Add APIchanges entry for the libavcore/imgutils.h addition.
[libav.git] / doc / ffserver-doc.texi
1 \input texinfo @c -*- texinfo -*-
3 @settitle FFserver Documentation
4 @titlepage
5 @sp 7
6 @center @titlefont{FFserver Documentation}
7 @sp 3
8 @end titlepage
10 @chapter Synopsys
12 The generic syntax is:
14 @example
15 @c man begin SYNOPSIS
16 ffserver [options]
17 @c man end
18 @end example
20 @chapter Description
21 @c man begin DESCRIPTION
23 FFserver is a streaming server for both audio and video. It supports
24 several live feeds, streaming from files and time shifting on live feeds
25 (you can seek to positions in the past on each live feed, provided you
26 specify a big enough feed storage in ffserver.conf).
28 FFserver runs in daemon mode by default; that is, it puts itself in
29 the background and detaches from its TTY, unless it is launched in
30 debug mode or a NoDaemon option is specified in the configuration
31 file.
33 This documentation covers only the streaming aspects of ffserver /
34 ffmpeg. All questions about parameters for ffmpeg, codec questions,
35 etc. are not covered here. Read @file{ffmpeg-doc.html} for more
36 information.
38 @section How does it work?
40 FFserver receives prerecorded files or FFM streams from some ffmpeg
41 instance as input, then streams them over RTP/RTSP/HTTP.
43 An ffserver instance will listen on some port as specified in the
44 configuration file. You can launch one or more instances of ffmpeg and
45 send one or more FFM streams to the port where ffserver is expecting
46 to receive them. Alternately, you can make ffserver launch such ffmpeg
47 instances at startup.
49 Input streams are called feeds, and each one is specified by a <Feed>
50 section in the configuration file.
52 For each feed you can have different output streams in various
53 formats, each one specified by a <Stream> section in the configuration
54 file.
56 @section Status stream
58 FFserver supports an HTTP interface which exposes the current status
59 of the server.
61 Simply point your browser to the address of the special status stream
62 specified in the configuration file.
64 For example if you have:
65 @example
66 <Stream status.html>
67 Format status
69 # Only allow local people to get the status
70 ACL allow localhost
71 ACL allow
72 </Stream>
73 @end example
75 then the server will post a page with the status information when
76 the special stream @file{status.html} is requested.
78 @section What can this do?
80 When properly configured and running, you can capture video and audio in real
81 time from a suitable capture card, and stream it out over the Internet to
82 either Windows Media Player or RealAudio player (with some restrictions).
84 It can also stream from files, though that is currently broken. Very often, a
85 web server can be used to serve up the files just as well.
87 It can stream prerecorded video from .ffm files, though it is somewhat tricky
88 to make it work correctly.
90 @section What do I need?
92 I use Linux on a 900 MHz Duron with a cheapo Bt848 based TV capture card. I'm
93 using stock Linux 2.4.17 with the stock drivers. [Actually that isn't true,
94 I needed some special drivers for my motherboard-based sound card.]
96 I understand that FreeBSD systems work just fine as well.
98 @section How do I make it work?
100 First, build the kit. It *really* helps to have installed LAME first. Then when
101 you run the ffserver ./configure, make sure that you have the
102 @code{--enable-libmp3lame} flag turned on.
104 LAME is important as it allows for streaming audio to Windows Media Player.
105 Don't ask why the other audio types do not work.
107 As a simple test, just run the following two command lines where INPUTFILE
108 is some file which you can decode with ffmpeg:
110 @example
111 ./ffserver -f doc/ffserver.conf &
112 ./ffmpeg -i INPUTFILE http://localhost:8090/feed1.ffm
113 @end example
115 At this point you should be able to go to your Windows machine and fire up
116 Windows Media Player (WMP). Go to Open URL and enter
118 @example
119 http://<linuxbox>:8090/test.asf
120 @end example
122 You should (after a short delay) see video and hear audio.
124 WARNING: trying to stream test1.mpg doesn't work with WMP as it tries to
125 transfer the entire file before starting to play.
126 The same is true of AVI files.
128 @section What happens next?
130 You should edit the ffserver.conf file to suit your needs (in terms of
131 frame rates etc). Then install ffserver and ffmpeg, write a script to start
132 them up, and off you go.
134 @section Troubleshooting
136 @subsection I don't hear any audio, but video is fine.
138 Maybe you didn't install LAME, or got your ./configure statement wrong. Check
139 the ffmpeg output to see if a line referring to MP3 is present. If not, then
140 your configuration was incorrect. If it is, then maybe your wiring is not
141 set up correctly. Maybe the sound card is not getting data from the right
142 input source. Maybe you have a really awful audio interface (like I do)
143 that only captures in stereo and also requires that one channel be flipped.
144 If you are one of these people, then export 'AUDIO_FLIP_LEFT=1' before
145 starting ffmpeg.
