Scrubbing and Seeking

Peter 01May15: Very rough draft notes copied from Notes for Testers in the Wiki.

• Peter 20May15: Updated with Paul's revised UI - notes taken from Paul's email.

Scrubbing is an interaction in which a user drags a cursor across a segment of a waveform to hear it. Scrubbing is a convenient way to quickly navigate an audio file. The term comes from the early days of the recording industry and refers to the process of physically moving tape reels to locate a specific point in the audio track, this gave the engineer the impression that the tape was being scrubbed, or cleaned.

The transcription toolbar setting determines the initial scrubbing speed limit each time you start scrubbing (under discussion, subject to change).

Scrubbing

Scrubbing works only in Select tool mode.

Using the CTRL button and left-clicking with the mouse will put you into scrub play mode. When in this mode dragging the cursor right and left across the waveform will cause Audacity to scrub play forwards or backwards. The speed of the scrub play may be controlled by rotating the mouse wheel (if you have one).

Each 4-clicks of the rotated mouse wheel doubles, or halves the speed which is equivalent to one octave. One click of the mouse wheel is equivalent to 3 semitones.

Pressing the Stop button or its shortcut Space at any time will stop scrub playbay and return you to normal play and record mode. Alternative pressing CTRL + left-click when in scrubbing mode will also return you to normal Playback and Recording mode. The scrubbing position on completion can be marked with a left-click mouse gesture which moves the cursor to that position and then using CTRL + B to create a marker label at that point.

You can invoke scrub play while audio is playing normally and it will abandon the playback to perform the scrub play. You cannot invoke scrub play while you are recording or paused in recording mode. You can use the Pause button while scrubbing to pause and restart the scrub play.

Stationary play-head scrubbing

Peter 21May15: ToDo-2 we have, as yet no proper nomenclature for this type of scrubbing.

ctrl-double-leftclick then drag to scrub while keeping the playhead at the midline of the track display.

• Speed of play and direction of play is controlled by dragging left/right from the center of waveform display
• ctrl-click again to stop, or use space bar or stop button, etc.

Seeking

Like scrubbing but hold the SHIFT button down while in scrubbing mode to seek,

• Control wheel to vary the speed limit, while scrubbing (not seeking).

Also notice changes to status bar messages and the Mouse Preferences dialog.

Are there any other strong opinions about other details?

1. Keep the transcription toolbar interaction or not
   • Peter 20May15: Definitely not. I still *really*don't like having the single click initial speed and the double click maximum speeds tied to the Transcription Toolbar. Imo scrubbing should work totally independent of Transcription Toolbar - the link is not intuitive and it's not discoverable. I would prefer the single click initial speed to be always 1.0 and I personally would prefer the double click max speed to always be x3. One of the issues is if the user chages the Transcription Toolbar speed and then hides the toolbar. The two pieces of functionality are independent and should remain so and unlinked.
2. Appearance of the speed numbers (font, size, ...)
   • Peter 20May15: I *like* James' new colorway for the speed numbers, much less in-your-face.
3. Range of speed limits (it goes to 32x now, maybe that is excessive)
   • Peter 20May15: The maximum scrubbing speed for single click scrubbing is set to x32.0, that to me seems a ridiculously high speed. Is anybody ever going to scrub at that speed. Anything much above 3.0 is pretty unintelligible to me.
4. Scrubbing backwards (Peter likes it, Gale does not)
   • Peter 20May15: yes I *do* want to keep the backwards scrubbing
5. Others?
6. Scrubbing only works in selection tool now, no longer in Multi-tool in which ctrl-click already had another meaning (time shift).
   • Peter 20May15: I think that's absolutely fine
7. Bug #961 Play cursor broken after double-click scrub play
8. Bug #962 Scrubbing gesture during recording places Audacity in scrubbing mode when recording stops