Re: A working SIP Phone for Centos44?

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Patrick wrote:
On Mon, 2007-03-12 at 10:37 +0100, Theo Band wrote:
  
Theo Band wrote:
    
John R Pierce wrote:
      
Leonardo Vilela Pinheiro wrote:
        
On 3/10/07, *Theo Band* wrote:

    I try to find a softphone that works with Asterisk and Centos44, 
does
    anyone has a good suggestion or is it better to buy a hardphone?


AFAIK, microphone bad quality is more related to the hardware, not 
the software. My onboard "Intel high definition" sound chipset (ICH7 
compatible - Intel 945GNT) has a bad output sound, but a much worse 
input (microphone). I have tried using Windows XP, CentOS, Ubuntu, 
many softphones (Skype, X-Lite, Ekiga, Twinkle) and definitely the 
problem is hardware (or all drivers are broken).
          
the output quality of the Intel branded motherboards I've used has 
been quite good.   Microphone inputs somewhat less so, but still 
plenty good enough for telephony IF your microphone has high enough 
gain.     If someone  is recording high fidelity (music, etc) from 
microphones, I recommend they get an external microphone preamp and 
use the line input on their sound card, or even better a USB 
input/output box.

for voice/telephony, USB headsets are the way to go.
        
I also have one trust USB headset and it works, except the volume 
cannot be adjusted, it's always max (and that's not nice for a 
headset...).
I have 20 desktops running FC4/Centos44 on AMD based Motherboards. The 
sound is onboard using a Nvidia chipset. Using skype and esd/arts the 
sound is very good, no problem. As soon as I try any of the softphones 
the mic is heavily distorted. I can even hear a hum as if the ground 
shielding is not properly connected. Since skype works so nice (using 
eithers OSS or alsa) I expect this to be a software based problem not 
hardware. And one softphone is working with FC4 (slfphone) but not on 
Centos4.4. The mic sound is less compared to skype (there is a hiss, 
when pronouncing the letter 's' the sound is distorted) but upto now 
that's the only one that is acceptable for only FC4, not Centos :-(

      
Well I tried Twinkle and it works, but on a scale from 0 to 10 I give 
the sound a 5 were I can give the Skype sound quality a 9+. Strange that 
it seems to be so difficult to get good sound quality on Centos/FC. My 
motherboards are A8N32-SLI Deluxe and Foxconn NF4UK8AA-8EKRS both 
equipped with onboard Realtek ALC 850.
Has anyone experience (good or bad) with the Realtek ALC 850?
    

Comparing Skype & Twinkle sound quality is not really fair. The reason
is that Skype uses 16k samples while SIP clients like Twinkle use the
very common 8k samples. Skype will always sound better than standard SIP
clients or POTS. The only VoIP solution I know off that has similar
sound capabilities is Polycom's latest VoIP phone the IP650. Your VoIP
PBX will need to support this too off course or else it will fall back
to the plain old sound.

Regards,
Patrick 
  
Ok, that's a fair remark. I would be very satisfied with a proper 8k sampled sound quality (like a POTS). What I experience is distortion (hum, hiss). That has nothing to do with the sampling rate. Could the sampling rate difference 8k versus 16k explain why most softphones give distorted capture (mic) sound? Is there anything I can try in the driver settings (snd-intel8x0) to improve 8k sampled sound? I noticed there are some options:

modinfo -p snd-intel8x0
index:Index value for Intel i8x0 soundcard.
id:ID string for Intel i8x0 soundcard.
enable:Enable Intel i8x0 soundcard.
ac97_clock:AC'97 codec clock (0 = auto-detect).
ac97_quirk:AC'97 workaround for strange hardware.
buggy_irq:Enable workaround for buggy interrupts on some motherboards.
joystick:Enable joystick for Intel i8x0 soundcard.
mpu_port:MPU401 port # for Intel i8x0 driver.


I played with some of them (ac97_quirk,buggy_irq), but actually I have no idea what to set it to.

Theo
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