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ffmpeg - Utilities and libraries to record, convert and stream audio and video…  more info»


FFSERVER(1)                                              FFSERVER(1)

       ffserver - FFserver video server

       ffserver [options]

       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 in ffserver.conf).

       FFserver runs in daemon mode by default; that is, it puts
       itself in the background and detaches from its TTY, unless it
       is launched in debug mode or a NoDaemon option is specified
       in the configuration file.

       This documentation covers only the streaming aspects of
       ffserver / ffmpeg. All questions about parameters for ffmpeg,
       codec questions, etc. are not covered here. Read ffm‐
       peg-doc.html for more information.

       How does it work?

       FFserver receives prerecorded files or FFM streams from some
       ffmpeg instance as input, then streams them over

       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 vari‐
       ous formats, each one specified by a <Stream> section in the
       configuration file.

       Status stream

       FFserver supports an HTTP interface which exposes the current
       status of the server.

       Simply point your browser to the address of the special sta‐
       tus 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

       then the server will post a page with the status information
       when the special stream status.html is requested.

       What can this do?

       When properly configured and running, you can capture video
       and audio in real time from a suitable capture card, and
       stream it out over the Internet to either Windows Media
       Player or RealAudio player (with some restrictions).

       It can also stream from files, though that is currently bro‐
       ken. Very often, a web server can be used to serve up the
       files just as well.

       It can stream prerecorded video from .ffm files, though it is
       somewhat tricky to make it work correctly.

       What do I need?

       I use Linux on a 900 MHz Duron with a cheapo Bt848 based TV
       capture card. I'm using stock Linux 2.4.17 with the stock
       drivers. [Actually that isn't true, I needed some special
       drivers for my motherboard-based sound card.]

       I understand that FreeBSD systems work just fine as well.

       How do I make it work?

       First, build the kit. It *really* helps to have installed
       LAME first. Then when you run the ffserver ./configure, make
       sure that you have the "--enable-libmp3lame" flag turned on.

       LAME is important as it allows for streaming audio to Windows
       Media Player.  Don't ask why the other audio types do not

       As a simple test, just run the following two command lines
       where INPUTFILE is some file which you can decode with ffm‐

               ./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.

       What happens next?

       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.


       I don't hear any audio, but video is fine.

       Maybe you didn't install LAME, or got your ./configure state‐
       ment wrong. Check the ffmpeg output to see if a line refer‐
       ring to MP3 is present. If not, then your configuration was
       incorrect. If it is, then maybe your wiring is not set up
       correctly. Maybe the sound card is not getting data from the
       right input source. Maybe you have a really awful audio
       interface (like I do) that only captures in stereo and also
       requires that one channel be flipped.  If you are one of
       these people, then export 'AUDIO_FLIP_LEFT=1' before starting

       The audio and video loose sync after a while.

       Yes, they do.

       After a long while, the video update rate goes way down in

       Yes, it does. Who knows why?

       WMP 6.4 behaves differently to WMP 7.

       Yes, it does. Any thoughts on this would be gratefully
       received. These differences extend to embedding WMP into a
       web page. [There are two object IDs that you can use: The old
       one, which does not play well, and the new one, which does
       (both tested on the same system). However, I suspect that the
       new one is not available unless you have installed WMP 7].

       What else can it do?

       You can replay video from .ffm files that was recorded ear‐
       lier.  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.

       * You may want to adjust the MaxBandwidth in the
       ffserver.conf to limit the amount of bandwidth consumed by
       live streams.

       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 num‐
       ber 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 time‐
       stamps are handled.

       Does the "?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=xxxxxx" is 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 cur‐
       rent 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://local‐

           Show version.

       -L  Show license.

           Show available formats, codecs, protocols, ...

       -h  Show help.

       -f configfile
           Use configfile instead of /etc/ffserver.conf.

       -n  Enable no-launch mode. This option disables all the
           Launch directives within the various <Stream> sections.
           FFserver will not launch any ffmpeg instance, so you will
           have to launch them manually.

       -d  Enable debug mode. This option increases log verbosity,
           directs log messages to stdout and causes ffserver to run
           in the foreground rather than as a daemon.

       ffmpeg(1), ffplay(1), the ffmpeg/doc/ffserver.conf example
       and the HTML documentation of ffmpeg.

       Fabrice Bellard

                             2010-06-13                  FFSERVER(1)
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