Skype audio configuration tweaking
 

Hi fellow n900 users. I have had a disappointing experience doing skype-to-skype calls recently with my n900. The situation was as follows:

Friend on windows - me on windows ---> very good audio quality

Friend on windows - me on n900 ---> very poor audio quality


Both my laptop and my n900 were in the same wifi network, so I discarded any 3G related issue.

Of course I couldn't find any place to configure it on the phone. Not in the skype account settings, nowhere. After lots of googling and forum searching, I couldn't either find any clue to improve sound quality. Then I thought: silly you, there must be just a /etc configuration file.

And there it was:

/etc/skyhost/skypeaudiocodecs.conf


[G729]
payload-type=18
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=8000
max-bitrate=8000

[PCMA]
payload-type=8
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=64000
max-bitrate=64000

[PCMU]
payload-type=0
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=64000
max-bitrate=64000



First I found somewhere that the G729 codec was used for skype-to-phone calls. I don't know if I am right at that point. So since I'm not interested on that at this moment, I left it untouched.

In the other two codecs I have supposed that the channels lines refer to mono or stereo. I changed them to 2.

I have also tweaked bitrates up to 128000 and frequencies up to 32000. I have noticed some improvements, but still the quality is not as good as in a laptop-to-laptop skype call.


For the other parameters, payload-type and packet-size, I haven't changed anything because I'm not sure what's the effect.

Has anyone had any experience on this kind of tweaking? What would be the configuration that brings the best audio quality? Would anyone like to try and share what he / she finds out?

Thanks in advance and cheers to all the maemo community

Javier

Re: Skype audio configuration tweaking
 

I had terrible troubles with Skype over 3G - WiFi was better but still not perfect.
For me, the best method was to avoid Skype and use the googlechat instead - much better quality.

From the way my 3G data was used up, I can say that skype was using approximately twice the bandwidth that Gchat was.

I would be interested to see if Skype could be improved to the levels of Gchat.

Re: Skype audio configuration tweaking
 

Yeah I prefer gtalk too, but since some of my contacts are only on skype, I am using it as well. I'm over wifi so i dont care about the bandwidth now, I'm just figuring out to what extent the quality can be improved.

Re: Skype audio configuration tweaking
 

Few minutes ago I have tried to make a videocall thru 3G using google and quality was horrible, almost unusable. But hangup and tried again (same 3G connection) using skype (against same partner) and quality was just fine.

Re: Skype audio configuration tweaking
 

I have the same problem. It's barely missed first part of word. I presume it looks like the pulseaudio problem because one is eating about 40% CPU when skype is running and probably has high latency effect at begin playing.

Re: Skype audio configuration tweaking
 

I think I was being too optimistic. The changes I did in skypeaudiocodecs.conf don't seem to have any effect. I keep calling echo123 and finding the lady's voice darkened and very poor in high frequencies.

I own an android phone too and the same test, attached to the same WiFi network, gives me a much better sound quality. In android skype the lady sounds clear.

Repeating the same echo123 call with 3G connection in my n900 doesn't make any difference.

I also want to tell that I'm not meaning about choppiness or stutterness as I have read in other threads here.

So can anyone help? What's the matter with skype in the n900?

What is this skypeaudiocodecs.conf file for? I have read that skype uses SILK proprietary codec for skype-to-skype calls. But I can't see it in the conf file. Can I add an entry in the file with its settings and make skype use it?

Too many questions. I hope anyone can help me, I'm disappointed because I don't understand why maemo skype performs worse than on android or windows.

Thanks!!

Re: Skype audio configuration tweaking
 

I encourage above because I was looking for working out around Internet but useless. It's pity. Such powerful device with poor quality skype working. :(

Help people!

Re: Skype audio configuration tweaking
 

I've read the pulseaudio threads too, but why poor audio quality only happens with skype and not with other software using pulseaudio? My mp3 playback is just fine, and so it is playing any movie with mplayer. I don't understand why precisely skype has the problem.

Re: Skype audio configuration tweaking
 

No, I'm saying that there is lack before sounding a word. And It seems there are two problem: one before and poor quality sounding.

Re: Skype audio configuration tweaking
 

By the way there is no such problem on n810.

Re: Skype audio configuration tweaking
 

my skype works flawless on my n900. audio is very good

Re: Skype audio configuration tweaking
 

I've just tried deleting that configuration file. Rebooted the phone. It makes no difference, skype still works and the sound quality still remains poor. So I guess the file is not there for a configuration purpose of any kind. I don't know, it's so strange for me.

Re: Skype audio configuration tweaking
 

Are you using kernel-power?

Re: Skype audio configuration tweaking
 

Note that stereo brings no advantage as very likely whoever you talk to is using a single microphone.

Re: Skype audio configuration tweaking
 

Thanks for the hint, it's a very clever one! And what do you think about the other settings? And about the fact that removing the file makes no difference?

