[Asterisk-Users] Recording Prompts

[Richard Scobie]

The quality may be improved by filtering the original .wav to remove the 
frequencies above 4000Hz, as these will cause distortion due to aliasing 
  (the sox man page has an explanation under the "resample" option).

So, "sox infile.wav -r 8000 outfile.gsm resample -ql" may give a better 
result.

You could also play with the band and bandpass effects to reshape your 
input file before resampling to 8000 - removing the bass end helps 
clarity.

"sox infile.wav outfile.wav bandpass 1950 3000" will apply a 300Hz to 
3300Hz bandpass filter which you can then resample as above.

Hope this helps

Richard

Omar Abhari wrote:
> that is exactly what we used, but still the quality isn't all that. The 
> original wav file sounded good, so it is not that..
> 
> lizardbox
> Mike Reiling wrote:
> 
>> I believe you should use 8000...  Could be wrong though/
>>
>> sox infile.wav -r 8000 outfile.gsm
>>
>> --Mike
>>
>> On Friday, April 11, 2003, at 04:00  PM, David Davis wrote:
>>
>>> I've had luck with changing the sample rate with -r
>>> I think I used 8500 for windows wavs, you may need to mess with it.
>>>
>>> sox infile.wav -r 8500 outfile.gsm
>>>
>>> -----Original Message-----
>>> From: asterisk-users-admin at lists.digium.com
>>> [mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Omar Abhari
>>> Sent: Friday, April 11, 2003 5:10 PM
>>> To: asterisk-users at lists.digium.com
>>> Subject: [Asterisk-Users] Recording Prompts
>>>
>>>
>>>  From everyone's experience, what is the best way to record prompts?
>>>
>>> Last night, we recorded some wav files using a windows machines, and
>>> after conversion to gsm and wav for asterisk on our redhat box, the
>>> quality simply sucked. we used "sox" to do the conversion..
>>>
>>> any tips on achieving a better quality?
>>>
>>> thanks
>>>
>>> lizardbox
>>>
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>>
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> 
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