\input texinfo @c -*- texinfo -*- @settitle avserver Documentation@titlepage@center @titlefont{avserver Documentation}@end titlepage @top @contents @chapter Synopsys The generic syntax is: @example@c man begin SYNOPSISavserver [options]@c man end@end example @chapter Description@c man begin DESCRIPTION WARNING: avserver is unmaintained, largely broken and in need of acomplete rewrite. It probably won't work for you. Use at your ownrisk. avserver is a streaming server for both audio and video. It supportsseveral live feeds, streaming from files and time shifting on live feeds(you can seek to positions in the past on each live feed, provided youspecify a big enough feed storage in avserver.conf). avserver runs in daemon mode by default; that is, it puts itself inthe background and detaches from its TTY, unless it is launched indebug mode or a NoDaemon option is specified in the configurationfile. This documentation covers only the streaming aspects of avserver /avconv. All questions about parameters for avconv, codec questions,etc. are not covered here. Read @file{avconv.html} for moreinformation. @section How does it work? avserver receives prerecorded files or FFM streams from some avconvinstance as input, then streams them over RTP/RTSP/HTTP. An avserver instance will listen on some port as specified in theconfiguration file. You can launch one or more instances of avconv andsend one or more FFM streams to the port where avserver is expectingto receive them. Alternately, you can make avserver launch such avconvinstances 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 variousformats, each one specified by a <Stream> section in the configurationfile. @section Status stream avserver supports an HTTP interface which exposes the current statusof the server. Simply point your browser to the address of the special status streamspecified in the configuration file. For example if you have:@example<Stream status.html>Format status # Only allow local people to get the statusACL allow localhostACL allow 192.168.0.0 192.168.255.255</Stream>@end example then the server will post a page with the status information whenthe special stream @file{status.html} is requested. @section What can this do? When properly configured and running, you can capture video and audio in realtime from a suitable capture card, and stream it out over the Internet toeither Windows Media Player or RealAudio player (with some restrictions). It can also stream from files, though that is currently broken. Very often, aweb server can be used to serve up the files just as well. It can stream prerecorded video from .ffm files, though it is somewhat trickyto make it work correctly. @section What do I need? I use Linux on a 900 MHz Duron with a cheapo Bt848 based TV capture card. I'musing 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. @section How do I make it work? First, build the kit. It *really* helps to have installed LAME first. Then whenyou run the avserver ./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 INPUTFILEis some file which you can decode with avconv: @example./avserver -f doc/avserver.conf &./avconv -i INPUTFILE http://localhost:8090/feed1.ffm@end example At this point you should be able to go to your Windows machine and fire upWindows Media Player (WMP). Go to Open URL and enter @example    http://<linuxbox>: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 totransfer the entire file before starting to play.The same is true of AVI files. @section What happens next? You should edit the avserver.conf file to suit your needs (in terms offrame rates etc). Then install avserver and avconv, write a script to startthem 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. Checkthe avconv output to see if a line referring to MP3 is present. If not, thenyour configuration was incorrect. If it is, then maybe your wiring is notset up correctly. Maybe the sound card is not getting data from the rightinput 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' beforestarting avconv. @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. Thesedifferences extend to embedding WMP into a web page. [There are twoobject IDs that you can use: The old one, which does not play well, andthe 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 theavserver parameters must match the original parameters used to record thefile. If they do not, then avserver 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, andthere are a bunch more parameters that you cannot control. Post a messageto the mailing list if there are some 'must have' parameters. Look inavserver.conf for a list of the currently available controls. It will automatically generate the ASX or RAM files that are often usedin browsers. These files are actually redirections to the underlying ASFor RM file. The reason for this is that the browser often fetches theentire file before starting up the external viewer. The redirection filesare very small and can be transferred quickly. [The stream itself isoften 'infinite' and thus the browser tries to download it and neverfinishes.] @section Tips * When you connect to a live stream, most players (WMP, RA, etc) want tobuffer a certain number of seconds of material so that they can display thesignal continuously. However, avserver (by default) starts sending datain realtime. This means that there is a pause of a few seconds while thebuffering is being done by the player. The good news is that this can becured by adding a '?buffer=5' to the end of the URL. This means that thestream should start 5 seconds in the past -- and so the first 5 secondsof the stream are sent as fast as the network will allow. It will thenslow down to real time. This noticeably improves the startup experience. You can also add a 'Preroll 15' statement into the avserver.conf that willadd the 15 second prebuffering on all requests that do not otherwisespecify a time. In addition, avserver will skip frames until a key_frameis found. This further reduces the startup delay by not transferring datathat will be discarded. * You may want to adjust the MaxBandwidth in the avserver.conf to limitthe 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 successfullygrabbed is marginally less than the number that ought to be grabbed. Thismeans that the timestamp in the encoded data stream gets behind realtime.This means that if you say 'Preroll 10', then when the stream gets 10or more seconds behind, there is no Preroll left. Fixing this requires a change in the internals of how timestamps arehandled. @section Does the @code{?date=} stuff work. Yes (subject to the limitation outlined above). Also note that whenever youstart avserver, 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 oneof 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. Howevernote that @samp{?date=16:00:00} refers to 16:00 on the current day -- thismay 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 @chapter Options@c man begin OPTIONS @include avtools-common-opts.texi @section Main options @table @option@item -f @var{configfile}Use @file{configfile} instead of @file{/etc/avserver.conf}.@item -nEnable no-launch mode. This option disables all the Launch directiveswithin the various <Stream> sections. Since avserver will not launchany avconv instances, you will have to launch them manually.@item -dEnable debug mode. This option increases log verbosity, directs logmessages to stdout and causes avserver to run in the foregroundrather than as a daemon.@end table@c man end @ignore @setfilename avserver@settitle avserver video server @c man begin SEEALSO avconv(1), avplay(1), avprobe(1), the @file{avserver.conf}example and the Libav HTML documentation@c man end @c man begin AUTHORSThe Libav developers@c man end @end ignore @bye