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\input texinfo @c -*- texinfo -*-

@settitle ffserver Documentation

@titlepage

@center @titlefont{ffserver Documentation}

@end titlepage

@top

@contents

@chapter Synopsis

ffserver [@var{options}]

@chapter Description

@c man begin DESCRIPTION

@command{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

@file{ffserver.conf}).

@command{ffserver} receives prerecorded files or FFM streams from some

@command{ffmpeg} instance as input, then streams them over

RTP/RTSP/HTTP.

An @command{ffserver} instance will listen on some port as specified

in the configuration file. You can launch one or more instances of

@command{ffmpeg} and send one or more FFM streams to the port where

ffserver is expecting to receive them. Alternately, you can make

@command{ffserver} launch such @command{ffmpeg} instances at startup.

Input streams are called feeds, and each one is specified by a

@code{} section in the configuration file.

For each feed you can have different output streams in various

formats, each one specified by a @code{} section in the

configuration file.

@section 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 status stream

specified in the configuration file.

For example if you have:

@example

Format status

# Only allow local people to get the status

ACL allow localhost

ACL allow 192.168.0.0 192.168.255.255

@end example

then the server will post a page with the status information when

the special stream @file{status.html} is requested.

@section 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 broken. 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.

@section 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

@code{--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 work.

As a simple test, just run the following two command lines where INPUTFILE

is some file which you can decode with ffmpeg:

@example

ffserver -f doc/ffserver.conf &

ffmpeg -i INPUTFILE http://localhost:8090/feed1.ffm

@end example

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

@example

    http://:8090/test.asf

@end example

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.

@section 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.

@section Troubleshooting

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

Maybe you didn't install LAME, or got your ./configure statement wrong. Check

the ffmpeg output to see if a line referring 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 ffmpeg.

@subsection The audio and video lose sync after a while.

Yes, they do.

@subsection After a long while, the video update rate goes way down in WMP.

Yes, it does. Who knows why?

@subsection 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].

@section 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.]

@section Tips

* 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.

@section 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.

@section Does the @code{?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 @code{?date=xxxxxx} is fairly flexible. You should use one

of the following formats (the 'T' is literal):

@example

* YYYY-MM-DDTHH:MM:SS     (localtime)

* YYYY-MM-DDTHH:MM:SSZ    (UTC)

@end example

You can omit the YYYY-MM-DD, and then it refers to the current day. However

note that @samp{?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:   @samp{http://localhost:8080/test.asf?date=2002-07-26T23:05:00}.

@c man end

@section What is FFM, FFM2

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.

@chapter Options

@c man begin OPTIONS

@include fftools-common-opts.texi

@section Main options

@table @option

@item -f @var{configfile}

Use @file{configfile} instead of @file{/etc/ffserver.conf}.

@item -n

Enable no-launch mode. This option disables all the Launch directives

within the various  sections. Since ffserver will not launch

any ffmpeg instances, you will have to launch them manually.

@item -d

Enable debug mode. This option increases log verbosity, directs log

messages to stdout.

@end table

@c man end

@include config.texi

@ifset config-all

@ifset config-avutil

@include utils.texi

@end ifset

@ifset config-avcodec

@include codecs.texi

@include bitstream_filters.texi

@end ifset

@ifset config-avformat

@include formats.texi

@include protocols.texi

@end ifset

@ifset config-avdevice

@include devices.texi

@end ifset

@ifset config-swresample

@include resampler.texi

@end ifset

@ifset config-swscale

@include scaler.texi

@end ifset

@ifset config-avfilter

@include filters.texi

@end ifset

@end ifset

@chapter See Also

@ifhtml

@ifset config-all

@url{ffserver.html,ffserver},

@end ifset

@ifset config-not-all

@url{ffserver-all.html,ffserver-all},

@end ifset

the @file{doc/ffserver.conf} example,

@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe},

@url{ffmpeg-utils.html,ffmpeg-utils},

@url{ffmpeg-scaler.html,ffmpeg-scaler},

@url{ffmpeg-resampler.html,ffmpeg-resampler},

@url{ffmpeg-codecs.html,ffmpeg-codecs},

@url{ffmpeg-bitstream-filters.html,ffmpeg-bitstream-filters},

@url{ffmpeg-formats.html,ffmpeg-formats},

@url{ffmpeg-devices.html,ffmpeg-devices},

@url{ffmpeg-protocols.html,ffmpeg-protocols},

@url{ffmpeg-filters.html,ffmpeg-filters}

@end ifhtml

@ifnothtml

@ifset config-all

ffserver(1),

@end ifset

@ifset config-not-all

ffserver-all(1),

@end ifset

the @file{doc/ffserver.conf} example, ffmpeg(1), ffplay(1), ffprobe(1),

ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1),

ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1),

ffmpeg-devices(1), ffmpeg-protocols(1), ffmpeg-filters(1)

@end ifnothtml

@include authors.texi

@ignore

@setfilename ffserver

@settitle ffserver video server

@end ignore

@bye