Difference between revisions of "Proposal Crossfade"

Revision as of 22:35, 17 April 2008

• Display - The original mock-up is only effective at displaying a crossfade if a single linked fade that lasts the entire duration of the overlapping region is being displayed.
  • Single linked fade
  • Indicating Clip Overlap Regions
    • Zoomed Out - What does this text look like?
  • Single fade vs. Independent Fade

• Summary

I want to build an intuitive interface for creating non-destructive cross-fades in Audacity.

Here is a link to the origin project suggestion on the Audacity GSoC ideas page. GSoC_Ideas#Intuitive_cross-fading

• • Stage 1 - half way target deliverables
  • end of summer deliverables

• Proposal

For the first stage of the project, I will implement the basic functionality implied by the the cross-fade mockup at http://limpet.net/mbrubeck/temp/cross-fade/ (need to make this an external link).

• Cross-fade functionality - For this stage of the project, the fade-in and fade-out shapes will be a single linked fade. Three fade shapes will be selectable.
  • Linear - A constant-gain cross fade in which a linear envelope decreasing from 1 to 0 over the course of the fade is applied to the left-hand clip and a linear envelope increasing from 0 to 1 is applied to the right-hand clip.
  • Logarithmic - A constant-power cross fade in which a logarithmically decreasing envelope is applied to the left-hand clip and the mirror image of this envelope is applied to the right-hand clip.
  • S-Curve - A commonly discussed fade shape - see for instancehttp://transom.org/tools/editing_mixing/200309.stupidfadetricks.html. An envelope of 1/2+1/2 cos (2*pi*w/T) is applied to the left-hand clip where w is the number of samples from the start of the fade and T is the fade length in samples. The mirror image of this envelope is applied to the right-hand clip.
• Display -

When a modifier is held down (I propose ctrl-shift), clips dragged near each other will no longer snap

• • draft gui images
    • zoomed in view
    • zoomed out view
  • define keystrokes and behavior

With

• • define mouse behavior
  • undo-stack
  • stereo track support
    • display different from mono tracks
  • crossfade type:
    • constant amplitude cross-fade
    • constant sum power cross-fade
    • fade-out-and-back-again "crossfade"
    • picker for fade type
  • presets / repeat effect (having done one cross fade, do the next one with the same 'parameters')
  • files/classes affected
    • planned changes to affected files

• possible optional extensions
  • fade in/out with out another clip