Re: Skype audio configuration tweaking
 

I would assume there are some defaults at play, but it might be just that it's the wrong section (i.e. that those are not the ones used in your particular case). I can't really test it as I don't have any quality issues (I use it fairly often to talk with both people on win and linux and it sound pretty good to me).

Re: Skype audio configuration tweaking
 

I haven't used skype in a while but whenever I have done so in the past (PR1.2/1.3, on both wifi & GPRS) the quality has been excellent - I'd say it's usually noticably better than a normal mobile call, with better clarity and "brightness" to the sound, very few echo/dropouts and genrally good background noise cancellation. That includes calls to/from Europe, UK and USA, mainly to landline/mobile (via Skype out), but occasionally to windows PC's.

I was about to hit "post quick reply" at this point ... but I then decided to call the skype echo/test service first, just out of interest. The quality was definitely poor - I tried 3 times, and on each occasion there were multiple audio dropouts on the call.

CPU load was ~60% during each test, not sure if that's normal or not for a skype call, but regardless it was neither CPU or RAM bound during tests. On two of the test calls the dropouts were pretty minor and didn't much affect audibility; on the other call, they were quite severe, and I'd have struggled to hold a conversation.

All tests were on my home wifi (rock solid 4Mb/s). I tried one more test on 3G - quality was the same as the better two wifi tests.

So, I'm also seeing a definite reduction in skype call quality on calls made from N900. I double checked on my desktop PC skype client (on same wifi as above) and quality (again to the skype echo/test service) was excellent, so definitely the N900 skype client (or something else on my N900 interfering with it) to blame. I did one final test with my phone overclocked to 805Mhz - the dropouts were worse at that freq than at stock 600Mhz, so I don't think CPU load is relevant.

I've had my phone over a year, with loads of -devel stuff installed, and it's never been flashed - my guess is that if I flashed a clean image, skype may improve? I don't want to reflash my own N900 as I seldom use skype, but perhaps one of the others who are suffering may give it a go and see if it helps.

Re: Skype audio configuration tweaking
 

I too have choppy skype quality. My call partner on windows has no problems understanding me, but I receive only chopped up audio fragments. Had to ditch the n900 a few times and fetch a laptop. Interestingly, enabling video doesn't have any impact on the audio choppiness.

Re: Skype audio configuration tweaking
 

i have no issues with skype on my n900 ;)

Re: Skype audio configuration tweaking
 

I reflashed my phone. Both eMMC and fiasco images. The skype bad audio quality persists. So what do you think?

Re: Skype audio configuration tweaking
 

hi All,

I wanted to share some testing I've done with my nokia n900 and /etc/skyhost/skypeaudiocodecs.conf config. I have this phone only for few weeks, but I do work with linux everyday.

I had lots of issues with choppy audio, but only for my end of the conversation. So after googling around and playing with several files I've had some success with this setup.

This setup I've found originally:
=============================

[G729]
payload-type=18
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=8000
max-bitrate=8000

[PCMA]
payload-type=8
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=64000
max-bitrate=64000

[PCMU]
payload-type=0
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=64000
max-bitrate=64000

====================================

I've started with doubling bitrates from 64000 to 12800 and I had couple of very good test calls to skype echo123 testing number.

I've also tweaked frequency, but this had no affect. I did at least 10-20 calls before doing any sort of conclusions.

I noticed that calls over 3G network were better then calls over WIFI... This gave me idea that high quality codecs do not perform well and I decided to change around payloads so originally I had 18, 8, 0 and switched it to 0, 8, 18 (swapped g729 for pcmu). After doing lots of test calls I noticed huge improvement in overall quality.

I think sound quality has dropped to g729 level, but choppiness was gone. After experimenting further with payloads I had some really crisp and clean calls on other codecs too.

Originally I had choppy gaps at random times and after changing bitrates and payloads I noticed that I have choppy gaps in the first few seconds but later call quality is good.

I think phone must be trying to figure out which codec to use during the call and this is a problem.

Please share your experiences here, so we all know what works... I have a feeling different bitrates+codecs is key to getting skype call quality right.

After doing changes on the conf file you do not need to restart your phone - just dial skype call and test the quality. Make a backup first - if you modify it too much your skype will not work.

My current set-up:

=============================

[G729]
payload-type=0
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=8000
max-bitrate=8000

[PCMA]
payload-type=8
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=64000
max-bitrate=64000

[PCMU]
payload-type=18
frequency=8000
channels=1
packet-sizes=20,30,40
default-packet-size=40
min-bitrate=64000
max-bitrate=64000


====================================

UPDATE: this method only works for some phones. On the latest kernels/power kernels this doesn't work.

Re: Skype audio configuration tweaking
 

Made a 30 minute call to my brother in Australia from USA using wifi and these settings. Was crystal clear and no chop.

Take from that what you will.

