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Home > Archive > Voice over IP Cisco > May 2006 > Creating PCM samples??
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Creating PCM samples??
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| Tim Reimers 2006-05-29, 4:57 pm |
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Anyone got any clue on how to set the zero crossings and the number of
samples to be divisible by 240??
CCMstuff. org and cisco say to do that..
I've created a steelpan ringer, and the phone plays it, but it's all
distorted--
Sounds as if I've violated one of the rules regarding the PCM file.
I followed the instructions of 8k samples, 8 bit..pcm ulaw format...
I guess it's the number of samples or something, or not divisible by
240...
I have no idea how to do that last in Audacity or in Sound Recorder...
Not sure what to do from here....
Thanks, Tim
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| Ryan Ratliff 2006-05-29, 4:57 pm |
| These are the specs:
=95Raw PCM (no header)
=958000 samples per second
=958 bits per sample
=95ulaw compression
=95Maximum ring size=9716080 samples
=95Minimum ring size=97240 samples
=95Number of samples in the ring evenly divisible by 240
=95Ring starts and ends at the zero crossing.
So if you've got 8000 samples per second and your total number of =
samples needs to be evenly divisible by 240 then to keep the math =
simple make the total length of the ringer some increment of 1.5 =
seconds. Of course the max ring size allows for a 2.01 second ring =
file at 16080 samples.
As for the zero crossing I have no idea what that means. Maybe just =
that the beginning and end of the audio has 0 amplitude (ie silent)?
HTH,
-Ryan
On May 26, 2006, at 12:11 PM, Tim Reimers wrote:
Anyone got any clue on how to set the zero crossings and the number =
of samples to be divisible by 240??
CCMstuff. org and cisco say to do that..
I've created a steelpan ringer, and the phone plays it, but it's all =
distorted--
Sounds as if I've violated one of the rules regarding the PCM file.
I followed the instructions of 8k samples, 8 bit..pcm ulaw format=85
I guess it's the number of samples or something, or not divisible by =
240=85
I have no idea how to do that last in Audacity or in Sound Recorder...
Not sure what to do from here=85.
Thanks, Tim
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