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I am using Dell inspiron 1525 laptop with Fedora 10. I have problem with recording from external mic. When I connect the external mic, it is not active. Always internal mic of the laptop used for recording because of which recording quality is low. How to enable external mic?
My alsa mixer always shows recording capture and mux with red buttons means not active. I have to uncheck every time? Is this problem with sound card configuration?
To keep / save / restore your current settings. Baring any overrides from the other mixer applications. kmix, gmix, aumix, .......
From whence is the "external" source? USB mic? USB/Firewire Soundcard? Mystical Fairies? ???
Most apps default to card 0 (as shows in /proc/asound/cards). Many recording apps let you override this default. But some don't. Need more information to determine which applies.
Thanks for your reply. Which information do you require.
I am working on speech recognition. I am using sphinx developed at CMU for speech recognition. Earlier I was using Fedora 9 (kernel 2-6-25-14). That time sphinx was working fantastic. When I record there is not any background noise.
I upgraded kernel to 2.6.27.7-53. recently. Then My alsa mixer configuration is totally changed. From then onwards, the recordings have lots of external noise but I am able to record without external headphone mic also.
I am not using pulse audio at all in both cases.
Then I recently installed Fedora 10. In this OS also I removed all pulse audio rpms. I installed all alsa rpms from livna and atrpms. I am able to play real player or vlc without any problem.
When I start recording, if there is lots of external noise because of the internal mic taking outside noise. This effects my speech recognition performance a lot.
Even if I connect external headphone mic, the internal mic with laptop is active taking external noise. Also in volume control options->recording tab-> all capture and mux options are not active when i restart recording. This is not the case earlier in fedora 9.
What extra information you want please tell me? I will reply soon.
Sounds like you have your mixer settings a little off. Mic Boost plus low mic gain? In alsamixer use <tab><tab> to show ALL mixer channels. Since it defaults to playback, with one <tab> to show capture channels.
For audio you really need a low latency kernel, and probably realtime priority (/etc/security/limits.conf) to achieve best results. Without a low latency kernel you get some gaps in the recording when other apps and processes chew up resources. Without realtime priority you get clicks and other audio artifacts when using other devices like the network card at the same time. Beyond that there really shouldn't be any reason for your audio to sound worse between "upgrades".
As far as background noise. That's a given for laptops and integrated soundcards. Which if you're developing a product is probably your target market. But if you're an audio guy like me, you've already gone for a pro/semi-pro low noise soundcard, and a quality microphone preamp and microphone. At which point background noise outside of wind noise, or ambient room noise is the least of your worries.
Any amixer output? How does it compare to previous more cooperative installs (if you still have access to one)?
$ cat /proc/asound/cards
$ lspci
$ amixer
tack on " > tempfile.txt" to capture the infomation for cut and paste ease from a text editor (bluefish). Or tack on " 2>&1 | tee tempfile.txt" for slightly more information depending on the task.
I don't have access to old configuration. The outputs you have asked I posted here. There is lot of crackling noise background when I use alsa. I think its mostly problem with either alsa drivers or alsa configuration.
Is there some reason you have all of your levels set to 100%? A lot of consumer cards sound horridly bad if you crest 85%. Especially with regards to laptops. I tend to set mic gain at about 70% depending on the level I need with/without mic boost. If it's a signal strength issue to power your speakers, then consider getting an amplified set of speakers. Or a headphone preamp to boost the signal to your speakers. Certain headphones pretty much require a headphone preamp just to function as intended.
Try adding these to your /etc/security/limits.conf file and rebooting, or re-login.
That should enable realtime priority for users in the audio group. Which should help get rid of clicks that happen during xruns and other issues that crop up with a multi-tasking computer. Also try NOT to drape your mic cable across your LCD or CRT display. Shielding only does so much in a strong RFI / EMI environment.
You might also try other recording applications. There's time when audacity does those strange noises for me, where ardour with jackd wont. And the hda-intel chipset is particularly prone to issue with it's development status and wide range of implementations. I think I had to increase the periods (whatever they are) when using arecord to overcome some noise issues. -p 3 (defaults to 2) or something like that. Or was it -n 3, it doesn't seem to be an arecord option in current renditions. Must have been moved to .asoundrc only or something. Anyway, it was specific to my snd-hda-intel type card MCP61? and part of my motivation for getting a pro-ish after market sound card.
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