Waveform is entirely above zero

Audacity Help Forum GNU/Linux
1

My test waveform is entirely above the zero center line.
I generated the test waveform by speaking into a microphone plugged into front of my Toshiba laptop.

To center the waveform, using Audacity, I have to set:
Normalize maximum amplitude to: -50 db

From what I am reading about DCoffset in audacity documentation, I should instead adjust my hardware settings by downloading new drivers from the manufacturer. However, when I access the Toshiba website, I am only presented with a driver file in Windows executable format. However, I am using Linux, therefore I believe I am forced to use linux ALSA drivers.

The Toshiba Satellite laptop is running:
linux: Ubuntu 10.04.
Audacity 1.3.12-beta (downloaded via Synaptic)

I can hear the recorded voice on playback within Audacity.
only after I switched Playback and Recording settings:
FROM: the ALSA (default driver that I believe is appropriate for linux)
TO: HDA Intel: ALC268 Analog (hw 0,0)

Note that the same setting dialog box shows the setting: Interface: Host: ALSA

Audacity, Audio Device displays:

==============================
Default capture device number: 7
Default playback device number: 7
==============================
Device ID: 0
Device name: ALSA: HDA Intel: ALC268 Analog (hw:0,0)
Input channels: 2
Output channels: 2
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
    192000
==============================
Device ID: 1
Device name: ALSA: front
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
    192000
==============================
Device ID: 2
Device name: ALSA: surround40
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
    192000
==============================
Device ID: 3
Device name: ALSA: surround51
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
    192000
==============================
Device ID: 4
Device name: ALSA: surround71
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.011610
High Input Latency: -1.000000
High Output Latency: 0.046440
Supported Rates:
    44100
    48000
    96000
    192000
==============================
Device ID: 5
Device name: ALSA: pulse
Input channels: 32
Output channels: 32
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    8000
    9600
    11025
    12000
    15000
    16000
    22050
    24000
    32000
    44100
    48000
    88200
    96000
    192000
==============================
Device ID: 6
Device name: ALSA: dmix
Input channels: 0
Output channels: 2
Low Input Latency: -1.000000
Low Output Latency: 0.042667
High Input Latency: -1.000000
High Output Latency: 0.042667
Supported Rates:
    48000
==============================
Device ID: 7
Device name: ALSA: default
Input channels: 32
Output channels: 32
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
    8000
    9600
    11025
    12000
    15000
    16000
    22050
    24000
    32000
    44100
    48000
    88200
    96000
    192000
==============================
Device ID: 8
Device name: OSS: /dev/dsp
Input channels: 16
Output channels: 16
Low Input Latency: 0.011610
Low Output Latency: 0.011610
High Input Latency: 0.046440
High Output Latency: 0.046440
Supported Rates:
==============================
Selected capture device: 0 - ALSA: HDA Intel: ALC268 Analog (hw:0,0)
Selected playback device: 0 - ALSA: HDA Intel: ALC268 Analog (hw:0,0)
Supported Rates:
    44100
    48000
    96000
Unable to open Portmixer
2

Audacity 1.3.12 no longer receives technical support. Please see the pink panel at the top of this page.

Sound devices built into laptops will not give you professional results not arguably will any mic with a TRS connector. You could try another mic in case the major part of the problem is with the mic.

Laptop manufacturers are not (unless they explicitly say so) expecting you to run Linux. You can run a more modern 2.0.x version of Audacity for Windows under WINE ( http://www.winehq.org/ ).

Alternatively you can ask on the Ubuntu Forums if there are known issues with your specific machine. Note that unless you are on Ubuntu Server your version of Ubuntu is also unsupported, so you may get no answer. If you considered updating to Ubuntu 13.04 then you would get a 2.0.3 version of Audacity that you would get support with here.

Either way, if you are serious about recordings I would suggest you get a USB interface and a professional mic with an XLR connector, or a decent USB mic.

Default is probably the pulseaudio sound server, but again since you are running an old version of Ubuntu there could be problems with its pulse support.


Gale