ffserver - ffserver video server
ffserver is a streaming server for both audio and video. It supports several live feeds, streaming from files and time shifting on live feeds. You can seek to positions in the past on each live feed, provided you specify a big enough feed storage.
ffserver is configured through a configuration file, which is read at startup. If not explicitly specified, it will read from /etc/ffserver.conf.
ffserver receives prerecorded files or FFM streams from some ffmpeg instance as input, then streams them over RTP/RTSP/HTTP.
An ffserver instance will listen on some port as specified in the configuration file. You can launch one or more instances of ffmpeg and send one or more FFM streams to the port where ffserver is expecting to receive them. Alternately, you can make ffserver launch such ffmpeg instances at startup.
Input streams are called feeds, and each one is specified by a
<Feed>section in the configuration file.
For each feed you can have different output streams in various formats, each one specified by a
<Stream>section in the configuration file.
ffserver works by forwarding streams encoded by ffmpeg, or pre-recorded streams which are read from disk.
Precisely, ffserver acts as an HTTP server, accepting POST requests from ffmpeg to acquire the stream to publish, and serving RTSP clients or HTTP clients GET requests with the stream media content.
A feed is an FFM stream created by ffmpeg, and sent to a port where ffserver is listening.
Each feed is identified by a unique name, corresponding to the name of the resource published on ffserver, and is configured by a dedicated
Feedsection in the configuration file.
The feed publish URL is given by:
where ffserver_ip_address is the IP address of the machine where ffserver is installed, http_port is the port number of the HTTP server (configured through the HTTPPort option), and feed_name is the name of the corresponding feed defined in the configuration file.
Each feed is associated to a file which is stored on disk. This stored file is used to send pre-recorded data to a player as fast as possible when new content is added in real-time to the stream.
A live-stream or stream is a resource published by ffserver, and made accessible through the HTTP protocol to clients.
A stream can be connected to a feed, or to a file. In the first case, the published stream is forwarded from the corresponding feed generated by a running instance of ffmpeg, in the second case the stream is read from a pre-recorded file.
Each stream is identified by a unique name, corresponding to the name of the resource served by ffserver, and is configured by a dedicated
Streamsection in the configuration file.
The stream access HTTP URL is given by:
The stream access RTSP URL is given by:
stream_name is the name of the corresponding stream defined in the configuration file. options is a list of options specified after the URL which affects how the stream is served by ffserver. http_port and rtsp_port are the HTTP and RTSP ports configured with the options HTTPPort and RTSPPort respectively.
In case the stream is associated to a feed, the encoding parameters must be configured in the stream configuration. They are sent to ffmpeg when setting up the encoding. This allows ffserver to define the encoding parameters used by the ffmpeg encoders.
The ffmpeg override_ffserver commandline option allows one to override the encoding parameters set by the server.
Multiple streams can be connected to the same feed.
For example, you can have a situation described by the following graph:
_________ __________ | | | | ffmpeg 1 -----| feed 1 |-----| stream 1 | \ |_________|\ |__________| \ \ \ \ __________ \ \ | | \ \| stream 2 | \ |__________| \ \ _________ __________ \ | | | | \| feed 2 |-----| stream 3 | |_________| |__________| _________ __________ | | | | ffmpeg 2 -----| feed 3 |-----| stream 4 | |_________| |__________| _________ __________ | | | | | file 1 |-----| stream 5 | |_________| |__________|
FFM, FFM2 formats
FFM and FFM2 are formats used by ffserver. They allow storing a wide variety of video and audio streams and encoding options, and can store a moving time segment of an infinite movie or a whole movie.
FFM is version specific, and there is limited compatibility of FFM files generated by one version of ffmpeg/ffserver and another version of ffmpeg/ffserver. It may work but it is not guaranteed to work.
FFM2 is extensible while maintaining compatibility and should work between differing versions of tools. FFM2 is the default.
ffserver supports an HTTP interface which exposes the current status of the server.
Simply point your browser to the address of the special status stream specified in the configuration file.
