Arch Linux

juray

Member

Registered: 2012-01-12

Posts: 26

Realtek AC97: accelerated speed of playback

Hi,

I have an old computer with Windows XP and very fresh Arch Linux in dualboot. Everything works fine, but sound card plays sounds, in both OS, with accelerated speed. Playback of music, or any other system sound, are maybe two times faster, than normal.

Thanks for your advices. I hope that is not a HW problem with soundcard.

Configuration of PC

MOTHERBOARD: MSI MS-6566E 1.0
CPU: Intel Celeron 2.20 GHz
SOUND: Realtek AC'97 Audio
RAM: DDR 1536 MB

Thank you. J.

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: Realtek AC97: accelerated speed of playback

I'd guess that it's some mismatch between hardware configuration and software expectations which makes the soundcard eat more samples than it's supposed to and discard half of them.

First of all, I really hope that the pitch also goes up, doesn't it?
Are channels (left/right) OK?
Are you sure it's exactly two times faster? You can play some recording of know length and measure the exact speedup.
How does /proc/asound/card0/pcm0p/sub0/hw_params compare to expected playback parameters (sample rate, channel count, bit depth)?

juray

Member

Registered: 2012-01-12

Posts: 26

Re: Realtek AC97: accelerated speed of playback

i agree. i tried playback of music in Windows XP with newest drivers from Realtek (soundcard manufacturer) and drivers from MSI (motherboard manucacturer), in very fresh installation of ArchLinux with ALSA and in Ubuntu Hardy Heron live DVD from 2008. And result is same.

This is output of your suggested file, while music plays in audacious

$ cat /proc/asound/card0/pcm0p/sub0/hw_params
access: MMAP_INTERLEAVED
format: S32_LE
subformat: STD
channels: 2
rate: 48000 (48000/1)
period_size: 1024
buffer_size: 8192

Thank you.

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: Realtek AC97: accelerated speed of playback

OK, so you use Audacious. Start with switching output device to "hw:0" instead of "default" to ensure that we are working directly with hardware.

This probably isn't the case, but maybe your 44kHz files are played back at 48kHz without resampling. Once you switch to "hw:0", hw_params should definitely show "rate: 44100" when playing such files (or the card may refuse to play them at all if it's 48kHz-only).
It's possible that the card is stuck at higher sample rate (probably 96kHz) than software tells it to use. Enable "resample" effect plugin and tell it to output at 96kHz (or 48kHz as well, who knows what will happen).
Maybe the card thinks it's being fed 4- or 6-channel signal and sends part of samples to some phantom channels. Try changing output to "surround40" or "surround51".
Try 16 or 24 bit output format, IIRC AC97 is limited to 20 bits anyway.

Finally, there is a "speed and pitch" plugin; set both to 0.5 and all will be good, at least for Audacious

juray

Member

Registered: 2012-01-12

Posts: 26

Re: Realtek AC97: accelerated speed of playback

HeHe thaks for your advices. I played with "Sample rate converter" in Audacious but it has not helped. I can change these values to anything you can imagine but it has not efect on played sound - strange, .. why this effect does not work?

Setting values to 0.80 in "Speed and Pitch" effect has helped but the playback is still not perfect.

I tried some settings in .asoundrc conf file of ALSA, but again without changes.

I need to resolve this problem globally, because i setting up machine for my parents, only for internet and Skype. And with this problem, Skype calls goes very very wrong.

And yes, after setting to "hw:0". hw_params show 44100, but sound is not correctly resampled and playback is faster.

According to this mail, im thinking about buying a real soundcard
http://www.monkey.org/openbsd/archive/m … 00587.html

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: Realtek AC97: accelerated speed of playback

Well, 5/4 speed doesn't make much sense to me. Maybe it really is broken.

Max-P

Member

Registered: 2011-06-11

Posts: 164

Re: Realtek AC97: accelerated speed of playback

5/4 does make a lot of sense to me. 48kHz played at 44.1kHz is very close to 5/4.

That card advertises it plays at 44.1, is probably filled at 44.1, but plays it at 48000, resulting at a 5/4 increase.

Have you tried playing the sound at 0.91875 for the pitch thing?

Otherwise I guess you could open the case and see if you can see some blown capacitors, these are responsible of the timing so if they are damaged, it could increase the playback rate as well (assuming the card does its own timing). I there are any, then we probably can tell it's really broken right away. (But I'm no hardware expert at all).

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: Realtek AC97: accelerated speed of playback

That's rather crazy, but maybe this AC97 host sources clock from PCI bus, PCI clock is locked to FSB clock and FSB has been overclocked from 133 to 166?

Anyway, some SB Live! or Audigy of similar vintage should be easily found for cheap and probably won't sound worse than some AC97 Realtek.

juray

Member

Registered: 2012-01-12

Posts: 26

Re: Realtek AC97: accelerated speed of playback

Hi,

i have bought SB Live! for 6 EUR but i have problem with its installation. What kind of driver i need?

Please look at this strange lspci output. What does it mean?

03:01.0 Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev ff) (prog-if ff)
        !!! Unknown header type 7f
        Kernel modules: snd_emu10k1

and

$ aplay -l
aplay: device_list:268: no soundcards found...

Thank you

juray

Member

Registered: 2012-01-12

Posts: 26

Re: Realtek AC97: accelerated speed of playback

OK. Problem Solved !!!

I have few times plugged off and on from/to PCI and sound card works without any configuration. Playback of sound has desirable speed and quality.

Thanks.