1 \input texinfo @c -*- texinfo -*-
3 @settitle avserver Documentation
5 @center @titlefont{avserver Documentation}
14 The generic syntax is:
23 @c man begin DESCRIPTION
25 WARNING: avserver is unmaintained, largely broken and in need of a
26 complete rewrite. It probably won't work for you. Use at your own
29 avserver is a streaming server for both audio and video. It supports
30 several live feeds, streaming from files and time shifting on live feeds
31 (you can seek to positions in the past on each live feed, provided you
32 specify a big enough feed storage in avserver.conf).
34 avserver runs in daemon mode by default; that is, it puts itself in
35 the background and detaches from its TTY, unless it is launched in
36 debug mode or a NoDaemon option is specified in the configuration
39 This documentation covers only the streaming aspects of avserver /
40 avconv. All questions about parameters for avconv, codec questions,
41 etc. are not covered here. Read @file{avconv.html} for more
44 @section How does it work?
46 avserver receives prerecorded files or FFM streams from some avconv
47 instance as input, then streams them over RTP/RTSP/HTTP.
49 An avserver instance will listen on some port as specified in the
50 configuration file. You can launch one or more instances of avconv and
51 send one or more FFM streams to the port where avserver is expecting
52 to receive them. Alternately, you can make avserver launch such avconv
55 Input streams are called feeds, and each one is specified by a <Feed>
56 section in the configuration file.
58 For each feed you can have different output streams in various
59 formats, each one specified by a <Stream> section in the configuration
62 @section Status stream
64 avserver supports an HTTP interface which exposes the current status
67 Simply point your browser to the address of the special status stream
68 specified in the configuration file.
70 For example if you have:
75 # Only allow local people to get the status
77 ACL allow 192.168.0.0 192.168.255.255
81 then the server will post a page with the status information when
82 the special stream @file{status.html} is requested.
84 @section What can this do?
86 When properly configured and running, you can capture video and audio in real
87 time from a suitable capture card, and stream it out over the Internet to
88 either Windows Media Player or RealAudio player (with some restrictions).
90 It can also stream from files, though that is currently broken. Very often, a
91 web server can be used to serve up the files just as well.
93 It can stream prerecorded video from .ffm files, though it is somewhat tricky
94 to make it work correctly.
96 @section What do I need?
98 I use Linux on a 900 MHz Duron with a cheapo Bt848 based TV capture card. I'm
99 using stock Linux 2.4.17 with the stock drivers. [Actually that isn't true,
100 I needed some special drivers for my motherboard-based sound card.]
102 I understand that FreeBSD systems work just fine as well.
104 @section How do I make it work?
106 First, build the kit. It *really* helps to have installed LAME first. Then when
107 you run the avserver ./configure, make sure that you have the
108 @code{--enable-libmp3lame} flag turned on.
110 LAME is important as it allows for streaming audio to Windows Media Player.
111 Don't ask why the other audio types do not work.
113 As a simple test, just run the following two command lines where INPUTFILE
114 is some file which you can decode with avconv:
117 ./avserver -f doc/avserver.conf &
118 ./avconv -i INPUTFILE http://localhost:8090/feed1.ffm
121 At this point you should be able to go to your Windows machine and fire up
122 Windows Media Player (WMP). Go to Open URL and enter
125 http://<linuxbox>:8090/test.asf
128 You should (after a short delay) see video and hear audio.
130 WARNING: trying to stream test1.mpg doesn't work with WMP as it tries to
131 transfer the entire file before starting to play.
132 The same is true of AVI files.
134 @section What happens next?
136 You should edit the avserver.conf file to suit your needs (in terms of
137 frame rates etc). Then install avserver and avconv, write a script to start
138 them up, and off you go.
140 @section Troubleshooting
142 @subsection I don't hear any audio, but video is fine.
144 Maybe you didn't install LAME, or got your ./configure statement wrong. Check
145 the avconv output to see if a line referring to MP3 is present. If not, then
146 your configuration was incorrect. If it is, then maybe your wiring is not
147 set up correctly. Maybe the sound card is not getting data from the right
148 input source. Maybe you have a really awful audio interface (like I do)
149 that only captures in stereo and also requires that one channel be flipped.
150 If you are one of these people, then export 'AUDIO_FLIP_LEFT=1' before
153 @subsection The audio and video loose sync after a while.
