I have a very choppy sound in linux e.g. when calling to echo123. I first suspected the choppy sound would be due to sound alsa emulator settings, but nothing seems to help. No sound daemons should be running. I enabled the technical info of calls (move cursor to the middle of the skype window to get a tooltip) and noticed that I have high packet loss, varying from 23% to 99%. I tested Skype (1.1) also with Windows in the same hardware and network connection and same time a day and the sound is always 100% fine and technical info shows 0 % packet loss.

How is that packet loss number calculated? What could be the reason it being so high?

My hardware is: Abit BH6, Celeron 400 MHz, 384 MB RAM, SB Live value, PCI NIC with realtek chip.
Linux: up to date Fedora Core 2, kernel 2.6.10-1.12_FC2, firewall on,
Skype: 1.0.0.1

The CPU usage during the call is around 80 %.

Anybody similar problems?

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EDIT:
Solution found - follow the thread

The CPU is close to the minimum required by Skype, as also indicated by the high usage %. While direct ALSA support might reduce the usage a bit so the sound wouldnt have to be piped through various daemons, your best option might be to try to upgrade CPU a bit. To see if it would help, you could perhaps first try on another computer with faster CPU to see if you get better results.

Hallo!

Same Problem here!
I use 3 different computers:

Pentium III 550MHz 512MB RAM

Pentium III 800MHz 512MB RAM

Pentium III 1.2GHz 512MB RAM


On the 1.2GHz machine sound quality is good, packet loss around 3%.

On the 800MHz computer sound quality is bad, mostly over 50% packet loss.

On the 550MHz one sound is worst, i got here over 80% packet loss.


I am using the statically linked version of Skype for Linux 1.0.0.1, because
I don't want to install Qt libraries. I don't need them, I'm not using KDE.



Kazuki

Interesting! There must be something wrong in the Linux version if even 1.2 GHz machine is not capable to put the packet Loss to 0% when 400MHz is enough in Windows!

Kazuki: Have you done the same tests in Windows? What is your Linux distro and kernel? Are the computers otherwise identical? Same network?

My opinion: 400MHz should be enough for sound only!

I guest 400MHz should work fine, on my Centrino notebook, even when running @600MHz (smallest value allowed by stepping) I get good quality connection (0 percent loss) and still small CPU usage. (~30-40%). (Sound quality as such depends on audio settings, sound daemon, alsa, dmix & co, that's another subject).

What is your connection speed, is there enough free bandwidth?

There is enough bandwidth: 10 MBit half duplex and the Windows works fine with 0 % packet loss, although there has been lately some network problems from the operator side.

Does anyone have a step by step instructions for Fedora 2 or 3 and Gnome of tuning alsa and other sound daemons for skype?

Alsa, oss an esound are working well when I try them with XMMS. When I start skype call no esd appears on my process list, so I guess this is alsa oss module which should give the best sound quality - but not. I tried also starting the Skype with "esddsp skype" and then the esd becomes visible into process list. The sound quality is similar in both cases.

Hi!

Yes, I got a Windows install on all 3 computers, too.
The Windows version of Skype work well there, even on the
slow 550MHz machine.

I tried following Linux distros:

Slackware 10 with stock kernel 2.4.26

Slackware 9.0 with kernel 2.6.10 and kernel 2.4.28

Computers nearly the same:

PIII 550MHz, 512MB RAM, ASUS P3B-F mainboard
RTL8139 NIC
SoundBlaster Live! 5.1

PIII 800MHz, 512MB RAM, ASUS TUV4X mainboard
RTL8139 NIC
C-Media CMI8738

PIII 1.2GHz, 512MB RAM, ASUS TUSL2-C mainboard
RTL8139 NIC
SoundBlaster Live! 5.1

These 3 computer build my private network behind a DSL
bradband router.

So bandwidth should be no problem, I'm the only one
how using the computers.



Kazuki

Forgot one thing:
I don't use KDE, so there is no arts sound daemon or such
things.

I only use the simple OSS sound modules from kernel.



Kazuki

Strange....

I get really breaking sound.... But no packetloss is shown....

I tried running the proggy with real time permissions, still no improvements.

Using alsa with OSS emulation...

try running those two commands:

echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0p/oss
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0c/oss

only thing that might be different is the number of your soundcard if you have more than one and you are not using the first one. you'd have to change "card[0-9]" parameter.
also the subdevice on your card can be a different one. parameter "pcm[0-9][pc]". but most of the ppl will be alright with the above. should help you. i'm running skype on a old ibm thinkpad x20 (600mhz PIII, 320MB ram, 512/192 adsl) with no problem. also had the choppy-sound problem and this fixed it.

Yay, greatest thanks!!!

you dont have to use KDE if you install QT, just to mention that

these are two completely different things: qt and KDE

its like you say: i dont want to install gtk, i dont use gnome. but gtk has hardly anything to do with gnome, gnome just utilizes it.
you can have xfce4 and gtk e.g. and no gnome at all.

i recommend to use non-static version with native installed qt. qt is a fast thing, and making it non-static avoids problems which the static libraries may have. and you dont have to use kde for using qt.