For example if you have:
<Stream status.html> Format status # Only allow local people to get the status ACL allow localhost ACL allow 192.168.0.0 192.168.255.255 </Stream>
then the server will post a page with the status information when the special stream status.html is requested.
How do I make it work?
As a simple test, just run the following two command lines where INPUTFILE is some file which you can decode with ffmpeg:
ffserver -f doc/ffserver.conf & ffmpeg -i INPUTFILE http://localhost:8090/feed1.ffm
At this point you should be able to go to your Windows machine and fire up Windows Media Player (WMP). Go to Open URL and enter
You should (after a short delay) see video and hear audio.
WARNING: trying to stream test1.mpg doesn’t work with WMP as it tries to transfer the entire file before starting to play. The same is true of AVI files.
You should edit the ffserver.conf file to suit your needs (in terms of frame rates etc). Then install ffserver and ffmpeg, write a script to start them up, and off you go.
What else can it do?
You can replay video from .ffm files that was recorded earlier. However, there are a number of caveats, including the fact that the ffserver parameters must match the original parameters used to record the file. If they do not, then ffserver deletes the file before recording into it. (Now that I write this, it seems broken).
You can fiddle with many of the codec choices and encoding parameters, and there are a bunch more parameters that you cannot control. Post a message to the mailing list if there are some ’must have’ parameters. Look in ffserver.conf for a list of the currently available controls.
It will automatically generate the ASX or RAM files that are often used in browsers. These files are actually redirections to the underlying ASF or RM file. The reason for this is that the browser often fetches the entire file before starting up the external viewer. The redirection files are very small and can be transferred quickly. [The stream itself is often ’infinite’ and thus the browser tries to download it and never finishes.]
* When you connect to a live stream, most players (WMP, RA, etc) want to buffer a certain number of seconds of material so that they can display the signal continuously. However, ffserver (by default) starts sending data in realtime. This means that there is a pause of a few seconds while the buffering is being done by the player. The good news is that this can be cured by adding a ’?buffer=5’ to the end of the URL. This means that the stream should start 5 seconds in the past — and so the first 5 seconds of the stream are sent as fast as the network will allow. It will then slow down to real time. This noticeably improves the startup experience.
You can also add a ’Preroll 15’ statement into the ffserver.conf that will add the 15 second prebuffering on all requests that do not otherwise specify a time. In addition, ffserver will skip frames until a key_frame is found. This further reduces the startup delay by not transferring data that will be discarded.
Why does the ?buffer / Preroll stop working after a time?
It turns out that (on my machine at least) the number of frames successfully grabbed is marginally less than the number that ought to be grabbed. This means that the timestamp in the encoded data stream gets behind realtime. This means that if you say ’Preroll 10’, then when the stream gets 10 or more seconds behind, there is no Preroll left.
Fixing this requires a change in the internals of how timestamps are handled.
Does the CW?date= stuff work.Yes (subject to the limitation outlined above). Also note that whenever you start ffserver, it deletes the ffm file (if any parameters have changed), thus wiping out what you had recorded before.
The format of the
?date=xxxxxxis fairly flexible. You should use one of the following formats (the ’T’ is literal):
* YYYY-MM-DDTHH:MM:SS (localtime) * YYYY-MM-DDTHH:MM:SSZ (UTC)
You can omit the YYYY-MM-DD, and then it refers to the current day. However note that ?date=16:00:00 refers to 16:00 on the current day — this may be in the future and so is unlikely to be useful.
You use this by adding the ?date= to the end of the URL for the stream. For example: http://localhost:8080/test.asf?date=2002-07-26T23:05:00.
All the numerical options, if not specified otherwise, accept a string representing a number as input, which may be followed by one of the SI unit prefixes, for example: ’K’, ’M’, or ’G’.
If ’i’ is appended to the SI unit prefix, the complete prefix will be interpreted as a unit prefix for binary multiples, which are based on powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit prefix multiplies the value by 8. This allows using, for example: ’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
Options which do not take arguments are boolean options, and set the corresponding value to true. They can be set to false by prefixing the option name with no. For example using -nofoo will set the boolean option with name foo to false.
Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers are used to precisely specify which stream(s) a given option belongs to.
