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Amplify linux sound output for quiet laptop seakers using pulseaudio LADSP plugin

Sunday, 10 July 2011 20:36

Sound too quiet on your linux laptop? I have been plagued by this issue with Lenovo's thinkpad line for years, and searching has shown many many other people too have trouble with laptop speakers being driven too weakly in linux. Gnome now offers a volume slider that goes past 100% volume, but kde does not, and the keyboard volume buttons wont go past 100%. What to do? Well if your using a a modern distribution with pulseaudio, I have figured out a solution by loading an amp plugin as a new sound sink.

First, install Steve Harris' LADSP plugins. In fedora these are avalable by installing the package 'ladspa-swh-plugins'

From there, you simply edit your /etc/pulse/default.pa file, but first we need to know some things:

What device should we pass the amp'd signal to?
How much to amp? I did 10db and that worked well.
Name for our new sound sink? I call mine simply 'amp'

Pulseaudio comes with some handy tools I never knew about. One is pacmd, which lets you examine and configure the various sound sources and sinks available. Run pacmd, and it brings up its own little command-line interface. Type list-sinks, and make a note of the index of your sound card. My laptop (Lenovo W520) has an nvidia sound chip which does not seem to be used on index 0, and an intel one on 1 which IS used. So for me, we will tell the amp plugin to use master=1.

Now you can edit the /etc/default.pa (or system.pa depending on distribution). At the end, add the following line to create your new sound sink:

load-module module-ladspa-sink sink_name=amp master=1 plugin=amp_1181 label=amp control=10

ladspa-sink is a module that interfaces between standard ladspa sound maniuplation plugins, and pulse. The amp plugin from Steve's collection is what we want to load.

The control=10 tells amp to bump up by 10db, so you can adjust to your liking. You can issue this command in pacmd first (and also unload-module x where x is the new index which is printed after it loads, to remove it and try again).

I suggest installing pavucontrol which is a nice little gui for pulse sources and sinks. You should see your new device show up, and in the list of things playing (start up amarok or something) you can switch sinks. You should hear it get louder when you switch to the new amp sink.

Lastly, if you add to the very end of /etc/pulse/default.pa:

set-default-sink amp

then you should see applications playing on your new amped sound sink by default. Yay!

IRC Etiquette: Can I PM you?

Tuesday, 26 April 2005 14:53

Since IRC evolved out of college UNIX nerds into the average PC user, many of the customs of IRC were overwhelmed by new users who simply didn't know the culture around IRC.

One of the results are little annoyances when sub-groups came up with their own rules which conflict. One example is the question "Can I PM you?", or strangers trying to chat with you in PM who could be talking in a channel.

IRC, unlike IM clients, is built around channels. As a general rule, conversations should be carried out in channels. Private Messages (PMs) should be reserved for when you have some 'need' for secrecy, or if the conversation youre having would be inappropriate in the channels you share with your target. So instead of asking if its OK to PM someone, use your own judgment. If you find a PM is necessary, asking is not necessary.

What does Software Have to do with Freedom?

Friday, 27 February 2004 20:39

Just today I was trying to describe to a friend why Linux is important, and I came across a speech at Harvard covering the same topic. I'll sumarize my own thoughts below.

Why do I choose to use Free Software when I can? It is not because its faster, though in many ways it is. It is not because its more secure, though it has far superior security. It is not because it costs less, though an entire server or workstation can be outfitted without a single license fee. Many people DO choose Free Software for these reasons, and they are good reasons, but they are only side-effects. If Linux was slower, less secure, and more expensive, I would still use it. Why?

In the Beginning was the Command Line

Thursday, 31 October 2002 00:00

This is an unbelievably cool short story about Life and Operating Systems bye Neal Stephenson (Author of Cryptonomicon)

Debian Linux on a Dell Inspiron 8200

Saturday, 11 September 2004 13:47

I have a Dell Inspiron 8200, and found James Strandboge's webpage on the Inspiron 8200 very valuble. It seems to be down recently (and was being hosted on a dialup) so I am mirroring a copy here in case anyone needs it, along with my own (2.6.8 kernel with pre-emption, acpi and reliable swsuspend) advances:

About Me

Friday, 20 February 2004 13:44

Who is rubin? Since the first time that question was answered on my origional site, the answer has probably changed. I'm not the same person who went to U.S. Grant High School.

Back then, I was the picture on the right. Its been nearly eight years though, and I definately look different now.

I now go to Oregon State University in Corvallis, Oregon. I also work for the university, designing information systems (databases, and the websites, interfaces, and glue that hold them together and make them usefull) for UHDS and RCN.

While there at the university, I met my sweetheart Jenn. She is "uber" cool, but since I suck at expressing things like that (especally here, you never know who reads this stuff :P), its best for you to take my word for it, and visit her page. There are some really cool shots from her trip to Europe there too.

I used to be an avid skiier, but lately paying for college and skiing a lot have proven to be mutually exclusive. I still manage to make it up every year for my birthday though, generally to Mt. Hood Medows.

Computers

I am as you probably guessed, avidly into computers. I consider myself a "hacker", but not a "cracker" which is what people these days think hacker means. (hacker is someone who uses a tool for other than its intended purpose, where as a cracker is someone who breaks into other peoples computers). In general it just means that I'm into Linux, and I know how to make a bash prompt hum. In fact I tend to use Linux as my primary OS when possible. More on that later though, in the tech zone.

I started my computer addiction with the BBS back in '92 - The Simulated Planet. For those familiar with BBS's, it was a Wildcat board, with 2 phone lines (28.8 and 9600 baud). We kicked BRE ass on the exchange net every round we played. Also widely known for my custom Trade Wars universes.

From there, I discovered the internet--Gopher, FTP, and Internet Relay Chat. IRC is a largely misused and misunderstood medium, and has an only partally diserved bad name amung sysadmins and network administrators. I can easily say that I would not be anywhere near as good with coding if it were not for the close friends I had on IRC who guided me though the learning process. I started out IRCing on efnet, then Undernet, and finally helped to found AfterNET, my baby.

Books

I'm a big fan of Sci-Fi, though I don't make the time to read very much for pleasure. I like Isaac Asimov's robot books, and foundation and Empire series, and Orson Scott Card's Ender and Homecoming books. I've read quite a few other good sci-fi too, but thats all that pops into my head at the moment (oh, wait, how about Nightfall, Wyrms, The Hacker and the Ants, Necromancer, and some others). 'Course mostly I read textbooks and technical manuals (I am in college after all).

I have also read quite a few short stories, and even written a few of my own which are available here.

Hope this provided some mildly interesting insights. Bet you never wanted to know so much about me eh?

Why Software Should Not Have Owners

Monday, 24 June 2002 00:00

The GNU Foundation explains why free software (free as in speech, not as in beer) is a good idea.

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