Guest Bidski Posted July 24, 2008 Posted July 24, 2008 Sorry if im posting in the wrong area here. Im experiencing a problem that is boggling my mind on biblical proportions. I have a Gigabyte GA-M56S-S3 motherboard with Realtek ALC888 Audio Codec (Realtek HD Audio) onboard sound card. I have 2 problems which may or may not ne related (most probably not related). Firstly, my Mic In port (both on the front and the rear) produce a distorted and ever repeating noise whenever a signal is applied and i am unable to source where this sound is coming from or where it originated from. This has only recently shown up and nothing has changed in the system either software or hardware wise. Secondly, the "Line In" audio device listed in the Volume Control is lagging a couple of seconds behind the actual audio stream. Is anyone aware of what might be causing such problems or are aware of what could be done to possibly fix these? If i have described these badly or further information is needed, just let me know Thanks In Advance Bidski
Guest Paul Posted July 25, 2008 Posted July 25, 2008 Re: Delayed audio input and Mic In problems Bidski wrote: > Sorry if im posting in the wrong area here. > > Im experiencing a problem that is boggling my mind on biblical proportions. > > I have a Gigabyte GA-M56S-S3 motherboard with Realtek ALC888 Audio Codec > (Realtek HD Audio) onboard sound card. > > I have 2 problems which may or may not ne related (most probably not > related). > > Firstly, my Mic In port (both on the front and the rear) produce a distorted > and ever repeating noise whenever a signal is applied and i am unable to > source where this sound is coming from or where it originated from. This has > only recently shown up and nothing has changed in the system either software > or hardware wise. > > Secondly, the "Line In" audio device listed in the Volume Control is lagging > a couple of seconds behind the actual audio stream. > > Is anyone aware of what might be causing such problems or are aware of what > could be done to possibly fix these? > > If i have described these badly or further information is needed, just let > me know > > Thanks In Advance > Bidski Various sound effects rely on delay. You can check the Realtek control panel for any "virtual" environment buttons. Try to reduce the configuration to have as few special effects as possible. Mute unused inputs, if they haven't already been muted. "Concert hall realism" can be added by a sound driver, by adding echo on purpose to the signal output. For example, my old sound chip, had a 30 millisecond echo added, which caused music played through the speakers to sound "muddy". Disabling all sound effects did not remove the special effect, and I had to replace the sound device with a PCI sound card. It doesn't have the same problem. The problem was at the driver level, and wasn't a hardware problem. If the driver is badly coded by the manufacturer, there is nothing an end-user can do about it. In addition to echo being added on purpose, certain programs will add their own echo suppression software (the exact opposite process). This software appears to stay in place all the time, and has been known to interfere with the normal operation of the sound subsystem. Examples of applications that might add that kind of software, would be multiplayer games with in-game audio communications, or another example would be telephony applications, where the speaker and microphone are allowed to operate in close proximity (speakerphone). If a telephony program you add, allows speakerphone operation, then it may be adding its own echo suppression software. Echo suppression involves subtracting a copy of the microphone signal, from the signal fed to the speakers. I don't really know anything about it. There is more here on the topic. http://en.wikipedia.org/wiki/Echo_cancellation I would say your two symptoms are related, but I don't know if I could spot the offending software if I was sitting in front of your computer. The kind of testing I've done in the past involved. 1) A copy of Audacity from http://audacity.sourceforge.net/ 2) I draw a test waveform in Audacity. For example, a step waveform or an impulse waveform, with a trapezoidal shape (as audio signals should be band limited, so they don't exceed the Nyquist limit). _____ __ / / \ ___/ ___/ \_____ 3) Using a second program, I record the sound output. I wasn't able to make Audacity record from the microphone, at the same time as I was playing the test waveform. So I needed two programs running. 4) Say I make a test waveform 16 seconds long, with a large impulse every four seconds. By recording the speaker output via the line_in or Microphone jack, I can examine the waveform, and see how the result correlates to the input. Using that test, that is how I determined my sound subsystem had a 30 millisecond echo added. You might see something in the recorded result, that suggests what kind of effect is involved. For example, if there is a mathematical loop between input and output (with a fixed delay buffer), which does not attenuate the signal being added, then noises in the system can remain at a constant level or grow with time. The hard part, will be associating a piece of software, with the symptoms. And I can't really help you there, as I have a lot of trouble understanding software stacks, shims, and drivers. HTH, Paul
Recommended Posts