[h323plus] H.261 and G.722

Simon Horne s.horne at packetizer.com
Sun Jan 9 05:14:48 EST 2011

Thanks Alessandro

I have made the change to H.261 plugin please check if it ok.

I have also checked into the CVS a working G.722.1(16k) codec. The G.722.1c
(32k) is commented out for now as it has not been properly tested.
You are welcome to test it and report back.


-----Original Message-----
From: h323plus-bounces at lists.packetizer.com
[mailto:h323plus-bounces at lists.packetizer.com] On Behalf Of Alessandro
Sent: Saturday, January 08, 2011 8:20 AM
To: h323plus at lists.packetizer.com
Subject: [h323plus] H.261 and G.722

The H.261 VIC codec does not work with hardware devices like Polycom's. 
The device complains about invalid sbit/ebit values.

The codec resets the sbit to 0 on a new picture, introducing an apparent
discontinuity in the bitstream. However the device expects the bitstream to
be continuos (prev.ebit + this.sbit = 8).

The fix is quite simple: just comment out
H261PixelEncoder::PreIncEncodeSetup() { ... sbit_ = 0; ... } in

The G.722 codec is never initialized. The codec reports a format of
"PCM-16-16kHz" (L16Desc[] in "opal\plugins\audio\G722\g722codec.c")
while the plugin manager only accepts "L16" 
(H323PluginCodecManager::RegisterCodecs() in

Shouldn't the codec report "L16" in the 8 kHz descriptor? Or is there a
deeper issue? Replacing "PCM-16-16kHz" with "L16" enables the decoder but
not the encoder and the decoder doesn't decode anything.

G.722.2 seems to have the same issue.


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