[Asterisk-Dev] codec configuration thoughts

[Brian West]

Ok we want an 8k codec.. why not just default speex to 8k?

bkw

On Wed, 3 Sep 2003, John Todd wrote:

> At 2:37 PM -0400 9/3/03, James Golovich wrote:
> >
> >I've been trying to come up with a way to pass config options to specific
> >codecs (see bug #149) and I haven't run across anything that strikes me as
> >the best way to do it.  So I thought I'd share some of my thoughts and
> >maybe someone else will have some thoughts as well.
> >
> >One idea I had was to allow the setup of codec classes, setup in something
> >like codecs.conf.  Each codec could have a numbered priority, or they
> >could be listed in order of priority.  Hopefully this would make it
> >possible to keep the existing way of handling things, but just add another
> >option.
> >
> >[lowbandwidth]
> >disallow => ulaw
> >disallow => alaw
> >allow => gsm
> >allow => ilbc
> >allow => speex,B8V1a1D1
> >allow => speex,B15
> >
> >The options would hopefully be similar between all codecs, but if its just
> >a string to be passed to the codec then it might make it easy.
> >
> >My hypothetical options:
> >B6 = bitrate of 6kbits/sec (B2, B4, B6, B8, B11, B15, B18, B24 would be
> >valid for speex)
> >v1 = enable variable bit rate
> >a1 = enable average bit rate
> >c2 = set complexity (cpu usage) default is 2 (1-10 is valid)
> >V1 = enable VAD
> >D1 = enable discontinuous transmission
> >p1 = enable perceptual enhancement
> >
> >Then in a user/peers configuration (in iax.conf,sip.conf,etc.) it could
> >have an option like codecclass => lowbandwidth.  In theory there could
> >also be a SetCodecClass application so the class could be changed by
> >extensions.conf
> >
> >I really don't like the way this looks like it would work, but its the
> >best I could come up with.  Hopefully someone will have a better idea
> >about this
> >
> >James
>
>
> This sounds reasonable, though I agree, there must be a "cleaner" way
> of doing it.  However, the different features in each codec does lend
> itself to a tightly locked feature list with each codec name, so
> perhaps this is the best that can be done.
>
> One more option, culled from a message to the users- list came close
> on the heels of your post: the ability to specify the ms per block
> and/or the number of blocks per packet.
>
> b1=blocks per packet (default: 1)
> m2=ms per block, x10 (1=10ms, 2=20ms, etc)
>
> I'm actually working on a rather large message that deals with
> sip.conf and using "include" statements in that configuration file as
> a possible method to make adding customers (and dealing with
> different equipment requirements) more template-based.
>
> Extracting codecs out into their own configuration file and naming
> scheme seems like a good idea to me, since that promises to get
> complex very quickly otherwise.
>
> JT
>
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