A stream specifier is a string generally appended to the option name and separated from it by a colon. E.g.
-codec:a:1 ac3contains the
a:1stream specifier, which matches the second audio stream. Therefore, it would select the ac3 codec for the second audio stream.
A stream specifier can match several streams, so that the option is applied to all of them. E.g. the stream specifier in
-b:a 128kmatches all audio streams.
An empty stream specifier matches all streams. For example,
-codec: copywould copy all the streams without reencoding.
Possible forms of stream specifiers are:
|stream_index||Matches the stream with this index. E.g.
|stream_type[:stream_index]||stream_type is one of following: ’v’ or ’V’ for video, ’a’ for audio, ’s’ for subtitle, ’d’ for data, and ’t’ for attachments. ’v’ matches all video streams, ’V’ only matches video streams which are not attached pictures, video thumbnails or cover arts. If stream_index is given, then it matches stream number stream_index of this type. Otherwise, it matches all streams of this type.|
|p:program_id[:stream_index]||If stream_index is given, then it matches the stream with number stream_index in the program with the id program_id. Otherwise, it matches all streams in the program.|
|#stream_id or i:stream_id||Match the stream by stream id (e.g. PID in MPEG-TS container).|
|m:key[:value]||Matches streams with the metadata tag key having the specified value. If value is not given, matches streams that contain the given tag with any value.|
|u||Matches streams with usable configuration, the codec must be defined and the essential information such as video dimension or audio sample rate must be present.
Note that in ffmpeg, matching by metadata will only work properly for input files.
These options are shared amongst the ff* tools.
|-h, -?, -help, --help [arg]||Show help. An optional parameter may be specified to print help about a specific item. If no argument is specified, only basic (non advanced) tool options are shown.
Possible values of arg are:
|-formats||Show available formats (including devices).|
|-demuxers||Show available demuxers.|
|-muxers||Show available muxers.|
|-devices||Show available devices.|
|-codecs||Show all codecs known to libavcodec.
Note that the term ’codec’ is used throughout this documentation as a shortcut for what is more correctly called a media bitstream format.
|-decoders||Show available decoders.|
|-encoders||Show all available encoders.|
|-bsfs||Show available bitstream filters.|
|-protocols||Show available protocols.|
|-filters||Show available libavfilter filters.|
|-pix_fmts||Show available pixel formats.|
|-sample_fmts||Show available sample formats.|
|-layouts||Show channel names and standard channel layouts.|
|-colors||Show recognized color names.|
|-sources device[,opt1=val1[,opt2=val2]...]||Show autodetected sources of the input device. Some devices may provide system-dependent source names that cannot be autodetected. The returned list cannot be assumed to be always complete.
|-sinks device[,opt1=val1[,opt2=val2]...]||Show autodetected sinks of the output device. Some devices may provide system-dependent sink names that cannot be autodetected. The returned list cannot be assumed to be always complete.
|-loglevel [repeat+]loglevel | -v [repeat+]loglevel||Set the logging level used by the library. Adding repeat+ indicates that repeated log output should not be compressed to the first line and the Last message repeated n times line will be omitted. repeat can also be used alone. If repeat is used alone, and with no prior loglevel set, the default loglevel will be used. If multiple loglevel parameters are given, using ’repeat’ will not change the loglevel. loglevel is a string or a number containing one of the following values:
By default the program logs to stderr. If coloring is supported by the terminal, colors are used to mark errors and warnings. Log coloring can be disabled setting the environment variable AV_LOG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting the environment variable AV_LOG_FORCE_COLOR. The use of the environment variable NO_COLOR is deprecated and will be dropped in a future FFmpeg version.
|-report||Dump full command line and console output to a file named
Setting the environment variable FFREPORT to any value has the same effect. If the value is a ’:’-separated key=value sequence, these options will affect the report; option values must be escaped if they contain special characters or the options delimiter ’:’ (see the ‘‘Quoting and escaping’’ section in the ffmpeg-utils manual).
The following options are recognized:
For example, to output a report to a file named ffreport.log using a log level of
Errors in parsing the environment variable are not fatal, and will not appear in the report.
|-hide_banner||Suppress printing banner.
