ffserver.texi 9.6 KB

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