[libav.git] / doc / HOWTO-STREAM
1 The FFserver streaming HOWTO
2 ----------------------------
4 Philip Gladstone <philip-ffserver@gladstonefamily.net>
5 Last updated: May 8, 2002
7 0. What is this HOWTO about?
9 This covers only the streaming aspects of ffserver / ffmpeg. All questions about
10 parameters for ffmpeg, codec questions, etc. are not covered here.
12 You should also read the ffserver.txt file in this directory. It contains
13 roughly the same information.
15 1. What can this do?
17 When properly configured and running, you can capture video and audio in real
18 time from a suitable capture card, and stream it out over the Internet to
19 either Windows Media Player or RealAudio player (with some restrictions).
21 It can also stream from files, though that is currently broken. Very often, a
22 web server can be used to serve up the files just as well.
24 2. What do I need?
26 I use Linux on a 900MHz Duron with a cheapo Bt848 based TV capture card. I'm
27 using stock linux 2.4.17 with the stock drivers. [Actually that isn't true,
28 I needed some special drivers from my motherboard based sound card.]
30 I understand that FreeBSD systems work just fine as well.
32 3. How do I make it work?
34 First, build the kit. It *really* helps to have installed LAME first. Then when
35 you run the ffserver ./configure, make sure that you have the --enable-mp3lame
36 flag turned on.
38 LAME is important as it allows streaming of audio to Windows Media Player. Don't
39 ask why the other audio types do not work.
41 As a simple test, just run the following two command lines:
43 ./ffserver -f doc/ffserver.conf &
44 ./ffmpeg http://localhost:8090/feed1.ffm
46 At this point you should be able to go to your windows machine and fire up
47 Windows Media Player (WMP). Go to Open URL and enter
49 http://<linuxbox>:8090/test.asf
51 You should see (after a short delay) video and hear audio.
53 4. What happens next?
55 You should edit the ffserver.conf file to suit your needs (in terms of
56 frame rates etc). Then install ffserver and ffmpeg, write a script to start
57 them up, and off you go.
59 5. Troubleshooting
61 * I don't hear any audio, but video is fine
63 Maybe you didn't install LAME, or get your ./configure statement right. Check
64 the ffmpeg output to see if a line referring to mp3 is present. If not, then
65 your configuration was incorrect. If it is, then maybe your wiring is not
66 setup correctly. Maybe the sound card is not getting data from the right
67 input source. Maybe you have a really awful audio interface (like I do)
68 that only captures in stereo and also requires that one channel be flipped.
69 If you are one of these people, then export 'AUDIO_FLIP_LEFT=1' before
70 starting ffmpeg.
72 * The audio and video loose sync after a while.
74 Yes, they do.
76 * After a long while, the video update rate goes way down in WMP.
78 Yes, it does. Who knows why?
80 6. What else can it do?
82 There seems to be a bunch of code that allows you to replay previous
83 video. I've never tried it, so it probably doesn't work properly. YMMV.
84 In fact, in order to get some level of stability, ffserver now deletes
85 all the previously sent video whenever it restarts.
87 You can fiddle with many of the codec choices and encoding parameters, and
88 there are a bunch more parameters that you cannot control. Post a message
89 to the mailing list if there are some 'must have' parameters. Look in the
90 ffserver.conf for a list of the currently available controls.
92 7. Tips
94 * When you connect to a live stream, most players (WMP, RA etc) want to
95 buffer a certain number of seconds of material so that they can display the
96 signal continuously. However, ffserver (by default) starts sending data
97 in real time. This means that there is a pause of a few seconds while the
98 buffering is being done by the player. The good news is that this can be
99 cured by adding a '?buffer=5' to the end of the URL. This says that the
100 stream should start 5 seconds in the past -- and so the first 5 seconds
101 of the stream is sent as fast as the network will allow. It will then
102 slow down to real time. This noticeably improves the startup experience.