157 @subsection After a long while, the video update rate goes way down in WMP.
159 Yes, it does. Who knows why?
161 @subsection WMP 6.4 behaves differently to WMP 7.
163 Yes, it does. Any thoughts on this would be gratefully received. These
164 differences extend to embedding WMP into a web page. [There are two
165 object IDs that you can use: The old one, which does not play well, and
166 the new one, which does (both tested on the same system). However,
167 I suspect that the new one is not available unless you have installed WMP 7].
169 @section What else can it do?
171 You can replay video from .ffm files that was recorded earlier.
172 However, there are a number of caveats, including the fact that the
173 avserver parameters must match the original parameters used to record the
174 file. If they do not, then avserver deletes the file before recording into it.
175 (Now that I write this, it seems broken).
177 You can fiddle with many of the codec choices and encoding parameters, and
178 there are a bunch more parameters that you cannot control. Post a message
179 to the mailing list if there are some 'must have' parameters. Look in
180 avserver.conf for a list of the currently available controls.
182 It will automatically generate the ASX or RAM files that are often used
183 in browsers. These files are actually redirections to the underlying ASF
184 or RM file. The reason for this is that the browser often fetches the
185 entire file before starting up the external viewer. The redirection files
186 are very small and can be transferred quickly. [The stream itself is
187 often 'infinite' and thus the browser tries to download it and never
192 * When you connect to a live stream, most players (WMP, RA, etc) want to
193 buffer a certain number of seconds of material so that they can display the
194 signal continuously. However, avserver (by default) starts sending data
195 in realtime. This means that there is a pause of a few seconds while the
196 buffering is being done by the player. The good news is that this can be
197 cured by adding a '?buffer=5' to the end of the URL. This means that the
198 stream should start 5 seconds in the past -- and so the first 5 seconds
199 of the stream are sent as fast as the network will allow. It will then
200 slow down to real time. This noticeably improves the startup experience.
202 You can also add a 'Preroll 15' statement into the avserver.conf that will
203 add the 15 second prebuffering on all requests that do not otherwise
204 specify a time. In addition, avserver will skip frames until a key_frame
205 is found. This further reduces the startup delay by not transferring data
206 that will be discarded.
208 * You may want to adjust the MaxBandwidth in the avserver.conf to limit
209 the amount of bandwidth consumed by live streams.
211 @section Why does the ?buffer / Preroll stop working after a time?
213 It turns out that (on my machine at least) the number of frames successfully
214 grabbed is marginally less than the number that ought to be grabbed. This
215 means that the timestamp in the encoded data stream gets behind realtime.
216 This means that if you say 'Preroll 10', then when the stream gets 10
217 or more seconds behind, there is no Preroll left.
219 Fixing this requires a change in the internals of how timestamps are
222 @section Does the @code{?date=} stuff work.
224 Yes (subject to the limitation outlined above). Also note that whenever you
225 start avserver, it deletes the ffm file (if any parameters have changed),
226 thus wiping out what you had recorded before.
228 The format of the @code{?date=xxxxxx} is fairly flexible. You should use one
229 of the following formats (the 'T' is literal):
232 * YYYY-MM-DDTHH:MM:SS (localtime)
233 * YYYY-MM-DDTHH:MM:SSZ (UTC)
236 You can omit the YYYY-MM-DD, and then it refers to the current day. However
237 note that @samp{?date=16:00:00} refers to 16:00 on the current day -- this
238 may be in the future and so is unlikely to be useful.
240 You use this by adding the ?date= to the end of the URL for the stream.
241 For example: @samp{http://localhost:8080/test.asf?date=2002-07-26T23:05:00}.
247 @include avtools-common-opts.texi
249 @section Main options
252 @item -f @var{configfile}
253 Use @file{configfile} instead of @file{/etc/avserver.conf}.
255 Enable no-launch mode. This option disables all the Launch directives
256 within the various <Stream> sections. Since avserver will not launch
257 any avconv instances, you will have to launch them manually.
259 Enable debug mode. This option increases log verbosity, directs log
260 messages to stdout and causes avserver to run in the foreground
261 rather than as a daemon.
267 @setfilename avserver
268 @settitle avserver video server
272 avconv(1), avplay(1), avprobe(1), the @file{avserver.conf}
273 example and the Libav HTML documentation