[h323plus] ask for help about H264 PLUGIN in H323Plus

Simon Horne s.horne at packetizer.com
Wed Feb 24 04:49:14 EST 2010


There has been 2 major stumbling block to getting X264 "Real Time" friendly
and usable with h323plus. 
1. NAL Size (NAL must not exceed the UDP MTU size (about 1200bits)) Fixed as
of X264 v80.
2. X264 buffering caused up to 5 sec delay encoding images. Fixed as of X264

With these changes in X264. I have just checked in the CVS an updated H.264
plugin. You can build it on linux, windows (mingw and vs2008, X264 must be
done with mingw)  

Check out the h323plus CVS Head and the plugins should now come with it.

Some comments.
You must compile against X264 80+ as the single NAL support required is only
available from version 80 onwards. Use X264 with care 80 works but there is
a 1.5s latency issue, this has been fixed in the latest code 85 but may
cause problems with some H.323 hardware. The X264 code is still very

The plugin contains definitions up to 1080p however some hardware will try
and send less than expected frame sizes as they deem anything over about
4CIF as a custom size. The custom size code handling is still a work in


-----Original Message-----
From: h323plus-bounces at lists.packetizer.com
[mailto:h323plus-bounces at lists.packetizer.com] On Behalf Of Jan Willamowius
Sent: Monday, 22 February 2010 9:00 PM
To: h323plus at lists.packetizer.com
Subject: Re: [h323plus] ask for help about H264 PLUGIN in H323Plus

Hi Andrew,

there is hardly any documentation available on how the video plugins work.
Also, beware that while audio plugins work pretty much the same as in OPAL,
there are a lot of differences for the video plugins.

You can take a look at the H.323-ffmpeg plugin in the H323Plus CVS to see an
example plugin that delegates the actual encoding to a 3rd party library
(ffmpeg in that case).


andrew wang wrote:
> hi all,
> I'm trying to build h264 plugin, which I think is really tricky. How 
> do you build h264 plugin in h323plus? Could you do me a favor to show 
> the building process? I appreciate very much if you help. :)
> Best regards
> Andrew

Jan Willamowius, jan at willamowius.de, http://www.gnugk.org/

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