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Re: Re : [Linphone-developers] grandstream gxv3000

From: Kelvin Chua
Subject: Re: Re : [Linphone-developers] grandstream gxv3000
Date: Tue, 2 Feb 2010 22:58:11 +0800

i have written an application where i used sip to stream h264 320x240 videos to grandstreams one-way, it's a VOD-type application. and it works. so i don't think it has something to do with 
the video size. i think the problem is more of the x264 encoding side. i wonder if there is a 
way for linphone to show me the NAL headers, that way i can check whether the NAL types
are within the 1-23 range and the F-bit 0. i have seen some instances where x264 could chew
up NAL units with the F bit always set to 1 and i suspect gxv does not like this.

Kelvin Chua

On Tue, Feb 2, 2010 at 10:48 PM, Aurelien Bouin <address@hidden> wrote:
I have been testing with a GXV3140 Grandstream and I figured out that the grandstream encoding format was 320x240 which could be the problem, I am not sure but I feel like linphone cannot handle it ... ???But if not we should try to find a solution...

Aurelien BOUIN

--- En date de : Mar 2.2.10, Kelvin Chua <address@hidden> a écrit :

De: Kelvin Chua <address@hidden>
Objet: [Linphone-developers] grandstream gxv3000
À: address@hidden
Date: Mardi 2 Février 2010, 15h23

been trying to do some interop with grandstream gxv3000.
i know for a fact that the h263 stack of grandstream is very poor. so i am using h.264 for my tests.
compiled everything from source, ffmpeg, x264, linphone. msx264 plugin already shows up in linphone, both for packetization=1
and another one with blank parameters which i assume to be packetization=0.

source code versions are as follows:
x264 core:83 r1400 20fa784
ffmpeg r21566
libswscale r29972

don't know if it matters, my OS is karmic koala

so anyway, i was looking at the code and trying to figure out, why linphone shows the h.264 video streaming from gxv but gxv
does not show the video from linphone. i was speculating that the x264 plugin is not working in single NALU mode as defined in the
RFC or packetization=0.
i then stumbled into the parameter in msx264.c which sets  params.i_slice_max_size=ms_get_payload_max_size()-100;
so that means, a slice is being fitted into 100 less than the MTU which is correct for single NALU mode. i then fired up wireshark 
and was surprised to see no video packets coming from linphone to gxv :( only the 2-way g.711 and the h.264 stream from gxv.

i think this all boils down to x264. i wonder what x264 revision you guys are using in your tests?

Kelvin Chua

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