CORRECTION to original post: " - mic audio very low with MicBoost (setting in alsamixer and gnomealsamixer)." should read: " - mic audio very low with 0 MicBoost (0 setting in alsamixer and gnomealsamixer)."
** Description changed: - - Running Ubuntu Intrepid (will attach full uname, etc. once I figure out how to add attachments). + Running Ubuntu Intrepid with Intel-HDA (ALC882) sound: MicBoost does + not seem to work properly. History: Prior to seeing symptoms (below), have never been able to get microphone to work well for Skype: - - mic audio very low with MicBoost (setting in alsamixer and gnomealsamixer). + - mic audio very low with 0 MicBoost (0 setting in alsamixer and gnomealsamixer). - mic audio completely distorted and nearly inaudible with full MicBoost. - intermediate MicBoost caused distortion but audible. - Skype setting "let Skype adjust audio..." caused mic audio to be distorted and inaudible (so did not use). Always assumed problem with Skype was some problem with pulseaudio until I tried recording from Audacity and noticed that adjusting MicBoost while recording from microphone shows four steps of DC-Offset (0 - 3). (see attached screenshot). Audacity has same result with Recording Device ID 0 (OSS: /dev/dsp) and Device ID 2 (ALSA: HDA Intel: ALC882 Analog (hw:0,0)). (will attach the Audacity Device Info output next) According to the screenshot, MicBoost seems to be amplifying the microphone (good), but also creating an extreme negative DC-bias (bad), i.e. shifting the signal into the negative until only the largest positive peaks are not clipped. Each step corresponds to one of the four steps of the MicBoost control. Examining the output of the alsa-info.sh script: http://www.alsa-project.org/db/?f=386a234a728c1b20f88f717d7839651e6938f7aa shows control.17 of the AlsaCtl section: control.17 { comment.access 'read write' comment.type INTEGER comment.count 2 comment.range '0 - 3' comment.dbmin 0 comment.dbmax 3000 iface MIXER name 'Mic Boost' value.0 2 value.1 2 } - This is a total SWAG, but two possibilities come to mind: + This is a total SWAG, but one possibility comes to mind: Could the type INTEGER be wrong? Perhaps it should be a FLOAT and we are seeing the results of an aliased setting? If someone can point me in the right direction, I would be willing to look at the source to try and track it down. I know C/C++/Java, but I have no idea where it might be in the source (i.e. kernel?, module?, driver?). Where do I find the definition and use of the Control.17 configuration above? ** Tags added: alsa audio hda intel intrepid micboost oss sound ** Description changed: Running Ubuntu Intrepid with Intel-HDA (ALC882) sound: MicBoost does not seem to work properly. - History: + Background: + ====== Prior to seeing symptoms (below), have never been able to get microphone to work well for Skype: - mic audio very low with 0 MicBoost (0 setting in alsamixer and gnomealsamixer). - mic audio completely distorted and nearly inaudible with full MicBoost. - intermediate MicBoost caused distortion but audible. - Skype setting "let Skype adjust audio..." caused mic audio to be distorted and inaudible (so did not use). Always assumed problem with Skype was some problem with pulseaudio until I tried recording from Audacity and noticed that adjusting MicBoost while recording from microphone shows four steps of DC-Offset (0 - 3). (see attached screenshot). + Problem: + ====== + According to the screenshot, MicBoost seems to be amplifying the microphone (good), but also creating an extreme negative DC-bias (bad), i.e. shifting the signal into the negative until only the largest positive peaks are not clipped. Each step corresponds to one of the four steps of the MicBoost control. + Audacity has same result with Recording Device ID 0 (OSS: /dev/dsp) and Device ID 2 (ALSA: HDA Intel: ALC882 Analog (hw:0,0)). (will attach the Audacity Device Info output next) - - According to the screenshot, MicBoost seems to be amplifying the - microphone (good), but also creating an extreme negative DC-bias (bad), - i.e. shifting the signal into the negative until only the largest - positive peaks are not clipped. Each step corresponds to one of the - four steps of the MicBoost control. Examining the output of the alsa-info.sh script: http://www.alsa-project.org/db/?f=386a234a728c1b20f88f717d7839651e6938f7aa shows control.17 of the AlsaCtl section: control.17 { comment.access 'read write' comment.type INTEGER comment.count 2 comment.range '0 - 3' comment.dbmin 0 comment.dbmax 3000 iface MIXER name 'Mic Boost' value.0 2 value.1 2 } This is a total SWAG, but one possibility comes to mind: Could the type INTEGER be wrong? Perhaps it should be a FLOAT and we are seeing the results of an aliased setting? If someone can point me in the right direction, I would be willing to look at the source to try and track it down. I know C/C++/Java, but I have no idea where it might be in the source (i.e. kernel?, module?, driver?). Where do I find the definition and use of the Control.17 configuration above? -- MicBoost with HDA-Intel introduces DC-bias https://bugs.launchpad.net/bugs/316165 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
