Which audio format take less CPU resource?

Hi all friends,
I am using FreePBX with a lot of custom prompts in wav format. I want to save CPU resource for call processing instead of waste too much CPU for playing audio prompts. I see some audio format such as: wav, ulaw, gsm … . My question is "which audio format that CPU spends less time and power to play?"
Greatly appreciate your help!

Transcoding places the highest load on the CPU. Use the format that matches the CODEC you are using on your trunks and endpoints.

Thanks SkyingOH,
I’m new to Asterisk. I’m using FreePBX in AsteriskNOW. Could you please show me how to check the CODEC and its details about format thing?
Thank you so much!

No I can’t because it’s not just one command. You need to check your extensions and trunks then make sure your custom recordings and system recordings match. FreePBX only installs wav and sln by default (I think). However if you look in the Asterisk packages there are system sounds in many formats.

Is you system so busy that you have a CPU resource issue?

"Is you system so busy that you have a CPU resource issue? "
Thank you so much for this question. I got a big issue with CPU resource (I think).
My system are:

  • Intel Celeron G530 2.40 GHz, 2M Cache, Dual Core (65W)
  • 4G DDR2 Memory.
  • AsteriskNOW distro
  • All coming calls are from SIP external and out going calls are out side of local (I have no extensions registered to Asterisk)
  • Recording all calls

The big issue is that when there are more than 10 calls, the system get very very slow to process a call and calling parties are waiting too long so they hang up phones before called parties pick up phones.
I thought that one of the reason of the issue is I have a lot of wav format prompts which cause the CPU gets slow when playing the audio files. Is that right, SkyingOH? Please correct me if I was wrong and advise me for solving this big issue!
Really appreciate your help

How many concurrent calls do you have? 10 calls should not be an issue.

Have you looked at the CPU utilization with top when this is occurring?

Yes, If there are 10 current calls (20 people are talking), the system is getting slow.
In that situation, sometimes, the CPU goes up to 80-100% when there is a call coming then it goes down to about 10%; and memory is still about 20% (according to FreePBX status) , but if I used command TOP to check the Memory, it shows only 6-7M left on the system.
Thank you!