RTSP keeplive & video/audio freezing (incl. patch to fix this)

[Bernie Hoeneisen]

Binary package hint: vlc

Description
--------------

Some (badly behaving) servers stop sending media streams after a short while and the user experiences a freeze in video and audio.

If an RTSP server does not advertise GET_PARAMETER in its Public Header Field of the OPTIONS response, VLC does not send GET_PARAMETER requests as keepalives (as it used to in earlier releases). As a consequence, some badly behaving servers, such as [WMServer/9.1.1.3814], stop sending media streams after a while.

This behavior of VLC is not wrong, but rather unfortunate for those users who want to view streams originating from badly behaving servers.

  Release: lucid
  Installed: vlc-1.0.6-1ubuntu1.1
  Source Package: vlc-1.0.6

References:
  http://forum.videolan.org/viewtopic.php?f=2&t=75843&p=261097#p261097

Patch
-------

I have included a patch that adds a configuration option to enforce sending GET_PARAMETER for keep-alive, if the user explicitly wants this.

This is a workaround for RTSP servers that are badly behaving (i.e. they do not inform that they need GET_PARAMETER requests for keep-alive, but stop the media stream after a short time if they do not get GET_PARAMETER requests :-( ).

After applying the patch, you can find the new setting on:
Tools -> Preferences -> [Show Settings: All] -> Input / Codes -> Demuxers -> RTP/RTSP -> [Always send GET_PARAMETER for keep-alive]
or, alternately, add the following lines to your "vlcrc" config file (on Ubuntu this config file is: ~/.config/vlc/vlcrc ).

    # Always send GET_PARAMETER for keep-alive (boolean)
    rtsp-force-get-param=1

cheers,
 Bernie Hoeneisen

--

http://ucom.ch/
Tech Consulting for Internet Standardization

[Rémi Denis-Courmont (rdenis)]

The VideoLAN project is NOT endorsing this patch.

[Adam Guthrie (therigu)]

Marking as patch-rejected-upstream due to Rémi's comments in linked forum thread:

I thought I made myself clear but to reiterate:
1/ No, we won't add an option for this. There are already enough obscure options in VLC, including in the RTSP stack. This does not solve the problem in any meaningful way. One in a million user would know to use that option to work around a broken RTSP server.
2/ The bug is in the RTSP server. The fix belongs in the RTSP server. The VideoLAN project has enough of its own bugs to cope with.
3/ For servers that don't support GET_PARAMETER (or pretend not to), VLC or rather liblive555 also sends RTCP-RR. So there is no excuse for RTSP server to time out VLC-based clients.

Open-source is not a synonym for working around bug in proprietary software. Quite the opposite - those who make money from their software have no excuse not to fix their bugs.

[Bernie Hoeneisen (bhoeneis)]

I am glad to see that in the meantime this problem has been addressed upstream and is resolved in Maverick.

To get rid of the described freezing-effect, set the parameter "WMServer RTSP dialect" as follows:
- Goto Tools - Preferences [or Ctrl-P]
- Set "Show settings" to "All" (in the lower left corner)
- Goto Input/Codecs - Demuxers - RTP/RTSP (left side)
- Check the box for "WMServer RTSP dialect"

Thanks a lot to the developers of vlc to take care about this.

cheers
 Bernie

[Bernie Hoeneisen (bhoeneis)]

Please close this bug as the problem has been fixed upstream.