All FFmpeg tools will normally show a copyright notice, build options and library versions. This option can be used to suppress printing this information.
|-cpuflags flags (global)||Allows setting and clearing cpu flags. This option is intended for testing. Do not use it unless you know what you’re doing.
Possible flags for this option are:
|-opencl_bench||This option is used to benchmark all available OpenCL devices and print the results. This option is only available when FFmpeg has been compiled with
When FFmpeg is configured with
This option assists the selection of the most efficient configuration by identifying the appropriate device for the user’s system. The built-in benchmark is run on all the OpenCL devices and the performance is measured for each device. The devices in the results list are sorted based on their performance with the fastest device listed first. The user can subsequently invoke ffmpeg using the device deemed most appropriate via -opencl_options to obtain the best performance for the OpenCL accelerated code.
Typical usage to use the fastest OpenCL device involve the following steps.
Run the command:
Note down the platform ID (pidx) and device ID (didx) of the first i.e. fastest device in the list. Select the platform and device using the command:
|-opencl_options options (global)||Set OpenCL environment options. This option is only available when FFmpeg has been compiled with
options must be a list of key=value option pairs separated by ’:’. See the ‘‘OpenCL Options’’ section in the ffmpeg-utils manual for the list of supported options.
These options are provided directly by the libavformat, libavdevice and libavcodec libraries. To see the list of available AVOptions, use the -help option. They are separated into two categories:
For example to write an ID3v2.3 header instead of a default ID3v2.4 to an MP3 file, use the id3v2_version private option of the MP3 muxer:
|generic||These options can be set for any container, codec or device. Generic options are listed under AVFormatContext options for containers/devices and under AVCodecContext options for codecs.|
|private||These options are specific to the given container, device or codec. Private options are listed under their corresponding containers/devices/codecs.|
ffmpeg -i input.flac -id3v2_version 3 out.mp3
All codec AVOptions are per-stream, and thus a stream specifier should be attached to them.
Note: the -nooption syntax cannot be used for boolean AVOptions, use -option 0/-option 1.
Note: the old undocumented way of specifying per-stream AVOptions by prepending v/a/s to the options name is now obsolete and will be removed soon.
|-f configfile||Read configuration file configfile. If not specified it will read by default from /etc/ffserver.conf.|
|-n||Enable no-launch mode. This option disables all the
|-d||Enable debug mode. This option increases log verbosity, and directs log messages to stdout. When specified, the CustomLog option is ignored.|
CONFIGURATION FILE SYNTAX
ffserver reads a configuration file containing global options and settings for each stream and feed.
The configuration file consists of global options and dedicated sections, which must be introduced by "<SECTION_NAME ARGS> on a separate line and must be terminated by a line in the form </SECTION_NAME>". ARGS is optional.
Currently the following sections are recognized: Feed, Stream, Redirect.
A line starting with
#is ignored and treated as a comment.
Name of options and sections are case-insensitive.
An ACL (Access Control List) specifies the address which are allowed to access a given stream, or to write a given feed.
You can repeat the ACL allow/deny as often as you like. It is on a per stream basis. The first match defines the action. If there are no matches, then the default is the inverse of the last ACL statement.
It accepts the following forms
|o||Allow/deny access to address.
|o||Allow/deny access to ranges of addresses from first_address to last_address.
Thus ’ACL allow localhost’ only allows access from localhost. ’ACL deny 22.214.171.124 126.96.36.199’ would deny the whole of network 1 and allow everybody else.
|RTSPPort port_number||HTTPPort sets the HTTP server listening TCP port number, RTSPPort sets the RTSP server listening TCP port number.
Port is the equivalent of HTTPPort and is deprecated.
You must select a different port from your standard HTTP web server if it is running on the same computer.
If not specified, no corresponding server will be created.
|RTSPBindAddress ip_address||Set address on which the HTTP/RTSP server is bound. Only useful if you have several network interfaces.
