @item If @option{localrtcpport} (the local RTCP port) is not set it will be set to the the local RTP port value plus 1. @end enumerate @section rtsp RTSP is not technically a protocol handler in libavformat, it is a demuxer and muxer. The demuxer supports both normal RTSP (with data transferred over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with data transferred over RDT). The muxer can be used to send a stream using RTSP ANNOUNCE to a server supporting it (currently Darwin Streaming Server and Mischa Spiegelmock's @uref{http://github.com/revmischa/rtsp-server, RTSP server}). The required syntax for a RTSP url is: @example rtsp://@var{hostname}[:@var{port}]/@var{path} @end example The following options (set on the @command{ffmpeg}/@command{ffplay} command line, or set in code via @code{AVOption}s or in @code{avformat_open_input}), are supported: Flags for @code{rtsp_transport}: @table @option @item udp Use UDP as lower transport protocol. @item tcp Use TCP (interleaving within the RTSP control channel) as lower transport protocol. @item udp_multicast Use UDP multicast as lower transport protocol. @item http Use HTTP tunneling as lower transport protocol, which is useful for passing proxies. @end table Multiple lower transport protocols may be specified, in that case they are tried one at a time (if the setup of one fails, the next one is tried). For the muxer, only the @code{tcp} and @code{udp} options are supported. Flags for @code{rtsp_flags}: @table @option @item filter_src Accept packets only from negotiated peer address and port. @item listen Act as a server, listening for an incoming connection. @end table When receiving data over UDP, the demuxer tries to reorder received packets (since they may arrive out of order, or packets may get lost totally). This can be disabled by setting the maximum demuxing delay to zero (via the @code{max_delay} field of AVFormatContext). When watching multi-bitrate Real-RTSP streams with @command{ffplay}, the streams to display can be chosen with @code{-vst} @var{n} and @code{-ast} @var{n} for video and audio respectively, and can be switched on the fly by pressing @code{v} and @code{a}. Example command lines: To watch a stream over UDP, with a max reordering delay of 0.5 seconds: @example ffplay -max_delay 500000 -rtsp_transport udp rtsp://server/video.mp4 @end example To watch a stream tunneled over HTTP: @example ffplay -rtsp_transport http rtsp://server/video.mp4 @end example To send a stream in realtime to a RTSP server, for others to watch: @example ffmpeg -re -i @var{input} -f rtsp -muxdelay 0.1 rtsp://server/live.sdp @end example To receive a stream in realtime: @example ffmpeg -rtsp_flags listen -i rtsp://ownaddress/live.sdp @var{output} @end example @table @option @item stimeout Socket IO timeout in micro seconds. @end table @section sap Session Announcement Protocol (RFC 2974). This is not technically a protocol handler in libavformat, it is a muxer and demuxer. It is used for signalling of RTP streams, by announcing the SDP for the streams regularly on a separate port. @subsection Muxer The syntax for a SAP url given to the muxer is: @example sap://@var{destination}[:@var{port}][?@var{options}] @end example The RTP packets are sent to @var{destination} on port @var{port}, or to port 5004 if no port is specified. @var{options} is a @code{&}-separated list. The following options are supported: @table @option @item announce_addr=@var{address} Specify the destination IP address for sending the announcements to. If omitted, the announcements are sent to the commonly used SAP announcement multicast address 224.2.127.254 (sap.mcast.net), or ff0e::2:7ffe if @var{destination} is an IPv6 address. @item announce_port=@var{port} Specify the port to send the announcements on, defaults to 9875 if not specified. @item ttl=@var{ttl} Specify the time to live value for the announcements and RTP packets, defaults to 255. @item same_port=@var{0|1} If set to 1, send all RTP streams on the same port pair. If zero (the default), all streams are sent on unique ports, with each stream on a port 2 numbers higher than the previous. VLC/Live555 requires this to be set to 1, to be able to receive the stream. The RTP stack in libavformat for receiving requires all streams to be sent on unique ports. @end table Example command lines follow. To broadcast a stream on the local subnet, for watching in VLC: @example ffmpeg -re -i @var{input} -f sap sap://224.0.0.255?same_port=1 @end example Similarly, for watching in @command{ffplay}: @example ffmpeg -re -i @var{input} -f sap sap://224.0.0.255 @end example And for watching in @command{ffplay}, over IPv6: @example ffmpeg -re -i @var{input} -f sap sap://[ff0e::1:2:3:4] @end example @subsection Demuxer The syntax for a SAP url given to the demuxer is: @example sap://[@var{address}][:@var{port}] @end example @var{address} is the multicast address to listen for announcements on, if omitted, the default 224.2.127.254 (sap.mcast.net) is used. @var{port} is the port that is listened on, 9875 if omitted. The demuxers listens for announcements on the given address and port. Once an announcement is received, it tries to receive that particular stream. Example command lines follow. To play back the first stream announced on the normal SAP multicast address: @example ffplay sap:// @end example To play back the first stream announced on one the default IPv6 SAP multicast address: @example ffplay sap://[ff0e::2:7ffe] @end example @section sctp Stream Control Transmission Protocol. The accepted URL syntax is: @example sctp://@var{host}:@var{port}[?@var{options}] @end example The protocol accepts the following options: @table @option @item listen If set to any value, listen for an incoming connection. Outgoing connection is done by default. @item max_streams Set the maximum number of streams. By default no limit is set. @end table @section srtp Secure Real-time Transport Protocol. The accepted options are: @table @option @item srtp_in_suite @item srtp_out_suite Select input and output encoding suites. Supported values: @table @samp @item AES_CM_128_HMAC_SHA1_80 @item SRTP_AES128_CM_HMAC_SHA1_80 @item AES_CM_128_HMAC_SHA1_32 @item SRTP_AES128_CM_HMAC_SHA1_32 @end table @item srtp_in_params @item srtp_out_params Set input and output encoding parameters, which are expressed by a base64-encoded representation of a binary block. The first 16 bytes of this binary block are used as master key, the following 14 bytes are used as master salt. @end table @section tcp Trasmission Control Protocol. The required syntax for a TCP url is: @example tcp://@var{hostname}:@var{port}[?