I use IVR menu. In my IVR menu i want use some sound files for question (For sales press 1, for support press 2, …). Which sound format you prefer for ivr (wav, ulaw, alaw, gsm, …)? and why?
I prefer all formats I use for calls, cause * won’t have to do any codec translation for the IVR on runtime.
All the formats that can be selected as codecs for a call. However the cost of converting wav to G.711 (A-law or μ-law) is negligible, so wav is sufficient if those are the only codecs usable. Converting to gsm is relatively expensive, as is converting to G.729, so you should provide variants in those formats if your calls can use them.
(slin has the same costs as wav. Note that, in Asterisk, wav is not the same as WAV. The latter has the same relation to gsm as wav has to slin.)
For most commonly used codecs, and certainly if the PSTN is involved, wav (slin) will not result in any unnecessary degradation of the sound quality as a result of transcoding.
If multiple codec choices are possible, it might be the case that the cost of page faults exceeds the cost of algrorithmically converting between formats.
In other words, the optimum choice depends on information that you haven’t told us.
can i put only Wav format? And asterisk self convert it to corresponding codec?
Other i can record WAV format then with sox i can convert it to all another formats. it can be?
For Asterisk wav is not the same as WAV, and Wav doesn’t exist.
Asterisk will convert on the fly if it can find a sequence of installed transcoders that will get from one format to the other. If it can’t get from wav, you will not here any tones generated by Asterisk (although for SIP, most come from the phone). Quite a few people use G.729 codecs but without a transcoding path from wav, to avoid licence fees.