BindAddress is the equivalent of HTTPBindAddress and is deprecated.
|MaxHTTPConnections n||Set number of simultaneous HTTP connections that can be handled. It has to be defined before the MaxClients parameter, since it defines the MaxClients maximum limit.
Default value is 2000.
|MaxClients n||Set number of simultaneous requests that can be handled. Since ffserver is very fast, it is more likely that you will want to leave this high and use MaxBandwidth.
Default value is 5.
|MaxBandwidth kbps||Set the maximum amount of kbit/sec that you are prepared to consume when streaming to clients.
Default value is 1000.
|CustomLog filename||Set access log file (uses standard Apache log file format). ’-’ is the standard output.
If not specified ffserver will produce no log.
In case the commandline option -d is specified this option is ignored, and the log is written to standard output.
|NoDaemon||Set no-daemon mode. This option is currently ignored since now ffserver will always work in no-daemon mode, and is deprecated.|
|NoDefaults||Control whether default codec options are used for the all streams or not. Each stream may overwrite this setting for its own. Default is UseDefaults. The last occurrence overrides the previous if multiple definitions exist.|
A Feed section defines a feed provided to ffserver.
Each live feed contains one video and/or audio sequence coming from an ffmpeg encoder or another ffserver. This sequence may be encoded simultaneously with several codecs at several resolutions.
A feed instance specification is introduced by a line in the form:
where FEED_FILENAME specifies the unique name of the FFM stream.
The following options are recognized within a Feed section.
|ReadOnlyFile filename||Set the path where the feed file is stored on disk.
If not specified, the /tmp/FEED.ffm is assumed, where FEED is the feed name.
If ReadOnlyFile is used the file is marked as read-only and it will not be deleted or updated.
|Truncate||Truncate the feed file, rather than appending to it. By default ffserver will append data to the file, until the maximum file size value is reached (see FileMaxSize option).|
|FileMaxSize size||Set maximum size of the feed file in bytes. 0 means unlimited. The postfixes
Default value is 5M.
|Launch args||Launch an ffmpeg command when creating ffserver.
args must be a sequence of arguments to be provided to an ffmpeg instance. The first provided argument is ignored, and it is replaced by a path with the same dirname of the ffserver instance, followed by the remaining argument and terminated with a path corresponding to the feed.
When the launched process exits, ffserver will launch another program instance.
In case you need a more complex ffmpeg configuration, e.g. if you need to generate multiple FFM feeds with a single ffmpeg instance, you should launch ffmpeg by hand.
This option is ignored in case the commandline option -n is specified.
|ACL spec||Specify the list of IP address which are allowed or denied to write the feed. Multiple ACL options can be specified.|
A Stream section defines a stream provided by ffserver, and identified by a single name.
Server status stream
The stream is sent when answering a request containing the stream name.
A stream section must be introduced by the line:
where STREAM_NAME specifies the unique name of the stream.
The following options are recognized within a Stream section.
Encoding options are marked with the encoding tag, and they are used to set the encoding parameters, and are mapped to libavcodec encoding options. Not all encoding options are supported, in particular it is not possible to set encoder private options. In order to override the encoding options specified by ffserver, you can use the ffmpeg override_ffserver commandline option.
Only one of the Feed and File options should be set.
|Feed feed_name||Set the input feed. feed_name must correspond to an existing feed defined in a
When this option is set, encoding options are used to setup the encoding operated by the remote ffmpeg process.
|File filename||Set the filename of the pre-recorded input file to stream.
When this option is set, encoding options are ignored and the input file content is re-streamed as is.
|Format format_name||Set the format of the output stream.
Must be the name of a format recognized by FFmpeg. If set to status, it is treated as a status stream.
|InputFormat format_name||Set input format. If not specified, it is automatically guessed.|
|Preroll n||Set this to the number of seconds backwards in time to start. Note that most players will buffer 5-10 seconds of video, and also you need to allow for a keyframe to appear in the data stream.
Default value is 0.
|StartSendOnKey||Do not send stream until it gets the first key frame. By default ffserver will send data immediately.|
|MaxTime n||Set the number of seconds to run. This value set the maximum duration of the stream a client will be able to receive.
