[Freeswitch-users] Sample rate and recordFile

[Mathieu Rene]

Most calls are at 8kHz. The formula for bandwidth is sampling rate *  
bit rate * channels, so 8000 * 8 * 1 = 64000 = 64kbps (per way).

Math

On 18-Jun-09, at 1:01 PM, Andy wrote:

> Thanks Brian,
>
> So, just to calrify will the base call always be 8kHz?
>
> On a related note, do you happen to know the bitrate of each open  
> channel/live call? Is it 16 kilobits per second like the recorded  
> audio? I need to do some calculations on the badwidth required to  
> handle a certain number of concurrent calls.
>
> Many thanks
> Andy
>
> From: freeswitch-users-bounces at lists.freeswitch.org [mailto:freeswitch-users-bounces at lists.freeswitch.org 
> ] On Behalf Of Brian West
> Sent: 18 June 2009 18:11
> To: freeswitch-users at lists.freeswitch.org
> Subject: Re: [Freeswitch-users] Sample rate and recordFile
>
>
> On Jun 18, 2009, at 11:54 AM, Andy wrote:
>
>> 1) I notice that when I change the sample rate it automatically  
>> changes the bit rate too. I understand why this is the case but  
>> wondered if it was just as easy to be able to control the bitrate  
>> as well as the sample rate.
>
> If you're talking about mod_shout, NO.  You'll end up picking an  
> invalid bitrate and asking why it doesn't work... been there done  
> that... I changed it a few months back to pick the optimal bitrate  
> for the sample rate.
>
>> 2) When I use a sample rate other than 8000 I get a warning 'Sample  
>> rate doesn't match'. I guess this puts some extra load on the  
>> server. If all my calls are being recorded and all at 11025 can/ 
>> should I alter the sample rate of the base call to 11025?
>
> NO.  Your phone call is running at 8kHz, Your sound file is 11025  
> and they don't match, If you were to play this file into an 8k  
> channel without a resample it would sound a little like satan.  or a  
> dragging tape deck.  The file has to be resampled to match the  
> current session rate.
>
> /b
>
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