[Asterisk-Users] G729 Codec

[Steve Underwood]

Adam Hart wrote:

> Steve Underwood wrote:
>
>> Adam Hart wrote:
>>
>>> Daniel Niasoff wrote:
>>>
>>>> Is G729 more sensitive to packet loss or delays due to it’s higher 
>>>> compression. If I’ve generally got the bandwidth available, am I 
>>>> best sticking to ulaw.
>>>>
>>>
>>> G.729 has lost packet concealment, G.711 doesn't. G.711 will sound 
>>> better otherwise if you can afford the bandwidth.
>>
>>
>>
>> Eh? G.729 has no particular features to allow more effective packet 
>> loss concealment. iLBC has, but at the cost of a substantially higher 
>> bit rate. In fact G.711 is a little ahead of G.729 in the regard, 
>> since packets are completely independant. The smoothing in G.729 
>> means you need the previous packet to decode the current one properly.
>>
>> Regards,
>> Steve
>>
>
> I believe you're mistaken - G.729 works similar to iLBC and speex. 
> iLBC works better as the packets are independent but G.729 still has a 
> function for packet loss concealment.
>
> prehaps have a look at http://www.speex.org/comparison.html
>
It would probably help if you understood what that table means. It is 
very misleading. G.729 has features to mitigate the awfulness of a lost 
packet. It has nothing to help conceal lost packets really well. What I 
said is correct. If you fudge over a lost G.711 packet it has less bad 
effect than fudging over a lost G.729 packet. There is no missing 
smoothing data, so at least the packets you have are handled properly.

Regards,
Steve