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