Scrubbing and Seeking

Peter 05Jun16: ToDo-1 This page will require a major update for the revised GUI including pinned playhead - not to be updated until Paul's GUI changes stabilize and finalize.

• Peter 05Aug16 in an email note to James:

Although Paul has implemented some vast complexities, at its simplest it works quite well

1) get some audio

2) normal zoom or normal working zoom

3) Click on the visible, new (and thus discoverable) Scrub Play button

4) Waggle the cursor position about over the waveform

5) lo and behold you get 1x forward/backward scrubbing.

Things only start to get complicated when you discover the speed control when you accidentally nudge the mousewheel, when you toggle over into seeking - or when you pin the playhead and discover you get a different form of speed-controlled Scrubbing. Or when you play with turning the Scrub Bar on and off and wonder just why you need it at all.

• Gale replies 05Aug16:

I don't think it's immediately user-obvious that pinning the playhead is going to something else, though.

The whole thing is "see what it does and explore", rather than intuitive.

To which James and I both agreed.

Scrubbing is the action of moving the mouse pointer across a segment of the waveform to hear the audio - a convenient way to quickly navigate the waveform to find a particular event of interest.

The term "Scrubbing" comes from the early days of the recording industry and refers to the process of physically rotating tape reels to move the tape past the playhead to locate a specific point in the audio track.

Mac OS X users: In the below instructions, use COMMAND instead of CTRL. So for example, COMMAND + left-click starts scrubbing.

Scrubbing

Pressing the Scrub button in the Scrub Toolbar will put you into scrub play mode. Alternatively you can use the Transport>Scrubbing and select Scrub from the dropdown menu. The green playhead cursor will appear but otherwise nothing will happen until you move the mouse pointer. You can now move the pointer right and left across the waveform. This will cause Audacity to scrub play forward or backward respectively. Once you move the cursor you will note that you get a scrub widget, a green double-headed triangle similar to the Scrub button in bottom of the Timeline, this widget is draggable by moving the mouse left or right. A vertical white line through the waveform will follow this green widget. Scrub play will temporarily stop when the green playback cursor (the "playhead") catches up with the mouse pointer but will restart again as soon as you move the mouse left or right.

• Once you have placed Audacity in scrub play mode it will remain in that mode until you Stop Scrub play which would then allow you to restart in normal play mode. Click the Scrub button again or the Stop button (or its shortcut SPACE) to stop scrub play at the current play position from where you mark that point (with a Label) or restart normal playback from there.

If instead you wish to retain your current cursor position or selection just use the ESC button to stop and exit from scrubbing.

• The speed of scrub play can be controlled by rotating the mouse wheel (if your mouse is so equipped). The changed scrub speed will be shown temporarily in yellow-ochre superimposed on the track.

• It is possible to zoom while you are scrubbing by holding the CTRL key down and rotating the mouse wheel, or by using the zoom buttons (or their shotcuts) ot the View menu zoom cammands.

• You can invoke scrub play while audio is playing normally and it will abandon the playback to perform scrub play.

• For safety reasons. you cannot invoke scrub play while you are recording (or paused in recording mode).

Seeking

Seeking is similar to Scrubbing except that many small slices of the audio are played (at normal speed even if you have changed speed). The playhead is always moved very close to the mouse pointer enabling you to move across the audio rapidly. This is similar to using the seek button on a CD player.

Pressing the Seek button in the Scrub Toolbar will put you into seek play mode. Alternatively you can use the Transport>Scrubbing and select Seek from the dropdown menu.

When seeking the widget in the Timeline will appear as a quadruple arrow similar to the Seek button.

The Scrub Bar

Pressing the Scrub Bar button File:Scrub Bar button 60%.png in the Scrub Toolbar will cause the Scrub Bar to appear below the timeline (or to hide it if you had previously turned it on).

Peter 08Aug16: ToDo-2 This image will need updating if the icon for the unpinned playhead changes.

File:Timeline with Scrub Bar.png

When the Scrub Bar is displayed the green double-headed and quadruple-headed scrub and seek widgets move from the Timeline to the Scrub Bar as shown in the image where Scrubbing is in play.

The key benefits of having the Scrub Bar showing are:

• When scrubbing or seeking you can click anywhere in the Scrub Bar with the left mouse button to move the center of the scrub or seek to that point.
• When scrubbing if you click in the Scrub Bar (with the left mouse button) and hold the button down then the scrubbing will temporarily change to seeking. Once you release the mouse button then scrubbing will resume again, but from the point at which you stopped seeking.

Pinned playhead Scrubbing and Seeking

If you use Scrubbing or Seeking with the playhead Pinned then control of the playback speed behaves differently to when you do so in default unpinned playback mode.

In pinned playhead mode the mouse pointer position determines the speed of the scrub or seek. The further away you move the mouse pointer from the play cursor (in either direction), the faster the speed of the scrub/seek. The current scrub/seek speed is shown permanently in lime green, superimposed on the track as you move the pointer. The default maximum speed is x1.0, that is normal speed.

The speed of the scroll-scrub as determined by the mouse position can be varied by rotating the mouse wheel (if your mouse is so equipped). Move the wheel upwards to increase the speed or downwards to reduce the speed. This works at the same time as modifying the speed by moving the pointer left or right.

A very useful setting for using scrubbing with pinned playhead is to move the cursor to the extreme right and increase the maximun speed to x2.0. With this setting, when you move the cursor to the 25% or 75% postions on the waveform you will get x1.0 playbck. Moving the cursor towards the center from there will give you gradually slower speeds and moving the cursor towards the right or left edges will give you gradually increasing speeds up to the maximum x2.0 speed. But please note that this setting is only temporary, you will need to reset it each time you invoke Scrubbing or Seeking.

Image of forwards scrubbing at x1 speed having set a x2 maximum speed, waveform moves leftwards.