I got choppy sound only after a period of time. strange, i have a 700 MHz Laptop with debian on it.

will try the tricks later.

Now it works!

I tried those magic lines:
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0p/oss
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0c/oss

and now the sound quality is perfect - at least when calling the echo123 service.

I was playing with those settings yesterday and I noticed this setting has effect to the skype sound quality, but my values (number of fragments and fragment size) was way too low (around 30 and 128).

I'am still worried if those large values affect delay. I have to test it by calling someone, echo123 doesn't help in that.

Thanks carrot!

PS. My setup once again: FC2, Abit BH6, Celeron 400, SB Live value

Hi!

@ryanvalor:
Of course, I know that. I also don't use gnome, but I have gtk 1.2 installed.
I have many programs using gtk.
Skype is the only one program I have, using QT. So I don't like to install QT
only for Skype.
:wink:


About our sound problem:
This is for ALSA, is there a similar thing for OSS?

Anyway, when using ALSA it seem to help.
On my Pentium3 with 550MHz the sound quality *during* calls is now good.

But it doesn't solve my problem with the ring tone, I described here:
http://forum.skype.com/viewtopic.php?t=17424

And with the ALSA modules for my C-Media sound card I still have this
problem:
http://forum.skype.com/viewtopic.php?t=17180


And a thing I like to know:
Is there a documentation for the ALSA modules, where I can read what
these things "echoed" to /proc file system exactly does?
Maybe I need to do other adjustment to solve my other problems.
So it would be very interesting to know.



Kazuki

Here is the page describing the syntax of the echo command:
http://www.alsa-project.org/~iwai/OSS-Emulation.html

The syntax is:
app_name fragments fragment_size [options]

I found good settings by starting from the suggested value for fragment size (65535), and then I halved it until the sound quality got worse:
65535 -> 32767 -> 16383 -> 8191 (at this point I noticed some cracles in the sound).

I think the latency gets down this way, but I have not tested extensively.

I'am just wondering what would be a good place to put those echo commands, so that they are executed automatically after boot. The difficulty is that the snd-pcm-oss module must be loaded before those commands have any effect.

Any solutions?

What about putting them in the boot-script for alsa-modules? Just at the ent of start section... eventually preceding them with "modprobe snd-oss-pcm"...

I had choppy sound and after reading this post entered the commands:

echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0p/oss
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0c/oss

Now the robot lady is talking at a million miles per hour. I tried variations on the 65535 but the voices are still too fast.

Sound driver 3.1.1a-980706 (ALSA v 1.06a emulation code)
Kernel: Linux mepis1 2.6.7

This happend to me too.
But I solved that by removing "direct" from the lines:

This is what solved the problem for me:
echo "skype 256 1024 block" > /proc/asound/card0/pcm0p/oss
echo "skype 256 1024 block" > /proc/asound/card0/pcm0c/oss

I dont even have a /proc/asound at all but I have choppy echo123.

[quote=zygut]I dont even have a /proc/asound at all but I have choppy echo123.[/quote]

Well I do if I modprobe snd, but I dont get a /proc/asound/card0 I get only:

cards devices modules oss/ seq/ version

:?

I fixed sound problems also with the commands

echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0p/oss
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0c/oss


My problem manifested as call echo123 and I would hear about three seconds of the call, then nothing.

Running on Suse 9.0, Intel P4 1.6

Thanks to forum users for support

im using OSS and have the same problem: choppy sound under linux...

can anyone help me? the echo-command only works for ALSA, but what should OSS-Users do?!

THX
clumsy

I've fixed choppy sound using the echo commands specified here, but I believe that these changes will not persist following a restart. Where is best to put these commands in order to make these changes permanent?

Thanks in advance.

Jon

I have to use skype-dsp-hijacker so i can use my usb mic, so do I put the trick lines after?

MIXERDEV=/dev/mixer MICDEV=/dev/dsp1 SPEAKERDEV=/dev/dsp LD_PRELOAD=/usr/local/lib/libskype_dsp_hijacker.so:/lib/libdl.so.2 skype
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0p/oss
echo "skype 256 65535 direct block" > /proc/asound/card0/pcm0c/oss


or before?

Do I need to run them everytime I do skype, or after a reboot, etc?

Anyone else using dsp hijacker? I don't know if it's just me, but I may be getting choppier sound(from the other person talking) when I use it.


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actually, I can't stick that in the same script, because it must be done as root.

where should it be put? i THINK I see a difference if you remove "direct".

Also, I'd like to fix the problem with sound when I use dsp hijacker. the person can hear me through my usb mic fine, but i get choppy sound through the speakers.

AMAZING, I just figured out how to solve the choppy sound and packet loss problem if you have a router.

I altered my router's virtual server to automatically forward UDP (not TCP) protocol to my stand-alone machine. This allows Skype to bypass my router and go directly to my computer.

I forwarded three ports. 80, 443, and a third one. Go into TOOLS>OPTIONS>ADVANCED>CONNECTION, and look at the top field next to "use port". That is your third port, or you can change it like I did. Make sure you forward all 3.

My packet loss was at about 50% and the sound was super choppy.

Now it is at 0.0% PERFECT!.

Email me from Skype if you need help. Geffeney, D