147 @subsection The audio and video loose sync after a while.
149 Yes, they do.
151 @subsection After a long while, the video update rate goes way down in WMP.
153 Yes, it does. Who knows why?
155 @subsection WMP 6.4 behaves differently to WMP 7.
157 Yes, it does. Any thoughts on this would be gratefully received. These
158 differences extend to embedding WMP into a web page. [There are two
159 object IDs that you can use: The old one, which does not play well, and
160 the new one, which does (both tested on the same system). However,
161 I suspect that the new one is not available unless you have installed WMP 7].
163 @section What else can it do?
165 You can replay video from .ffm files that was recorded earlier.
166 However, there are a number of caveats, including the fact that the
167 ffserver parameters must match the original parameters used to record the
168 file. If they do not, then ffserver deletes the file before recording into it.
169 (Now that I write this, it seems broken).
171 You can fiddle with many of the codec choices and encoding parameters, and
172 there are a bunch more parameters that you cannot control. Post a message
173 to the mailing list if there are some 'must have' parameters. Look in
174 ffserver.conf for a list of the currently available controls.
176 It will automatically generate the ASX or RAM files that are often used
177 in browsers. These files are actually redirections to the underlying ASF
178 or RM file. The reason for this is that the browser often fetches the
179 entire file before starting up the external viewer. The redirection files
180 are very small and can be transferred quickly. [The stream itself is
181 often 'infinite' and thus the browser tries to download it and never
182 finishes.]
184 @section Tips
186 * When you connect to a live stream, most players (WMP, RA, etc) want to
187 buffer a certain number of seconds of material so that they can display the
188 signal continuously. However, ffserver (by default) starts sending data
189 in realtime. This means that there is a pause of a few seconds while the
190 buffering is being done by the player. The good news is that this can be
191 cured by adding a '?buffer=5' to the end of the URL. This means that the
192 stream should start 5 seconds in the past -- and so the first 5 seconds
193 of the stream are sent as fast as the network will allow. It will then
194 slow down to real time. This noticeably improves the startup experience.
196 You can also add a 'Preroll 15' statement into the ffserver.conf that will
197 add the 15 second prebuffering on all requests that do not otherwise
198 specify a time. In addition, ffserver will skip frames until a key_frame
199 is found. This further reduces the startup delay by not transferring data
200 that will be discarded.
202 * You may want to adjust the MaxBandwidth in the ffserver.conf to limit
203 the amount of bandwidth consumed by live streams.
205 @section Why does the ?buffer / Preroll stop working after a time?
207 It turns out that (on my machine at least) the number of frames successfully
208 grabbed is marginally less than the number that ought to be grabbed. This
209 means that the timestamp in the encoded data stream gets behind realtime.
210 This means that if you say 'Preroll 10', then when the stream gets 10
211 or more seconds behind, there is no Preroll left.
213 Fixing this requires a change in the internals of how timestamps are
214 handled.
216 @section Does the @code{?date=} stuff work.
218 Yes (subject to the limitation outlined above). Also note that whenever you
219 start ffserver, it deletes the ffm file (if any parameters have changed),
220 thus wiping out what you had recorded before.
222 The format of the @code{?date=xxxxxx} is fairly flexible. You should use one
223 of the following formats (the 'T' is literal):
225 @example
226 * YYYY-MM-DDTHH:MM:SS (localtime)
228 @end example
230 You can omit the YYYY-MM-DD, and then it refers to the current day. However
231 note that @samp{?date=16:00:00} refers to 16:00 on the current day -- this
232 may be in the future and so is unlikely to be useful.
234 You use this by adding the ?date= to the end of the URL for the stream.
235 For example: @samp{http://localhost:8080/test.asf?date=2002-07-26T23:05:00}.
236 @c man end
238 @chapter Options
239 @c man begin OPTIONS
241 @include fftools-common-opts.texi
243 @section Main options
245 @table @option
246 @item -f @var{configfile}
247 Use @file{configfile} instead of @file{/etc/ffserver.conf}.
248 @item -n
249 Enable no-launch mode. This option disables all the Launch directives
250 within the various <Stream> sections. FFserver will not launch any
251 ffmpeg instance, so you will have to launch them manually.
252 @item -d
253 Enable debug mode. This option increases log verbosity, directs log
254 messages to stdout and causes ffserver to run in the foreground
255 rather than as a daemon.
256 @end table
257 @c man end
259 @ignore
261 @setfilename ffserver
262 @settitle FFserver video server
264 @c man begin SEEALSO
266 ffmpeg(1), ffplay(1), ffprobe(1), the @file{ffmpeg/doc/ffserver.conf}
267 example and the FFmpeg HTML documentation
268 @c man end
270 @c man begin AUTHORS
271 The FFmpeg developers
272 @c man end
274 @end ignore
276 @bye