Re: Skype audio configuration tweaking
 

did you previously have issues with skype on such calls?

Re: Skype audio configuration tweaking
 

Some - main problem was not so much call quality as chop. I didn't notice any chop in the 30 minutes or so.

Re: Skype audio configuration tweaking
 

I have the impression that using earphones works much better than using the phone directly.
Maybe the sound suppression system is the problem? In that case, I don't really know what could be done about it.

Re: Skype audio configuration tweaking
 

ATLAST! someone noticed!!!

BAD QUALITY on skype! but this tweak is doing good. anymore tweaks?

Re: Skype audio configuration tweaking
 

All these things wrong. I've tried once again to figure out influence any changes in file skypeaudiocodecs.conf. I've done 'cat /dev/random >skypeaudiocodecs.conf'. As you know its file got binary. After that I killed all skyhost processes. And do you know? It works as nothing has happened.

It seems to me there is only way to communicate with skype company or developers. There is no another way!

Re: Skype audio configuration tweaking
 

guys , more bitrate means more data need to be sent , lower it

Re: Skype audio configuration tweaking
 

Your assumption is incorrect, but your results are correct:

skypeaudiocodecs.conf is set of optional settings - these settings are used if they are available - if file is missing it will default to default settings. Try corrupting the file and you will see effects :)

Re: Skype audio configuration tweaking
 

This is true... But my guess is that problems with choppiness are caused by the payload - software is optimizing the quality by switching codecs. This is great on paper, but nobody bother to check if this works. Well it used to work, but now it doesn't. It is a shame really.

I'm a programmer and I'm embarrassed for the guys who did this work. After upgrading to the newer kernels - I got so many issues that I cannot use Skype at all.

Back to the topic - increasing bitrate strangely helps in a way... As soon as I get CPU more stable Skype quality is much better. But this is all very temperamental - fixes do work for few days till some other patch or update breaks this balance.

Re: Skype audio configuration tweaking
 

Im on my second n900 now, my old one had no problems with skype but my new new one does have a lot of choppiness with the audio! even before any updates to the operating system or kernel were made

Re: Skype audio configuration tweaking
 

This is poo man, skypes built in for god sake and it just doesn't work?? Mine on wifi does work rather well but not once on 3g and i've tried many times. Choppy as ya like. I thought about a reflash myself as i've installed and uninstalled loads from devel but an ealier post says it makes no difference. Well dissapointed. Kind of makes having skype on ya phone a bit pointless if it only works on wifi? Where's there's wifi, there's usually a pc so you end up using that instead? Grrrr :(

Can i ad.. i've been all over the net trying to find anything out and all it returns is "skype not working" There appears to be no solution and skype themselves don't seem to have acknowledged the problem neither. i've read a couple of posts made by people months ago in their blog section but no reply from skype. Its a joke if i'm honest. I know skype is free but i'm sure many would use their paid service if it worked? Their loss

Re: Skype audio configuration tweaking
 

I've tried paul_maemo's settings for skypeaudiocodecs.conf and it doesn't work for me. I will go on testing.

Re: Skype audio configuration tweaking
 

Just found this thread.

Skype quality was poor on my old n900, and it is poor on new one as well.

I've noticed that pulseaudio takes quite a few of cpu time while on skype call, and also some time after call is finished. That made me to think that it may be useful to check if audio stream that pulseaudio receives from skyhost is already poor, or it is broken by pulseaudio processing. If later, that problem should be fixable.

Anyone ever managed to get pulseaudio command line plugin working with pulseaudio daemon running on n900?

Re: Skype audio configuration tweaking
 

is there any way to try a different codec?

Re: Skype audio configuration tweaking
 

any updates?

Re: Skype audio configuration tweaking
 

****bump****

Re: Skype audio configuration tweaking
 

hi All,

There is no 100% solution, but with:

final global 1.3 firmware,
apt-get install –reinstall -y kernel-power kernel-power-flasher kernel-power-modules
config tweak to use G729;
ARM CPU set to "userspace" and freq [600000]

skype is usable on my n900 now. Not perfect but works over 3g and wifi 9/10 times. I have also got iphone 3gs it seems usable on iphone too: sound quality is better but i had issues with lag and incoming calls. I've tested iphone 4 and I was well impressed by it, but not sure if i want to by another phone for skype. Sometimes n900 i3GS are also very stable, so I'm sticking with my old phones for now.

There are so many new phones and android also seems to got better with skype... Does anybody have any experience with skype on latest galaxy2, atrix, nexusS, other 4g androids ??? It is probably much easier to buy new phone then to get old phones working well... But i'm struglling to find any info about actually living with skype every day... especially about how they handle week signal, incoming calls, etc.

Re: Skype audio configuration tweaking
 

hi could you post a step by step guide?

Re: Skype audio configuration tweaking
 

any new solution ? non of this tweaks worked....mayby some from community have some ideas?