A value of 0 means that no limit is set on the stream duration.
|ACL spec||Set ACL for the stream.|
|FaviconURL url||Set favicon (favourite icon) for the server status page. It is ignored for regular streams.|
|Title value||Set metadata corresponding to the option. All these options are deprecated in favor of Metadata.|
|Metadata key value||Set metadata value on the output stream.|
|NoDefaults||Control whether default codec options are used for the stream or not. Default is UseDefaults unless disabled globally.|
|AudioCodec codec_name (encoding,audio)||Set audio codec.|
|AudioBitRate rate (encoding,audio)||Set bitrate for the audio stream in kbits per second.|
|AudioChannels n (encoding,audio)||Set number of audio channels.|
|AudioSampleRate n (encoding,audio)||Set sampling frequency for audio. When using low bitrates, you should lower this frequency to 22050 or 11025. The supported frequencies depend on the selected audio codec.|
|AVOptionAudio [codec:]option value (encoding,audio)||Set generic or private option for audio stream. Private option must be prefixed with codec name or codec must be defined before.|
|AVPresetAudio preset (encoding,audio)||Set preset for audio stream.|
|VideoCodec codec_name (encoding,video)||Set video codec.|
|VideoBitRate n (encoding,video)||Set bitrate for the video stream in kbits per second.|
|VideoBitRateRange range (encoding,video)||Set video bitrate range.
A range must be specified in the form minrate-maxrate, and specifies the minrate and maxrate encoding options expressed in kbits per second.
|VideoBitRateRangeTolerance n (encoding,video)||Set video bitrate tolerance in kbits per second.|
|PixelFormat pixel_format (encoding,video)||Set video pixel format.|
|Debug integer (encoding,video)||Set video debug encoding option.|
|Strict integer (encoding,video)||Set video strict encoding option.|
|VideoBufferSize n (encoding,video)||Set ratecontrol buffer size, expressed in KB.|
|VideoFrameRate n (encoding,video)||Set number of video frames per second.|
|VideoSize (encoding,video)||Set size of the video frame, must be an abbreviation or in the form WxH. See the Video size section in the
Default value is
|VideoIntraOnly (encoding,video)||Transmit only intra frames (useful for low bitrates, but kills frame rate).|
|VideoGopSize n (encoding,video)||If non-intra only, an intra frame is transmitted every VideoGopSize frames. Video synchronization can only begin at an intra frame.|
|VideoTag tag (encoding,video)||Set video tag.|
|BitExact (encoding,video)||Set bitexact encoding flag.|
|IdctSimple (encoding,video)||Set simple IDCT algorithm.|
|Qscale n (encoding,video)||Enable constant quality encoding, and set video qscale (quantization scale) value, expressed in n QP units.|
|VideoQMin n (encoding,video)|
|VideoQMax n (encoding,video)||Set video qmin/qmax.|
|VideoQDiff integer (encoding,video)||Set video qdiff encoding option.|
|LumiMask float (encoding,video)|
|DarkMask float (encoding,video)||Set lumi_mask/dark_mask encoding options.|
|AVOptionVideo [codec:]option value (encoding,video)||Set generic or private option for video stream. Private option must be prefixed with codec name or codec must be defined before.|
|AVPresetVideo preset (encoding,video)||Set preset for video stream.
preset must be the path of a preset file.
A server status stream is a special stream which is used to show statistics about the ffserver operations.
It must be specified setting the option Format to status.
A redirect section specifies where to redirect the requested URL to another page.
A redirect section must be introduced by the line:
where NAME is the name of the page which should be redirected.
It only accepts the option URL, which specify the redirection URL.
|o||Ogg Vorbis audio
|o||Real with audio only at 32 kbits
|o||Real with audio and video at 64 kbits
|o||For stream coming from a file: you only need to set the input filename and optionally a new format.
The FFmpeg developers.
For details about the authorship, see the Git history of the project (git://source.ffmpeg.org/ffmpeg), e.g. by typing the command git log in the FFmpeg source directory, or browsing the online repository at <http://source.ffmpeg.org>.
Maintainers for the specific components are listed in the file MAINTAINERS in the source code tree.