@var{options}] @end example @table @option @item listen Listen for an incoming connection @item timeout=@var{microseconds} In read mode: if no data arrived in more than this time interval, raise error. In write mode: if socket cannot be written in more than this time interval, raise error. This also sets timeout on TCP connection establishing. @example ffmpeg -i @var{input} -f @var{format} tcp://@var{hostname}:@var{port}?listen ffplay tcp://@var{hostname}:@var{port} @end example @end table @section tls Transport Layer Security (TLS) / Secure Sockets Layer (SSL) The required syntax for a TLS/SSL url is: @example tls://@var{hostname}:@var{port}[?@var{options}] @end example The following parameters can be set via command line options (or in code via @code{AVOption}s): @table @option @item ca_file, cafile=@var{filename} A file containing certificate authority (CA) root certificates to treat as trusted. If the linked TLS library contains a default this might not need to be specified for verification to work, but not all libraries and setups have defaults built in. The file must be in OpenSSL PEM format. @item tls_verify=@var{1|0} If enabled, try to verify the peer that we are communicating with. Note, if using OpenSSL, this currently only makes sure that the peer certificate is signed by one of the root certificates in the CA database, but it does not validate that the certificate actually matches the host name we are trying to connect to. (With GnuTLS, the host name is validated as well.) This is disabled by default since it requires a CA database to be provided by the caller in many cases. @item cert_file, cert=@var{filename} A file containing a certificate to use in the handshake with the peer. (When operating as server, in listen mode, this is more often required by the peer, while client certificates only are mandated in certain setups.) @item key_file, key=@var{filename} A file containing the private key for the certificate. @item listen=@var{1|0} If enabled, listen for connections on the provided port, and assume the server role in the handshake instead of the client role. @end table Example command lines: To create a TLS/SSL server that serves an input stream. @example ffmpeg -i @var{input} -f @var{format} tls://@var{hostname}:@var{port}?listen&cert=@var{server.crt}&key=@var{server.key} @end example To play back a stream from the TLS/SSL server using @command{ffplay}: @example ffplay tls://@var{hostname}:@var{port} @end example @section udp User Datagram Protocol. The required syntax for a UDP url is: @example udp://@var{hostname}:@var{port}[?@var{options}] @end example @var{options} contains a list of &-separated options of the form @var{key}=@var{val}. In case threading is enabled on the system, a circular buffer is used to store the incoming data, which allows to reduce loss of data due to UDP socket buffer overruns. The @var{fifo_size} and @var{overrun_nonfatal} options are related to this buffer. The list of supported options follows. @table @option @item buffer_size=@var{size} Set the UDP socket buffer size in bytes. This is used both for the receiving and the sending buffer size. @item localport=@var{port} Override the local UDP port to bind with. @item localaddr=@var{addr} Choose the local IP address. This is useful e.g. if sending multicast and the host has multiple interfaces, where the user can choose which interface to send on by specifying the IP address of that interface. @item pkt_size=@var{size} Set the size in bytes of UDP packets. @item reuse=@var{1|0} Explicitly allow or disallow reusing UDP sockets. @item ttl=@var{ttl} Set the time to live value (for multicast only). @item connect=@var{1|0} Initialize the UDP socket with @code{connect()}. In this case, the destination address can't be changed with ff_udp_set_remote_url later. If the destination address isn't known at the start, this option can be specified in ff_udp_set_remote_url, too. This allows finding out the source address for the packets with getsockname, and makes writes return with AVERROR(ECONNREFUSED) if "destination unreachable" is received. For receiving, this gives the benefit of only receiving packets from the specified peer address/port. @item sources=@var{address}[,@var{address}] Only receive packets sent to the multicast group from one of the specified sender IP addresses. @item block=@var{address}[,@var{address}] Ignore packets sent to the multicast group from the specified sender IP addresses. @item fifo_size=@var{units} Set the UDP receiving circular buffer size, expressed as a number of packets with size of 188 bytes. If not specified defaults to 7*4096. @item overrun_nonfatal=@var{1|0} Survive in case of UDP receiving circular buffer overrun. Default value is 0. @item timeout=@var{microseconds} In read mode: if no data arrived in more than this time interval, raise error. @end table Some usage examples of the UDP protocol with @command{ffmpeg} follow. To stream over UDP to a remote endpoint: @example ffmpeg -i @var{input} -f @var{format} udp://@var{hostname}:@var{port} @end example To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer: @example ffmpeg -i @var{input} -f mpegts udp://@var{hostname}:@var{port}?pkt_size=188&buffer_size=65535 @end example To receive over UDP from a remote endpoint: @example ffmpeg -i udp://[@var{multicast-address}]:@var{port} @end example @section unix Unix local socket The required syntax for a Unix socket URL is: @example unix://@var{filepath} @end example The following parameters can be set via command line options (or in code via @code{AVOption}s): @table @option @item timeout Timeout in ms. @item listen Create the Unix socket in listening mode. @end table @c man end PROTOCOLS