Proposal DC Management
|Proposal pages help us get from feature requests into actual plans. This page is a proposal for automatically removing DC bias.|
Proposal pages are used on an ongoing basis by the Audacity development team and are open to edits from visitors to the wiki. They are a good way to get community feedback on a proposal.
- Note: Proposals for Google Summer of Code projects are significantly different in structure, are submitted via Google's web app and may or may not have a corresponding proposal page.
Newer Windows PCs may have a DC offset cancellation feature when recording from the built-in sound inputs. To check or enable:
- Right-click over the speaker icon in the , or click , then the "Recording" tab
- Right-click over empty space, show disabled and disconnected devices, then right-click over each device and enable it
- Right-click or select each device, choose "Properties" then look in the "Enhancements" tab
- If there is no "Enhancements" tab, look in the sound device's own control panel in "Hardware and Sound".
The proposal is an option (defaulted to on) to apply a low frequency high-pass filter to all audio in Audacity so that DC offset is removed.
- None so far.
- For most users of Audacity for audio processing:
- DC offset is not audible (so may not be corrected by the user) but reduces headroom for subsequent processing
- Differences in DC offset cause unwanted clicks where audio is tacked together
- It is suggested that where a waveform is inherently asymmetrical, such as in recordings of brass instruments, Audacity's DC removal method (making the average positive and negative sample values equal) may create an offset.
Previous Feature Requests relating to this proposal
Correct as at October 2012.
Better management of DC offset:
- Automatic removal of DC offset after recording (rather than just as an option in Normalize) (7 votes)
- Audacity should block DC at source because of the problems it causes. DC is not sound, and passing DC should only be a fringe purpose for scientists/researchers. (2 votes)